W O R L D H E A L T H ORGANIZATION
REGIONAL OFFICE FOR THE L , I U ; ~ : ~ I ~ Q , ~ / ~ I BUREAU REGIONAL DE LA
EASTERN MEDITERRANEAN MEDITERRANEE ORIENTALE
REGIONAL C0MMITE.E FOR THE EASTERN MED-AN
Einhteenth Session Agenda item g (b)
ORIGINAL: ENGILSH
HEALTH EXAMINATIONS AND SCREENING
PRCCEDURES
FOR CHRONIC NON-COIWJNICABIE DISEASES
The Early Detection of Disease and Screening Procedures Periodic Health Examinations
The Present Status of Certain Screening Proceedings Ischaemic Heart Disease
Breast Cancer
Cancer of the Cervix Uteri Chronic Bronchitis
Diabetes Mellitus Intra-occular Tension Unreported Mental I l l n e s s
The Organization of Early Disease Detection A Broad Conclusion
Appendix I
-
Conditions Screened by Age and Type of CountryIntroduction
Since the early years of the century, the periodic medical examination and health surveillance and more recently screening procedures and the
sophisticated medical 'check-upf have become increasingly prominent features of health care in the highly developed countries.
In 1964, "Pre-symptomatic Diagnosis by Organized Screening procedures"
was the subject of a Technical Discussion in the European ~egionl; and in 1967 a comprehensive paper on "The Practice of Screening for Disease'' was completed by two consultants in WHO ~eadquarters~.
The participants in the European Regional Discussion stated that in
their unanimous opinion "screening procedures were probably one of the import- ant recent developments in preventive medicine and that there could be no question as to their usefulness".
With notable exceptions, e.g. the periodic examination of school children, the medical supervision of the pregnant woman, the health surveillance of
certain occupational groups and the "medical check-up" for a privileged few- medical care is given for the most part to persons who consult a doctor because they are sick. This is adequate for meeting many medical care needs, but clearly insufficient to provide medical care for all who could benefit from it.
Disregarding persons who, though aware that something is amiss fail for one reason or another to seek medical advice, the usual method of obtaining medical care fails for two categories of patients:
1. Persons with undeclared, or pre-symptomatic disease which they are, therefore, unaware of, but which might be discovered by the physician, e.g. cancer of the cervix uteri, early diabetes.
l ~ u r o Tech. ~ i s c
.6
'~r J.M.G. Wilson, Ministry of Health, London, and Dr G. Jungner of Sahlgren's Hospital, Gothenburg, Sweden
- WHO- PA/66.7.
2. Persons, who though not ill, migilt be a t s p e c i a l risk.; of developing c e r t a i n d i s e a s e s and who might b e n e f i t from advice about how t o reduce t h e r i s k . Advice of t h i s kind would, so t o speak, be a tailor-made p r e s c r i p t i o n f o r personal conduct which took account of t h e i n d i v i d u a l ' s proneness t o c e r t a i n d i s e a s e s , h i s h a b i t s , environment and s o f o r t h . A s e r v i c e which reaches t h e s e groups might be expected t o provide a b a s i s f o r preventing, postponing or a l l e v i a t i n g t h e chronic non-communicable d i s e a s e s and t h e degenerative d i s e a s e s whose a e t i o l o g i e s a r e obscure, whose c a u s a t i o n i s m u l t i p l e and whose incidence i s o f t e n r e l a t e d t o personal h a b i t s and h e a l t h a t t i t u d e s , e.g. d i e t , overweight, e x e r c i s e , smoking.
To provide medical care f o r t h e s e groups it has t o be offered without people having t o t a k e t h e i n i t i a t i v e i n seeking advice because they a r e s i c k . They a r e reached through screening procedures and p e r i o d i c h e a l t h examinations.
The expression "Early d e t e c t i o n " i s used t o include a l l forms of e a r l y d i s e a s e discovery by screening t e s t s , physical examination and o t h e r means.
