S ince the publication in 1979 by Karasek,

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1 509 ORIGINAL ARTICLE Psychosocial factors at work ad self health: comparative results of cross sectioal ad prospective aalyses of the Frech GAZEL cohort I Niedhammer, M Chea... See ed of article for authors affiliatios... Correspodece to: Dr I Niedhammer, INSERM U88, Hôpital Natioal de Sait Maurice, 14 rue du Val d Ose, F Sait-Maurice Cedex, Frace; isabelle.iedhammer@ st-maurice.iserm.fr Accepted 8 October Occup Eviro Med 2003;60: Backgroud: Psychosocial factors at work have bee foud to be sigificat cotributors to health, especially cardiovascular health. Aims: To explore the relatio betwee psychosocial factors at work ad self health, usig cross sectioal ad prospective aalyses for a large occupatioal cohort of me ad wome. Methods: Psychosocial factors at work were evaluated usig the Karasek questioaire, desiged to measure psychological demads, decisio latitude, social support, ad physical demads. Self health was used as health outcome. Covariates icluded chroic diseases, ad sociodemographic, occupatioal, ad behavioural factors. The cross sectioal ad prospective aalyses cocered respectively ad 7664 workers. Me ad wome were aalysed separately. Results: Cross sectioal aalysis revealed sigificat associatios betwee psychological demads, decisio latitude, social support, ad physical demads, ad self health for both me ad wome. Prospective aalysis showed that high psychological demads for both geders, low decisio authority for me, ad low social support ad high physical demads for wome were predictive of health. These results were idepedet of potetial cofoudig variables. Coclusios: Results highlight the predictive effects of psychosocial factors at work o self health i a oe year follow up study. They also uderlie the eed for logitudial study desig ad separate aalyses for me ad wome i the field of psychosocial factors at work. S ice the publicatio i 1979 by Karasek, 1 psychosocial factors at work have bee recogised as occupatioal risk factors. I most subsequet epidemiological studies, Karasek s model ad the Job Cotet Questioaire (JCQ) 23 were used to evaluate: (1) psychological demads, which measure job demads, time pressure, ad coflictig demads; ad (2) decisio latitude, i which both cotrol over work (decisio authority) ad the possibility of learig ew skills (skill discretio) are measured. A third scale was added to this model: social support from colleagues ad the supervisor. Karasek postulated that health may be affected by job strai, defied as a combiatio of high levels of psychological demads ad low levels of decisio latitude. Health risks Mai messages Psychosocial factors at work were foud to be predictive factors of health i a oe year follow up study. Geder specific associatios were observed, as psychological demads for both geders, decisio authority for me oly, ad social support ad physical demads for wome oly predicted poor health. Strog differeces were foud betwee cross sectioal ad prospective results, uderlyig the eed for prospective study desig i the field of psychosocial factors at work. Policy implicatios Psychosocial aspects of work should be the target of prevetive actios o the workplace. Attetio should be paid to specific psychosocial factors at work for wome. might be icreased by low levels of social support, a combiatio kow as iso-strai that is, social isolatio ad job strai. 4 The above psychosocial factors at work have bee foud to be importat cotributors to health, especially cardiovascular health. 56 Various studies also showed that these aspects of work were associated with other health outcomes, such as musculoskeletal disorders, 78 metal disorders, 910 ad behavioural risk factors such as smokig ad drikig. Some recet studies dealt with the relatios of psychosocial factors at work to health status or health related quality of life, ad either self health or the Short-Form 36 questioaire (a geeric health status measuremet istrumet) was used as health outcome Some of them had a prospective desig As by Zapf ad colleagues, 20 most of the literature o stressors ad health is cross sectioal, ad the weakesses of this desig are widely ackowledged, because it usually makes the demostratio of causal relatios impossible. Amog the cross sectioal studies, the study by Amick ad colleagues 13 showed that job strai ad iso-strai were associated with health status. Lerer ad colleagues 16 a associatio betwee job strai ad health related quality of life. Schrijvers ad colleagues 17 foud that the odds of poor perceived health was larger amog people reportig hazardous physical workig coditios, low job cotrol, low social support at work, ad high psychological demads. Pikhart ad colleagues 19 showed a sigificat associatio betwee effort-reward imbalace ad rated health. Borg ad colleagues 14 foud that repetitive work, high psychological demads, low social support, job isecurity, ad high ergoomic exposures were predictive of a declie i self rated health i a prospective study over five years. Cheg ad colleagues 15 foud that low cotrol, high demads, ad low social support were associated with poor health status at Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. Protected by copyright.

