Psychosocial, musculoskeletal and somatoform comorbidity in patients with chronic low back pain: original results from the Dutch Transition Project

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doi:10.1093/fampra/cmv027 Advance Access publication 24 April 2015

Epidemiology

Psychosocial, musculoskeletal and somatoform comorbidity in patients with chronic low back pain: original results from the Dutch Transition Project

Aline Ramond-Roquin

^a,b

, Florian Pecquenard

^a

, Henk Schers

^c

, Chris Van Weel

^c,d

, Sibo Oskam

^e

and Kees Van Boven

^c

aDepartment of General Practice, PRES LUNAM, Angers, France, ^bLaboratory of Ergonomics and Epidemiology in Occupational Health, PRES LUNAM, Angers, France, ^cDepartment of Primary and Community Care, Radboud University Medical Centre, Nijmegen, The Netherlands, ^dAustralian Primary Health Care Research Institute, Australian National University, Canberra, Australia and ^eFormerly of the Department of General Practice, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.

*Correspondence to Dr A. Ramond-Roquin, Faculté de médecine - département de médecine générale, 1 rue Haute de Reculée, 49045 Angers Cédex 1, France; E-mail: aline.ramond@univ-angers.fr

Abstract

Background. Better insight into frequent comorbidities in patients with chronic (≥ 3 months) low back pain (LBP) may help general practitioners when planning comprehensive care for these patients.

Objective. To prospectively study the prevalence of psychological, social, musculoskeletal and somatoform disorders in patients presenting with chronic non-specific LBP to general practitioners, in comparison to a contrast group of patients consulting in the same setting.

Methods. This case-control study is embedded in a historical cohort, based on a primary care practice-based research network. All the health problems presented by the patients were prospectively coded according to the international classification of primary care between 1996 and 2013. The prevalence of psychological, social, musculoskeletal and somatoform disorders presented by the adult patients from 1 year before the onset of chronic LBP to 2 years after onset was compared to that of matched patients consulting without LBP, using conditional logistic regressions.

Results. The 1511 patients with chronic LBP more often presented musculoskeletal disorders than the contrast group during the year before the onset of LBP and during the second year after it, with odds ratios (95%confidence intervals) of 1.39 (1.20–1.61) and 1.56 (1.35–1.81), respectively. They did not more often present psychological, social or non-musculoskeletal somatoform disorders.

Conclusions. General practitioners should consider all the musculoskeletal symptoms when caring for patients with chronic LBP. Rather than systematically screening for specific psychological, social or somatoform disorders, they should consider with the patient how LBP and any type of potential comorbidity interfere with his/her daily functioning.

Key words: Comorbidity, general practice, low back pain, musculoskeletal pain, psychology, somatoform disorders.

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Introduction

Low back pain (LBP) is a common condition worldwide and is responsible for individual pain and disability (1). Chronic LBP, defined as LBP lasting for more than 3 months, generates consider- able work absenteeism and high costs for society (2). GPs are in most cases the first contact for patients with LBP and provide most of the professional care throughout follow-up (3). About 80% of patients presenting LBP to their general practitioners (GP) suffer from non-specific LBP (4). Biomechanical, psychosocial, occupational and socioeconomic factors have been identified as influ- encing the evolution of non-specific LBP (5). However, managing patients with acute LBP as those with chronic LBP remains chal- lenging (6–9).

The literature has suggested that people with LBP, and especially chronic LBP, more often presented comorbidities, in particular psychological disorders, other musculoskeletal pain and somatoform disorders (10–12). This comorbidity is of particular importance because it has been associated with poorer outcome (13). Greater insight into the frequent comorbidities in patients with chronic LBP may help GPs in planning comprehensive and pro-active care for these patients.

