Table 2 Results of meta-analyses of trials of high intensity nursing to reduce smoking using standard§ and 'treat-as-one-trial' methods, with relative risk as effect measure
From: Meta-analysis, Simpson's paradox, and the number needed to treat
Setting (no. of trials) | Number quitting/total | Pooled risk ratio (95% CI) | NNT (95% CI) | |
|---|---|---|---|---|
| Â | Intervention | Control | Â | Â |
Hospital (7) | 435/1367 | 318/1295 | Â | Â |
   Meta-analysis |  |  | 1.30 (1.16 to 1.47) | 13.6 (8.7 to 25.5)¶¶ |
   Treat-as-one-trial |  |  | 1.30 (1.15 to 1.47) | 13.8 (9.4 to 25.9) |
Primary Care (3) * | 111/2453 | 41/1006 | Â | Â |
   Meta-analysis |  |  | 1.01 (0.71 to 1.42) | 2454 (58.4 to H84.6¶)¶¶ |
   Treat-as-one-trial |  |  | 1.11 (0.78 to 1.58) | 222.5 (52.0 to H97.7¶) |
Primary Care (2) ** | 87/2246 | 25/958 | Â | Â |
   Meta-analysis |  |  | 1.54 (0.97 to 2.44) | 71.0 (26.6 to H1277¶)¶¶ |
   Treat-as-one-trial |  |  | 1.48 (0.96 to 2.30) | 79.1(39.2 to H4369¶) |