Twenty databases (including MEDLINE, EMBASE, CINAHL, PsycINFO, BIOSIS Previews and ECONLIT) were searched from inception to June 2007. Searches were not limited by study design or language. Experts in the conduct of econometric studies and with an interest in the systematic review of econometric studies were contacted.
Eligible studies were those assessing the impact of price on smoking behaviour in young people aged 25 years or under, either by focusing on young people or by presenting the data separately for young people and adults.
Data from each study were extracted by one reviewer and independently checked for accuracy by a second reviewer. Due to heterogeneity between studies in terms of the sources of data, outcomes and modelling methods, formal meta-analysis was considered inappropriate and a narrative synthesis was undertaken. The studies grouped according to whether they used longitudinal, repeated cross-sectional data or cross-sectional data; within these groupings described in relation to the type of controls they used, in particular policy variables (such as restrictions of sales to young people) and indoor air regulations.
Where available, the differential impact of price by subgroups and evidence on the impact of cross-border purchasing of cigarettes on price elasticity estimates were also assessed. Smoking outcomes were categorised into participation, prevalence, levels of smoking, initiation, and cessation.