REGIONAL OFFICE FOR THE WESTERN PACIFIC of the
.
World Health Organization Manila
A TUBERCULOSIS PREVALENCE SURVEY IN CHIMA (TAIWAN)
Manila, Philippines
·-
• WPR/122/66
StJl.t.!ARY REPOffi'
ON A TUBERCULOSIS PREVAlENCE SURVEY IN TAIWAN (1962-1963)
Akio 'niZlBlal_. M.D.
wPO Statistician
Regional TUberculosis Advisory Team
World Health Organization
Regional Office for the Western Pacific Manila, Philippines
April 1966
.. l.
Introduction ...•...•...•....•... • • • · Selection of Samples...
Pop'Ulation Covered ...•.•.•...•...•.•.•••..••• · •••
Sampling }lfethod Applied •••••••••.••.•••.•..•••••••.••••
Outline of Survey Procedures
...
}.l
3·2 3·33.4
3·5
}.6 3·7
S'urv'ey Team. ••••••••••••••••••••••••••••••••••••••••••••
Scheduling of Field Operations and Survey Period •••••••
Arrangements tor F~eld Operation •••••••••••••••••••••••
Registration and Follow-up of Examinees ••••••••••••••••
TUberculin Test ••••••••••••••••••••••••••••••••••••••••
X-ray Examination ••••••••••••••••••••••••••••••••••••••
Bacteriological Examination •.••.•••.•.•.•..•..•••.•••..
4.
Tabulation...
5·
6.
1·
Results of Survey
...
Persons Normally Resident and Those Actually Present in Sample Areas
...
Response to Testing and Examination
X-ray and Bacteriological Findings
...
...
Tuberculin Reaction
...
liiscussion
...
6.1 6.2 6.3
6.4
Reliability of Estimated Prevalence of
...
Positive X-ray and Bacteriological Findings
Representati~ness of the Population examined
Estimation of Number of TUberculous Cases in Taiwan Comparison of Prevalence Among Persons with
...
Positive X-ray and Bacteriological Findings and Tuberculin Reaction during 1962-1963 and 1957-1958
....
Conclusion
...
Tables l-4o Figures 1-8
l 2 2 2
4
4
4 5 5 5 66 6
61
lO
9 17 19 1920
21 22 23
..
•.
The tuberculosis mortality rate in China (Taiwan) decreased remarkably after World War U, from 285 per 100 000 ·in 1947 to 65 per 100 000 in 1957 and to '9 per 100 000 in 1962.
The first attempt to investigate the prevalence of pulmonary tuber- culosis in Taiwan, which accounts for more than ~ of all tuberculosis, was made in 1957-1958. '1he survey was c~tnducted on a random sampling basis and was carried out by the Provincial Taipei 'lUberculosis Control Centre •1
From the data obtained during the survey, the prevalence of tuber- culosis suspects based on X-ray examination for the whole population of ten years of age and over, was estimated to be 3.7'f, with a standard error of 0.~. The prevalence of bacteriologically proven tuberculosis cases was estimated to be 0. 7'f, with a standard error of 0.0,5%. '!he ratios were estimated by sex, Me group and conm.mity (villages, towns, small cities and large cities).2
In 1962, five years after the first survey was made, the Government decided to carry out a second survey in order to obtain an up-to-date
epidemiological picture of tuberculosis prevalence, comparable to that obtained during the first survey and consequently showing the changes which had occurred during the five years.
The second survey was also carried out by the Provincial Taipei 'lUberculosis Control Centre during the period 25 May 1962 to 31 July 1963 with the financial assistance of
UNICEF
and the technical assistance of WHO. It comprised (1) miniature photofluorography of all persons of ten years of age and over. (2) bacteriolcgical examination by microscopy and culture of sputum and laryngeal swab of those whose photofluorograp~sshowed abnomal lung shadows and (') tuberculin testing of all children over one month and below five years of age. About
26
000 persons aged ten years and over and 7000 children of one month and over and below five years.living in seventy sample areas selected randomly from almost all over the province. were photofluorographed and tubercUlin tested respectively.3 Among
26
000 persons photographed. 2000 had laryngeal swabs examined and 300 had sputa examined.lMr. T. Zeiner-Henriksen: Assignment Report for Taiwan (WPR, 8 August 1957}
%z..
S.K. Quo: Statistical Survey Report on a Sample Survey of Tuberculosis Prevalence Survey in Taiwan, July 1957-June 1958 (WPR/STAT/13.22
January
1959)3Akio Tanaka: Assignment Report for the Republic of China (Taiwan) 11-25 April 1963 and 21-23 May 1962 (WPR0-75 (China), 21 November 1962)
2. SELECTION OF SAMPLES
2.1 Popu1ation covered
The survey was so plarmed as to cover the whole province with the exception of some islands and remote villages in the mountains which were inaccessible to an X-ray van. 'lhus, of a total of 6500 cities, towns and villages in Taiwan only seventy-two villages were excluded, (Table l).
All persons of ten years of age and over, and all children over one month and below five years of age who were actually living in the selected sample areas during the examination days were designated as the examinees for X-ray examination and tuberculin testing respectively,
(Persons below ten years of age were excluded from X-ray examination because of technical difficulties. Infants less than two months old and children aged five years and over were excluded from tuberculin testing because of technical difficulties and high coverage of BCG vaccination
respectively), Among the persons X-rayed, those whose photonuorograms showed any intrathoracic abnonnali ty (other than cardiac or skeletal) were examined bacteriologically. '!hose residents temporarily absent during the examination days were excluded from the examinees while residents from outside the areas temporarily living in the areas during the examination days were included. In addition, military personnel in camps, foreigners and persons temporarily staying in hotels and hospitals in the areas were excluded from examination.
2.2 Sampling method applied
A two stage sampling method with stratificat1-:>n was applied to the survey.