By screening procedures i s meant t h e a p p l i c a t i o n of t e s t s o r examinations t o s o r t people i n t o two c a t e g o r i e s :
1. Those without evidence of e a r l y o r e s t a b l i s h e d d i s e a s e and who can be reassured without f u r t h e r examination.
2. Those who e i t h e r have a d i s e a s e and need treatment or who need c l i n i c a l assessment t o decide t h e i s s u e (bard-erline c a s e s ) .
When screening t e s t s a r e used f o r t h e whole population or f o r l a r g e groups t o i d e n t i f y undeclared d i s e a s e o r d e f e c t , t h e procedure i s c a l l e d
"mass screening".
When used f o r a "high r i s k " group i n t h e population, i t i s known a s
" s e l e c t i v e screening", e . g . f o r pregnant women, i n f a n t s , occupational groups, old people.
The use of a b a t t e r y of t e s t s i n combination i s c a l l e d "multiple screenirig".
The degree of r e l i a b i l i t y of a t e s t t o d e t e c t d i s e a s e whenever it i s p r e s e n t , and t o miss l i t t l e , i s known a s " s e n s i t i v i t y " . R e l i a b i l i t y t o i n d i c a t e d i s e a s e only when it i s present, i . e . not t o give f a l s e p o s i t i v e r e s u l t s , i s c a l l e d " s p e c i f i c i t g " .
When used f o r case-finding
,
t h e main ob3ect of screening i s the d e t e c t i o n of d i s e a s e f o r t h e purpose of bringing t h e p a t i e n t t o treatment.The h e a l t h worker i s mainly i n t e r e s t e d i n t h i s use of screening t e s t s . Screening t e s t s a r e a l s o used i n epidemiological surveys, when t h e o b j e c t i s t o e l u c i d a t e t h e prevalence, d i s t r i b u t i o n and n a t u r a l h i s t o r y of a d i s e a s e , o r t h e d i s t r i b u t i o n i n t h e c o d t y of t h e l e v e l of a v a r i a b l e c h a r a c t e r such a s blood pressure o r blood-sugar concentration.
For e a r l y case-finding by screening t o be f e a s i b l e two c r i t e r i a must be s a t i s f i e d :
1. There has t o be a s u i t a b l e t e s t , i . e . one which i s s u f f i c i e n t l y s e n s i t i v e and s p e c i f i c , r e l a t i v e l y simple t o perform and acceptable t o those f o r wkon it i s intended.
2. The d i s e a s e it i s used t o d e t e c t should have a recognizable l a t e n t , or e a r l y d e c l a r e d , stage.
For t h e r o u t i n e a p p l i c a t i o n of a screening t e s t t o be j u s t i f i e d , two a d d i t i o n a l requirements have t o be f u l f i l l e d :
1. There should be an e f f e c t i v e treatment f o r t h e d i s e a s e i n question.
2. The medical-care servicesshould be capable of t r e a t i n g t h e volume of c a s e s discovered.
A s a r u l e , mass screening i s only worth-while f o r diseases which a r e f a i r l y common, e.g. chronic b r o n c h i t i s . It i s a l s o worth-while, however,
for diseases, which though rare, are attended by grave consequences unless they are detected and controlled at an early stage, e.g. phenylketonuria.
A decision to employ feasible screening procedures is taken therefore, by balancing the probable yield of cases and the gravity of a condition against the labour and cost involved.
Screening tests in connnon use include serology, clinical procedures such as blood pressure estimation and urine analysis, special examinations such as chest X-ray, ECG, cervical cytology, mammography and the use of questionnaires.
The questionnaire, which is either completed by the patient himself or by a professional attendant at interview, is used especially in screening for mental disorders. For this purpose it usually includes questions about:
1. Disturbances of feeling, thought and behaviour.
2. Social relations.
3.
School or work performance.4. Physical functions such as sleep, eating, motor impairment, enuresis and habit spasms.