However, the literature has most often studied the comorbidity of patients who were not representative of those consulting with LBP in primary care, and compared it with data from the general population. Therefore, it is not clear whether the prevalence of such comorbidity is specifically higher (or not) in the patients presenting with non-specific chronic LBP compared to other patients consulting in general practice. Finally, social problems presented to GPs have rarely been studied in patients with LBP.

Our aim was therefore to investigate the prevalence of the health problems presented to their GPs by patients with chronic LBP, compared to patients consulting in the same setting without LBP, in terms of psychological, social, musculoskeletal morbidity and somatoform disorders.

Method

Design

This work is part of a larger study of LBP in primary care. We performed a case-control study embedded in a historical cohort, evaluating the prevalence of the health problems in patients consulting with an episode of LBP, in comparison to a contrast group of matched patients without LBP. We studied morbidity patterns start- ing 1 year before the onset of the episode of LBP until 2 years after it. We stratified the analyses according to the duration of the LBP episode and therefore this article presents the results related to the patients with chronic LBP.

Setting

The data were extracted from the Dutch Transition Project database, a practice-based research network currently of nine GPs in four practices with 15,000 patients. Since the beginning of the Project in 1985, GPs have routinely and prospectively coded all contacts with patients according to the International Classification of Primary Care (ICPC).

This standardized classification is based on codes which are classified in seventeen chapters representing body systems and problem areas.

Each code uses well-defined inclusion and exclusion criteria. The GPs code for each consultation: the patient’s reason for encounter (RFE), the GP’s diagnosis, and the interventions (examination, referral, pre- scriptions, etc). An episode of care is defined as “a health problem

in an individual from the first encounter until the completion of the last encounter for it with a health care provider (14)”. An episode of care can include one or several consultations; its duration is the time between the first and the last consultation for the health problem considered. The diagnosis can evolve during the episode (for example from cough to chronic obstructive pulmonary disease). Finally the title of the complete episode is the diagnosis considered by the GP to describe the patient’s condition the most accurately, as entered in the last consultation of the episode. It can be a syndrome, a disease, or remain a symptom if the aetiology is unknown.

The regular participation of all the GPs of the Transition Project in recording-related training activities and the existence of multiple validity processes maximize the reliability of the registration into the database.

Patients Cases

All patients older than 18 years and diagnosed with one (or more) episode(s) of non-specific LBP (ICPC code L03: “Low back symptom / complaint”) between 1 January 1996 and 1 February 2013 were considered, whereas patients diagnosed with thoracic back pain, pain radiating to a lower limb or LBP secondary to specific causes (recorded with other codes in the ICPC) were not. The patients were included if the episode of LBP had lasted for 90 days or longer and if they had been registered with the practice for at least 1 year before and at least 2 years after the date of diagnosis. The date of first consultation in the episode was taken as the index date. If a patient had more than one episode of chronic LBP during the data extraction time frame, only the first episode was taken into account, so that one patient could only be included once.

Contrast group

For each included case, a patient was selected from the database, among those who had never been diagnosed by their GP with an episode of LBP for all the time they were registered in the practice during the period considered for the study, in order to constitute a contrast group.

For the selection process, they had to have consulted the practice as close in time as possible as their case counterparts (index date) and also had to have been listed with the practice for at least 1 year before and 2 years after the index date. The cases and the patients from the contrast group were also matched for gender, age and practice of listing.

Procedure

First we reviewed the population included in terms of age, gender, duration of registration in the practice, duration of the episode of chronic LBP under consideration and number of episodes of acute and chronic LBP during the period of registration in the practice.

Secondly, we studied the prevalence of the health problems presented to the GPs in the cases and compared it to that presented by their matched patients from the contrast group. We considered every episode that started in the time frame of 1 year before to 2 years after the index date.

