Age at smoking initiation and self-rated health among second grade high school boys and girls in Scania, Sweden, a cross-sectional study

BACKGROUND Smoking is usually initiated early in life and most adult regular smokers have started smoking before 18 years of age. A younger age at smoking initiation is associated with risk taking behaviours and worse health outcomes regarding psychological and somatic conditions, suggested to be caused by exposure during critical developmental periods. The present study aims to investigate self-rated health among second grade high school boys and girls related to age at smoking initiation (<14 years of age and ≥ 14 years of age) among current and former smokers, compared to never smokers. METHODS Data was derived from the Scania public health survey among children and adolescents in 2012. The study was cross-sectional with retrospective information about first time cigarette smoking experiences among 3245 boys and 3434 girls in second grade of high school. Self-rated health was assessed with the question "How do you rate your general health". Associations of age at smoking initiation, current smoking status and poor self-rated health were investigated with logistic regression models. RESULTS Crude odds ratios of poor self-rated health were increased for all smoking groups compared to never smokers. Former smoking boys and currently smoking girls with early smoking initiation had the highest odds ratios of poor self-rated health, with odds ratios (OR) 2.4 (95 % confidence interval (CI): 1.5-3.7) and OR 2.9 (95 % CI: 2.3-3.6), respectively. After adjustments for sociodemographic factors, health-related behaviours, psychosocial factors, weight and functional disabilities, the results were attenuated, but remained statistically significant regarding former and current smoking boys with early smoking initiation, OR 2.0 (95 % CI: 1.1-3.7) and OR 1.7 (95 % CI: 1.1-2.4) and for current smoking girls with early and later smoking initiation, OR 2.1 (95 % CI: 1.5-2.8) and OR 1.5 (95 % CI: 1.1-2.0). CONCLUSION Boys and girls in second grade of high school with early smoking initiation reported poorer self-rated health than later initiators and never smokers. Poorer self-rated health persisted also after smoking cessation among early initiating boys. Further studies are needed to understand the adverse health effects associated with timing of smoking initiation.