Does a population-based multifactorial lifestyle intervention increase social inequality in physical activity? The Inter99 study

Aim To examine the effect of a multifactorial lifestyle intervention on 5-year change in physical activity (PA) and to explore whether length of education had an impact on the effect of the intervention. Methods Two random samples (high intervention group A, n=11 708; low intervention group B, n=1308) were invited for a health examination, assessment of absolute risk of ischemic heart disease and individual lifestyle counselling. The participation rate was 52.5%. High-risk individuals in group A were also offered group-based counselling on diet and PA and/or smoking cessation. High-risk individuals in group B were referred to usual care. All high-risk individuals were reinvited for examination and counselling after 1 and 3 years, and all participants were reexamined after 5 years. The control group (group C, n=5264, response rate 61.1%) answered a mailed questionnaire. Change in self-reported PA from baseline to 5-year follow-up was the main outcome. Level of education was classified as no vocational training, <= 4 years and >4 years. Data were analysed using longitudinal linear regression models with random intercepts. Results In men, the high-intensity intervention had a beneficial effect on PA level after 5 years. The age-or time-related decrease in PA was approximately 30 min/week less compared to men in the control group (p<0.0001). Level of education had no significant impact on the effect of the intervention neither in men (p=0.39) nor in women (p=0.32). Conclusion A population-based multifactorial lifestyle intervention did not influence social inequality in PA.