Survival analytic approach to long-term prescription of benzodiazepine hypnotics.

Eight hundred and sixty-two patients who visited the department of neuropsychiatry and who were prescribed benzodiazepine (BZ) hypnotics were investigated to evaluate the actual state of their use, in terms of age, gender, diagnostic categories according to ICD-9, duration of prescription and dose equivalent to diazepam prescribed. The frequency of prescriptions in subjects were surveyed using Kaplan-Meier survival analysis at every 3 months. Mean survival time to discontinuation was 8.5 months. A total of 60% of the subjects did not receive BZ hypnotics at the end of the third month, but 20% remained to be prescribed after 1 year. Moreover, 7.9% of the subjects were prescribed BZ hypnotics even after 3 years. The results indicated that 20% of patients who had started prescriptions for BZ hypnotics had the potential to induce dependence. The following variables were found in the long-term prescription: male patients; aged patients over 60; and affective psychoses (which mainly consisted of depression) including neurotic depression, in the present study. A low dose was considered to be associated with an ability to be free from BZ hypnotics in an early period.