Seven studies (n=901 women) were included in the review. Of these, three studies were excluded from the meta-analysis: two studies that were open-label, uncontrolled pilot studies; and one study that was a randomised uncontrolled Phase III trial comparing gabapentin plus an anti-depressant with antidepressant treatment alone. Of the four RCTs in the meta-analysis, three trials included post-menopausal women and one trial included women with a history of breast cancer. The κ statistic result for interrater agreement on study quality was 0.86. The quality scores of the seven included studies ranged from 4 to 8 points. The Egger test for publication bias showed no evidence of significant bias.
In three RCTs (n=273 women), there were statistically significant larger reductions observed in the gabapentin-treated group for both the frequency of hot flashes (WMD 23.72, 95% CI 16.46 to 30.97) and the composite score (WMD 27.26, 95% CI 21.24 to 33.29). For both these outcomes, heterogeneity was high and statistically significant (frequency I2=97.8% and composite score I2=95.6%).
In the four RCTs for which data were available (n=736), dropouts due to adverse events were observed to be higher in women treated with gabapentin (RR 2.09, 95% CI 1.13 to 3.85; I2=0%).