Nine-year trajectory of purchases of prescribed pain medications before and after in-patient interdisciplinary rehabilitation for chronic musculoskeletal disorders: a prospective, cohort, register-based study of 4,365 subjects.

OBJECTIVE

To investigate whether an interdisciplinary rehabilitation for chronic musculoskeletal disorders is associated with changes in the purchase of prescribed pain medication.

DESIGN

Prospective register-based study.

SUBJECTS

Employees in the public sector (n = 4,365) who participated in the rehabilitation programme between 1996 and 2009.

METHODS

The changes in annual purchases of prescribed pain medication were measured for a 9-year exposure window, starting from 4 years before the start date of rehabilitation and ending 5 years after this date.

RESULTS

Purchases of prescribed pain medication increased throughout the follow-up in all medication groups. The steepest increase was observed for analgesics, antidepressants, and hypnotics and sedatives. The growth rate of annual purchase, however, slowed significantly following the year of the start of rehabilitation for analgesics (annual growth rate (rate ratio) before and after rehabilitation 1.27 and 1.04, respectively, difference in trend p < 0.001); antidepressants (rate ratio 1.17 and 1.09, p = 0.005); and muscle relaxants (rate ratio 1.31 and 1.01, p < 0.001). For anxiolytics, and hypnotics and sedatives, no differences were observed in the trends of annual purchase before and after rehabilitation.

CONCLUSION

Rehabilitation was associated with a slowing increase in purchases of prescribed pain medication amongst rehabilitants. This may be a reflection of the positive effect that rehabilitation has on the need for pain medication.