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Accuracy of a Single Item on Mentally Tiring Work as Proxy Measure of Job Demands and Efforts in the Gazel Cohort

Descatha, Alexis MD, PhD; Hanson, Linda L. Magnusson PhD; Madsen, Ida E.H. PhD; Rugulies, Reiner PhD; Peristera, Paraskevi PhD; Westerlund, Hugo PhD

Journal of Occupational and Environmental Medicine: August 2017 - Volume 59 - Issue 8 - p e156–e158
doi: 10.1097/JOM.0000000000001093
LETTER TO THE EDITOR
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Inserm U011, Population-based Epidemiologic Cohorts Unit, Villejuif, France; Inserm, VIMA U1168 Aging and Chronic Diseases, Epidemiological and Public Health Approaches, Villejuif, France; Versailles St-Quentin University UVSQ, France; AP-HP (Paris Hospital “Assistance Publique Hôpitaux de Paris”), Occupational Health Unit, University Hospital of West Suburb of Paris, Poincaré site, Garches, France

Stress Research Institute, Stockholm University, Stockholm, Sweden

National Research Centre for the Working Environment, Copenhagen, Denmark

National Research Centre for the Working Environment, Copenhagen, Denmark, Departments of Public Health and Psychology, University of Copenhagen, Denmark

Stress Research Institute, Stockholm University, Stockholm, Sweden

Stress Research Institute, Stockholm University, Stockholm, Sweden.

Address correspondence to: Alexis Descatha, MD, PhD, UVSQ, AP-HP, Garches, France (alexis.descatha@rpc.aphp.fr).

Funding This study was supported by the Swedish Research Council [2015–02279, LMH].

No relevant conflict of interest: Authors received fees from their institutions for their work. Alexis Descatha has received fees from Elsevier Masson as editor-in-chief of the journal “les archives des maladies professionnelles et de l’environnement”.

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To the Editor:

Psychosocial models and scales are widely used in occupational research.1,2 The two most commonly used models are the Demand-Control (DC) and the Effort Reward Imbalance (ERI) models.3,4 In line with a previous study about the accuracy of proxy measures on physically tiring work,5 we examine whether an item about mentally tiring work may approximate the DC and ERI models.

We used data from the Gazel cohort6 from the years 1997, 1998, and 1999, where DC (1997 and 1999) and ERI (1998) scales were administered, as well as a question about mentally tiring work (MTW).7,8 The question about MTW was: “do you find your work mentally tiring” with response options ranging from 0 (not at all) to 8 (very). We divided the scores into two categories (1 to 4 and 5 to 8) and three categories (1 to 3, 4 to 5, and 6 to 8) for examining a dose–response relationship. With regard to the DC model, we defined high demands as a score greater than 23 points (range 9 to 36), low job control as a score less than 72 points (range 24 to 96), and job strain as the simultaneous exposure to high demands and low job control.9 Regarding the ERI model, we defined high effort as a score greater than 12 points, low reward as a score less than 18 points, and ERI as a ratio between effort and rewards greater than 1.4 We calculated the correlation and accuracy (sensitivity, specificity, predictive values, likelihood ratio)10 for MTW in relation to the DC dimensions in 1997/1999, and MTW in relation to ERI in 1998. Temporal stability analyses were also carried out between 1997 and 1999 among those with or without high demands. Sensitivity analyzes included gender stratification and adjustments for age (DC and effort).

For the years considered, 5706 (1998) to 11,304 (1997) workers had responded to the questionnaires. Table 1 summarizes the results. The demands and effort dimensions were fairly well correlated with MTW, with good sensitivity (greater than 0.8), negative likelihood ratio (less than 0.33), and area under curves (greater than 0.7), and a possible dose–response relationship. Specificity was low (0.42 to 0.49) and the positive likelihood ratio was low (less than 2), albeit statistically significant. We found medium temporal stability between 1997 and 1999 with 0.36 of discrepancies between subjects with or without high demands. No statistically significant changes were found when age and sex were taken into account. Job control and ERI were not captured by MTW, and reward only partly.

TABLE 1

TABLE 1

MTW seems to be a satisfying proxy measure for psychological demands and effort but not for job control, ERI, and only partly for reward, especially for screening purpose. A major strength of the study is the use of a large and diversified occupational cohort, which, however has somewhat limited generalisability as it is based on a single national gas and electricity company. Other factors and dimensions related to general health may have affected the responses. Each year's questionnaire included both the MTW and the validated scales, but the MTW question was at the beginning of the questionnaire. The low specificity and positive likelihood ratios might be due to mentally tiring work including other dimensions than demands, efforts, job control, and rewards, for example violence and harassment at work, bullying, organizational injustice or role conflicts, to name just a few examples.11

Though a single question does not in any way replace validated scales as the DC and the ERI scales, these results indicate that it would be possible to use simple measures in questionnaires and in working population for screening purpose which allow researchers to capture some aspects of psychological demands and efforts.

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Acknowledgments

The authors express their thanks to EDF-GDF, especially to the Service Général de Médecine de Contrôle and to the “Caisse centrale d’action sociale du personnel des industries électrique et gazière.” We also wish to acknowledge the “Population-Based Epidemiological Cohorts” unit responsible for the GAZEL database management. The GAZEL Cohort Study was funded by EDF-GDF and INSERM and received grants from the “Cohortes Santé TGIR Program.” This study is supported by the French National Research Agency (ANR). Richard Carter helped us to correct the English.

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