Overcrowding in hospital wards as a predictor of antidepressant treatment among hospital staff.

OBJECTIVE This report assessed whether hospital ward overcrowding predicts antidepressant use among hospital staff. METHOD The extent of hospital ward overcrowding was determined using administrative records of monthly bed occupancy rates between 2000 and 2004 in 203 somatic illness wards in 16 Finnish hospitals providing specialized health care. Information on job contracts for personnel was obtained from the employers' registers. Comprehensive daily data on purchased antidepressant prescriptions (World Health Organization's Anatomical Therapeutic Chemical classification code N06A) for nurses (N=6,699) and physicians (N=641) was derived from national registers. Cox proportional hazards models were used to examine the association between bed occupancy rate and subsequent antidepressant treatment. Monthly bed occupancy rates were used as a time-dependent exposure that could change in value over the course of observation. Hazard ratios were adjusted for sex, age, occupation, type and length of employment contract, hospital district, specialty, and calendar year. RESULTS Exposure over 6 months to an average bed occupancy rate over 10% in excess of the recommended limit was associated with new antidepressant treatment. This association followed a dose-response pattern, with increasing bed occupancy associated with an increasing likelihood of antidepressant use. There was no evidence of reverse causality; antidepressant treatment among employees did not predict subsequent excess bed occupancy. CONCLUSIONS The increased risk of antidepressant use observed in this study suggests that overcrowding in hospital wards may have an adverse effect on the mental health of staff.