Equity impact of population-level interventions and policies to reduce smoking in adults: a systematic review.

BACKGROUND AND AIMS There is strong evidence about which tobacco control policies reduce smoking. However, their equity impact is uncertain. The aim was to assess the effectiveness of population-level interventions/policies to reduce socioeconomic inequalities in adult smoking. METHODS Systematic review of studies of population-level interventions/policies reporting smoking-related outcomes in adults of lower compared to higher socioeconomic status (SES). References were screened and independently checked. Studies were quality assessed. Results are presented in a narrative synthesis. Equity impact was assessed as: positive (reduced inequality), neutral (no difference by SES), negative (increased inequality), mixed (equity impact varied) or unclear. RESULTS 117 studies of 130 interventions/policies were included: smokefree (44); price/tax (27); mass media campaigns (30); advertising controls (9); cessation support (9); settings-based interventions (7); multiple policies (4). The distribution of equity effects was: 33 positive, 36 neutral, 38 negative, 6 mixed, 17 unclear. Most neutral equity studies benefited all SES groups. Fourteen price/tax studies were equity positive. Voluntary, regional and partial smokefree policies were more likely to be equity negative than national, comprehensive smokefree policies. Mass media campaigns had inconsistent equity effects. Cigarette marketing controls were equity positive or neutral. Targeted national smoking cessation services can be equity positive by achieving higher reach among low SES, compensating for lower quit rates. CONCLUSIONS Few studies have assessed the equity impact of tobacco control policy/interventions. Price/tax increases had the most consistent positive equity impact. More research is needed to strengthen the evidence-base for reducing smoking inequalities and to develop effective equity-orientated tobacco control strategies.