We studied specifically three chapters of the ICPC: psychological, social and musculoskeletal (Box 1). We then looked at the ICPC codes corresponding to 13 items from the PHQ-15 (Patient Health Questionnaire), an instrument specifically developed for the detec- tion of somatoform disorders in primary care, and clustered them into four different groups, as suggested by Fink et al.: cardiopulmonary symptoms (palpitations, chest symptoms, shortness of breath), gastrointestinal symptoms (abdominal pain, nausea, constipation),

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musculoskeletal symptoms (thoracic back complaints, muscle pain) and general symptoms (tiredness, fainting, headache, dizziness, sleep disorder) (15). The last two items from the PHQ-15 (menstrual problems and sexual pain/problems) were not considered in the

analyses because of their very low prevalence and lack of matching with the clustering classification used.

Each of these chapters and clusters was considered as a whole:

the prevalence of a given “chapter”/”cluster” was determined by the Box 1. International classification of primary care (2nd version): codes of the chapters of interest

Psychological chapter (P) Social chapter (Z) Musculoskeletal chapter (L)

P01 Feeling anxious/nervous/tense Z01 Poverty/financial prob L01 Neck sympt/compl

P02 Acute stress reaction Z02 Food/water prob L02 Back sympt/compl

P03 Feeling depressed Z03 Housing/neighbourhood prob L03 Low back sympt/compl

P04 Feeling/behaving irritable/angry Z04 Social cultural prob L04 Chest sympt/compl

P05 Senility, feeling/behaving old Z05 Work prob L05 Flank/axilla sympt/compl

P06 Sleep disturbance Z06 Unemployment prob L07 Jaw sympt/compl

P07 Sexual desire reduced Z07 Education prob L08 Shoulder sympt/compl

P08 Sexual fulfilment reduced Z08 Social welfare prob L09 Arm sympt/compl

P09 Sexual preference concern Z09 Legal prob L10 Elbow sympt/compl

P10 Stammering/stuttering/tic Z10 Health care system prob L11 Wrist sympt/compl P11 Eating prob in child Z11 Compliance/being ill prob L12 Hand/finger sympt/compl P12 Bedwetting/enuresis Z12 Relationship prob with partner L13 Hip sympt/compl P13 Encopresis/bowel training prob Z13 Partner’s behaviour prob L14 Leg/thigh sympt/compl

P15 Chronic alcohol abuse Z14 Partner illness prob L15 Knee sympt/compl

P16 Acute alcohol abuse Z15 Loss/death of partner prob L16 Ankle sympt/compl

P17 Tobacco abuse Z16 Relationship prob with child L17 Foot/toe sympt/compl

P18 Medication abuse Z18 Illness prob with child L18 Muscle pain

P19 Drug abuse Z19 Loss/death of child prob L19 Muscle sympt/compl NOS

P20 Memory disturbance Z20 Relationship prob with family L20 Joint sympt/compl NOS P22 Child behaviour sympt/compl Z22 Behaviour prob with family L26 Fear of cancer musculoskeletal P23 Adolescent behaviour sympt/compl Z23 Illness prob with family L27 Fear musculoskeletal disease other P24 Specific learning prob Z24 Relationship prob with friend L28 Limited function/disability P25 Phase of life prob adult Z25 Assault/harmful event prob L29 Sympt/compl musculoskeletal other P27 Fear of mental disorder Z27 Fear of social prob L70 Infections musculoskeletal system P28 Limited function/disability Z28 Limited function/disability L71 Malignant neoplasm musculoskeletal P29 Psychological sympt/compl other Z29 Social prob NOS L72 Fracture: radius/ulna