Established screening practices for infants, pregnant women and W e elderly are well known.
Screening procedures for many chronic diseases of middle life
-
chronicbronchitis, ischaemic heart disease, hypertension, chronic glaucoma and un- reported mental illness are at present under investigation. Before mass screening for these conditions can be offered, there are difficult problems to be solved.
The automation of laboratory procedures, the use of questionnaires and electronic methods of data handling promise to widen the practicable scope of mass screening in the future.
The principal conditions for which screening is done are given in Table
5.1
of the WHO paper referred to earlier (reproduced here as Appendix
I).
C o d c a b l e and non-communicable d i s e a s e s a r e l i s t e d s e p a r a t e l y , i n each case by age and type of country i n which tney have been used. It w i l l be seen t h a t t h e use of screening procedures f o r non-communicable d i s e a s e s i s r e s t r i c t e d mainly t o t h e highly developed countries. For this g o u p of d i s e a s e s , screening i s undertaken only f o r m a l n u t r i t i o n and anaemia i n t h e developing c o u n t r i e s , and i n a d d i t i o n only f o r cancers of t h e mouth and bladder i n c o u n t r i e s i n intermediate s t a g e s of development.
Periodic Heal +.h Fanminirtions
There i s no hard and f a s t l i n e between the h e a l t h examination and t h e use of screening procedures f o r t h e e a r l y d e t e c t i o n of disease. The h e a l t h examination h a s , however, d i s t i n c t i v e f e a t u r e s .
T y p i c a l l y , i n t h e h e a l t h examination, everyone i n a population or group i s seen by a doctor who thereupon decides what laboratory t e s t s and s p e c i a l examinations ( i f any) a r e needed t o a s s i s t a diagnosis. The p a t i e n t i s seen by t h e doctor on a second occasion when t h e r e s u l t s of t h e t e s t s and examina- t i o n a r e known. The f i r s t v i s i t t o t h e doctor i s , i n e f f e c t , a screening c o n s u l t a t i o n . By c o n t r a s t , when screening i s used, everyone has t h e t e s t ( s ) , b u t only a s e l e c t e d group proceed t o a medical consultation.
The h e a l t h examination has obvious advantages over screening by mechanical, e l e c t r o n i c , and bio-chemical procedures. A t t h e i n i t i a l c o n s u l t a t i o n , t h e doctor i s a b l e t o make a s k i l l e d assessment of the p a t i e n t ' s h e a l t h s i t u a t i o n and t o arrange t e s t s and s p e c i a l examinations, not a s a uniformed r o u t i n e , b u t i n h i s informed d i s c r e t i o n . He i s a l s o a b l e t o d e t e c t much which would otherwise escape discovery, e.g. unsuitable c l o t h i n g and footwear, varicose v e i n s , f l a t f o o t , h e r n i a and bunions.
The Present S t a t u s of C e r t a i n Screening Proceedings
Although screening has a n undeniably g r e a t f u t u r e i n t h e e a r l y d e t e c t i o n and secondary prevention of chronic d i s o r d e r s , t h e b r i e f note which follows
leaves no doubt t h a t much research i s s t i l l needed
-
p a r t i c u l a r l y community based s t u d i e s-
t o evaluate conclusively most of t h e procedures now used.Ischaemic Heart Disease
Electro-cardiography, serum l i p i d l e v e l s and questionnaires have not y e t been s u f f i c i e n t l y v a l i d a t e d t o j u s t i f y t h e i r use f o r r o u t i n e screening i n t h e absence of symptoms. Observer d i f f e r e n c e s a r e o f t e n considerable i n t h e i r i n t e r p r e t a t i o n and t h e r e i s no general agreement about t h e advice t o be given t o s u b j e c t s with healed i n f a r c t s .
