i need an essay on your own opinion talking about the article attached. like 2 pages without counting the initial page and references

Persistent Pain and Well-being A World Health Organization Study in Primary Care Oye Gureje, MBBS, PhD, FWACP; Michael Von Korff, ScD;

Gregory E. Simon, MD, MPH; Richard Gater, MRCPsych

Context.— There is little information on the extent of persistent pain across cul- tures. Even though pain is a common reason for seeking health care, information on the frequency and impacts of persistent pain among primary care patients is in- adequate.

Objective.— To assess the prevalence and impact of persistent pain among pri- mary care patients.

Design and Setting.— Survey data were collected from representative samples of primary care patients as part of the World Health Organization Collaborative Study of Psychological Problems in General Health Care, conducted in 15 centers in Asia, Africa, Europe, and the Americas.

Participants.— Consecutive primary care attendees between the age of major- ity (typically 18 years) and 65 years were screened (n = 25 916) and stratified ran- dom samples interviewed (n = 5438).

Main Outcome Measures.— Persistent pain, defined as pain present most of the time for a period of 6 months or more during the prior year, and psychological ill- ness were assessed by the Composite International Diagnostic Interview. Disabil- ity was assessed by the Groningen Social Disability Schedule and by activity- limitation days in the prior month.

Results.— Across all 15 centers, 22% of primary care patients reported persis- tent pain, but there was wide variation in prevalence rates across centers (range, 5.5%-33.0%). Relative to patients without persistent pain, pain sufferers were more likely to have an anxiety or depressive disorder (adjusted odds ratio [OR], 4.14; 95% confidence interval [CI], 3.52-4.86), to experience significant activity limitations (adjusted OR, 1.63; 95% CI, 1.41-1.89), and to have unfavorable health perceptions (adjusted OR, 1.26; 95% CI, 1.07-1.49). The relationship between psychological disorder and persistent pain was observed in every center, while the relationship between disability and persistent pain was inconsistent across centers.

Conclusions.— Persistent pain was a commonly reported health problem among primary care patients and was consistently associated with psychological illness across centers. Large variation in frequency and the inconsistent relation- ship between persistent pain and disability across centers suggests caution in drawing conclusions about the role of culture in shaping responses to persistent pain when comparisons are based on patient samples drawn from a limited num- ber of health care settings in each culture.

JAMA. 1998;280:147-151

PAIN is one of the most common1 and among the most personally compelling reasons for seeking medical attention.

People seek health care for pain not only for diagnostic evaluation and symptom relief, but also because pain interferes with daily activities, causes worry and emotional distress, and undermines con- fidence in one’s health. When pain per- sists for weeks or months, its broader effects on well-being can be profound. Psychological health and performance of social responsibilities in work and family life can be significantly impaired.2

Despite evidence that pain affects well-being, little is known about how

common persistent pain is among pri- mary care patients. There is evidence that the effects of persistent pain on psy- chological health and functional status are similar for pain problems at different anatomical sites.3 However, it is not known whether impaired emotional well-being and increased disability are consistent correlates of persistent pain, or whether the impacts of persistent pain on well-being are consistent across cultures. Several recent studies have compared pain perceptions and coping across cultures,4-6 but cross-cultural re- search on pain has typically studied rela- tively small numbers of patients in con- venience samples. Comparison groups of pain-free controls have often been lacking.

This article reports data from a World Health Organization (WHO) survey of primary care patients, the WHO Col- laborative Study of Psychological Prob- lems in General Health Care.7 As part of a broader assessment of health and men- tal health status, this cross-national sur- vey collected information on persistent pain. This report estimates the preva- lence of persistent pain among primary care patients in different countries, and determines the association of persistent pain with health perceptions, psycho- logical distress, and activity limitations. (Persistent pain was defined as pain present most of the time for a period of 6 months or more during the prior year.) This article provides the first cross- national data on the prevalence of per- sistent pain among primary care pa- tients, and is also the first large-scale cross-national study to assess whether persistent pain shows consistent rela- tionships to impaired well-being and functioning among primary care pa- tients in many different countries. While this study was not designed or intended to test specific hypotheses about cross- cultural differences in the prevalence or impacts of persistent pain, it provides new information on the frequency and the impacts of persistent pain among primary care patients in a range of cul- tural settings.

From the Department of Psychiatry, University College Hospital, Ibadan, Nigeria (Dr Gureje); Center for Health Studies, Group Health Cooperative of Puget Sound, Seattle, Wash (Drs Von Korff and Simon); and Depart- ment of Psychiatry, Withington Hospital, West Didsbury, Manchester, England (Dr Gater). Dr Gureje is now with the Department of Psychiatry, Royal Melbourne Hospital, Parkville, Australia.

Corresponding author: Michael Von Korff, ScD, Center for Health Studies, Group Health Cooperative of Puget Sound, 1730 Minor Ave, Suite 1600, Seattle, WA 98101.