P70 Dementia L73 Fracture:tibia/fibula

P71 Organic psychosis other L74 Fracture: hand/foot bone

P72 Schizophrenia L75 Fracture: femur

P73 Affective psychosis L76 Fracture: other

P74 Anxiety disorder/anxiety state L77 Sprain/strain of ankle

P75 Somatization disorder L78 Sprain/strain of knee

P76 Depressive disorder L79 Sprain/strain of joint NOS

P77 Suicide/suicide attempt L80 Dislocation/subluxation

P78 Neurasthenia/surmenage L81 Injury musculoskeletal NOS

P79 Phobia/compulsive disorder L82 Congenital anomaly musculoskeletal

P80 Personality disorder L83 Neck syndrome

P81 Hyperkinetic disorder L84 Back syndrome without radiating

pain

P82 Post-traumatic stress disorder L85 Acquired deformity of spine

P85 Mental retardation L86 Back syndrome with radiating pain

P86 Anorexia nervosa/bulimia L87 Bursitis/tendinitis/synovitis NOS

P98 Psychosis NOS/other L88 Rheumatoid/seropositive arthritis

P99 Psychological disorders, other L89 Osteoarthrosis of hip

L90 Osteoarthrosis of knee L91 Osteoarthrosis other L92 Shoulder syndrome L93 Tennis elbow L94 Osteochondrosis L95 Osteoporosis

L96 Acute internal damage knee L97 Neoplasm benign/unspecific muscu-

loskeletal

L98 Acquired deformity of limb L99 Musculoskeletal disease, other

sympt: symptom; compl: complaint; prob: problem.

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existence (or absence) of at least one episode labelled with one of the codes of this chapter of cluster. The code L03 “Low back symptoms/complaint” was excluded in the review of the musculoskeletal chapter, due to the definitions of the cases and of the contrast group.

We compared the prevalence of the episodes in the cases and in the contrast group independently during three periods: the year before, the first year after and the second year after the index date.

For each period and each ICPC chapter or cluster selected, univari- ate conditional logistic regressions were implemented, the appropri- ate tool to analyse such matched data. Odds-ratios (OR), their 95%

confidence intervals (CI₉₅) and P values (P) were extracted. We cor- rected the traditional threshold of statistical significance of 5% by the Bonferroni method: because of the implementation of 21 succes- sive tests (7 chapters or clusters of interest, 3 periods), the threshold of 0.05/21 = 0.0024 was chosen.

Data were analyzed with SAS software, 9.2 version.

Results

There were 1511 patients with at least one episode of chronic LBP within the Transition Project who fulfilled the inclusion criteria, and 1511 matched patients could be included in the contrast group (Fig. 1). The median (interquartile range) of the difference between the cases and their matched patients of the contrast group for the index date was 0 day (-1;1) and for date of birth it was 5 days (-359;356).

Women represented 60.1% of the chronic LBP patients. Mean age (standard deviation) at the index date was 49.8 years (15.9) for men and 52.0 (17.0) years for women (Fig. 2). The mean duration of registration in the practice was 11.1 years. The median duration (interquartile range) of the episode of chronic LBP under consideration was 2.1 years (9.6 months–5.2 years). During their period of registration, 83.8% of the cases presented a single episode of chronic LBP, 12.4% two episodes of chronic LBP and 3.8% three or more episodes of chronic LBP. (Table 1).

The prevalence of musculoskeletal problems was found to be significantly higher in the cases than in the patients of the contrast group, with OR (CI₉₅) of 1.39 (1.20–1.61) during the year before the onset of the episode, and 1.56 (1.35–1.81) during the second

year after it, considering the whole musculoskeletal chapter, and OR (CI₉₅) of 2.39 (1.60–3.59) during the first year after the onset, and 2.26 (1.44–3.55) during the second year after it, considering the somatoform symptoms from the musculoskeletal cluster (Table 2).

The prevalence of psychological and social problems was not sta- tistically different between the groups. With regard to the non-musculoskeletal somatoform symptoms, only a non-significant trend for higher prevalence of cardiopulmonary symptoms in the cases in comparison to the contrast group was observed during the year before the onset of the episode, with OR (CI₉₅) of 1.39 (1.01–1.90), P = 0.041.

