A double-blind, randomised, placebo controlled study of venlafaxine XL in patients with generalised anxiety disorder in primary care.

BACKGROUND Generalised anxiety disorder (GAD) is one of the commonest anxiety disorders and is treated almost entirely in primary care. Most recent studies performed in GAD have excluded depression for regulatory reasons. As GAD is usually a co-morbid disease, often co-existing with depression, the results from recent studies have only limited relevance to the naturalistic population. This study was set up to investigate venlafaxine XL in a more naturalistic population of patients with GAD. AIM To assess the efficacy of venlafaxine XL in patients with generalised anxiety disorder with and without co-morbid depression. DESIGN OF STUDY Double-blind, randomised, placebo controlled, parallel-group, 24-week study. SETTING Primary care in the UK. METHODS Patients enrolled in the study were over 18 years old, met DSM-IV criteria for GAD, and had a score of 20 or more on the Hamilton Anxiety Scale (HAM-A). A score of more than 23 on the Montgomery Asberg Depression Rating Scale (MADRS) excluded patients. Eligible patients were randomised to receive 75 mg of venlafaxine or a matching placebo. After 2 weeks the dose could be doubled if the physician considered the response to be poor. The study duration was 24 weeks. RESULTS 244 patients were enrolled, with 122 randomised to the placebo and 122 to venlafaxine. Baseline characteristics were similar for both groups, each having a mean total HAM-A score at baseline of 28. The difference from the placebo group at 24 weeks on the total HAM-A score was 2.1 points (95% 0 to 4.2), which was statistically significant (P = 0.05). Remission rates at week 24 were 27.9% for the venlafaxine XL group and 18.9% for placebo group (P = 0.11). CONCLUSION Venlafaxine was efficacious in the treatment of patients with GAD with and without depression over a 24-week period.