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METHODS

TheWHOCollaborativeStudyofPsy- chological Problems in General Health Care was conducted at 15 centers in 14 countries.7,8 A detailed account of the methods of this study is provided else- where9; results from this study concern- ingtherelationshipbetweenpsychologi- cal illness and disability were previously reported in this journal.10 The 15 partici- pating centers in 14 different countries were selected to represent broad diver- sity of culture and socioeconomic devel- opment. Centers were selected on the basis of previous successful collabora- tion with WHO, experience with re- search in primary care settings, access to primary care patient populations, availability of appropriately skilled per- sonnel to ensure full adherence to the study protocol, and approval for the study by local ethics committees. Each center was required to identify health care facilities that could be regarded as prototypical of primary health care ser- vices in that country.

The study population was consecutive patients attending the participating pri- mary care facilities, including both new andreturningpatients.Patientswere in- cluded if they were between the age of majority (typically 18 years) and 65 years. Eligible subjects were not too ill to participate, had a fixed address, were attending the clinic for a medical consul- tation, and gave informed consent. In- formation on the presenting problems of patients enrolled in the study is present- ed for each center elsewhere.7 The 12- item General Health Questionnaire (GHQ)11 was administered as a screen- ing instrument to obtain a stratified random sample in which patients who were psychologically distressed were sampledwithhigherprobabilitythanpa- tients who were not distressed.

A total of 25 916 patients were suc- cessfully screened. This represented a response rate of 96%. Patients were se- lected for the second-stage assessment using stratified random sampling based on their GHQ score. Using center-spe- cific GHQ score norms determined from a large pilot test in each center,9 patients were placed in a low GHQ score stratum (approximately 60% of consecutive pa- tients in a particular center), a medium GHQ score stratum (20% of patients), or a high GHQ score stratum (20% of pa- tients).ThehighGHQscorestratumcor- responds to a moderate to severe level of psychologicaldistress, themediumGHQ stratum to a mild level of distress, and the low GHQ score stratum to a low level of psychological distress. All high GHQ scorers, 35% of medium GHQ scorers, and 10% of low GHQ scorers were ran-

domly sampled for the second-stage as- sessments.Theanalysisofdata fromthis stratified random sampling scheme was weighted taking the sample selection probabilities in each stratum into ac- count (as explained below), so that un- biased estimates were obtained for the population of consecutive primary care attendees in each center. Sampled pa- tients were interviewed at a place of their choice, commonly their home. Of 8729 eligible patients, 5447 completed the second-stage assessments (average response rate, 62%).

Assessment Patients sampled for the second-stage

evaluation were assessed by highly trained interviewers using the WHO primary care version of the Composite International Diagnostic Interview (CIDI).12 This version assessed persis- tent pain in addition to identifying psy- chological disorders (eg, anxiety and de- pressive disorders) defined according to International Statistical Classification of Diseases, 10th Revision (ICD-10)13 di- agnostic criteria. Using this question- naire,apainproblem wasdefinedascur- rent and persistent if pain was present most of the time for a period of 6 months or more during the prior year. To elimi- nate insignificant aches and pains, pa- tients needed to report that at some time during their lifetime they talked to ei- ther a physician or other health profes- sional about the pain, had taken medica- tion for the pain more than once, or had reported that the pain had interfered with life or activities a lot. Although the CIDI obtained ratings of whether per- sistent pain was “medically explained” or not, these ratings were ignored for the purposes of this report. Review of these ratings indicated that the ratings of what conditions were medically ex- plained were inconsistent across cen- ters. Moreover, understanding the fre- quency of persistent pain is clinically important whether the pain is medically explained or not.

Disability was assessed using the “Oc- cupational Role” section of the Social Disability Schedule (SDS).14 The SDS is a semistructured interview that rates disability on the basis of work role per- formance relative to cultural expecta- tions. Daily work activities (including gainful employment, volunteer work, or housekeeping), activities directed at se- curing a job for individuals not employed (study and job searching), and the struc- turing of daily activities for retired indi- viduals were assessed. Interviewer rat- ings were made on a 4-point scale: 0 (no disability), 1 (mild disability), 2 (moder- ate disability), and 3 (severe disability). Interviewer-observer reliability of the

SDSoccupationalrolewasassessedwith 19 videotaped interviews circulated across the centers. An overall k of 0.85 was obtained, with a range of 0.72 and 0.93 on items.9 In addition, each subject was asked the number of days in the pre- vious month they had been unable to carry out their usual activities.15 Pa- tients rated their overall health status as excellent, very good, good, fair, or poor.

The physician seeing each patient in thesamplecompletedanencounter form that included a rating of the patient’s physical health status at the time of the visit. Patients were rated by their phy- sicians as completely healthy, having some symptoms but subclinical physical illness, mild physical illness, moderate physical illness, or severe physical ill- ness. All participating physicians were instructed in the use of the encounter form in practice sessions with the local investigators. These ratings were used to control for severity of physical illness in multivariate analyses.

