Int. J. Environ. Res. Public Health 2012, 9 205 Table 4 shows the main results in terms percentage of abstinent participants with intervention and placebo. The quit rate with placebo in the two larger reviews was 15% and 30%, with an overall average cessation rate of 18% in 2,082 participants on placebo. Only acamprosate had sufficient information to demonstrate effectiveness, with an NNT of 12 (95% CI 9 to 17). Table 4. Results of alcohol cessation reviews, ordered by number of participants. The order is by numbers of participants in the reviews. Intervention is as described in each review, and details of the reviews is in Table 1. Intervention Acamprosate Naltrexone Opioid antagonists Number of patients 3,324 1,077 208 Percent abstinent with Active Placebo 23 15 35 30 52 37 Relative benefit (95% CI) 1.6 (1.4 to 1.8) 1.2 (1.0 to 1.4) 1.4 (1.0 to 2.0) NNT (95% CI) 12 (9 to 17) not calculated 6 (3 to 43) 3.3. Cocaine Information was available from seven systematic reviews [27-33], six of which were Cochrane reviews. Six reviews examined drug therapies, and one cognitive behavioural therapy. There was data on over 2,600 participants with cessation rates ranging between one and six months, though most comparisons were relatively small in size. All used only properly randomised trials in participants with defined cocaine addiction, used a mixture of non-use of cocaine by measurement or retention in a programme to assess abstinence, and used placebo or counselling. Studies using validated non-use by measurement or maintenance in programme appeared not to differ in cessation rates with placebo. Table 5. Results of cocaine cessation reviews, ordered by number of participants. The order is by numbers of participants in the reviews. Intervention is as described in each review, and details of the reviews is in Table 1. Intervention CNS stimulants Cognitive behavioural therapy Anticonvulsants Carbamazepine Desipramine Amantadine Antipsychotics Number of patients 640 Percent abstinent with Active Placebo 51 53 570 468 313 266 215 208 54 47 39 43 39 58 46 52 32 50 27 45 Relative benefit (95% CI) 1.0 (0.8 to 1.1) 1.2 (1.0 to 1.4) 0.9 (0.8 to 1.1) 1.3 (0.9 to 1.7) 0.9 (0.7 to 1.1) 1.4 (1.0 to 2.1) 1.3 (1.0 to 1.7) NNT (95% CI) not calculated not calculated not calculated not calculated not calculated not calculated not calculated Table 5 shows the main results in terms percentage of abstinent participants with intervention and placebo, and the relative benefit. The quit rate with placebo varied between 27% and 53%, with an overall average cessation rate of 47% in 1,134 participants on placebo (not double counting carbamazepine results with those of anticonvulsants). A review of psychosocial interventions had a