2.2.1 Stratification
The area covered was stratified on the basis of two characteristics:
(l) type of population concentration and (2) geographical region. First, in accordance with the administrative structure, the area was stratified into ( 1) villages, ( 2) towns, (3) small cities and ( 4) large cities • Each of the four strata was then stratified on the basis of geographical region into (l) north-west (N-W), (2) central-west (C-W).
(3)
south-west (S-W), and east (E) districts, with the exception of the large cities each of which was made a stratum. 'lhus the whole province was stratified into seventeen strata as mentioned below:Villages: N-w. c-w. s-w. E.
Towns: N-w. c-w. s-w. E.
Small Cities: N-W, C-W. S-W, E.
Large Cities: Keelung (lr-w). Taipei (N-W). Taichung (C-W), Tainan (s-w). Kaoshinh (S-W)
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2.2.2. Sampling units
The first staee sampling unit was "Tslm" in the villages and "Li"
in the towns and cities, which were the second smallest administrative units.1
'lhe second. stage sampling un1 t was "Lin 11, which was the smallest administrative unit with an average of 125 inhabitants.
2.2.3 F.rame for samplin§
The list of Lis and Tsuns in the province with the number of Lins and inhabitants in each Li and Tsun, which was prepared at the Provincial Malaria Institute at the end of 1961. was used.
2.2.4 Sampling fraction
Two fixed overall sampling fractions were applied: approximately 5/2100 for the villages and towns in the west district and approximately 5/700 for the villages and towns in the east and for all the cities. 'lhe latter was three times as large as the fo11ner because of the smaller
number of Tsuns or Lis and the greater variance of tre number of inhabi tents in each Lin.
2.2.5 Sampling method
The first staee sampling un1 ts (Tsuns or Lis) within the different strata were selected randomly with probabilities proportional to the number of Lins in the respective Tsuns and Lis. The number of Tsuns or Lis
selected at this stage was approximately l/2100 of the total number in each stratum for the villages and towns in the west district and approximately 1/700 for the villages and towns in the east and for all the cities.
In the second stage a cluster of five Lins was selected randomly in each Tsun or Li designated by the first staee sampling. 'lhis meant that the second stage sampling was made with probabUi ty inversely proportional to the number of Lins in the first stage sampling unit; so that the overall sampling fraction for all the respective strata was adJusted as mentioned above.
2.2.6 Samples designated
'lllus, clusters comprising five Lins in each were selected from the whole province. The number of samples selected and the sampling ratio in each stratum are given in Table l . The names of the selected sample areas and their location are mentioned in Table 2 and Figure l.
l'lhe
Administrative Drganization in Taiwan Province, Republic of China. was as below:rLarse
City (Ta-Shih) - District (Clil) - Li - LinProvince (Sheng) Small City (Hsio-Shih) - District (Clil) - Li - Lin
Lcounty (Hsien) - Town (Cheng) - Li - Lin
- Village (Hsiang) - Tslm - Lin
3.
Outline of survey procedures 3.1 Survey teamThe survey team was composed of 17 staff members of the Provincial Taipei TUberculosis Control Centre and was equipped with 2 X-ray vans with an Odelca Camera each, and one ambulance. '!he team was composed of the following:
Medical Officer (Team Leader) Medical Officer (Assistant Leader) Liaison Officer
Supply and Maintenance Clerk Public Health Nurse
X-ray Technician Laboratory Technician Statistical Clerk Home Visitor Driver
Cook Total
3.2 Scheduling of field operations and survey period l 1 l 1 1 2 2 1 2
4
1 17
'!he field operations in a sample area were usually completed in five days, as follows:
First day
. .
Final registration of those eligible for examination • Second day : TUberculin testing and X-ray examination (includingfilm reading) 1bird day
Fourth day
Fifth day
: X-ray examination and collection of sputum and
laryngeal swabbing from persons whose photofl~orograms
showed abnormal intrathoracic shadows (other than cardiac or ske:etal).
X-ray examination and collection of sputum and laryngeal swabbing.
TUberculin reaction reading and collection of sputum and laryngeal swabbing.
The operations in a new area usually started on the day after
work had been completed in the previous area. In some oases an additional day was required to move to a new area. ~. field operations in the
seventy sample areas were completed in thirteen months, from
4
July 1962 to 31 July 1963, except for the first area which served as a pilot area and where field operations were carried out at the end of May 1962.•
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Arrangements for field operationsSeveral weeks before field operations were started in a county, the team laader and the liaison officer of the survey team visited the county office. A meeting was held with the director of the oounty health bureau,· the directors of health stations, and the chiefs of the villages, towns, districts, in the cities attached to the sample areas, as well as the personnel in charge of civic affairs, including the regis- tration of inhabitants in these communi ties. Arrangements for the field operations were made at this meeting.
3.4
Registration and follow-up of examineesAfter the meeting, the civic affairs section of the village, town or city district office prepared a preliminary household card and an individual card for each household and household member over one month and below five years, and of ten years of age and over, in the designated sample area, based on the register kept at the office. They also filled in individual cards with the address, name, relationship to the head of the household, sex, date of birth, place of birth and marital status of each household member.
On the day preceding the examination, two home visitors, a statistical clerk and the other team members available checked and confirmed the entries in the household and individual cards prepared at the community office. This was done by house-to-house visits with the assistance of the chiefs of Lins. On this occasion the occupations of the examinees were investigated and recorded.
The two home visitors and other available team members were responsible for guiding persons to the examination site. The reasons for absence were investigated by them,and recorded.
3.5
Tuberculin testingTuberculin testing was carried out on children over one month and below five years of age. All the tests and readings were done by the same public health nurse in the survey team, usually at fixed examination sites and, if necessary, by home visiting.
One-tenth ml of tuberculin .dilntion (1 TU of P.P.D. RT 23 .with Tween 8o) was given intraoutaneously in the middle of the flexor side of the left forearm. The transverse diameter of induration was read seventy-two hours after testing.