Discussion

Summary

Our study showed that musculoskeletal problems were significantly more frequent in the patients consulting their GP for chronic LBP in comparison to the non-LBP patients, with moderate association when considering the whole musculoskeletal chapter (ORs between 1.14 and 1.56 depending on the period considered around the beginning of their episodes of LBP), and stronger association when considering the somatoform symptoms related to the musculoskeletal cluster (ORs between 1.33 and 2.39). In contrast, patients with chronic LBP did not more often present psychological disorders, social problems or non-musculoskeletal somatoform disorders than other patients consulting in the same setting.

Comparison with existing literature

Our results are congruent with the literature regarding the musculoskeletal disorders which have been shown as comorbid conditions strongly linked to chronic LBP, whatever the populations studied, the musculoskeletal conditions considered and the methodological characteristics of the studies (10–12,17,18,22). This is congruent also with pathophysiological hypotheses and findings related to multisite pain (23). Our results tend to suggest that the association may be stronger with non-specific musculoskeletal pain such as those considered in the somatoform cluster (thoracic back complaints, muscle pain), rather than with more specific musculoskeletal diagnoses,

Figure 1. Flow chart of the patients included in the study: 1511 cases with chronic low back pain LBP and 1511 matched patients of the contrast group. GP, general practitioner.

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at least during the 2 years following the beginning of the episodes.

Indeed, LBP and other non-specific musculoskeletal pain have common risk factors and similar biological mechanisms of vulnerability to chronic pain, and seeking care for any pain syndrome is depend- ent on comparable behavioural and socio-cultural characteristics (24,25). In contrast, several previous studies reported higher prevalence rates of psychological disorders in people with LBP (10–12,16).

Methodological differences may explain these different results, such as selection of cases with LBP of longer duration (10), with occupational disability (16) or as retrospective designs based on use of questionnaires, which make their results sensitive to participation, recall and declaration bias (11,12). On the other hand, two studies, conducted in primary care and investigating the prevalence of comorbidities in patients with LBP in comparison to other patients consulting in this setting, found only very weak associations between non-specific LBP and depressive or anxiety disorders (17,18). Recent literature has suggested that patients’ social characteristics and environments (such as socio-economic status, low job security, social support, family conflict, compensation system) may influence the occurrence and prognosis of LBP (19,20). However, the prevalence of social problems as a comorbidity leading to medical consultations in patients with chronic LBP has not been extensively studied to our knowledge. Finally, few studies have focused on somatoform disorders in patients with LBP to date. In one of these, the prevalence of chest pain, palpitations, nausea and headaches was found to be higher in patients with LBP than in their matched controls, but the very limited sample size and the specific context of recruitment (male American veterans) make it difficult to draw conclusions regarding the “average” chronic LBP patient (21). Another study evaluating a

wide range of subjective health complaints in workers sickled list for LBP found only higher prevalence of thoracic back complaints and sleep problems in comparison to the general population (12).

Strengths and limitations of our study

Our study was based on a daily primary-care practice-based network, including patients with LBP of varying severity. Our findings are therefore highly relevant to the majority of patients with non- specific LBP, most of whom are seen and followed up by GPs (3).