2 510 Niedhammer, Chea Table 1 Prevalece ad icidece of health by sociodemographic ad health related characteristics Me Cross sectioal study (=8277) baselie, as well as greater fuctioal declies over a four year follow up period. I the five year prospective study by Stasfeld ad colleagues, 18 high psychological demads, low decisio latitude, low social support, ad effort-reward imbalace were predictors of a declie i several dimesios of health fuctioig. The last three studies had a prospective desig. Self health (or alteratively self rated, self assessed, or self perceived health) has bee much studied over the past decade. This parameter has several advatages for epidemiological research. It costitutes a geeral sigle item questio to which the aswers ca easily be collected via a self admiistered questioaire. It reflects a perso s itegrated perceptio of health ad is kow to take ito accout the various aspects of health, as suggested by the World Health Orgaisatio s defiitio of health, which icludes its physical, metal, ad social aspects. Several authors have strog associatios betwee self health ad more objective measures of morbidity Further, i prospective studies, health was foud to be a sigificat predictor of mortality The objective of this study was to explore the associatios betwee psychosocial factors at work, measured with the full recommeded versio of the JCQ, ad self health. The data collected uderwet cross sectioal ad prospective aalyses, whose results were the compared. I additio, as Prevalece of (=5575) Icidece of Wome Cross sectioal study (=3170) Prevalece of (=2089) Self health Good Poor Number of chroic coditios or more Age (y) *** *** *** *** < > Marital status * s s s Sigle Married Cohabitig Separated Divorced Widowed Number of stressful persoal *** s ** s evets > Smokig ** s *** s No-smokers Smokers Alcohol * *** * s Abstaiers Light drikers Moderate drikers Heavy drikers Overweight *** s ** s No Yes *** *** *** * *p<0.05, **p<0.01, ***p< the study populatio icludes a large umber of me ad wome, the aalyses were doe separately for me ad wome. METHODS Study populatio The GAZEL cohort was established i 1989 ad origially icluded subjects workig at Electricité De Frace Gaz De Frace (EDF-GDF), comprisig me aged ad wome aged at baselie. 27 Sice 1989, this cohort has bee followed up by meas of yearly self admiistered questioaires ad by data collectio from the compay s persoel ad medical departmets. Research o psychosocial factors at work ad health has bee coducted i this cohort sice Psychosocial factors at work The full recommeded JCQ scales of decisio latitude, psychological demads, social support, ad physical demads were icluded i the self admiistered questioaire of the GAZEL cohort for the year The Frech versio used here has already bee used ad/or validated elsewhere I additio, the iteral cosistecy, factorial validity, ad coverget validity of this versio were studied i the GAZEL cohort i a previous ivestigatio. 33 Decisio latitude ad psychological demads each comprised ie items; social support, eight Icidece of Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. Protected by copyright.

3 Psychosocial factors at work 511 Table 2 Prevalece ad icidece of health by occupatioal characteristics Me Cross sectioal study (=8277) Prevalece of (=5575) items; ad physical demads, five items. Aswers were graded accordig to the followig Likert-type scale: totally disagree, disagree, agree, ad totally agree. The scores for each scale were costructed accordig to Karasek s recommedatios ad were dichotomised at the media of the total sample of me ad wome, for use i the aalyses. 3 Decisio latitude icluded the two subscales of decisio authority ad skill discretio, ad social support, support from colleagues, ad from the supervisor. Self health Self health was based o a eight level scale ragig from very good (coded 1) to very poor (coded 8). The questio was formulated as follows: How do you rate your geeral health status?. Poor self health was defied by levels ragig from 5 to 8 that is, with a cut off i the middle. Self health was icluded i the questioaires for 1997 ad It has bee show previously that this idicator was strogly associated with the presece of diseases i the GAZEL cohort. 37 Covariates Several covariates were used as potetial cofoudig variables of the relatio betwee psychosocial factors at work ad self health: the umber of chroic coditios withi the 12 previous moths (icludig chroic brochitis, asthma, hypertesio, agia pectoris, myocardial ifarctio, claudicatio, osteoarthritis, diabetes, hyperlipidaemia, ad Icidece of Wome Cross sectioal study (=3170) Prevalece of (=2089) Educatioal level Uiversity Upper vocatioal Upper secodary Lower vocatioal Lower secodary Primary Occupatio ** s s s Maagers Egieers Admiistrative associate professioals Techicias Foreme Clerks Skilled idustrial workers Craftsme Number of stressful *** * *** * occupatioal evets > Psychological demads *** s *** s Low High Decisio latitude *** *** *** *** High Low Social support *** s *** s High Low Physical demads *** ** *** *** Low High *** ** *** *** *p<0.05, **p<0.01, ***p< cacer); age (i five-year groups); marital status (six categories); the umber of stressful persoal evets occurrig durig the previous 12 moths (the 12 evets icluded death of a spouse, death of a close relative, divorce, ad marital separatio); the umber of stressful occupatioal evets withi the previous 12 moths (job chage, trasfer, recoversio, ad departmet restructurig); smokig (osmokers versus smokers); overweight (defied by body mass idex, calculated as weight/height 2 exceedig 27.2 kg/m 2 for me ad 26.9 for wome) 38 ; ad alcohol cosumptio, graded accordig to the frequecy (umber of days/week), the quatity (glasses/day), ad the type cosumed (wie, beer, or spirits). Drikers were classified as: abstaiers, light drikers (1 13 driks/week for me ad 1 6 driks/week for wome), itermediate drikers (14 27 driks/week for me ad 7 20 driks/week for wome), ad heavy drikers (28 driks/week or more for me ad 21 driks/week or more for wome). Data for these variables were obtaied from the 1997 questioaire. The validity of self weight ad height has bee explored previously. 39 The two other covariates studied were educatioal level (six categories) ad occupatioal group (eight categories for me, ad five for wome). Data for these two variables were supplied by the EDF-GDF persoel departmet. Statistical methods The cross sectioal aalysis of the data was desiged to explore the associatios betwee psychosocial factors at work Icidece of Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. Protected by copyright.

4 512 Niedhammer, Chea Table 3 Psychosocial factors at work i 1997 as risk factors of health i 1997: cross sectioal results of logistic regressio aalyses Me as evaluated i 1997 ad the prevalece of health, also as evaluated at that time, ad the prospective aalysis, to establish whether the psychosocial factors at work cosidered i 1997 were predictive of health oe year later amog the subgroup of the study populatio who rated their health as good at baselie that is, i I both aalyses, adjustmets were made for covariates measured at baselie. The crude relatios betwee each of the four JCQ scales of decisio latitude, psychological demads, social support, ad physical demads, ad self health were submitted to Pearso s χ 2 test, as were those betwee the covariates ad self health. Logistic regressio aalysis was used to adjust for cofoudig variables. Poor self health was used as the depedet variable ad the four JCQ scales as idepedet variables. Three models were costructed. First, a model was costructed icludig the four JCQ scales simultaeously. Secod, adjustmet was made for chroic coditios, sociodemographic variables (age, marital status, ad stressful persoal evets), ad occupatioal variables (educatio, occupatio, ad stressful occupatioal evets). Third, additioal adjustmet was made for behavioural risk factors (smokig, alcohol cosumptio, ad overweight). The four JCQ scales were itroduced ito these models simultaeously to assess their ow effect. The iteractio betwee psychological demads ad decisio latitude was also explored by icludig the two way iteractio term: high demads ad low latitude. I additio, we explored the subscales of decisio latitude (decisio authority ad skill discretio) ad the subscales of social support (from colleagues ad supervisor). Me ad wome were studied separately to explore potetial geder specific associatios. Statistical aalysis was performed with the SAS statistical software package. RESULTS Study populatio I 1997, subjects i the GAZEL cohort aswered the self admiistered questioaire that is, 74.1% of the subjects asked to complete it (402 of the subjects i the iitial cohort were ot set a questioaire i 1997, because 307 had died ad 95 had bee lost to follow up). Of the respodets, (76.4%) were workig i 1997, 3344 (22.3%) had retired, 157 (1.0%) were ot workig because of log illess or disability, ad 39 (0.3%) were ot workig for other reasos (upaid holidays, compassioate leave, omiatio for a future appoitmet, etc). The preset cross sectioal Wome Model 1, =7349 Model 2, =7314 Model 3, =7237 Model 1, =2642 Model 2, =2630 Model 3, =2580 OR 95% CI OR 95% CI OR 95% CI OR 95% CI OR 95% CI OR 95% CI Psychological demads High to to to to to to 2.11 Decisio latitude Low to to to to to to 1.83 Social support Low to to to to to to 2.03 Physical demads High to to to to to to 1.62 Model 1: icluded Karasek s dimesios oly. Model 2: additioally adjusted for chroic coditios, age, marital status, stressful persoal evets, educatio, occupatio, ad stressful occupatioal evets. Model 3: additioally adjusted for smokig, alcohol, ad overweight. study is therefore based o the subjects, comprisig 8277 me ad 3170 wome, who were workig i 1997 ad aswered the questioaire that year. Of these workers, 9100 rated their health as good i Amog them, 8366 (91.9%) respoded to the questioaire of 1998; 7664 were still workig i that year. The other 702 were ot, because of retiremet (682 subjects), log illess or disability (11 subjects), or other reasos (ie