3.6
X-ray examinationX-ray examination was carried out on persons of ten years of age and over. One 70 DID photofluorograph was taken of each person in the ordinary postero-anterior projection, using a Picker's mobile ph~to
f'luorographic unit with an Odelca Camera. The films exposed were usually developed on the first and the third days following the X-ray examination and were read on the same day by the two medical officers of the team.
The preliminary readings were made independently. Joint readings were subsequently made by the doctors of those films which had originally been read as abnormal by either or both doctors and a final decision was arrived at in each case.
3.7
Bacteriological examinationThose whose photofluorograms were read as showing some abnormal shadows in the pulmonary and/or pleural regions in the Joint readings were bacteriologically examined. Two laryngeal swabs and, if available, a "spit on the spot" were collected from each of the eligibles by the laboratory technician of the team. The collection was usually made at
the place of examination or, if necessary, at eligible's home. Two laryngeal swabs from each person were inoculated on Lowenstein-Jensen medium, two bottles for ee.ch swab, and each spu'b.un sample was inoculated
on two bottles of the same medium and smeared directly on a slide. This processing was done in the field. The smears were examined by direct microscopy after Ziehl-Nielsen staining. Examinations were also done in
the field. The media inoculated were packed in a wooden box and sent the same day by airmail or car to the laboratory of the Provincial Taipei TUberculosis Hospital, where they were kept in an incubating room, and the results of cultures were read up to eight weeks after inoculation.
4.
TabulationAll the ~vidual cams, filled in with the findings obtained during field operations, were sent to the Provincial Taipei TUberculosis Control Centre each sample unit separately. The recorded findings,
including the bacteriological findings reported later trom ·the laboratory, were coded 1n the Statistics Room of the Centre and punched on International Business Machine Cards at the IBM office in Taipei where they were tabulated.
5.
Results of the surveyAs described in the chapter on "Selection of samples", two different sampling fractions were a~plied: (1) 5/2100 or 1/420 to villages and towns in the west and (2) 5/700 or l/14o to villages and towns in the east and to all the cities. The mean figures obtained from the former areas weighed three times as much as the same figures obtained from the latter areas. Therefore, in order to calculate the overall
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figures applicable to the whole province, numbers obtained from the former areas had to be mu1 tiplied three times and added to figures obtained from the latter areas. Figures and ratios mentioned in the following paragraphs and the tables were calculated after applying this modification, except where note is attaohed.Originally, thirty-seven tables were listed in Table
3.
In view of their length, only the abstracts have been presented and attached to this report.5.1 Persons normally resident and those actually present in sample areas Seven thousand two hundred ninety-four children over one month
and below five years of age and 28 926 persons aged ten years and over were registered as normally resident in the sample areas;. Among these residents
289
children and2984
other persons were temporarily absent during the examination days in the sample areas. On the other hand, 14 children and 89 other persons from outside the sample areas were temporarily present in the areas during the examination days. The number of children eligible for tuberculin test and persons eligible for X-ray examination, who were actually present in the sample area during examination days weretherefore 7019 and 26 031 respectively.
As 1/420 of villages and towns in the west and 1/140 of villages and towns in the east and all the cities were sampled, the modified popula- tion in the sample areas {three times the population in villages and towns in the west plus the population in villages and towns of the east and in all the cities) should have been 1/140 of the total popu~ation in the whole province excluding seven~-two villages inaccessible to X-ray van.
{The population in the excluded villages was ~ess than 1% of the total population) •
The ratio of the sample population to the total population in the
whole province {including those in the excluded seventy-two villages) by sex and age group is shown in Table
4.
The ratios of the resident popula- tion below five years of age and of ten years and over were both 1/150.The ratio was 1/112 for males of 20-24 years of age and less than 1/160 for males of 40-59 years of age. The ratios of the population actually present during examination days in the sample areas were 1/156 for children below five years of age and 1/168 for persons aged ten years and over.
They were evidently smaller in males than in females through all age groups except children below five years and those aged 65 years and over.
This difference between the ratios of the habitual residents and
of those actually present during examination days was evidently due to
the large number of temporary absentees among. the residents in the sample areas and to the small number of those temporarily present in the sample areas from outside. The percentage of temporarily absent by sex was higher in male than in female through al.l age groups except children below five years and those aged 60 years and over. By age groups, it
was higher among the 15-24 years group. And a close examination by sex and age group shows that the highest was 48.$ of males of 20-24 years of age. The second and third were 22.~ and 19.2% of males of 15-19 and
25-29 years respectively# and the fourth and fifth were 15.~ and 13.6%
of females of 15-19 and 20-24 years respectively. The percentages of the
temporarily present of the 15-19 years group# although higher among all
the age groups, is much lower when compared with the absentees of the same age group.
The main reason for temporary absence among persons aged ten years
and over was "work" to which 53 .1~ of the total temporary absences were due. This was the main reason for both sexes and in all age groups,
except males of 20-24 years, in which group "military service" caused 65.7%
of total temporary absences (Table
6}.
The main reason for the temporary presence of persons aged ten years and over was also "work"# which accounted for
66.9%
of the total.The reason among children below five years was "social" (50.~)# (Table 9).
Table 5 shows the ratio of person;.; under five years and of ten years and over in the sample areas to the total population of all ages in the whole province by community and locality because population figures for the whole province by age group and by community and locality were not obtainable. The ratio of habitual residents of the sample population was 1/178 for the whole province. It was higher by community in small cities
(1/158) and towns (1/172) and lower in villages (1/184) and large cities (1/182); by locality it was higher in the south-west (1/173), the east (1/174) and the central-west (1/176) and lowest in the north-west (1/185).
The ratio by community and locality or by stratum ranged from 1/118 for towns in the south-west to 1/248 for Kaoshung City 1 also in the south-west.
