Objectives The relation between psychosocial work characteristics, employment grade, and sickness absence due to back pain was studied among office workers.

Methods Base-line questionnaire data and sickness absence data collected continuously with a mean of 4 years of follow-up were analyzed. The subjects were 6894 men and 3414 women aged 35 to 55 years at recruitment. The main outcome measures were short (³7 days) and long (>7 days) absences due to back pain.

Results There was a strong inverse association between employment grade and rate of absences due to back pain (P for linear trend <0.001); for example, the rate ratio for short absences among the men in a comparison of lowest versus highest employment grade was 8.21. The age adjusted rate ratio for the effect of low versus high control over work among the men was 2.22 [95% confidence interval (95% CI) 1.77--2.79] for short and 1.61 (95% CI 1.01--2.58) for long absences due to back pain. For short absences due to back pain among the men in high grades of employment, the rate ratio for low control was 3.42 compared with 0.78 for the lower grades (P for interaction <0.001). For the women the corresponding rate ratios were 0.80 and 1.35, respectively (P for interaction 0.08). Conclusions Absence from work due to back pain was strongly inversely related to employment grade. The effects of psychosocial work characteristics -- particularly control -- differed by grade and gender in magnitude and direction. The psychosocial work environment represents a potentially reversible cause of ill health.

Key terms cohort study; etiology; MSD; musculoskeletal disorder; prospective study; socioeconomic status