Breast Cancer
There i s no evidence t h a t e a r l i e r diagnosis by palpation has ever reduced t h e death r a t e from b r e a s t cancer i n any country. The same i s t r u e of mammography, but randomized, c o n t r o l l e d t r i a l s now going on i n New York should provide a n answer one way o r t h e other. (The b e n e f i t of e a r l y treatment i n reducing s u f f e r i n g should a l s o be taken i n t o account).
Cancer of t h e Cervix U t e r i
There i s no evidence of a f a l l i n the death r a t e from t h i s condition i n a r e a s where a high proportion of women a r e examined compared with a r e a s i n which few a r e examined
-
perhaps because t h e r e has not been time enough anywhere f o r t h e e f f e c t of screening t o become apparent. The opportunity of conducting c o n t r o l l e d t r i a l s was unfortunately missed when screening was f i r s t introduced. Here again, t h e r e remain doubts about t h e value of screening f o r t h e avowed, primary purpose.Chronic B r o n c h i t i s
It i s l i k e l y t h a t simple t e s t s f o r measuring r e s p i r a t o r y functions com- bined with a questionnaire would enable
a
s p e c i a l r i s k group t o be i d e n t i f i e d . It i s a l s o l i k e l y t h a t they would benefit from simple measures such a s giving up smoking and avoiding cold bedrooms.Diabetes M e l l i t u s
I n screening f o r d i a b e t e s , blood sugar l e v e l a f t e r a glucose load has been shown t o be more s a t i s f a c t o r y than t e s t i n g f o r glycosuria. The main q u e s t i o n i s t h a t of borderline l e v e l s , o r the "cut-off" l e v e l t o be adopted.
A t p r e s e n t , t h e t e s t i n g of high r i s k groups ( e S g . r e l a t i v e s of d i a b e t i c s , hypertensive p a t i e n t s , o l d e r overweight s u b j e c t s and persons with symptoms) appears t o be t h e most rewarding course.
I n t r a - o c c u l a r Tension
A r e l a t i v e l y l a r g e proportion of persons have t e n s i o n s over 21 m.m.
There is no conclusive evidence t h a t treatment prevents v i s u a l f i e l d l o s s and it i s doubtful if many s u b j e c t s could be persuaded t o pursue t h e lengthy treatment recommended. Screening concentrated on r e l a t i v e s of known cases might be j u s t i f i e d .
Unreported Mental I l l n e s s
I n s u f f i c i e n t i s known of t h e diagnostic c r i t e r i a t o be adopted, t h e c h a r a c t e r of t h e t e s t s t o be used and t h e form which treatment should take.
There i s l i t t l e doubt t h a t the questionnaires now used would y i e l d a volume of cases L-equiring i'upthar i n v e s t i g a t i o n which few e x i s t i n g s e r v i c e s could cope with.
The Organization of E a r l y Disease Detection
The choice of a p a r t i c u l a r organization f o r providing screening and h e a l t h s u r v e i l l a n c e s e r v i c e s c l e a r l y depends on a multitude of f a c t o r s which d i f f e r g r e a t l y from country t o country. Disease p a t t e r n s , h e a l t h resources i n terms of money and personnel, pub3.i~ a t t i t u d e s and educational l e v e l s , s t a g e of development and t h e e x i s t i n g s t r u c t u r e of health-care s e r v i c e s a r e among t h e f a c t o r s which have t o be taken i n t o account. Whatever t h e c i r - cumstances, however, a number of general p r i n c i p l e s a r e widely agreed:
1. For extending screening and health surveillance to c o m i t i e s a new way of thinking about health care is needed by both health personnel and thc public, i.e, there are substantial problems of medical education and training to be faced and probiems of health education.
2. Early detection and health surveillance are within the proper provincc of primary medical care services, i.e. the general practitioner or the health centre doctor.
3 These functions can only be discharged when general health care services include an organized system of records and are associated with adequate laboratory and other special diagnos- tic facilities.
4. General health surveillance is fully effective only when screening tests and health examinations are repeated systematically at intervals.
5.
