A longitudinal study on the impact of income change and poverty on smoking cessation.

OBJECTIVES: Research on the association between income and smoking cessation has examined income as a static phenomenon, either cross-sectionally or as a predictor variable in longitudinal studies. This study recognizes income as a dynamic entity and examines the relationship between a change in income and subsequent smoking behaviour.
METHOD: Longitudinal data from the National Population Health Survey (1994/5 to 2008/9) were used to examine the impact of (1) change in income and (2) change in poverty status, on the probability of being a former or current smoker among a sample of Canadians identified as having ever smoked. Covariates include socio-demographic characteristics, number of cigarettes smoked per day, and smoking in the home.
RESULTS: Smoking behaviour was not associated with a change in household income but was associated with a change in household income that moved an individual across the poverty threshold. Canadians whose income increased to above the poverty threshold were less likely to continue smoking than someone who remained in poverty (OR = 0.72, 95% CI: 0.62-0.84). Those who remained out of poverty were also less likely to continue smoking than someone who remained in poverty (OR = 0.66, 95% CI: 0.57-0.75). There was no significant difference between those who remained in poverty and those whose income decreased to below the poverty level.
CONCLUSION: This study strengthens the link between smoking and poverty and supports strategies that address income as a socio-economic determinant of health. Policies that increase household incomes above the poverty line may lead to improvements in smoking cessation rates.