Randomised controlled trials and population studies of effectiveness of NRT
| Reference | Sample and design | Major findings | |
| Randomised controlled trials | Fiore et al 1 | Meta-analysis of 83 studies, including 77 individual NRT treatment arms and 80 placebo arms | Effectiveness was higher in NRT treatment arms than placebo treatment arms (OR 1.5–3.1) |
| Stead et al 5 | Meta-analysis of 111 studies, with over 40 000 participants, typically of adult cigarette smokers, average age 40 to 50 years and smoked at least 15 cigarettes per day | Abstinence rates were higher among users of NRT relative to persons in control groups (RR 1.58) | |
| Silagy et al 38 | Meta-analysis of 103 studies with over 35 600 participants | Abstinence among NRT treatment groups was greater than persons in control groups (OR 1.77) | |
| Population studies | Pierce et al 11 | Cross-sectional state-wide samples of previous-year cigarette smokers in 1996 and 1999 California Tobacco Survey | No difference in time to relapse among moderate-to-heavy smokers using over-the-counter NRT compared with those using no medication |
| Fiore et al 6 | Cross-sectional national sample of 13 031 adult ever-smokers in 1986 Adult Use of Tobacco Survey | Quitters with unassisted cessation were more successful than quitters using assisted cessation (OR 3.3) | |
| Alberg et al 8 | Longitudinal cohort study of 1954 current cigarette smoker residents in Washington County, Maryland, in 1989 and 1998 | Quitting rates among NRT users were 4.9% less than among non-NRT users |
NRT, nicotine replacement therapy.