Systematic and prospective collection of data constitutes another major strength as there is currently no tool to keep a reliable record of the health problems we were interested in over time. It was based on a primary-care practice-based network that has had a long experience in morbidity registration. Securing the quality of the data recorded in regular general practice care is essential for clinical and epidemiological research and for that reason a system of continuous supervision and monitoring of data collection in the practice has been in place. This has consisted of the following: (1) regular training of all GPs and practice assistants in the application of the coding system and application of coding and diagnostic criteria, including regular audit and feedback of vignette cases (26–29), which has minimised differences in coding between participating GPs and (2) comparisons of GPs practice-based diagnostic coding (of diabetes mellitus; migraine–headache; depression) with independently collected diagnostic characteristics of the same patients. From this a high concordance of diagnostic classification was concluded (26,30,31). Moreover, several strategies have been implemented in order to avoid under or over-reporting. In particular, the complete- ness of recording is supervised by the practice assistants, who check the electronic medical records for the coding of health problems of all patients who consulted on the day, or were visited at home or had a telephone consultation. The electronic medical record has also an algorithm to rule-out double coding and implausible coding (32). Finally, regarding the morbidity considered in this study, age and gender standardized prevalence rates issued from the Transition database were compared to the findings of the 2nd Dutch National Study of diseases and interventions in general practice, and were found to be systematically slightly higher in our database, with prevalence rates of 54.5‰ versus 39.7‰ for LBP, of 34.9‰ versus 21.2‰ for depression and of 9.2‰ versus 7.1‰ for anxiety, in the Transition Project and in the 2nd Dutch National Study, respectively (33). This can be explained by a more consistent retainment of cases over time in our longitudinal registration lasting for more than 30 years compared to survey that only recorded a number of years and confirms the reliability of our data.

The ICPC is a standardized classification system designed for primary care, particularly suitable for moderate psychological disorders, social problems and unspecific somatoform disorders that

Figure 2. Distribution by gender and age (in years) of 1511 cases with chronic low back pain (absolute frequencies).

Table 1. Distribution of number of episodes of acute (less than 90 days) and chronic (90 days or more) low back pain among 1511 cases, during their period of registration in the Transition database

No. of cases, % No. of episodes of acute LBP

No episode 1 episode ≥ 2 episodes Total

No. of episodes of chronic LBP 1 episode 780 (51.6) 317 (21.0) 169 (11.2) 1266 (83.8)

2 episodes 81 (5.4) 57 (3.8) 49 (3.2) 187 (12.4)

≥ 3 episodes 23 (1.5) 17 (1.1) 18 (1.2) 58 (3.8)

Total 884 (58.5) 391 (25.9) 236 (15.6) 1511 (100)

No., number; LBP, low back pain.

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are insufficiently taken into account in disease-based classification systems such as the International Classification of Diseases. The coding process is directed at the full characterization of the ‘episode of care’ and GPs record each of the bio-psycho-social dimensions of the health problem presented, as far as it is relevant for the encounter(s) between GP and patient (29). The multi-axial nature of ICPC is especially suitable for recording physical and psychological and social problems. On average, 1.4 codes are recorded on each encounter (34).

Chronic pain generally refers to pain lasting for more than 6 months and responsible for emotional, social or familial impact.

In this study, we considered episodes of LBP lasting for more than 3 months because this threshold has mostly been used, in research as in clinical literature, and this enabled us to compare our results with previous findings and to better fit with current clinical classi- fications (35,36). It is however noticeable that 84% of the patients included actually presented LBP lasting for more than 6 months.

Moreover, we only included patients consulting their GP repeatedly during a period of several months or years. Many people suffer- ing from LBP do not consult any HCP, and seeking care for LBP (especially repeatedly) is often an indicator of greater impact of and poor adaptation to LBP, especially in the emotional, social or familial fields (37). Thus we think that we have addressed as good as was possible the variation in definitions of chronic LBP and included patients that fulfilled criteria that had been used in other primary care studies. In this work, in cases of several episodes of chronic LBP during the patient’s period of practice registration, we only considered the first episode and then we only included each patient once. Indeed, we wanted to focus on patients rather than on episodes, which is more relevant from a clinical perspective. We studied the time frame from 1 year before the onset of the episode to 2 years after it to focus on the specific period around the transition from acute to chronic LBP. We chose to consider somatoform disorders within clusters rather than as isolated symptoms, in order to increase the statistical power of our analyses and because the clustering classification of Fink et al was considered of high rel- evance with regard to our research question (15). We tried to limit the risk of confusion bias by matching our samples according to four variables. Age and gender are known to influence morbidity (38). Different GPs’ practices might reflect different medical characteristics and different socio-cultural environments. Finally, dates of consultation were considered to take into account the tempo- ral variations in morbidity (28), and to select the patients of the contrast group among consulting patients (as were the cases). The probability of having another registered diagnosis is increased when people consult.

