Is a percentage a percentage? Systematic review of the effectiveness of Scandinavian behavioural modification smoking cessation programmes

Abstract

Introduction: Tobacco smoke is the leading preventable cause of death in the world. A total of 50% of all smokers will die from a smoking-related disease with a major impact upon quality of life and health-care costs. Tobacco-controlling policies, including smoking cessation, have increasingly been implemented across European countries. Reported effectiveness data on smoking cessation interventions are important for decision making.

Objective: This study aimed to conduct a literature review on how the effectiveness (quit rates) of behavioural modification smoking cessation programmes (BMSCPs) - counselling, quitlines and quit-and-win contests - were analysed in Denmark, Sweden and Norway.

Methods: A systematic review was carried out by using the search engines Medline (U.S. National Library of Medicine, Bethesda, MD, USA), Cinahl (CINAHL Information Systems, EBSCO Industries, Ipswich, MA, USA), Embase (Elsevier, New York, NY, USA) and the grey literature. Following the Russell Standards, studies were selected according to design, analysis of data [intention-to-treat (ITT)/per protocol (PP)], documentation of abstinence and length of follow-up. Cochrane reviews of pharmacological studies were used as the benchmark.

Results: Although ITT analysis is the standard scientific approach advocated, most studies of BMSCPs reviewed were analysed by using the PP approach and were based on self-reported point prevalence estimates. This resulted in the reported 1-year quit rates between 16%-45% (PP) and 9%-23% (ITT). In contrast, pharmacological studies are conservative, as they are randomised, use ITT analysis and have continuous quit rates with biochemical verification of abstinence.

Conclusion: This literature review reveals that quit rates of smoking cessation interventions are not always comparable. Scandinavian BMSCPs reported optimistic quit rates, confirmed by Cochrane literature review criteria. Care should be exercised when comparing smoking cessation interventions.