subjects). Therefore, our prospective aalysis is based o the 7664 subjects, 5575 me ad 2089 wome, who rated their health as good i 1997, were workig, ad respoded to both the 1997 ad 1998 questioaires. Tables 1 ad 2 give further details regardig the sociodemographic, occupatioal, ad health related characteristics of the populatio studied. The compariso betwee the respodets to the 1998 questioaire ad the o-respodets with respect to the study variables i 1997 showed that o-respodets were more likely to be wome. For me, o-respodets were youger, less educated, more likely to be separated, divorced, or widowed, ad smokers. For wome, o-respodets were more likely to be smokers, overweight, ad to have chroic diseases. For both geders, o-respodets also poorer health. For occupatioal factors, o differece was observed betwee respodets ad o-respodets, except for physical demads for me; o-respodets were exposed to higher levels of physical demads. Cross sectioal aalysis I 1997, the prevalece of health was 18.6% for me ad 23.2% for wome (table 1). The four JCQ scales displayed strog associatios with self health; thus high psychological demads, low decisio latitude, low social support, ad high physical demads icreased the prevalece of poor health for both me ad wome (table 2). After itroducig the four JCQ scales simultaeously ito a first model, the associatios betwee these variables ad self health remaied sigificat (table 3). After adjustmet for chroic coditios, ad sociodemographic ad occupatioal factors, the four JCQ scales remaied sigificat, but their odds ratios were slightly lower, except for social support for wome. Additioal adjustmet for behavioural risk factors did ot chage the results; the four JCQ scales were still foud to be sigificat risk factors for self health for both sexes. Furthermore, o iteractio was observed betwee psychological demads ad decisio latitude. Study of the subscales of decisio latitude ad social support showed that the two variables of support from colleagues ad supervisor Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. Protected by copyright.

5 Psychosocial factors at work 513 Table 4 Psychosocial factors at work i 1997 as predictive factors of health i 1998: prospective results of logistic regressio aalyses Me were risk factors for self health for me ad wome. Decisio authority was sigificat for me oly, ad skill discretio was sigificat for either me or wome (ot show). Prospective aalysis I 1998, the icidece of health was 11.6% for me ad 15.3% for wome (table 1). Study of the crude associatios betwee JCQ scales i 1997 ad self health oe year later showed that high psychological demads, low social support, ad high physical demads were predictive of health, but low decisio latitude was ot (table 2). Itroducig the four JCQ scales simultaeously ito a logistic regressio aalysis did ot greatly chage the results (table 4). Psychological ad physical demads were still sigificat predictors of poor health for both me ad wome. Social support was also a sigificat predictor for wome, but the associatio was o loger sigificat for me. Adjustmet for chroic coditios, ad sociodemographic ad occupatioal covariates did ot chage the results for wome, but made physical demads osigificat for me. Note that the fact that physical demads were o loger sigificat for me was maily due to the adjustmet for occupatioal grade. After additioal adjustmet for behavioural risk factors, the associatios remaied sigificat for psychological demads for both sexes, ad for social support ad physical demads for wome oly. No sigificat iteractio was foud betwee psychological demads ad decisio latitude. Study of the subscales of decisio latitude ad social support showed that decisio authority predicted poor health for me (OR 1.22, 95% CI: 1.00 to 1.49), ad support from colleagues was a sigificat predictor for wome (OR 1.41, 95% CI: 1.06 to 1.88). DISCUSSION Our fidigs uderlie the differeces betwee the respective results of the cross sectioal ad prospective aalyses for the relatios betwee psychosocial factors at work ad self health. Whereas the cross sectioal aalysis showed sigificat associatios betwee the four scales of psychological demads, decisio latitude, social support, ad physical demads ad self health for both me ad wome, the prospective aalysis showed that at oe year of follow up, psychological demads for both sexes, decisio authority for me oly, ad social support ad physical demads for wome oly, were sigificat predictors of health. Wome Model 1, =4973 Model 2, =4948 Model 3, =4907 Model 1, =1752 Model 2, =1745 Model 3, =1712 OR 95% CI OR 95% CI OR 95% CI OR 95% CI OR 95% CI OR 95% CI Psychological demads High to to to to to to 1.99 Decisio latitude Low to to to to to to 1.42 Social support Low to to to to to to 2.04 Physical demads High to to to to to to 1.90 Model 1: icluded Karasek s dimesios oly. Model 2: additioally adjusted for chroic coditios, age, marital status, stressful persoal evets, educatio, occupatio, ad stressful occupatioal evets. Model 3: additioally adjusted for smokig, alcohol, ad