The ratio of those actually present during examination days in the sample areas was 1/196 for the whole province. It was higher in small cities
(1/174), towns (1/191) and larger cities (1/195) and lowest in villages (1/206); by locality it was higher in the east (1/192) atd the central-west and south-west {both 1/194) and lowest in the north-west (1/202). The ratio by community and locality or by .stratum ranged from 1/133 for towns in the south-west to 1/270 for Kaoshung City also in the south-west.
The percentage of the temporarily absent among habitual residents aged ten years and over was 11.2% for the whole province, while the
percentage of the temporarily present to the habitual residents was 0.~.
The former by community was higher in villages (12.~} and towns (12.~}
and lower in large cities (8.~) and small cities (10.~}; by locality it was higher in the south-west (12.6%) and lower in the east (10.4~)# the north-west (10.4~) and the central-west (10.~). The highest percentage by community and locality was 15.~ of villages in the south-west and
the lowest was 7.1~ for Tainan City also in the south-west. In the latter#
the percentage of the temporarily present was higher in small cities (0.'7%) an:i lower in towns(O.~); it was higher in the south-west and lower in the north-west and central-west {both 0.2%}. The percentage by
cOIIIIIUility and locality ranged from
O.f:t'
of small cities in the north-west to nil.•
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The leading causes of' temporary absence among habitual residents aged ten years and over for the whole province as described before, were (l) "work" (53.1$), (2) "others" (18.'7%). (3) "military service" (17.3%) • This applied to all communities and localities. (Tables
7
and8).
5.2 Response to testing and examination 5.2.1 Children tuberculin tested and read
Among 7019 children who required tuberculin testing and were actually present in the sample areas during examination days, 6974 or
99.4~ were tested and 6962 or 99.2% were read. That is, those who were not tested were
45
or 0.~ and those who were tested but not read were 12 or 0.2%.The modified percentage for the tested and read was 99.~ of the total, 99.1~ of the male and 98.9% of' the female. (Table ll). Examination by community and locality shows that the ratio below 99.~ occurred only in five strata: towns in the north-west (94 .8%) and the east {97
.9%).
villages in the north-west (98.1~) and the east (98.~). and small cities in the north-west (98.8%). (Table 12).
The main reason for absence from tuberculin testing was "acute illness" which constituted 59.3% of the total (Table 10).
5.2.2 Persons examined by X-ray
Among
26
031 persons aged ten years and over who were eligible for X-ray examination and were actually present in the sample areas during examination, 25 850 or 99.3% were examined.The modified percentage for the examined was 99.3% of the total.
I t was higher among males (99.~) than females (99.~). It was below 98%
among those aged 65 years and over (Table ll). Examination by cormn.mity and locality shows that the ratios were 99.~ and over in all communities and localities except 98.~ in towns in the central-west (Table 12).
The main reason for absence from X-ray examination was "chronic illness" which constituted 54.~ of the total; the second was "confinement"
(22.1$ of the total and 31.4% of the female) (Table 10).
5.2.3 Persons examined bacteriologically
Of' the 1981 persons- whose X-ray films showed abnormal intrathoracic shadows and were eligible for bacteriological examination,
1966
persons had their laryngeal swabs collected while only297
persons could have raised sputa for examination (Tables 14 and 15) •5-.3
X-ray and bacteriological findings5.,3.1
Correlation of X-ray film readings by two medical officers and joint readingAll the X-ray films taken from 25 850 persons proved to be technically satisfactory and were read independently by two medical officers. All the films which were read as having some abnormal shadows in the chest region by either of the two doctors, were read jointly by the two doctors to reaah a final decision.
Correlation between the independent readings by the two medical
officers~ and the joint reading are shown in Table
1.3.
Among the 25 850 films~ 1471 were read as showing some abnormal shadows in the chest region by both readers. In addition,.379
were so read by Reader A only and.3.3.3
by Reader B only. This means that in addition to the films which were read as abnormal by both of the readers, as many as another
sqg
of the films were read as abnormal by one of the readers ani approximately 2~by the other. But more than ~ of these abnormal! ties were healed tuberculosis and very few were considered as advanced. 'l'wo hundred thirty films were read as showing advanced tuberculosis by both readers;
in add1 tion
58
were so read by Reader A and 64 by Reader B. The total of the last two made ~ of the first. But 8qg of the total were read by the other reader as minimal tuberculous shadows. Five :tnmdred eight films were read as minimal tuberculosis by both readers; in addition, 210 were so read by Read A and 262 by Reader B. The total of t.1'E last two made90%
of the first~4qg
by Reader A anisqg
by Reader B. More than40%
of these films were read as healed tuberculosis by one reader and nearly40%
as normal by the other reader. Three hundred thirteen films were read as showing health tuberculosis by both readers; in addition, 4~were so read by Reader A and
.305
by Reader B. The total of the last two made 2 •.3
times as many as the first. Sixty per cent. of the total wereread as normal and
.30%
read as minimal tuberculosis by one reader. Fifty- eight films were read as showing non-tuberculous lesions by both readers.In add1 tion 50 were so read by Reader A and 64 by Reader B. The total of the disagreed reading was twice as many as the agreed ones. l-tore than
50-'
of the disagreed films were read as normal and nearly
.30%
were read as healed tuberculosis by the other medical officer.When jointly read by the two medical officers, among 2183 films which were read as abnormal by both or either
(1471
by both,.379
by Reader A only and.33.3
by Reader B only),1981
films were finally considered asabnormal. These
1981
fUme consisted of183.3
which were read as abnormal by Reader A and148
were read as normal by him. These 1981 films consistedof
1615
which were read as abnormal by Reader B and the other.366
were read as normal by him. Th1s showed that the reading of Reader A was moreconsistent. This was confirmed by close examination of each category of the findings: the number of films read as advanced tuberculosis by the joint reading was
29.3,
of which 278 were so read by Reader A while 244 were so read by Reader B. Those read as minimal tuberculosis by thejoint reading were
755.
