Fig 2 Meta-analysis of smoking outcomes. Pooled estimates are Mantel Haenszel relative risks (fixed effects). Heterogeneity statistic Q for at least six months’ abstinence was 8.4 (P=0.078), for abstinence from week 6 to end of follow-up was 2.74 (P=0.840), for point prevalence of abstinence at end of follow-up was 10.86 (P=0.093), for reduction from week 6 to end of follow-up was 3.63 (P=0.604), and for point prevalence of reduction at end of follow-up was 9.43 (P=0.151)