overweight. Several limitatios of this study are worth otig. First, the rate of respose to the self admiistered questioaire i 1997 for the cross sectioal aalysis (74%), ad the respose rate for the prospective study (91%) ca be cosidered satisfactory. However, a selectio bias caot be totally excluded. A compariso betwee respodets ad o-respodets suggested a healthy worker effect. If subjects i poor health shifted to jobs with lower levels of job stress factors, such bias could lead to a uderestimatio of the associatios observed betwee psychosocial factors at work ad self health. Note also that to some extet the exclusio of the retired ad disabled subjects from the aalyses could have uderestimated these associatios. Secod, our results were based o a sigle evaluatio of psychosocial factors at work, ad ot o the history or duratio of exposure to these factors. As the results of our prospective aalysis provided evidece of the predictive effects of these factors o health, it would be potetially fruitful to evaluate the duratio of exposure to psychosocial factors at work ad explore its associatio with self health. Third, although our study desig was prospective, we caot coclude that there are causal relatios betwee psychosocial factors at work ad health. As stated by Zapf ad colleagues, 20 oly a full two-wave pael desig could overcome the problem of reserved causatio. Because i our study, psychosocial factors at work were evaluated oly oce, ad self health twice, we were uable to test the reverse causatio of self health o psychosocial factors at work. Therefore we could ot rule out this alterative explaatio ad coclude that psychosocial factors at work are a plausible cause of health. Furthermore, both psychosocial factors at work ad health were measured by self report; cosequetly a potetial bias could have arise from the egative reportig of both. This weakess, coected with commo method variace, for example through social desirability or egative affectivity, ca lead to iflated correlatios betwee stressors ad health. 20 Both these sources of bias that is, reverse causatio ad commo method variace, may partly accout for the associatios observed i our study. Objective evaluatios of psychosocial factors at work, ad iformatio about persoality, would be helpful i clarifyig these issues. The strog poits of this study should also be stressed. First, the study was based o a large prospective cohort, ad allowed compariso betwee the cross sectioal ad prospective approaches. Note that very few previous studies i this area had a prospective desig, although oe of them had a Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. 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6 514 Niedhammer, Chea full two wave pael desig. I additio, the preset study icluded both me ad wome, ad as each sex was aalysed separately, we were also able to explore sex related differeces regardig the effects of psychosocial factors at work o self health. 42 Sigificat associatios were observed for both geders (psychological demads), for me oly (decisio authority), ad for wome oly (social support ad physical demads). These geder specific associatios which are ot easily iterpretable may be related to cultural ad orgaisatioal aspects of the compay. Note that most of the employees of the Frech electric ad gas compay are me (80%), ad that there is a clear geder divisio of work; wome are ot egaged i the same work activities as me. Secod, as psychosocial factors at work were evaluated by meas of the full recommeded JCQ, 43 we were able to study the mai scales of the model, as well as the subscales of decisio authority, skill discretio, ad support from colleagues ad supervisor. These origial JCQ scales costituted a validated istrumet ad allowed the compariso of our results with those of others. Nevertheless, most of the previous authors metioed here did ot use the origial JCQ, but proxies. The few who did, used the short versio (five items) of the scale of psychological demads. Third, our study icluded relevat cofouders, such as sociodemographic, occupatioal, ad behavioural factors, ad chroic diseases, thus reducig the potetial effects of cofoudig. Note that additioal adjustmet for depressive symptoms (ot show) did ot modify the results. Furthermore, adjustmet for baselie chroic diseases reduced the effects of previous illess o both psychosocial factors at work ad self health. However, full adjustmet did ot greatly chage the results, except for physical demads for me, which i the prospective aalysis were o loger sigificat whe occupatioal grade were take ito accout. I this coectio, it has already bee that adjustig for occupatioal grade could costitute a overadjustmet i the study of psychosocial factors at work, especially for decisio latitude. It has already bee suggested that the true associatios betwee psychosocial factors at work ad health outcomes may be betwee the uadjusted ad adjusted results. 