of which677
were so read by Reader A while566
were so read by Reader B. '!hose read as healed tuberculosis by the Joint reading were
817,
of which671
were so read by Reader A while 406 were so•
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read by Reader B. Those read as showing non-tuberculous lesions by the joint reading were 116, of which 99 were so read by Reader A and
66
were so read by Reader B •netailed classification of abnormal shadows read by the joint reading, by actual number and percentage, and the corresponding revised ratio for the whole province, are shown below:
Actual Actual Modified X-ral FindiEilis Number Percent~e Ratio
1. Minimal 755 2.~ 2.7"/>
2. Moderately advanced without cavity
18o
0.7 o.63·
Moderately advanced with cavity 49 0.2 0.24. Far advanced without cavity 24 o.l 0.1
5·
Far advanced with cavity 38 0.1 0.16. Pleural effusion 2
Sub-total clinically significant tuberculosis(lo48) (4.0) (3.7)
1·
Healed lesions 8143.1
3.08. Deformity by thoracic surgery 3 0.0 o.o
Sub-total clinically not significant
(3.2)
tuberculosis (817) (3.0)
(1-8) Total tuberculous abnormality 1865 7.2 6.7
9·
Non-tuberculous abnormality 116 o.4 0.5(1-9) Total abnormality 1981
1·1
7.25.3.2 Correlation of three kinds of bacteriological findings
Among 1981 persons whose X-ray films showed abnormal shadows in the chest region and were eligible for bacteriological examination. 1966
(99.Z') had their laryngeal swabs collected while 297 (15.~) persons could raise sputa for examination. (Table 14)
Al.l the 1966 laryngeal swabs collected were cultured satisfactorily except 3 (o.zg) which were contaminated. Among the 1963 laryngeal swabs oultured satisfactorily. 124 (6.~) were positive for tubercle bacilli.
Among the
297
sputa collected, 254 were both cui tured andmicroscopically examined, 12 were cui tured only and 31 were microscopically examined only because of insufficient quantity of the specimen. Among the 266 sputa cultured 6 (2.~) were contaminated. Out of the remaining 26o oul tured satisfactorily 37 (14 .~) were found positive. Out of the
285 sputa examined microscopically
26
(9.1%) were found positive.Technique-wise, sputum by culture gave the highest percentage of positives and the culture of laryngeal swabs the lowest. However, in view of the fact that only 1~ of the eligibles could produce sputum for exam1 na-
tion while
99
.-;$ of the eligibles could be examined by laryngeal swabbing culture method, the latter has actually given more specimens a positive result. Thus, among a total of 133 bacteriologically positive cases,89
were proven by laryngeal swab culture only, 17 by all of the three methods, 14 by laryngeal swab and sputum cultures, 4 by laryngeal swab culture and sputum microscopic examination, and 4 by sputum culture only 1 3 by sputum microscopic examination onl.y and 2 by sputum culture and microscopic examina- tion. Or, the laryngeal swab culture method provided a total of 124 (93.-;$) positives, the sputum culture method 37 (27
.f3i)
positives wile the micros- copic examination of sputum provided 26 positives (19.51>) of the 133 proven cases, (Table14).
5.3.3 Correlation between X-ray findings and bacteriological findings Correlation between X-raY findings and bacteriological findings among 1981 persons whose X-ray films showed abnormal shadows and were eligible for bacteriological examination, is shows. in Table 15. One thousand nine hundred sixty-six (99-2%) persons of the total 1981 eligibles had their laryngeal swabs collected, except 15 who did not report for the specimen collection. The completeness of the collection of laryngeal swabs in various sample areas ranged from 100.0% to 97 .4%.
Only 297 (15.0%) of the total eligibles who reported for specimen collection could raise sputa in spite of' special efforts made in
persuasion. The collection of sputum was more successful among those who showed far advanced tuberculous cases with cavitation (55.3%), with- out cavitation (50.0%), moderately advanced tuberculous cases with
cavitation (42.9%), without cavitation (}4.4%); and it was less successful among those with healed tuberculous lesions (5.9%), non-tuberculous
shadows (12.1%) and minimal tuberculous diseases (15.6%).
Excluding those with contaminated laryngeal swab or sputum cultures,
1964
persons had their laryngeal swabs ~or sputa satisfactorily cultured and/or microscopically examined producing 133 (6.8%) positive cases. 'lhe highest overall positiveness by X-ray f'inding.was 70.?1/> among those showing far advanced tuberculous disease with cavitation, the second was45.8%
of those showing moderately advanced tuberculous disease with cav1 tation, the third was41.7%
of those showing far advanced tuberculous lesions without cavitation, the fourth was 19.2% of those showing moderately advanced tuberculous lesions without cavitation and the lowest was4.7%
of those showing minimal tuberculous shadows. '!he percentage for the totalclinically significant tuberculous suspects was 12.~. It was 0.$ among those with "healed" tuberculous shadows and 0.9% among those with "non- tuberculous" shadows.
•
•
•
..
..
•
•
ihe revised prevalence for the whole province of those w1 th X-ray films showing clinically significant tuberculous lesions was 3.7%. The percentage was higher 1n males (5.~) than in females (2.~) through all the age gr()ups except 20-24 years of age. The difference between males and females was very small among younger age groups, but among groups aged 30 years and over, the percentage among males was more than double that among females. This was particularly true among age groups of 40-49 years and 6o years and over. The former was about three times higher than the latter. The ratio was only 0.~ in the group of 10-14 years for both sexes, o.~ for males and o.~ for females; it increased with age and reached 13.0 in the group of' 60 years and over for both sexes: 20.~ for males and 7 .~ for females (Table 16 and Figures 2,
3
and 4).The prevalence of those with X-ray films showing moderately or far advanced tubercUlous lesions was 1.1,; for both sexes and in all age groups.