At non–English-speaking centers, questionnaires were translated by a panel of local bilingual experts. Back- translations to English were checked centrally at WHO. At least 1 English- speaking investigator from every center participated in a 5-day joint training ses- sion intheuseof the instruments. Ingen- eral, the interviewers who assessed study subjects had mental health train- ing and experience.

Data Analysis Because this study used a stratified

random sampling plan, the estimates we report are based on weighted data. Weighteddatafromthesecond-stageas- sessmentprovideunbiasedestimatesfor the base population of consecutive pri- mary care attendees. The weighting ac- counts for the stratified sampling scheme and differentials in response rate by GHQ stratum, sex, and center to controlnonresponsebiasassociatedwith these variables.9

Whether there was greater variation in the prevalence rate of persistent pain across centers than expected by chance was evaluated by a Wald statistic esti- mated for the center indicator variables from a logistic regression model that controlled for age and sex. Odds ratios (ORs) estimating the effect of sex (wom- en vs men) and their confidence inter- vals (CIs) were estimated for each cen- ter and for all centers combined. Whether ORs differed from unity more than expected by chance was evaluated by the Wald statistic. Using logistic re- gression, we contrasted the rates of hav- ingthe impairmentsof interest (eg,work disability) for persons with persistent

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pain vs those without persistent pain af- ter controlling for center, sex, age, phy- sician-rated physical health status, and whether a CIDI-diagnosed anxiety or depressive disorder was present in the prior month. For these analyses, we re- port the estimated ORs, CIs, and P val- ues for all centers combined. In addition, we report the percentage with each im- pairment comparing patients with and without persistent pain for each center, and indicate whether the difference was greater than expected by chance at the .05 significance level for a 2-sided test. These significance tests were based on Wald statistics from logistic regression models controlling for age, sex, physi- cian-rated severity of physical disease, and the presence of a depressive or anxi- ety disorder.

RESULTS Prevalence of Persistent Pain

Persistent pain was common among primary care patients across a wide range of settings in different countries. The prevalence of persistent pain for all centers combined was 21.5%, with prevalence rates varying from 5% to 33%. Sex-specific prevalence rates are shown in Table 1, with the centers or- dered from the highest overall preva- lence rate to the lowest. The difference in prevalence rates across centers was highly significant after adjusting for age and sex (Wald statistic = 217.7, df = 14, P,.001).

Among the European centers, Ath- ens, Greece (12%), and Verona, Italy (13%), had relatively low prevalence rates, while the remaining centers in Germany, France, the Netherlands, and England were found to have persistent pain prevalence rates in excess of 20%. The 2 Asian centers (Nagasaki, Japan, and Shanghai, China) had relatively low

prevalence rates of persistent pain (12% and13%,respectively),whilethe2South American centers (Rio de Janeiro, Bra- zil, and Santiago, Chile) had relatively high prevalence rates (31% and 33%, re- spectively). The center in Ibadan, Nige- ria, had the lowest prevalence rates of persistent pain of any center for both men and women.

As shown in Table 1, persistent pain was significantly more common among women than men based on a pooled es- timate for the 15 participating centers, with 25% of women compared with 16% of men reporting persistent pain. After adjusting for age, the prevalence of per- sistent pain was significantly higher among women than men in 9 of the 15 centers.

Anatomical Site As shown in Table 2, among patients

with persistent pain, the 3 most com- monly reported anatomical pain sites (in order of frequency) were back pain, headache, and joint pain. The large ma- jority (68%) of primary care patients with persistent pain reported pain in at least 2 anatomical sites (Table 2). Be- causepainwastypicallyreportedatmul- tiple sites, the remaining analyses con- cern persistent pain without differentia- tion by anatomical site.

Persistent Pain and Well-being Persons with persistent pain were

substantiallymore likelytohaveananxi- etyordepressivedisordermeeting ICD- 10 diagnostic criteria than persons not experiencing persistent pain (Table 3). After adjusting for center, age, sex, and physician-rated severity of physical dis- ease, the odds of having a psychological disorder meeting diagnostic criteria among persons with persistent pain showed a 4-fold increase over those not

affected by persistent pain. The associa- tion of persistent pain was not specific to depression, as both anxiety and depres- sive disorders showed a comparable as- sociation with persistent pain.16

For all 15 centers combined, the pres- ence of persistent pain was associated withamodest increase inthe likelihoodof patients rating their overall health as fair orpoor(Table3).Unfavorablehealthper- ceptions were reported by 33% of those with persistent pain compared with 21% of those without persistent pain.

