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Original research
Urbanisation and asthma in low-income and middle-income countries: a systematic review of the urban–rural differences in asthma prevalence
  1. Alejandro Rodriguez1,2,3,
  2. Elizabeth Brickley1,
  3. Laura Rodrigues1,
  4. Rebecca Alice Normansell4,
  5. Mauricio Barreto5,6,
  6. Philip J Cooper2,3,7
  1. 1 Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
  2. 2 Facultad de Ciencias Médicas de la Salud y la Vida, Universidad Internacional del Ecuador, Quito, Ecuador
  3. 3 Fundación Ecuatoriana para la Investigación en Salud, Quito, Ecuador
  4. 4 Population Health Research Institute, London, UK
  5. 5 Instituto de Saude Coletiva, Universidad Federal da Bahia, Salvador, Brazil
  6. 6 Centrode de Integração de Dados e Conhecimentos para Saúde (CIDACS), FIOCRUZ, Salvador, Brazil
  7. 7 Institute of Infection and Immunity, St George’s University of London, London, UK
  1. Correspondence to Alejandro Rodriguez, Facultad de Ciencias Médicas de la Salud y la Vida, Universidad Internacional del Ecuador, Quito, Pichincha, Ecuador; rorodriguezal{at}uide.edu.ec

Abstract

Background Urbanisation has been associated with temporal and geographical differences in asthma prevalence in low-income and middle-income countries (LMICs). However, little is known of the mechanisms by which urbanisation and asthma are associated, perhaps explained by the methodological approaches used to assess the urbanisation-asthma relationship.

Objective This review evaluated how epidemiological studies have assessed the relationship between asthma and urbanisation in LMICs, and explored urban/rural differences in asthma prevalence.

Methods Asthma studies comparing urban/rural areas, comparing cities and examining intraurban variation were assessed for eligibility. Included publications were evaluated for methodological quality and pooled OR were calculated to indicate the risk of asthma in urban over rural areas.

Results Seventy articles were included in our analysis. Sixty-three compared asthma prevalence between urban and rural areas, five compared asthma prevalence between cities and two examined intraurban variation in asthma prevalence. Urban residence was associated with a higher prevalence of asthma, regardless of asthma definition: current-wheeze OR:1.46 (95% CI:1.22 to 1.74), doctor diagnosis OR:1.89 (95% CI:1.47 to 2.41), wheeze-ever OR:1.44 (95% CI:1.15 to 1.81), self-reported asthma OR:1.77 (95% CI:1.33 to 2.35), asthma questionnaire OR:1.52 (95% CI:1.06 to 2.16) and exercise challenge OR:1.96 (95% CI:1.32 to 2.91).

Conclusions Most evidence for the relationship between urbanisation and asthma in LMICs comes from studies comparing urban and rural areas. These studies tend to show a greater prevalence of asthma in urban compared to rural populations. However, these studies have been unable to identify which specific characteristics of the urbanisation process may be responsible. An approach to understand how different dimensions of urbanisation, using contextual household and individual indicators, is needed for a better understanding of how urbanisation affects asthma.

PROSPERO registration number CRD42017064470.

  • urbanisation
  • asthma
  • urban and rural areas
  • LMICs

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

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Footnotes

  • Contributors Study design: AR, PJC, LCR. Data collection; AR, PJC, LCR. Data analysis: AR. Draft manuscript: AR, PJC. Manuscript review: AR, EB, RN, PJC, MLB.

  • Funding The research was supported by grants from the Wellcome Trust (072405/Z/03/Z and 088862/Z/09/Z). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data are available upon reasonable request.

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