44 The adjustmet was made i two steps, i order to distiguish behavioural risk factors from the other covariates. We assumed that the variables of smokig, alcohol cosumptio, ad overweight might be itermediate variables i the relatio betwee psychosocial factors at work ad self health. Therefore, i theory, if the associatio betwee psychosocial factors at work ad health had bee elimiated after adjustmet for behavioural risk factors, the latter might have costituted a step o a pathway from exposure to health. I fact, we observed o great chage after adjustmet for these variables, suggestig that as previously 18 they did ot mediate the associatio betwee psychosocial factors at work ad self health. This method of data aalysis comprisig several steps of adjustmet has already bee used by others to study the effects of potetial cofoudig variables. I our study, we may have disregarded other potetial cofoudig variables such as persoality factors, egative affectivity, or social desirability, as metioed earlier ad uderlied by Zapf ad colleagues. 20 However, it seems ulikely that these variables completely explai the associatios observed betwee psychosocial factors at work ad health. Note that other authors observed o strog cofoudig effects of persoality factors i the relatio betwee psychosocial factors at work ad health outcomes. The authors of certai cross sectioal studies that job strai ad iso-strai 13 were associated with health status 13 or health related quality of life. 16 However, these authors did ot explore the respective effects of demads, latitude, ad support. I the study by Schrijvers ad colleagues, 17 sigificat associatios were foud betwee physical workig coditios, job cotrol, social support, ad to a certai extet, psychological demads, ad perceived health. By costrast, Pikhart ad colleagues 19 did ot report ay sigificat associatios betwee proxies of the Karasek model ad self health, but showed a sigificat associatio betwee effort-reward imbalace ad self health. Amog the authors of the three logitudial studies that we foud i this field, Borg ad colleagues 14 used a method of data aalysis very similar to ours. Amog subjects i good self rated health i 1990, these authors studied the deterioratio of this health five years later. Note that they did ot coduct separate aalyses for me ad wome. Usig proxies of the Karasek model, their results suggested that job demads ad support were sigificat predictive factors, but ot decisio authority or skill discretio. The prospective study by Cheg ad colleagues 15 showed that demads, latitude, ad support were associated with a declie i health status amog a populatio of wome. Stasfeld ad colleagues 18 sex related differeces i the associatios betwee psychosocial factors at work ad health fuctioig; thus, decisio latitude for me, psychological demads for wome, ad social support for both were predictors of oe or more compoets of health fuctioig. I the preset study, the absece of sigificat iteractios betwee psychological demads ad decisio latitude was i agreemet with previous fidigs, ad suggested that there were o sigificat bufferig effects. Our study showed that the three psychosocial factors at work explored that is, psychological demads, decisio latitude, ad social support, as well as physical demads, were sigificatly associated with self health for both sexes i the cross sectioal aalysis. The results were very differet for the prospective aalysis, as psychological demads for both geders, decisio authority for me, ad social support ad physical demads for wome were predictors of poor health. Fially, it may be surprisig to observe that decisio latitude, the mai scale of the Karasek model, was ot the strogest predictor of self health. This fidig eeds further cosideratio. Note that some authors uderlied the effects of quatitative demads such as overtime o various health outcomes. Although we caot coclude that there is a causal relatio betwee psychosocial factors at work ad self health, some cosideratios support this possibility: previous reports from prospective studies, ad stregths of these associatios, idepedetly of potetial cofoudig variables. These cosideratios stregthe the possibility that psychosocial factors at work have a causal effect o self health. Our fidigs also uderlie the eed for logitudial desig, ad for separate aalyses for me ad wome whe studyig psychosocial factors at work. ACKNOWLEDGEMENTS The authors thaks go to the members of the GAZEL study team, especially to Marcel Goldberg ad Aette Leclerc, to the Medical Committee of EDF-GDF, to all the participatig workers of the GAZEL cohort, who made the study possible, ad to Mathilde Dreyfus for revisig the Eglish mauscript. The authors also thak the three reviewers for their helpful commets.... Authors affiliatios I Niedhammer, M Chea, INSERM Uit 88, Hôpital Natioal de Sait-Maurice, Frace REFERENCES 1 Karasek RA. Job demads, job decisio latitude, ad metal strai: implicatios for job redesig. Admiistrative Sciece Quarterly 1979;24: Karasek R, Theorell T. Healthy work: stress, productivity, ad the recostructio of workig life. New York, NY, Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. Protected by copyright.