Work role disability was assessed by a semistructured interview protocol tak- ing cultural norms into account in deter- mining the extent of disability.14 Across the participating centers, 31% of those withpersistentpainwereratedashaving moderate to severe work role interfer- ence, compared with 13% among those without persistent pain. After adjusting for center, age, sex, psychological disor- der status, and physician-rated severity of physical disease, the odds of work dis- ability showed a 2-fold increase among thosewithpersistentpain(Table3).Simi-

Table 1.—Subjects With Persistent Pain by Sex, World Health Organization Psychological Problems in General Health Care Survey, 1991-1992 (Weighted Data)

Participating Center (No. of Cases/No. of Subjects)

Men, % (n = 1919)

Women, % (n = 3519)

All Patients, % (n = 5438)

Adjusted OR (95% CI)* P

Santiago, Chile (130/274) 13.5 40.8 33.0 3.87 (1.87-8.02) ,.001

Berlin, Germany (140/400) 27.1 36.8 32.8 1.44 (0.92-2.26) .11

Rio de Janeiro, Brazil (149/393) 17.6 35.8 30.8 2.38 (1.36-4.18) .002

Ankara, Turkey (154/400) 21.1 32.9 28.9 1.77 (1.08-2.93) .02

Paris, France (124/405) 16.9 37.3 26.5 3.15 (1.96-5.06) ,.001

Mainz, Germany (130/400) 28.5 24.7 26.3 0.86 (0.55-1.35) .51

Groningen, the Netherlands (127/340) 19.7 29.3 25.5 1.84 (1.06-3.20) .03

Manchester, England (149/428) 26.4 18.1 20.7 0.68 (0.41-1.11) .12

Bangalore, India (109/398) 14.1 23.8 19.0 1.53 (0.89-2.62) .13

Seattle, Wash (88/373) 9.4 21.2 17.3 2.80 (1.40-5.61) .004

Verona, Italy (49/250) 3.9 18.6 13.3 5.81 (1.90-17.82) .002

Shanghai, China (106/576) 8.7 14.9 12.6 1.97 (1.11-3.50) .02

Athens, Greece (34/196) 5.4 15.5 12.0 3.47 (1.06-11.33) .04

Nagasaki, Japan (53/336) 9.2 14.2 11.8 1.68 (0.84-3.37) .14

Ibadan, Nigeria (27/269) 6.2 5.3 5.5 0.92 (0.28-2.95) .88

All centers (1569/5438) 16.2 24.8 21.5 1.69 (1.47-1.95) ,.001

*The adjusted odds ratio (OR) measures the risk of having persistent pain among women relative to the risk of persistent pain among men, after adjusting for age. The all centers OR was adjusted for age and center. CI indicates confidence interval.

Table 2.—Subjects Reporting Current Pain at Different Anatomical Sites and the Number of Anatomical Sites With Pain Among Subjects With Persistent Pain, World Health Organization Psychological Problems in General Health Care Survey, 1991-1992 (Weighted Data)

Variable Subjects Reporting

Current Pain, %

Anatomical site Back pain 47.8 Headache 45.2 Joint pain 41.7 Arms or legs 34.3 Chest 28.9 Abdominal pain 24.9 Pain elsewhere 11.7

No. of anatomical sites 1 32.1 2 27.5 3 22.8 $4 17.5

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larly, for data pooled across centers, pa- tients with persistent pain were more likely to report 3 or more days in the prior month when they were unable to carry out their usual activities (Table 3).

Consistency of Results Across Centers

We examined the consistency of dif- ferences in psychological disorder, self- rated health, work role disability, and activity-limitation days for persons with and without persistent pain across the participating centers (Table 4). For all 15 centers, the difference in the percent- age of patients with a depressive or anxi- ety disorder between patients with and without persistent pain was statistically significant. In contrast, the association of unfavorable ratings of health status with persistent pain was less robust across centers. This difference was sta- tistically significant for only 5 of the 15 centers (significant differences are indi- cated by numbers in boldface type in Table 4). Interviewer-rated work dis-

ability was significantly more common among those with persistent pain for 5 of the 15 centers, and patients with persis- tent pain were significantly more likely to report 3 or more days of activity limi- tation in the prior month for 6 of the 15 centers. For the centers with nonsignifi- cant differences in work disability or in activity-limitation days between those with and without persistent pain, pa- tients with persistent pain almost al- ways had a higher percentage with ac- tivity limitation than patients without persistent pain.

COMMENT This is the first large-scale cross-na-

tional study of persistent pain among primary care patients in which standard methods were applied to estimate its prevalence and impacts in a wide range ofcountries.Eventhoughtherewassub- stantial variation in prevalence rates across centers, persistent pain was a common problem among patients con- sulting primary care physicians in every

participating center. It should be noted that the patients eligible for this study were seeking professional health care, and that the care settings were gener- ally in urban areas. Persons seeking health care are likely to have higher prevalence rates of persistent pain than ageneralpopulationsample. Inaddition, the patient populations studied may dif- fer from those seeking services from tra- ditional providers or from persons seek- ing health care in rural areas. However, the kinds of primary care settings in- cluded in this study provide health care services to large segments of the popu- lation in each of the countries included in this study.

