To estimate the clinical benefit of pregabalin and venlafaxine-XR for the short-term treatment of generalized anxiety disorder (GAD) using the metric of symptom-free days (SFDs).

A post-hoc analysis of a clinical trial in which adults who met DSM-IV criteria for GAD, with a HAM-A total score ≥ 20, were randomized to 8-weeks of double-blind, flexible-dose treatment with pregabalin (300-600 mg/d), venlafaxine-XR (75-225 mg/d) or placebo. SFDs were estimated for each one-week period based on weekly HAM-A scores using a published algorithm. Differences were analyzed using pairwise comparisons from a GLM adjusting for baseline HAM-A and sites.

The sample consisted of 121 patients on pregabalin (female, 64%; mean age, 39.5 years; LS mean ± SE baseline HAM-A, 27.6 ± 0.5), 125 patients on venlafaxine-XR (female, 58%; mean age, 42.6 years; baseline HAM-A, 27.5 ± 0.5), and 128 patients on placebo (female, 61%; mean age, 40.2 years; baseline HAM-A, 26.8 ± 0.5). At endpoint, LS mean (± SE) number of SFDs was significantly higher for pregabalin (20.6 ± 1.4) compared with both venlafaxine-XR (16.5 ± 1.4; p=0.018) and placebo (15.5 ± 1.3; p=0.004). Values remained significant after adjusting for multiple comparisions (p=0.0447 and p=0.0107, respectively).

Treatment with pregabalin resulted in more SFDs compared with venlafaxine-XR and placebo. The lack of difference in SFDs for groups treated with venlafaxine-XR compared to placebo contrasts with a previously reported study. Further studies are warranted to explore the application of the SFD metric.