7 Psychosocial factors at work Karasek R. Job Cotet Questioaire ad user s guide. Los Ageles, CA, Johso JV, Hall EM, Theorell T. Combied effects of job strai ad social isolatio o cardiovascular disease morbidity ad mortality i a radom sample of the Swedish male workig populatio. Scad J Work Eviro Health 1989;15: Schall PL, Ladsbergis PA, Baker D. Job strai ad cardiovascular disease. Au Rev Public Health 1994;15: Theorell T, Karasek RA. Curret issues relatig to psychosocial job strai ad cardiovascular disease research. J Occup Health Psychol 1996;1: Bogers PM, de Witer CR, Kompier MA, et al. Psychosocial factors at work ad musculoskeletal disease. Scad J Work Eviro Health 1993;19: Davis KG, Heaey CA. The relatioship betwee psychosocial work characteristics ad low back pai: uderlyig methodological issues. Cli Biomech 2000;15: Bourboais R, Brisso C, Moisa J, et al. Job strai ad psychological distress i white-collar workers. Scad J Work Eviro Health 1996;22: Stasfeld SA, North FM, White I, et al. Work characteristics ad psychiatric disorder i civil servats i Lodo. J Epidemiol Commuity Health 1995;49: Brisso C, Larocque B, Moisa J, et al. Psychosocial factors at work, smokig, sedetary behavior, ad body mass idex: a prevalece study amog 6995 white collar workers. J Occup Eviro Med 2000;42: Hemmigsso T, Ludberg I. Work cotrol, work demads, ad work social support i relatio to alcoholism amog youg me. Alcohol Cli Exp Res 1998;22: Amick BC III, Kawachi I, Coakley EH, et al. Relatioship of job strai ad iso-strai to health status i a cohort of wome i the Uited States. Scad J Work Eviro Health 1998;24: Borg V, Kristese TS, Burr H. Work eviromet ad chages i self-rated health: a five year follow-up study. Stress Medicie 2000;16: Cheg Y, Kawachi I, Coakley EH, et al. Associatio betwee psychosocial work characteristics ad health fuctioig i America wome: prospective study. BMJ 2000;320: Lerer DJ, Levie S, Malspeis S, et al. Job strai ad health-related quality of life i a atioal sample. Am J Public Health 1994;84: Schrijvers CT, va de Mhee HD, Stroks K, et al. Socioecoomic iequalities i health i the workig populatio: the cotributio of workig coditios. It J Epidemiol 1998;27: Stasfeld SA, Bosma H, Hemigway H, et al. Psychosocial work characteristics ad social support as predictors of SF-36 health fuctioig: the Whitehall II study. Psychosom Med 1998;60: Pikhart H, Bobak M, Siegrist J, et al. Psychosocial work characteristics ad self rated health i four post-commuist coutries. J Epidemiol Commuity Health 2001;55: Zapf D, Dorma C, Frese M. Logitudial studies i orgaizatioal stress research: a review of the literature with referece to methodological issues. J Occup Health Psychol 1996;1: Moller L, Kristese TS, Hollagel H. Self rated health as a predictor of coroary heart disease i Copehage, Demark. J Epidemiol Commuity Health 1996;50: Kapla GA, Goldberg DE, Everso SA, et al. Perceived health status ad morbidity ad mortality: evidece from the Kuopio ischaemic heart disease risk factor study. It J Epidemiol 1996;25: Miilupalo S, Vuori I, Oja P, et al. Self-rated health status as a health measure: the predictive value of self- health status o the use of physicia services ad o mortality i the workig-age populatio. J Cli Epidemiol 1997;50: Idler EL, Beyamii Y. Self-rated health ad mortality: a review of twety-seve commuity studies. J Health Soc Behav 1997;38: McGee DL, Liao Y, Cao G, et al. Self- health status ad mortality i a multiethic US cohort. Am J Epidemiol 1999;149: Waamethee G, Shaper AG. Self-assessmet of health status ad mortality i middle-aged British me. It J