This study was not designed to ex- plain cross-cultural differences in the prevalence or cross-cultural differences in the impact of persistent pain. How- ever, the large variation in rates of occurrence of persistent pain across cen- ters, the inconsistency in the relation- shipbetweenpersistentpainanddisabil- ity, and the lack of a readily explainable pattern for the variation in results should give pause. This variability, and the lack of any clear pattern to the varia- tion across centers, suggests that it may be difficult to draw meaningful conclu- sions about cultural differences from samples of patients drawn from a limited number of health care settings in each culture being studied. Prior cross-cul- tural research on chronic pain has often used samples of pain patients smaller than the numbers available for the indi- vidual centers participating in this study. In this study, 10 of the 15 partici- pating centers had over 100 patients withpersistentpain(Table1).Mostprior cross-national studies of pain patients

Table 3.—Indicated Quality-of-Life Impairment by Persistent Pain Status and the Adjusted Odds Ratio (OR) for Impairment for Persons With vs Without Persistent Pain, World Health Organization Psychological Problems in General Health Care Survey, 1991-1992 (Weighted Data)

Quality of Life Impairment Persistent Pain

Present, % Persistent Pain

Absent, % Adjusted OR

(95% CI)* P ICD-10 definition of anxiety

or depressive disorder† 33.7 10.1 4.14 (3.52-4.86) ,.001

Health status rated fair to poor‡ 33.4 20.9 1.26 (1.07-1.49) .006

Interviewer-rated interference with work performance‡

31.4 13.0 2.12 (1.79-2.51) ,.001

$3 Activity-limitation days in prior month‡

41.2 26.0 1.63 (1.41-1.89) ,.001

*The adjusted OR measures the risk of the indicated form of impairment among persons with persistent pain relative to those without persistent pain, after adjusting for covariates. CI indicates confidence interval.

†The ORs were adjusted for center, age, sex, and physician-rated severity of physical disease. ICD-10 indicates International Statistical Classification of Diseases, 10th Revision.

‡The ORs were adjusted for center, age, sex, physician-rated severity of physical disease, and presence of an anxiety or depressive disorder.

Table 4.—Indicated Quality-of-Life Impairment Comparing Persons With and Without Persistent Pain, World Health Organization Psychological Problems in Gen- eral Health Care Survey, 1991-1992 (Weighted Data)*

Participating Center

Depressive or Anxiety Disorder Health Rated Fair to Poor

Interviewer-Rated Work Interference $3 Activity-Limitation Days

With Pain, % Without Pain, % With Pain, % Without Pain, % With Pain, % Without Pain, % With Pain, % Without Pain, %

Santiago, Chile 60.1 27.9 31.5 13.3 25.5 13.1 9.0 12.0

Berlin, Germany 23.1 8.8 48.1 24.0 22.1 15.4 38.5 26.5

Rio de Janeiro, Brazil 52.5 20.1 11.6 11.9 15.2 13.2 38.7 28.4

Ankara, Turkey 29.4 5.3 46.9 27.2 13.1 3.1 39.3 22.8

Paris, France 34.7 15.8 22.8 12.8 19.4 13.6 27.4 22.6

Mainz, Germany 27.6 11.5 51.4 37.8 37.7 18.3 50.3 33.1

Groningen, the Netherlands 37.8 10.6 22.3 10.5 51.1 20.7 42.7 35.7

Manchester, England 41.0 14.5 36.7 11.3 100.0 8.6 71.8 29.9

Bangalore, India 36.0 9.3 43.1 29.5 33.5 11.9 61.5 37.9

Seattle, Wash 18.5 5.4 27.8 5.4 22.6 6.0 48.8 20.7

Verona, Italy 27.5 4.0 40.9 29.7 11.9 7.5 23.5 16.3

Shanghai, China 13.3 3.9 21.8 26.5 28.9 16.8 31.6 17.0

Athens, Greece 39.1 14.6 8.3 12.8 25.7 8.5 53.5 25.2

Nagasaki, Japan 12.8 5.8 44.1 38.1 37.0 9.3 49.6 21.7

Ibadan, Nigeria 26.7 5.2 6.9 13.3 21.4 26.6 46.7 40.6

All centers 33.7 10.1 33.4 20.9 31.4 13.0 41.2 26.0

*Percentages in boldface type indicate that the percentage with the indicated quality-of-life impairment among persons with persistent pain exceeds those without persistent pain at P ,.05, for a 2-sided test. Significance of differences between persons with and without persistent pain was tested by logistic regression adjusting for age, sex, physician-rated severity of physical disease, and (except for the comparison for psychological illness) the presence of a depressive or anxiety disorder.

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have sampled patients from a limited number of health care settings and have lacked a pain-free control group. This points to the difficulty in differentiating true cultural differences from other sources of variation not related to cul- ture. Sources of variation that could be confused with cultural differences may include random variation, variation due to sociodemographic differences, varia- tion due to characteristics of the particu- lar care settings included, and variation in the application of study methods across centers.

