There were 18 studies included in the review: 12 double-blind placebo-controlled studies and 6 double-blind studies. There were 1,889 participants included in the overall comparison of the response rates for newer and older antidepressants. There were 851 and 783 patients included, respectively, in the overall comparisons of the discontinuation rates for newer antidepressants and TCAs, and newer antidepressants and NTCA-SSRIs.
Significant heterogeneity was found in the discontinuation rates compared for the newer antidepressants and TCAs (chi-squared 18.11, d.f.=7, p= 0.01). Two studies were excluded because they used low doses and caused significant heterogeneity. When these studies were excluded, the discontinuation rates were homogeneous.
The pooled OR of the newer and older antidepressants was 1.29 (95% CI: 1.07, 1.55), indicating a higher response of the newer antidepressant group.
In the overall comparison of the newer antidepressant and TCA discontinuation rates, the OR was 0.54 (95% CI: 0.38, 0.77); this showed a significantly lower discontinuation rate of the newer antidepressant group.
In the overall comparison of the newer antidepressant and NTCA-SSRI discontinuation rates, the pooled OR was 0.94 (95% CI: 0.66, 1.35), showing no significant difference between them.