Table 2.
Number Needed to Treat for the Prevention of Manic and Depressive Episodes and Polarity Index of Drugs Used for Maintenance treatment of Bipolar Disorder.
| Treatment | NNT mania | NNT depression | Polarity Index |
|---|---|---|---|
| Aripiprazole monotherapy (Keck et al., 2007) | 7.0 | 73.0 | 10.4 |
| Aripiprazole adjunctive to lithium/divalproex-pooled (Marcus et al., 2011; Woo et al., 2011) | 9.0 | 38.0 | 4.2 |
| Lamotrigine-pooled (Bowden et al., 2003; Calabrese et al., 2003) | 50.4 | 20.2 | 0.4 |
| Lithium-pooled (Prien et al., 1973; Bowden et al., 2000, 2003; Calabrese et al., 2003; Weisler et al., 2011) | 4.4 | 6.1 | 1.4 |
| Olanzapine monotherapy-pooled (Tohen et al., 2006; Vieta et al., 2012) | 4.4 | 17.5 | 4.0 |
| Olanzapine combined with lithium/divalproex (Tohen et al., 2004) | 11.2 | 6.2 | 0.5 |
| Oxcarbazepine combined with lithium (Vieta et al., 2008) | 8.2 | 5.1 | 0.6 |
| Quetiapine monotherapy (Weisler et al., 2011) | 2.4 | 3.3 | 1.4 |
| Quetiapine combined with lithium/divalproex-pooled (Vieta et al., 2008; Suppes et al., 2009) | 7.1 | 5.9 | 0.8 |
| Risperidone LAI monotherapy-pooled (Quiroz et al., 2010; Vieta et al., 2012) | 4.0 | 36.3 | 9.1 |
| Adjunctive risperidone LAI (Macfadden et al., 2009) | 7.9 | 15.8 | 2.0 |
| Divalproex (Bowden et al., 2000) | 21.3 | 10.5 | 0.5 |
| Ziprasidone Adjunctive to lithium/divalproex (Bowden et al., 2010) | 14.1 | 55.1 | 3.9 |
| Paliperidone ER (Berwaerts et al., 2012) | 8.0 | 17.0 | N/A |
NNT values in italic are negative, indicating that placebo was more effective than active treatment, although results of original trials did not reach statistical significance. When more than one RCT was available for a given treatment, calculations represent pooled results. LAI, long-acting injection; N/A, could not be calculated accurately as the NNT for the prevention of depression is negative; NNT, number needed to treat; RCT, randomized controlled trials.