evidence: the tailored letters intervention was significantly more effective than brief advice for 24-hour [odds ratio (OR) = 1.4; P = 0.047] but not for 7-day point prevalence abstinence (OR = 1.4; P = 0.068) for prolonged abstinence, or for alternative assumptions about participants lost to follow-up.
intervention: Tailored letters
comparator: Practitioner-delivered brief advice
outcome: 24-hour point prevalence abstinence