title: Length of urban residence and obesity among within-country rural-to-urban Andean migrants.
abstract: OBJECTIVE
  To evaluate the association between length of residence in an urban area and obesity among Peruvian rural-to-urban migrants.
  
  
  METHODS
  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.
  
  
  METHODS
  A peri-urban shantytown in the south of Lima, Peru.
  
  
  METHODS
  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.
authors.affiliation: 1CRONICAS Center of Excellence in Chronic Diseases,Universidad Peruana Cayetano Heredia,Av. Armendáriz 497,Miraflores,Lima 18,Peru.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Antiporta
authors.affiliation: 1CRONICAS Center of Excellence in Chronic Diseases,Universidad Peruana Cayetano Heredia,Av. Armendáriz 497,Miraflores,Lima 18,Peru.
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.affiliation: 1CRONICAS Center of Excellence in Chronic Diseases,Universidad Peruana Cayetano Heredia,Av. Armendáriz 497,Miraflores,Lima 18,Peru.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
authors.affiliation: 1CRONICAS Center of Excellence in Chronic Diseases,Universidad Peruana Cayetano Heredia,Av. Armendáriz 497,Miraflores,Lima 18,Peru.
authors.forename: J Jaime
authors.initials: JJ
authors.lastname: Miranda
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000453:epidemiology*; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D012111:Residence Characteristics; D012307:Risk Factors; D012424:Rural Population; D012680:Sensitivity and Specificity; D012959:Socioeconomic Factors; D013997:Time Factors; D014171:Transients and Migrants; D014505:Urban Population; D055815:Young Adult
keywords: Migration; Nutritional epidemiology; Obesity; Peru; Rural-to-urban; Skinfold