Differences in prevalence rates from surveys in different countries are often difficult to compare because of lack of comparability of study methods.17,18 In this study, uniform sampling and assess- ment procedures were used to reduce variation due to study methods. How- ever, it is difficult to guarantee uniform application of study methods in a widely dispersed multicenter study conducted in many different languages. It was only possible to study a limited number of care settings in each locale, so differences due to care setting are confounded with cul- tural differences. For these reasons, our results regarding differences in preva- lence and impacts of persistent pain be- tween countries are exploratory. While the differences in prevalence rates across centers were statistically significant af- ter controlling for age and sex differ- ences, this variation may be due to so- ciodemographic, care setting, and/or methodological differences rather than culture.

The observation that women tended to have elevated rates of persistent pain relative to men has been reported by oth-

ers.17-20 This study does not shed light on reasons for this sex difference, other than tosuggest that it isnotuniquetoWestern societies. Prior research has suggested sex differences in pain prevalence for some anatomical sites and not for oth- ers,19,20 butthisstudydidnotexaminesite- specific prevalence rates by sex.

Overall, persistent pain was associated with marked reductions in several differ- ent indicators of well-being, particularly psychological illness and interference with activities. Differences in self-rated health status were of smaller magnitude, although they were statistically signifi- cant for all centers combined. In the pooled analysis, patients with persistent pain were more likely to have impaired work role functioning and to have missed 3 or more days from their usual activities in the prior month. While patients with persistent pain were more disabled than thosewithoutpersistentpainoverall, this association was not consistently statisti- cally significant across the participating centers. However, the trend was in the same direction in almost every center for both disability measures.

The commonly reported association of persistent pain with psychological ill- ness16,17,21,22 was confirmed by this study. Asignificantassociationwasfoundinev- eryparticipatingcenter.Thisstudydoes not address the direction of causality between persistent pain and affective illness. Prior studies have yielded dif- fering results on this question.16,23,24 The results of this study indicate that psy- chological disorder is a common corre- late of persistent pain, and that this association is observed in a wide range of cultural settings.

In conclusion, persistent pain was com- monamongprimarycarepatientsinmany differentcultures.Acrossall centers,per- sistent pain was associated with psycho- logical disturbance and significant ac- tivity limitations. Further research is needed to better understand cross-na- tional variation in the prevalence of per- sistent pain, and variation in the effects of persistent pain on well-being and func- tioning. The results of this study point to thedifficultyindrawingconclusionsabout cultural differences in the frequency or the impacts of persistent pain from mod- estsamplesof painpatientssampledfrom a limited number of care settings in a par- ticular culture. While further research is needed, this study shows that persistent pain isacommonproblemamongprimary care patients in a wide range of cultural settings.

Dr Von Korff’s work on this report was supported in part by grant DE08773-10 from the National In- stitutes of Health, Bethesda, Md.

The data reported in this article were collected as part of a World Health Organization’s Psychological Problems in General Health Care project. Partici- pating investigators include O. Ozturk and M. Rezaki, Ankara, Turkey; C. Stefanis and V. Mavreas, Athens, Greece; S. M. Channabasavana and T. G. Sriram, Bangalore, India; H. Helmchen and M. Linden, Berlin, Germany; W. van der Brink and B. Tiemens, Groningen, the Netherlands; M. Olatawura, Ibadan, Nigeria; O. Benkert and W. Maier, Mainz, Germany; S. Kisely, Manchester, England; Y. Nakane and S. Michitsuji, Nagasaki, Japan; Y. Lecrubier and P. Boyer, Paris, France; J. Costa e Silva and L. Villano, Rio de Janeiro, Brazil; R. Florenzano and J. Acuna, Santiago, Chile; G. E. Simon, Seattle, Wash; Y. He-Quin and X. Shi Fu, Shanghai, China; and M. Tansella and C. Bellan- tuono, Verona, Italy. The study advisory group include J. Costa e Silva, D. P. Goldberg, Y. Lecru- bier, Michael Von Korff, and H-U Wittchen. Coor- dinating staff at World Health Organization head- quarters include N. Sartorius and T. B. Ustun.

