Twenty-five relevant studies were identified: 10 controlled studies (n=10,639) that comprised five randomised controlled trials (RCTs) (n=1,929, range 188 to 650), one cluster randomised trial (n=5,849) and four quasi-experimental studies (n=2,861, range 193 to 1297); and 15 pre-post test studies (n=67,177, range 87 to 44,761). Only eight (all controlled trials) of the 25 studies were rated as moderate or strong quality on at least three of the six quality criteria. The non-controlled studies had predominately weak methodologies.
The pooled analysis for controlled trials showed a statistically significant increase in provision of assistance and counselling to quit with the intervention (PRD 16.6, 95% CI 4.9 to 28.3, I2=93.7%; eight studies), but no significant effect for assessment of smoking status (PRD 13.7, 95% CI -11.4 to 38.7; two studies), advice to quit (PRD 21.0, 95% CI -0.6 to 42.6, I2=97.9%; six studies) or the provision or offer of nicotine replacement therapy (PRD 50.2, 95% CI -29.7 to 130.2; two studies). All meta-analyses showed significant heterogeneity. One RCT found provision of referral or follow-up was 47.1% higher in the intervention group than the control group. Another controlled study found significantly more health professionals in the intervention group provided three out of seven care items describing assistance or counselling to quit.