title: A global study on the influence of neighborhood contextual factors on adolescent health.
abstract: OBJECTIVE
  This study uses data collected as part of the Well-Being of Adolescents in Vulnerable Environments study to (1) compare the perceptions of neighborhood-level factors among adolescents across five different urban sites; (2) examine the associations between factors within the physical and social environments; and (3) examine the influence of neighborhood-level factors on two different health outcomes-violence victimization in the past 12 months and ever smoked.
  
  
  METHODS
  Across five urban sites (Baltimore, New Delhi, Johannesburg, Ibadan, and Shanghai), 2,320 adolescents aged 15-19 years completed a survey using audio computer-assisted self-interview technology. To recruit adolescents, each site used a respondent-driven sampling method, which consisted of selecting adolescents as "seeds" to serve as the initial contacts for recruiting the entire adolescent sample. All analyses were conducted with Stata 13.1 statistical software, using complex survey design procedures. To examine associations between neighborhood-level factors and among our two outcomes, violence victimization and ever smoked, bivariate and multivariate analyses were conducted.
  
  
  RESULTS
  Across sites, there was great variability in how adolescents perceived their neighborhoods. Overall, adolescents from Ibadan and Shanghai held the most positive perceptions about their neighborhoods, whereas adolescents from Baltimore and Johannesburg held the poorest. In New Delhi, despite females having positive perceptions about their safety and sense of social cohesion, they had the highest sense of fear and the poorest perceptions about their physical environment. The study also found that one of the most consistent neighborhood-level factors across sites and outcomes was witnessing community violence, which was significantly associated with smoking among adolescents in New Delhi and Johannesburg and with violence victimization across nearly every site except Baltimore. No other neighborhood-level factor exerted greater influence.
  
  
  CONCLUSIONS
  This study confirms the important associations between perceptions of a neighborhood and adolescent health. At the same time, it demonstrates that not all neighborhood-level factors are associated with adolescent health outcomes in the same way across different urban contexts. Further longitudinal research is needed to examine the direction of causation between adolescent health neighborhood contexts and health outcomes and the reasons for why different urban contexts may exert varying levels of influence on the health of adolescents.
authors.affiliation: Department of Population, Family and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland. Electronic address: kmmari@jhsph.edu.
authors.forename: Kristin
authors.initials: K
authors.lastname: Mmari
authors.affiliation: Department of Population, Family and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Hannah
authors.initials: H
authors.lastname: Lantos
authors.affiliation: Department of Population, Family and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Blum
authors.affiliation: Department of Population, Family and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Heena
authors.initials: H
authors.lastname: Brahmbhatt
authors.affiliation: Institute of Child Health, College of Medicine, University College Hospital, University of Ibadan, Ibadan, Oyo State, Nigeria.
authors.forename: Adesola
authors.initials: A
authors.lastname: Sangowawa
authors.affiliation: Department of Epidemiology and Social Science, Shanghai Institute of Planned Parenthood Research, Shanghai China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Yu
authors.affiliation: Wits Reproductive Health and HIV Institute, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Sinead
authors.initials: S
authors.lastname: Delany-Moretlwe
mesh_terms: D000293:Adolescent; D016497:Adolescent Health Services / Q000706:statistics & numerical data; D002681:China / Q000453:epidemiology; D019548:Crime Victims / Q000191:economics / Q000706:statistics & numerical data; D004777:Environment; D005239:Fear / Q000523:psychology; D005260:Female; D014943:Global Health; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D009549:Nigeria / Q000453:epidemiology; D010465:Perception; D011204:Poverty Areas; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012494:Sampling Studies; D012907:Smoking / Q000523:psychology; D066252:Sociological Factors; D013019:South Africa / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D014504:Urban Health / Q000191:economics; D014754:Violence / Q000191:economics / Q000523:psychology / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Adolescents; Neighborhood effects; Physical environment; Urban health