Summary of findings 1. Metformin compared to placebo or no treatment for prevention of weight gain in people with schizophrenia.
| Metformin compared to placebo or no treatment for prevention of weight gain in people with schizophrenia | ||||||
| Patient or population: people with schizophrenia with antipsychotic‐induced weight gain Setting: inpatients or outpatients Intervention: metformin Comparison: placebo or no treatment | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with placebo | Risk with metformin | |||||
| Weight: clinically important change in weight (kg) | Study population | Not estimable | (0 RCTs) | ‐ | No data available | |
| Not estimable | Not estimable | |||||
| Weight: average endpoint/change in weight (kg) | Average endpoint/change in weight ranged from 5.88 to 6.87 | MD 4.03 kg lower (5.78 lower to 2.28 lower) | ‐ | 131 (4 RCTs) | ⊕⊕⊝⊝ Lowa,b | |
| Weight: clinically important change in BMI (kg/m2) | Study population | Not estimable | (0 RCTs) | ‐ | No data available | |
| Not estimable | Not estimable | |||||
|
Weight Average endpoint/change in BMI (kg/m2) |
Average endpoint/change in BMI ranged from 1.93 to 2.26 | MD 1.63 lower (2.96 lower to 0.29 lower) | ‐ | 227 (5 RCTs) | ⊕⊕⊝⊝ Lowc,b | |
| Leaving the study early: for any reason | Study population | RR 1.02 (0.25 to 4.13) | 137 (4 RCTs) | ⊕⊝⊝⊝ Very lowa,c | ||
| 58 per 1000 | 59 per 1000 (14 to 239) | |||||
| Compliance with treatment | Study population | Not estimable | (0 RCTs) | ‐ | No data available | |
| Not estimable | Not estimable | |||||
| Reports of nausea | Study population | RR 2.38 (0.28 to 19.95) | 69 (2 RCTs) | ⊕⊕⊝⊝ Lowa | ||
| 57 per 1000 | 136 per 1000 (16 to 1000) | |||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). BMI: body mass index; CI: confidence interval; MD: mean difference; RCT: randomised controlled trial; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | ||||||
aThe total number of participants included in the review is less than the number of participants required for a single, adequately powered study. Also, the confidence interval is extremely wide. bWe deemed one of the included studies in this outcome to have high risk of bias. cHeterogeneity of the results was quite high making interpretation uncertain.