title: Obesity risk in rural, urban and rural-to-urban migrants: prospective results of the PERU MIGRANT study.
abstract: BACKGROUND
  Although migration and urbanization have been linked with higher obesity rates, especially in low-resource settings, prospective information about the magnitude of these effects is lacking. We estimated the risk of obesity and central obesity among rural subjects, rural-to-urban migrants and urban subjects.
  
  
  METHODS
  Prospective data from the PERU MIGRANT Study were analyzed. Baseline data were collected in 2007-2008 and participants re-contacted in 2012-2013. At follow-up, outcomes were obesity and central obesity measured by body mass index and waist circumference. At baseline, the primary exposure was demographic group: rural, rural-to-urban migrant and urban. Other exposures included an assets index and educational attainment. Cumulative incidence, incidence ratio (IR) and 95% confidence intervals (95% CI) for obesity and central obesity were estimated with Poisson regression models.
  
  
  RESULTS
  At baseline, mean age (±s.d.) was 47.9 (±12.0) years, and 53.0% were females. Rural subjects comprised 20.2% of the total sample, whereas 59.7% were rural-to-urban migrants and 20.1% were urban dwellers. A total of 3598 and 2174 person-years were analyzed for obesity and central obesity outcomes, respectively. At baseline, the prevalence of obesity and central obesity was 20.0 and 52.5%. In multivariable models, migrant and urban groups had an 8- to 9.5-fold higher IR of obesity compared with the rural group (IR migrants=8.19, 95% CI=2.72-24.67; IR urban=9.51, 95% CI=2.74-33.01). For central obesity, there was a higher IR only among the migrant group (IR=1.95; 95% CI=1.22-3.13). Assets index was associated with a higher IR of central obesity (IR top versus bottom tertile 1.45, 95% CI=1.03-2.06).
  
  
  CONCLUSIONS
  Peruvian urban individuals and rural-to-urban migrants show a higher incidence of obesity compared with their rural counterparts. Given the ongoing urbanization occurring in middle-income countries, the rapid development of increased obesity risk by rural-to-urban migrants suggests that measures to reduce obesity should be a priority for this group.
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: R M
authors.initials: RM
authors.lastname: Carrillo-Larco
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: A
authors.initials: A
authors.lastname: Bernabé-Ortiz
authors.affiliation: Medical School, University College London, London, UK.
authors.forename: T D
authors.initials: TD
authors.lastname: Pillay
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.|Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: R H
authors.initials: RH
authors.lastname: Gilman
authors.affiliation: US Naval Medical Research Unit No. 6 (NAMRU-6), Lima, Peru.
authors.forename: J F
authors.initials: JF
authors.lastname: Sanchez
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.|Primary Healthcare Center Santa Cruz de Ratacocha, Ministry of Health, Huanuco, Peru.
authors.forename: J A
authors.initials: JA
authors.lastname: Poterico
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: R
authors.initials: R
authors.lastname: Quispe
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: L
authors.initials: L
authors.lastname: Smeeth
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.|Department of Medicine, School of Medicine, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: J J
authors.initials: JJ
authors.lastname: Miranda
mesh_terms: D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000517:prevention & control; D004522:Educational Status; D005260:Female; D005500:Follow-Up Studies; D006292:Health Priorities; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000453:epidemiology* / Q000517:prevention & control; D056128:Obesity, Abdominal / Q000150:complications / Q000453:epidemiology; D010568:Peru / Q000453:epidemiology; D016012:Poisson Distribution; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012424:Rural Population / Q000639:trends; D012959:Socioeconomic Factors; D014171:Transients and Migrants / Q000706:statistics & numerical data*; D014505:Urban Population / Q000639:trends; D014507:Urbanization / Q000639:trends