References

1. Schappert SM. National Ambulatory Medical Care Survey: 1989 summary. National Center for Health Statistics. Vital Health Stat 13. 1992; No. 11. 2. Turk DC, Rudy TE. Toward an empirically de- rived taxonomy of chronic pain patients: integration of psychological assessment data. J Consult Clin Psychol. 1988;56:233-238. 3. Von Korff M, Ormel J, Keefe FJ, Dworkin SF. Grading the severity of chronic pain. Pain. 1992;50: 133-149. 4. BatesMS,Rankin-HillL,Sanchez-AyendezM,Men- dez-Bryan R. A cross-cultural comparison of adapta- tion to chronic pain among Anglo-Americans and na- tive Puerto Ricans. Med Anthropol. 1995;16:141-173. 5. Moore R. Ethnographic assessment of pain cop- ing perceptions. Psychosom Med. 1990;52:171-181. 6. Sanders SH, Brena SF, Spier CJ, Beltrutti D, McConnell H, Quintero O. Chronic low back pain patients around the world: cross-cultural similari- ties and differences. Clin J Pain. 1992;8:317-323. 7. Ustun TB, Sartorius, N, eds. Mental Illness in GeneralHealthCare:AnInternationalStudy. New York, NY: John Wiley & Sons Inc; 1995. 8. Sartorius N, Ustun TB, Costa e Silva JA, et al. An international study of psychological problems in pri- mary care. Arch Gen Psychiatry. 1993;50:819-824. 9. Von Korff M, Ustun TB. Methods of the WHO Collaborative Study on Psychological Problems in General Health Care. In: Ustun TB, Sartorius N, eds. Mental Illness in General Health Care: An In-

ternational Study. New York, NY: John Wiley & Sons Inc; 1995. 10. Ormel J, Von Korff M, Ustun TB, Pini S, Korten A, Oldehinkel T. Common mental disorders and dis- ability across cultures. JAMA. 1994;272:1741-1748. 11. Goldberg D, Williams P. A Users’ Guide to the General Health Questionnaire: GHQ. Windsor, Berkshire, England: NFER-NELSON Publishing Co Ltd; 1988. 12. World Health Organization. Composite Inter- national Diagnostic Interview. Geneva, Switzer- land: World Health Organization, Division of Men- tal Health; 1989. Publication MNH/NAT/89. 13. World Health Organization. International Sta- tistical Classification of Diseases, 10th Revision (ICD-10). Geneva, Switzerland: World Health Or- ganization; 1992. 14. Wiersma D, DeJong A, Ormel J. The Groningen Social Disability Schedule: development, relation- ship with ICIDH, and psychometric properties. Int J Rehabil Res. 1988;11:213-224. 15. Von Korff M, Ustun TB, Ormel J, Kaplan I, Si- mon G. Self-report disability in an international pri- mary care study of psychological illness. J Clin Epi- demiol. 1996;49:297-303. 16. Von Korff M, Simon G. The relationship of pain anddepression.BrJPsychiatry.1996;168(suppl30): 101-108. 17. Magni G, Marchetti M, Moreschi C, Merskey H, Luchini SR. Chronic musculoskeletal pain and de-

pressive symptoms in the National Health and Nu- trition Examination, I: epidemiological follow-up study. Pain. 1993;53:163-168. 18. Andersson HI, Ejlertsson G., Leden I, Rosen- berg C. Chronic pain in a geographically defined general population: studies of differences in age, gender, social class, and pain localisation. Clin J Pain. 1993;9:174-182. 19. Von Korff M, Dworkin SF, LeResche L, Kruger A. An epidemiologic comparison of pain complaints. Pain. 1988;32:173-183. 20. Le Resche L, Von Korff M. Epidemiology of chronic pain. In: Block AR, Kremer EF, Fernandez E, eds. Handbook of Pain Syndromes: Biopsycho- social Perspectives. Mahwah, NJ: Lawrence Er- baum Associates Inc. In press. 21. Roy R, Thomas M, Matas M. Chronic pain and depression: a review. Compr Psychiatry. 1984;25: 96-105. 22. Romano JM, Turner JA. Chronic pain and de- pression: does the evidence support a relationship? Psychol Bull. 1985;97:18-34. 23. Polatin PB, Kinney RK, Gatchel RJ, Lillo E, Mayer TG. Psychiatric illness and chronic low-back pain: the mind and the spine—which goes first? Spine. 1993;18:66-71. 24. Von Korff M, LeResche L, Dworkin SF. First onset of common pain symptoms: a prospective study of depression as a risk factor. Pain. 1993;55: 251-258.

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study suspect. I have coauthored publications and presented abstracts based on pharmaceutical industry–sponsored clini- cal trials for more than a decade. In no case were the results misrepresented. The articles cited by Barnes and Bero do not support their conclusion because of selection bias that is so different from the careful methods they used to support the primary claim of their article.

Pharmaceutical data are scrutinized by the US Food and Drug Administration (FDA) to a degree that is unimaginable to those outside the industry. When a study is used to gain approval for a drug indication, the FDA reviews all of the data, conducts independent analyses of the data, audits the sites from which the data were gathered, verifies that the data have been accurately reported, and often presents its findings publicly at advisory committees. The FDA audit reports are public information.

Although authors often question the integrity of pharma- ceutically sponsored research, the integrity of research spon- soredbygovernmentalorotherprivateorganizations israrely questioned. Ignoring the possibility that the granting agen- cies may have specific agendas for the research they sponsor, there are substantial pressures on scientists to publish and a well-known bias against publication of negative data. I wonder how publications not sponsored by the pharmaceutical indus- try would stand up to FDA-style scrutiny.