Early detection in high risk groups may be introduced by screen- ing hospital populations. The routine multiple screening of hospital admissions has been shown to have advantages over and above the detection of undiagnosed disease in as much as it in- creases the accuracy of diagnosis and reduces the length of time spent by patients in hospital.The following examples of schemes operated in non-hospital practice are cited:
Example 1. The Comprehensive Scheme of Medical Screening offered by the Kaiser Foundation Health Plan in the USA'
This scheme comprises an elaborate combination of tests and a medical examination offered annually to a large, insured population. The ordered sequence of tests and consultations under this scheme includes weighing,
1 See also WHO paper by Wilson and Jungner, page 145 ( 1 ~ 0 - P~166.7).
body-type e s t i m a t i o n , recording of blood p r e s s u r e , p u l s e , ECG, v i s u a l a c u i t y , tonometry, r e t i n a l photography, audiometry, c h e s t radiography, mammography and blood chemistry, i n a d d i t i o n t o a questionary h i s t o r y and a terminal medical examination. The whole sequence i s automated and computerized and occupies about two hours. P a t i e n t s e n t e r and leave t h e sequence a t t h r e e minute i n t e r v a l s .
Example 2. Medical Check-up Trends i n General P r a c t i c e i n UK
The main o b j e c t i o n s t o o f f e r i n g periodic examinations on a general s c a l e i s t h e amount of doctor time they would absorb. This i s a r e a l , b u t not insurmountable obstacle. A g r e a t d e a l of doctor time a t f i r s t interview can be spared by t h e completion beforehand of a s e l f - h i s t o r y questionnaire and a note about such a t t r i b u t e s a s h e i g h t , weight, blood p r e s s u r e , u r i n e , Hb l e v e l , e t c . , which can p e r f e c t l y well be done by s m e - one o t h e r than a doctor. A few medical p r a c t i t i o n e r s a l r e a d y record f a c t s of t h i s kind f o r p a t i e n t s on t h e i r lists. I n a d d i t i o n t o t h e i r immediate d i a g n o s t i c relevance, they a r e valuable a s base-line information with which
l a t e r presumptive d e p a r t u r e s from t h e norm can be compared. Checks a r e repeated every f i v e y e a r s i n middle-age f o r everyone. High r i s k cases a r e i d e n t i f i e d and revic.red more frequently.
Example
3 .
Advisory Health Centres f o r t h e E l d e r l y i n UKThe e l d e r l y c o n s t i t u t e a well-recognized high r i s k group who can b e n e f i t i n p a r t i c u l a r from t h e discovery and treatment of sensory and locomotor de- f e c t s , d i a b e t e s , anaemia, f o o t t r o u b l e s and mental disorders. A number of l o c a l h e a l t h a u t h o r i t i e s have e s t a b l i s h e d t r i a l advisory c e n t r e s f o r t h e e l d e r l y a s p a r t of t h e i r preventive s e r v i c e s .
Example 4. Cytological Screening f o r Carcinoma of t h e Cervic U t e r i i n England and Wales
There a r e a t present some 2 500 deaths a year i n England and Wales from cancer of t h e c e r v i x , mainly of women over t h e age of
35
years. The~ ~ / ? 3 ~ 1 8 / 5 page 10
invasive d i s e a s e js preceded by an i n s i t u l e s i o n which develops without symptoms over a period of t h r e e t o f i v e y e a r s . There i s s t r o n g evidence f o r t h e value of d i a g n o s i s a t t h e e a r l i e r non-invasive s t a g e . The
e a r l i e r t h e d i a g n o s i s , t h e b e t t e r i s t h e s u r v i v a l r a t e . Early d i a g n o s i s can be made by t h e c y t o l o g i c a l examination of a c e r v i c a l smear which i s r e l a t i v e l y easy t o prepare and which can be r e l i a b l y assessed i n a patho- l o g i c a l l a b o r a t o r y by p a t h o l o g i s t s and medical l a b o r a t o r y t e c h n i c i a n s t r a i n e d i n cytology.