Epidemiol 1991;20: Goldberg M, Chastag JF, Leclerc A, et al. Socioecoomic, demographic, occupatioal, ad health factors associated with participatio i a log-term epidemiologic survey: a prospective study of the Frech GAZEL cohort ad its target populatio. Am J Epidemiol 2001;154: Niedhammer I, Goldberg M, Leclerc A, et al. Psychosocial work eviromet ad cardiovascular risk factors i a occupatioal cohort i Frace. J Epidemiol Commuity Health 1998;52: Niedhammer I, Goldberg M, Leclerc A, et al. Psychosocial factors at work ad subsequet depressive symptoms i the Gazel cohort. Scad J Work Eviro Health 1998;24: Niedhammer I, Bugel I, Goldberg M, et al. Psychosocial factors at work ad sickess absece i the Gazel cohort: a prospective study. Occup Eviro Med 1998;55: Niedhammer I, Siegrist J. [Psychosocial factors at work ad cardiovascular diseases: cotributio of the Effort-Reward Imbalace model]. Rev Epidemiol Sate Publique 1998;46: Niedhammer I, Siegrist J, Ladre MF, et al. [Psychometric properties of the Frech versio of the Effort-Reward Imbalace model]. Rev Epidemiol Sate Publique 2000;48: Niedhammer I. Psychometric properties of the Frech versio of the Karasek Job Cotet Questioaire: a study of the scales of decisio latitude, psychological demads, social support, ad physical demads i the GAZEL cohort. It Arch Occup Eviro Health 2002;75: Brisso C, Blachette C, Guimot C, et al. Reliability ad validity of the Frech versio of the 18-item Karasek Job Cotet Questioaire. Work Stress 1998;12: Larocque B, Brisso C, Blachette C. [Iteral cosistecy, factorial validity ad discrimiat validity of the Frech versio of the psychological demads ad decisio latitude scales of the Karasek Job Cotet Questioaire ]. Rev Epidemiol Sate Publique 1998;46: Houtma I, Koritzer M, de Smet P, et al. Job stress, abseteeism ad coroary heart disease Europea cooperative study (the JACE study): desig of a multicetre prospective study. Eur J Public Health 1999;9: Goldberg P, Guegue A, Schmaus A, et al. Logitudial study of associatios betwee perceived health status ad self diseases i the Frech Gazel cohort. J Epidemiol Commuity Health 2001;55: Burto BT, Foster WR, Hirsch J, et al. Health implicatios of obesity: a NIH Cosesus Developmet Coferece. It J Obes 1985;9: Niedhammer I, Bugel I, Boefat S, et al. Validity of self- weight ad height i the Frech GAZEL cohort. It J Obes 2000;24: SAS Istitute. SAS/STAT user s guide, release 6.03 editio SAS Istitute. SAS/STAT software: chages ad ehacemets through release Niedhammer I, Saurel-Cubizolles MJ, Piciotti M, et al. How is sex cosidered i recet epidemiological publicatios o occupatioal risks? Occup Eviro Med 2000;57: Karasek R, Brisso C, Kawakami N, et al. The Job Cotet Questioaire (JCQ): a istrumet for iteratioally comparative assessmets of psychosocial job characteristics. J Occup Health Psychol 1998;3: North FM, Syme SL, Feeey A, et al. Psychosocial work eviromet ad sickess absece amog British civil servats: the Whitehall II study. Am J Public Health 1996;86: Kawakami N, Haratai T, Araki S. Effects of perceived job stress o depressive symptoms i blue-collar workers of a electrical factory i Japa. Scad J Work Eviro Health 1992;18: Kawakami N, Araki S, Takatsuka N, et al. Overtime, psychosocial workig coditios, ad occurrece of o-isuli depedet diabetes mellitus i Japaese me. J Epidemiol Commuity Health 1999;53: Hayashi T, Kobayashi Y, Yamaoka K, et al. Effect of overtime work o 24-hour ambulatory blood pressure. J Occup Eviro Med 1996;38: Occup Eviro Med: first published as /oem o 1 July Dowloaded from o 29 September 2018 by guest. Protected by copyright.