The percentage was also higher 1n males (1.$) than 1n females (0.5'%) through all age groups except 'the groups of less than 25 years. The ratio also increased with age from
o.Q%
in 10-14 years group to 5.~ 1n the 6o-64 years group for both sexes; 8.~ for male and 1.7'/J for female.The prevalence of those with X-ray films showing cavitary disease was 0.~ for the total of all~e groups. The ratio was also higher in males (0.5%) than 1n females (0.~) through all age groups except 1n the 50-59 years group. The percentage also increased with age from o.~ in the 10.:19 years group of both sexes, to 1.5'% in the 6o years and over group# 2.6% for male and o.~ for female.
The prevalence of bacteriologically proven tuberculosis was 0.5'%
for the total of' all age groups. The ratio wa,s also higher in males ( 0. 7%) than 1n females (0.~} through all age groups 'except in the 50-59 years group. The percentage also went up with increasing age from 0.~ in the lQ-19 years group for both sexes, (0.1$ for male) to 0.5'% in the 60 years and over group for both sexes: 0.7% for male and o.~ for female.
5.3.5 X-rar and bacteriological findings by community and locality Observation by cOIIIl!Wli ty shows that the prevalence of those with X-ray fUms showing clinically significant tuberculosis was highest 1n large cities (4.6%), followed by small cities (3.~). towns (3.~). and lowest 1n villages (.;.~). '!'he prevalence of those with moderately and far advanced lesions was slightly higher 1n large cities (1.~) than 1n the other cOIIJIII.U'l1t1es (1.0%). The percentage of those with cavitary leshrswas also slightly higher 1n large cities and towns (both 0.4%) than 1n villages (0.~) and small cities (0.~). But the prevalence of bacteriologically proven cases was slightly higher in villages (0.6,%) than 1n large and small cities (both 0.5%) and towns (0.4%) (Table 17) •
By local.! ty, the preval.enoe of those with clinioaJ.ly significant tuberculous lesions was highest in t..lre east (4.8%), followed by the north- west (4.~) and south-west (3.'7%), and lowest in the oentraJ.-west (3.~).
The preval.enoe of those with moderately and far advanced tuberculous lesions was al.so higher in the east (14%) than in the west: the north-west (1.1%)
central.- and south-west (both 1.()%). The preval.ence of oavi tary disease was higher in the east and north .. west (both 0.4%) than in the central.- and south-west (both 0 .}%) • 'lhe preval.enoe of baoteriologioal.ly proven oases was al.so higher in the east (0.9%) than the west: the north- and oentral.- west (both 0.5%) and south-west (0.}%).
The prevalence of clinically significant tuberculosis suspects ranged from
6.7%
in Keelung City in the north-west to 2.~ in villages in the north-west. The preval.enoe of advanced tuberculous lesions rangedfrom 2.4% in Keelung City to 0.5% in smal.l cities in the central-west.
And the prevalence of cavitary disease ranged from 0.~ in Keelung City to
o.O%
in towns in the east and in smell cities in the south-west.The prevalence of bacteriologically proven cases ranged from 1.~ in Keelung City to 0.1% in Taichung City in the central-west.
5.3.6
As described above, the preval.enoe of clinically significant tuberculous shadows was higher in cities than in villageftowns. Close examination of this difference by sex and age group showed that the ratio was higher 1n cities than in villages/towns for both sexes, of nearly al.l age groups. T.he prevalence of cavitary disease and bacteriologically proven cases, which showed no difference between villages/towns and cities as a total, was slightly higher in villages/towns than in cities among males of middle and older age groups, while it was slightly higher in cities than in villages/towns among both sexes of younger age groups and among females of middle age groups, {Table
18).
5.3.7
X-ray and bacteriological findings by sex and age group in 'itest and eastf..s described above, +.J1e prevalence of cl:!.Ilically sigr:if:!.c~:::r':
tuberculous suspects and bacteriologically proven ca.ses "1-le.s higher in the east than in the 'ties-:;. Close examination of the difference by sex and age group shows the.t the ratios v1ere higher in the east than in the "\'lest f0r both sexe3, ;;nd through nearly all age groups. ~e prevalence of cavl tru•y d.ise_a,:,e 1 vlhic!: :;ho>·led little difference beb·:ee:n the east ar.d the west as a total, showed no particular tendency by sex ~~ age group,
(Table 19).
5.3.8
X-ray and bacteriological findings by occupationObservation of X-ray and bacteriological findings according
to occupation shows that the prevalence of clinically significant tuber- culous and bacteriologically proven cases were higher among those "presently
•
"
•
..
0
..
•
•
unemployed, previously ga1nfully employed" (21.~ and
7
.1$) "retired and livins on rent" (l4.3!t and l.?t(} and "unemployed" (14.0% and o.?,() who had no occupation at the time of examination and. were composed of more aged persons. Those who had some occupation, "administrative, executive and managerial workers" who were also composed of more aged persons also showed a hish p~valence (13.1.% and 1.$), while "students" who were composed mainly of younger persons showed the lowest percentage (0.4~ and 0.0%) followed by "housewives" (2.9)C and 0.~), (Table 20).5.3.9 X-ray and bacteriological findings by industry
Observation according to industr,v shows that the prevalence of clinically significant tuberculosis was highest among those engaged in
"minins and quarrying11 (9.0%) followed by those engaged 1n "electricity, gas, water and sanitary services" (7 .0%) and in "commerce" and "services"
(both 6.8%). 'Jl1e prevalence was lowest among those with "no industry
(2.$) followed by those engaged 1n "construction" (3.5%) and "agriculture, forestry, hunting and fishing" (4.~). (Table 21).