To the shame of the pharmaceutical industry, some compa- nies have suppressed data from publication4 or published data in a manner not consistent with that reviewed by the FDA.5 Such cases have become public embarrassments that received widespread coverage in the popular press. These examples aretheexception,nottherule.Physiciansandthepublicshould be assured of the validity of pharmaceutical clinical research and of the integrity of those who conduct and oversee it.

Kenneth J. Gorelick, MD DuPont Merck Pharmaceutical Company Wilmington, Del

1. Barnes DE, Bero LA. Why review articles on the health effects of passive smoking reach different conclusions. JAMA. 1998;279:1566-1570. 2. Cho MK, Bero LA. The quality of drug studies published in symposium proceed- ings. Ann Intern Med. 1996;124:485-489. 3. Rochon PA, Gurwitz JH, Simms RW, et al. A study of manufacturer-supported tri- als of nonsteroidal anti-inflammatory drugs in the treatment of arthritis. Arch Intern Med. 1994;154:157-163. 4. Rennie D. Thyroid storm [published correction appears in JAMA. 1997;277:1762]. JAMA. 1997;277:1238-1243. 5. Wenzel RP. Anti-endotoxin monoclonal antibodies—a second look. N Engl J Med. 1992;326:1151.

In Reply.—Every independent scientific body that has re- viewed the scientific evidence has concluded that exposure to passive smoke is harmful to health.1 As the title of our article suggests, the goal of our study was to determine why many published review articles reach conclusions that differ from these independent scientific bodies. We investigated several factors in addition to quality and funding source that might be associated with outcome, including peer review, date of pub- lication, and topic of review. The only factor associated with the conclusion of a review article was the affiliation of its au- thor: 94% of reviews by tobacco industry–affiliated authors concluded that passive smoking is not harmful compared with 13% of reviews by authors without tobacco-industry affiliations.

We did not define tobacco-industry affiliation “generously,” as Dr Heck states. Rather, we used strict, well-defined crite- ria: an author must have received funding from the tobacco industry, submitted a statement on behalf of the tobacco in- dustryregardingtheEnvironmentalProtectionAgency’srisk assessment on passive smoking, or participated in (not simply attended, as misstated by Heck) at least 2 tobacco-industry– sponsored symposia. Moreover, our data are not “testament to the legitimate diversity of scientific opinion on the topic of ETS,” as Heck suggests. Rather, our findings suggest that, among scientists who are not affiliated with the tobacco in- dustry, there is consensus that passive smoking is harmful. The only diversity of opinion comes from the authors with tobacco-industry affiliations.

Dr Gorelick takes issue with 2 articles we cited to support our statement that original research articles sponsored by the pharmaceutical industry tend to draw proindustry conclu- sions. A careful reading of both articles reveals that they do support our statement. The article by Cho and Bero2 did not examine“onlyarticles fromsymposiasponsoredbysingledrug companies.” It examined 127 articles from symposia (of which 39% were sponsored by a single drug company) and 45 articles from peer-reviewed journals: 98% of the articles with drug company support favored the drug of interest compared with 79% of the articles without drug company support (P,.01).

In the article by Rochon et al,3 the analysis was limited to manufacturer-associated trials due to “the scarcity of non- manufacturer-associated trials.” However, the authors found that the manufacturer-associated drug was reported as com- parable or superior to the comparison drug in all cases and that the claims often were not supported by trial data.

We do not suggest that industry-sponsored research is al- ways biased. However, to our knowledge, every study that has examined the relationship between sponsorship and outcomes has found that industry-sponsored research is more likely to draw proindustry conclusions than non–industry-sponsored research. We recommend that financial interests always shouldbedisclosedandthatreadersofresearcharticlesshould consider these disclosures when deciding how to judge an ar- ticle’s conclusions.

Lisa A. Bero, PhD University of California, San Francisco Deborah Barnes University of California, Berkeley

1. Barnes DE, Bero LA. Why review articles on the health effects of passive smoking reach different conclusions. JAMA. 1998;279:1566-1570. 2. Cho MK, Bero LA. The quality of drug studies published in symposium proceed- ings. Ann Intern Med. 1996;124:485-489. 3. Rochon PA, Gurwitz JH, Simms RW, et al. A study of manufacturer-supported tri- als of nonsteroidal anti-inflammatory drugs in the treatment of arthritis. Arch Intern Med. 1994;154:157-163.

CORRECTION

Incorrect P Value.—An error occurred in the Original Contribution entitled “Persistent Pain and Well-being: A World Health Organiza- tion Study in Primary Care,” published in the July 8, 1998, issue of THE JOURNAL (1998;280:147-151). On page 150, in Table 4, the P value in the first footnote should be P,.05 [not P..05].

1142 JAMA, October 7, 1998—Vol 280, No. 13 Letters

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