Study protocol: health survey of Sao Paulo: ISA-Physical Activity and Environment

Many studies have investigated the association between the built environment and physical activity behavior in urban settings. However, most of the studies conducted in low- and middle-income countries were cross-sectional, which are limited to identify behavioral determinants. We propose a prospective cohort study to verify the relationship between built environment features and leisure-time and transport-related physical activity in adults from Sao Paulo city, Brazil. Prospective multilevel cohort, denominated "ISA-Physical Activity and Environment". It will build on the Health Survey of Sao Paulo in 2015 ("Inquérito de Saúde de São Paulo (ISA)" in Portuguese). The Health Survey of Sao Paulo, originally designed as a cross-sectional survey, had a multi-stage sample, covering 150 census tracts distributed in five health administrative areas. Data collection was performed by face-to-face interviews until December 2015 and the sample comprised 4043 individuals aged 12 years or more. The ISA-Physical Activity and Environment study will reassess people who are aged 18 years or more in 2020, including telephone and household interviews. The primary outcome will be leisure-time and transport-related physical activity, assessed through the International Physical Activity Questionnaire long version. Exposure variables will be built environment features in the areas participants live and work in the follow-up. Data analysis will include multivariate multilevel linear and logistic models. We will also conduct cost-effectiveness analysis and develop agent-based models to help inform decision-makers. The study will be conducted by an interdisciplinary research team specialized in physical activity epidemiology, nutritional epidemiology, georeferencing applied to health, statistics, agent-based modeling, public health policy, and health economics. There are few longitudinal studies on the relationship between the built environment and physical activity behavior in low- and middle-income countries. We believe that the ISA-Physical Activity and Environment study will contribute with important results for the progress of the knowledge in this field and for the implementation of policies that promote leisure-time physical activity and active travel in Sao Paulo and similar cities across the world.