On t h e b a s i s of t h e s e f a c t s , a n a t i o n a l scheme f o r screening women f o r t h e c o n d i t i o n has been e s t a b l i s h e d . For t h e p r e s e n t , a t t e n t i o n i s focussed on women over
35
years of age, and screening i s done a t i n t e r v a l s of f i v e years. I n order t o screen a l l women over35
every f i v e y e a r s , some 2 500 000 examinations a year would have t o be performed. Although t h e scheme i s s t i l l i n i t s e a r l y days a s u b s t a n t i a l proportion of women a t r i s k a r e a l r e a d y being t e s t e d . The annual r a t e of screening has now(December, 1965) reached over 750 000, and screening has s t a r t e d throughout t h e country.
Smears a r e taken i n h o s p i t a l c l i n i c s from women a t t e n d i n g gynaecological and o b s t e t r i c departments. For women who a r e not h o s p i t a l p a t i e n t s smears a r e taken a t l o c a l h e a l t h a u t h o r i t y c l i n i c s , by general p r a c t i t i o n e r s , and a t voluntary family-planning c l i n i c s .
Cjrtological k i t s , comprising a s p a t u l a , s l i d e s , s l i d e c o n t a i n e r and f i x a t i v e s , a r e supplied by h o s p i t a l a u t h o r i t i e s . Smears a r e taken by a doctor o r a t r a i n e d nurse working under medical supervision, and a r e d i s - patched t o a h o s p i t a l l a b o r a t o r y f o r examination and r e p o r t . A standardized recording system enables follow-up and r e - c a l l t o be e f f e c t e d . Women from whom a smear has been taken a r e n o t i f i e d of t h e r e s u l t and advised t o c o n s u l t t h e i r general p r a c t i t i o n e r if t h e smear i s p o s i t i v e o r doubtful. The g e n e r a l p r a c t i t i o n e r i s r e s p o n s i b l e f o r r e f e r r i n g p a t i e n t s with p o s i t i v e o r doubtful smears t o a h o s p i t a l department of gynaecology, and f o r follow-up.
W C 1 8 / 5 page 11
Screening services are planned jointly by Hospital Authorities,
Executive Councils, Local Medical Committees, and Local Health Authorities.
Other interested bodies are kept informed. General publicity for the scheme is the responsibility of local health authorities, but a personal approach by the general practitioner, the health visitor, and the midwife is particularly valuable in reaching women who are unlikely to respond to general publicity methods. Women in high risk groups who cannot be per- suaded to attend a clinic can have a smear taken in their homes by home nurses.
A Broad Conclusion
It seems clear that multiple screening and health surveillance for whole populations is at present beyond reach even in the most affluent societies. It would also probably be premature because of the inadequacy of our knowledge of the natural history of most diseases and the validity of many screening procedures.
An
alternative is the progressive introduction, according to resources, of a relatively simple medical surveillance based on the periodic medical check-up. In the older age groups, for example, extended trials of a medical consultation supported by a questionnaire and a record of body weight, visual and auditory acuity, blood pressure, and the results of urine tests would be relatively inexpensive and not too difficult to organize. Such trials would enable the value of periodic medical examinations to be assessed and would add considerably to our knowledge of disease prevalence and the natural his- tory of chronic disorders.EM/RC18/5 Appendix I
APPENDIX I
CONDITIONS SCREBNED BY AQE AND TYPE OF COUNTRY
D i s l o c a t i o n Xip.
n i c Qlaucoma gh Blood-Pressure
Cancer 3f Bladder Cancer o f Rectum Cancer of %uth Cancer of Cervix Cancer of Breast
Non-Spec. Lung Disease I n f e c t i v e H e p a t i t i s H i s t o p l a s m s i s Coccidiomycosis
Carrier Conditions:
Streptococcal
F i l a r i a s i s Schistosomiasis Trypanosomiasis