Mortality of patients dependent on benzodiazepines.

For patients dependent on benzodiazepines alone, or in combination with alcohol and/or other legal and illegal drugs, observed mortality rates were compared with the average population, and, in cases of isolated benzodiazepine dependence, also with a control group of non-dependent patients chosen to match each dependent not only in sex and date of birth, but also in pre-existing psychiatric illness besides dependence. For patients with an isolated benzodiazepine dependence, the mortality rate was increased, when compared with the average population, by a ratio of observed to expected numbers of deaths of about 3. However, this mortality rate did not differ from that of the control group (non-dependent patients with comparable psychiatric illnesses). For patients combining benzodiazepines with alcohol among other addictive drugs, and for patients combining benzodiazepines with illegal drugs among other addictive substances, the ratio of observed to excepted numbers of deaths was 6.2 resp. 21, thus corresponding well with other studies on mortality rates associated with alcoholism and dependence on illegal drugs. We conclude that our study does not give evidence of higher risk of early death correlated with dependence on benzodiazepines alone. However, it confirms the well-known fact of increased mortality rates in patients with psychiatric illnesses, especially with dependence on alcohol or illegal drugs.