The prevalence of bacteriologically proven cases was also hishest among those engaged 1n "mining and quarxr.rins" (l.~) followed by those engaged 1n "commerce" and 11agricul ture, forestry, hunting and fishing"
(both 0.8%). 'Jl1e prevalence was lowest among those with "no industry"
and engaged in "manufacturing" (both 0 .3!t) •
5.3.10 X-ray and bacteriological findings by place of birth
Observation of X-ray and bacteriological findings according to place of birth shows that the prevalence of clinically significant tuber- culosis was higher among those who were born 1n mainland China (8.1~}
than those born 1n Taiwan (3.~). The former group was composed of more males than females and more middle aged than younger persons than the latter
group. However, the prevalence of bacteriologically proven cases was a little higher among the latter (0.5%) than the fonner (0.3!t) (Table 22).
5.3.11 X-ray and bacteriological findings by marital status and sex Observation of X-ray and bacteriological findings according to marital status and sex shows that the prevalence of clinically signifi- cant tuberculosis and bacteriologically proven cases were both higher among married tsan single persons for both sexes. 'lbe prevalence of clinically significant tuberculosis among married persons was 5.~ for the total, 8.1$ for the male and 3.~ for the female; while that among single persons was 1.1$ for both sexes, l.~for the male and 0.8% for the female. 'lbe prevalence of bacteriologically proven cases among married persons was
0.~ for the total, 1.]$ for the male and 0.4~ for the female; while that among s1ngle persons was 0.]$ for the total, 0.2% for male and 0.]$
for female (Table~) •
5.3.12 X-rar and bacteriological findings by household status and sex Observation of X-ray and bacteriological findings according to household status and sex shows that the prevalence of clinically signifi- cant tuberculosis was highest among fathers or household heads (15.o;g), followed by grandmothers (11.~). male spouses (10.~). male heads of' families (9.o;g) and male lodgers (8.1%}; the prevalence was lowest among grandsons (0.~) followed by daughters (0.8%}, grandaughters (0.9%), sisters (1.1~) and sons (!.~)(Table 24).
The prevalence of bacteriologically proven cases was highest among male lodgers (2.~) followed by male heads {1.~). brothers (1.1%).
other male relatives (l.o;g) and mothers (l.o;g); it was lowest among grandchildren followed by daughters (0.1%) and sons (0.2%).
5.3.13 x-ray and bacteriological findings by household size
Observation of X-ray and bacteriological findi~s according to household size shows that the prevalence of clinically significant tuberculosis was highest in households consisting of one person (7 .4%) and goes down as the number of the household increases. The prevalence of bacteriologically proven cases, however, did not show such a clear tendency. It was highest in households with two and three persons,
(Table 25).
5.3.14 X-ray and bacteriological findings among parsons with and without BCG vaccination scar
ECG
vaccination scar was observed among 67.4% of the X-ray examined of the 10-14 age group,56.3%
of the 15-19 age group;24.7%
of the 20-24 age group; and 4.9% of the 25-29 age group. Comparison of the prevalence of clinically significant tuberculosis, cavitary and bacteriologically proven cases between persons of these age groups with and without BCG scar showed no obvious differences (Table
26).
5.3 .15 History of X-ray examination by age group among total
population and persons with positive X-ray and bacteriological findings
About one-quarter (25.~) of the total population aged ten years and over, who were X-ray examined during the survey, had previous
experience of X-ray examination. The percentage of those with experience of X-ray examination was highest in the 15-59 age group and was lower in the 10-14 age group (6.T,il) and the 6o and over age group (ll.S%).
The percentage of those with previous experience of X-ray examination among persons whose X-ray films taken during the survey showed abnonnal shadows was 38
.Sl'.
It was also higher in the 15-49 age group, and lower in the younger and the elder age groups.•
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•
The percentage was 42.~ among persons with clir.ically sig:lifica."lt tuberculous shadows. It was higher among the age groups from 15 tc
49;
but it '1as only
8.3%
in the 10-14 age group a."lli about 2C"% of th.e older age groups.The percentage was 50. 7~ amcng the 'baoterioloGicill:' p:r>("'>ve:r.. ca;:;es.
Because of the small number of cases no particular tendency '\'las observed by age group (Table 27).
5.3.16
History of medical treatment for tuberculosis byage
groupamong total population and persons with X-ra;v and bacteriological findings
Those who had a history of medical treatment for tuberculosis represented l.~ of the total. population aged 10 years end over. ~e
percentage was higher among middle and elder age groups and lower among younger age groups; "the highest was 3.~ in the 35-39 age group and the lowest was 0.1~ in the 10-14 age group.
The percentage of those with a r..istory of treat.11ent a,;.')r,g t!:-e total t·r:!. th '.!lidcal.ly significant tuberculosis f'our.d durir.g the survey was 18.}%. The P"'...I'Centage l~as approximately 3c:¢ for the 30-39 age g::-oup but it }'lea mu~h lower among tbe Y!=lunger and the elder age group~ in ;.;;hich
tr~ percentages were only
s.Q%
aP~3.1%
respectively •The percentage among the bacteriologically proven cases was
33.3%.
Because of the smal.l number of cases no particW.ar tendency was obsei'I/'ed by age group (Table
28).
5.4
TUberculin reaction5.4.1
Children with BCG vaccination scarsAmorg
6962
children who were tuberculin tested and read#482
or6.9%
had BCG vaccination scars.The revised percentage of children over one month and below five years of age with scars to the total was f
.4%.
