Objective To evaluate the association between length of residence in an urban area and obesity among Peruvian rural-to-urban migrants. Design Cross-sectional database analysis of the migrant group from the Peru MIGRANT Study (2007). Exposure was length of urban residence, analysed as both a continuous (10-year units) and a categorical variable. Four skinfold site measurements (biceps, triceps, subscapular and suprailiac) were used to calculate body fat percentage and obesity (body fat percentage >25% males, >33% females). We used Poisson generalized linear models to estimate adjusted prevalence ratios and 95 % confidence intervals. Multicollinearity between age and length of urban residence was assessed using conditional numbers and correlation tests. Setting A peri-urban shantytown in the south of Lima, Peru. Subjects Rural-to-urban migrants (n 526) living in Lima. Results Multivariable analyses showed that for each 10-year unit increase in residence in an urban area, rural-to-urban migrants had, on average, a 12 % (95 % CI 6, 18 %) higher prevalence of obesity. This association was also present when length of urban residence was analysed in categories. Sensitivity analyses, conducted with non-migrant groups, showed no evidence of an association between 10-year age units and obesity in rural (P=0·159) or urban populations (P=0·078). High correlation and a large conditional number between age and length of urban residence were found, suggesting a strong collinearity between both variables. Conclusions Longer lengths of urban residence are related to increased obesity in rural-to-urban migrant populations; therefore, interventions to prevent obesity in urban areas may benefit from targeting migrant groups. © Copyright The Authors 2015.

Migration Obesity Peru Skinfold Nutritional epidemiology rural-to-urban

Adipose Tissue urban population metabolism demography human middle aged rural population obesity time factor Time Factors Aged Residence Characteristics Cross-Sectional Studies Young Adult cross-sectional study Humans Adolescent male preschool child Socioeconomic Factors Infant risk factor Risk Factors Child, Preschool socioeconomics Multivariate Analysis female prevalence sensitivity and specificity adult migration Linear Models statistical model Transients and Migrants Peru Child