New benzodiazepine and Z-hypnotic users and disability pension: an eight-year nationwide observational follow-up study

OBJECTIVE To compare how newly initiated treatment with benzodiazepines, Z-hypnotics or both associates with the reception of disability pension among 40,661 individuals of a working age. DESIGN Prescription register study. SETTING Norwegian nationwide prescriptions socio-economic and disability status data. METHODS Cox regression analyses. SUBJECTS New benzodiazepine or Z-hypnotic users. MAIN OUTCOME MEASURE Time to receive disability pension given benzodiazepine or Z-hypnotic use or both. Additional analyses focused on the benzodiazepine first redeemed. RESULTS Among new users 8.65% of Z-hypnotic users, 12.29% of benzodiazepines users and 13.96% of combined Z-hypnotic and benzodiazepine users became disability pensioners. Z-hypnotic users were weaker associated with becoming disability pensioners (HR = 0.78, CI: 0.73-0.84) and combined users were stronger associated (HR = 1.09, CI: 1.01-1.17), than benzodiazepine users. Women had higher risk than men for becoming disability pensioners. Higher age, lower education, previous drug use and psychiatrist as first prescriber were risk factors. Comparing first benzodiazepine redeemed; clonazepam initiators were stronger associated with becoming disability pensioners than diazepam initiators were (HR = 2.22, CI: 1.81-2.71). No differences between other benzodiazepine users were found. CONCLUSIONS Adjusting for known risk factors gave lower risk for Z-hypnotic users compared to benzodiazepine users for receiving disability pension. Combined use increased the risk further. Clonazepam initiators are especially at risk. These findings may be helpful in prescribing situations to identify and guide individuals at risk for becoming disability pensioners.