I t was a l1 ttle higher in mal.es (7. ~) than in females (7 .~). '!he ratio went up with increasirg age from 1.1% at 0 yearto
16.~ at4
years of age (Table 30.1). Examina- tion by community shows that the percentage was relatively low in. small cities (4.~) as compared with large cities (8.~L towns (7.9%) and villages(7
.~). By locality it was lower in the east ( 2.4%)
and north- west (4.4%) and higher in the central.~west (9.~) and south-west (9.~).Close examination by community and locality indicates that the ratios ranged from 0.~ of' villages in the north-west to 12.6% of villages in the south-west (Table
31) •
5.4.2
TUberculin reaction (induration size)Induration sizes induced by 1 TU of P.P.D. RT ~ '\'lith Tween 80 among 648o children without BCG vaccination scars 'l'lere distributed a..c:
shown in Table 29 and Figure ll. The distribution curve, being smoothed by cutting off artificial peaks at every
5
and 10 mm, descends from the first peak at 0 mm rapidly until4
mm then slowly until it reaches a trough 9 mm; then the curve ascends slowly \l!ltil 1 t reaches the second peak at 17-18 mm, then .it descends again slowly dra>-ling a symmetric curve. \-11th the bimodal frequency distribution and a fe'l'l reactions of intermediate size (6-9 mm), it seems to be possible to separate thet'..:.berculin reactions into two groups: (l) weak and intermediate reactions with induration below 10 mm among pre~~ably non-infected children ar4
(2) strong reactions With induration of 10 mm and over among children presumably infected with tubercle bacillus.
The revised percentage of strong tuberculin reactors among children belol'l' 5 years without BCG \'accination saar was 3.9%. It went up with increasing age from 0.3% at 0 year to 8.3% at 4 years. It Nas a little higher in females
(4.1%)
than males(3.?%)
as a total; but close examination by sex and age proves that the prevalence tvas r..:l.;he:::- in males below 2 years and it became higher in females over 2 years ,1(Table
30-2) •
Exarninatior_ by Gcmmu::::. t~; prc:es w_at pre•!a- lence was highest in large citiel" (4.6%), st1.c-~ecd.ed by s:;Jall '-i".;ies ('+.5%)and towns (4.1%). and lowest in villages (3.Ci~). E:: localhy i-;; ~·1as highest in the east (6.~). followed by the north-west
(4.7%)
and thecentral-west (3.9%), and lowest in the south-west (2. 7%). By community and locality, the ratios ranged from 1.1% in tol•lns in the south-l'Iest to 9.9% at Keelung (Table 31).
5.4.3
Tuberculin reaction among children below five years of age without BCG vaccination scars in households with and without tuberculosis aged 10 years and overTuberqulin reactions of .ahildren below five years of age without BOG vaccination scars were compared between householos with and without person(s) aged ten years and over whose X-ray film showed some shadows suggesting tuberculosis. (Only the households, of which all the members aged ten years and over were X-ray examined satisfactorily. were included in this analysis.) 'lbe percentage of reactors with induration size of 10 mm and over was 3.4% among children in the households, in which all the household members showed normal X-ray shadow or a non-tuberculous shadow. The percentage among children in households with persons showing a suspicion of clinically significant tuberculosis was 10.~. or three times as high as the percentage in the households w1 thout any tuberculous suspect. 'lbe percentage of reactors in households with some bacteriolo- gically proven case(s) was much higher (27
.5%).
while the percentage in l i t should be borne in mind that the higher proportion of those with BOG vaccination scars ere excluded from the analysis of tuberculin reaction by natural infection made the higher strong reaction group, because those who reacted strongly to pre-vaccination tuberculin tests were included in the analysis.•
•
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•
~
•
households with bacteriologically non-proven suspects was o~~F 7.~.
The former was eight times as high as that in households without any tuberculous suspect, \'11'-.ile the latter was only a little more than twice
a..~ high. The percentage of reactors in households where no one showed clinically significant tuberculous lesions 'l'las 5.1% (!able 32) •
6.
Discussion6.1 Reliability of estimated prevalence of positive X-r~Y ~d
bacteriological findings
As all the exa'!linations and tests during the survey vere carried out by personnel selected tro:n the Provincial Taipei Tuberculosi"< Control Centre, and particularly since t..l-J.e error in rea...-tir.g; th: X-~·a;.- £'il!:1:::: 1·~r:..s
minimized by having two physicians read tr.~ films indepen1e~tly, the results
ot
the examil'lations can be considered qui.te .reliable· (9.nbles 33 and 34) • Some sampling error is however inevitable ir- allY sa'llple survey because onlya small fraction of the population is examined. The standard error is usually employed to indicate the extent of the sampling error.
Standard error is primarily a measure of the sampling va.l"iabili ty;
that is, the variations that might occur by chance. The chances h!'e about 68 out of 100 that an estimate from the sample would differ from a oanpl.ete survey of tm whole population within the standard error.
1he chances are about 95 out of 100 that the difference 'tlould be less than twice the standard error and about 99 out of 100 that it would be less than
2.5
times as large. In the present statistical. analysis, 1;he9~ probability, i.e., twice the standard error, is adopted.
Since the final stage sampling unit is a cluster of five Lins wr.ich is the smallest administrative unit in Te.iwan, and not individ.ual.s, it is clear that in the calculation cf standard er:'or the ::.•r•t~o l::El'C!l.Oit
should be applied and not the binomial method. '!he ratio f'orrnula given
b&l~w was used to calculate the variance of' percentages. The square roet of this variance is the standard error.
(1) Variance f•r each stratum:
v(p) • l/(U) 2 n/(n-1) (1: (y-J)2 - 2p ~ (x-i.)(y-l') + p2 <f:(x-i)2) Where :
v(p) n N
X
i y
'1
p
r
• Variance of an estimated percentage p for a stratum
• Number of sampling units selected for the stratum
= Total number of sampling units in the stratum
··Humber of eXftlidnees·:in:a,~ing Ul'lit aelecMd
• Aver~e muuber of exarn1•ees per·semplil}g unit •elected
• 1llunber of persons with pesi tive findings in a sampling unit selected
• Average number ef persons with positive f1nd1ngs per sampling un1 t selected
• Sample estimate •f percentage fsr the stratum,
i.e.,
"I:Y/lx or
Y'ix
• SUaluation of the sampl.ing units selected
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