Implications for research and practice

Our study strengthens the hypothesis of higher prevalence of musculoskeletal pain in patients with chronic LBP. GPs should consider all the musculoskeletal complaints when they undertake care of patients with persistent LBP. They should be aware that multisite musculoskeletal pain is frequent in patients presenting with LBP and deserves comprehensive preventive and management strategies beyond the only spinal symptoms (24,39). On the other hand, our results show that patients presenting with chronic LBP in primary care actually suffer from some psychosocial problems and somatoform disorders but do not support the view that they present these problems more often than other patients consulting in this setting. The study was based on a quantitative comparison of comorbidity between two groups of patients and does not account for the individual impact of

Table 2. Prevalence of the health problems presented to the general practitioners – comparison between 1511 cases with chronic low back pain and 1511 matched patients from the contrast group by conditional logistic regression Health problem1 year before the index date1 year after the index date2 years after the index date NcaNcoOR(CI95)PNcaNcoOR(CI95)PNcaNcoOR(CI95)P ICPC chapters Musculoskeletal6555341.39 (1.20–1.61)<0.0016325871.14 (0.98–1.32)0.0926494841.56 (1.35–1.81)<0.001 Psychological1831950.93 (0.75–1.15)0.511982190.89 (0.73–1.10)0.282071841.15 (0.93–1.42)0.21 Social961340.71 (0.55–0.93)0.0121221270.96 (0.74–1.24)0.74116961.23 (0.93–1.63)0.15 Clusters of symptoms related to somatoform disorders (PHQ-15) Cardiopulmonarya104781.39 (1.01–1.90)0.04193970.96 (0.71–1.28)0.76100951.05 (0.79–1.40)0.72 Gastrointestinalb79860.91 (0.67–1.25)0.5796771.29 (0.93–1.78)0.1277641.22 (0.87–1.73)0.25 Musculoskeletalc66501.33 (0.92–1.94)0.1383372.39 (1.60–3.59)<0.00161272.26 (1.44–3.55)<0.001 General symptomsd2201921.18 (0.95–1.46)0.131962060.94 (0.76–1.17)0.591911761.10 (0.88–1.38)0.39 ICPC, International Classification of Primary Care; Nca, number of cases; Nco, number of patients in the contrast group; OR (CI95), odds ratio (95% confidence interval); P, P value. aCardiopulmonary cluster: palpitations, chest symptoms, shortness of breath. bGastrointestinal cluster: abdominal pain, nausea, constipation. cMusculoskeletal cluster: thoracic back complaints, muscle pain. dGeneral symptoms cluster: tiredness, fainting, headache, dizziness, sleep disorder. by guest on May 28, 2015http://fampra.oxfordjournals.org/Downloaded from

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comorbid conditions. This was beyond the scope of this study, but similar frequency may translate into marked individual differences in impact. Moreover, this individual impact will determine health status, as health can be defined as the individual “ability to adapt and to self-manage in the face of social, physical and emotional chal- lenges (40)”. Repeated consultations for LBP and/or for comorbid conditions may sometimes be a sign of insufficient or inadequate coping resources. Rather than recommending systematic screening for certain specific comorbidities in patients with chronic LBP, we believe that GPs should remain aware of any comorbid condition and consider with the patient how, in that patient’s individual cir- cumstances and with that patient’s expectations and values, LBP and potential comorbidity may interact and interfere with his/her daily functioning.

Acknowledgements

Many thanks to the patients and the general practitioners who participated in the Transition Project. Many thanks too to Natacha Fouquet, Céline Bouton and Jean-François Hamel for their valuable advice on the statistical analyses, and to Doreen Raine for editing the English language.

Declaration

Funding: none.

Ethical approval: none.

Conflict of interest: none.

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