Efficacy of brief motivational interviewing on smoking cessation at tuberculosis clinics in Tshwane, South Africa: a randomized controlled trial.

BACKGROUND AND AIMS Tuberculosis (TB) patients who smoke risk adverse TB outcomes and other long-term health effects of smoking. This study aimed to determine the efficacy of brief motivational interviewing by lay health-care workers (LHCWs) in assisting TB patients to quit smoking. DESIGN Multi-centre two-group parallel individual randomized controlled trial. SETTING Six primary care tuberculosis clinics in a South African township. PARTICIPANTS Newly diagnosed adult TB patients identified as current smokers were randomized to brief motivational interviewing by a LHCW (intervention group, n = 205) or brief smoking cessation advice from a TB nurse (control group, n = 204). MEASUREMENTS The primary outcome was self-reported sustained 6-month smoking abstinence. Exhaled carbon monoxide (CO) testing was offered to about half the participants. Secondary outcomes were sustained abstinence at 3 months; 7-day point prevalence abstinence at 1, 3 and 6 months; and quit attempts. Allocation was concealed. Primary analysis relied on intention to treat. Multi-level analysis accounted for site heterogeneity of effect. FINDINGS Self-reported 6-month sustained abstinence was 21.5% for the intervention group versus 9.3% for the control group [relative risk (RR) = 2.29, 95% confidence interval (CI) = 1.34, 3.92]. Biochemically verified 6-month sustained abstinence was also higher in the intervention group (RR 2.21, 95% CI = 1.08, 4.51) for the 166 participants who were offered carbon monoxide testing. Self-reported 3-month sustained abstinence was 25.4% for the intervention group and 12.8% for the control group (RR = 1.98, 95% CI = 1.24, 3.18). CONCLUSIONS Motivational interviewing by lay counsellors to promote smoking cessation in tuberculosis patients in South Africa approximately doubled sustained smoking abstinence for at least 6 months compared with brief advice alone.