title: The association between obesity and outpatient visits for acute respiratory infections in Ontario, Canada.
abstract: OBJECTIVE
  Recent evidence suggests that obesity increases the risk of severe outcomes following respiratory infection. It is less clear whether obesity is associated with the risk of being infected with influenza or other respiratory pathogens. Therefore, we examined the association between obesity and outpatient visits for acute respiratory infections (ARIs).
  
  
  METHODS
  We conducted a retrospective cohort study for a period of over 13 years on 104,665 individuals in Ontario, Canada who responded to population health surveys and agreed to linkage with health administrative data. Individuals aged 18-64 years who responded to a survey within 5 years prior to the start of an influenza season were included. Poisson regression, with adjustment for relevant confounders, was used to measure the association between self-reported body mass index (BMI) and outpatient visits for ARI. We conducted numerous sensitivity analyses to assess the robustness of our findings.
  
  
  RESULTS
  We observed higher rates of outpatient visits for ARI during influenza season periods compared with normal weight individuals for those who were overweight (BMI 25-29.9; rate ratio (RR) 1.10; 95% confidence interval (95% CI) 1.07-1.13), obese class I (BMI 30-34.9; RR 1.17; 95% CI 1.13-1.22) and obese class II or III (BMI ≥35; RR 1.19; 95% CI 1.12-1.25). Associations of a similar magnitude were observed during non-influenza season periods. Obesity was a greater risk factor for ARIs managed in emergency departments than physician offices.
  
  
  CONCLUSIONS
  Obese individuals are at an increased risk of outpatient visits for ARI during both influenza and non-influenza season periods, suggesting that the effect of obesity on the risk of respiratory infections is not limited to influenza. Interventions designed to reduce the prevalence of obesity may have the added benefit reducing the population burden of respiratory infections.
authors.affiliation: Department of Primary Care and Population Health, Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Campitelli
authors.affiliation: 1] Department of Primary Care and Population Health, Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada [2] Public Health Ontario, Toronto, Ontario, Canada [3] The Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: L C
authors.initials: LC
authors.lastname: Rosella
authors.affiliation: 1] Department of Primary Care and Population Health, Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada [2] Public Health Ontario, Toronto, Ontario, Canada [3] The Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada [4] The Department of Family and Community Medicine, University of Toronto, Toronto, Ontario, Canada [5] University Health Network, Toronto, Ontario, Canada.
authors.forename: J C
authors.initials: JC
authors.lastname: Kwong
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D016017:Odds Ratio; D009819:Office Visits / Q000706:statistics & numerical data*; D009864:Ontario / Q000453:epidemiology; D010045:Outpatients / Q000706:statistics & numerical data*; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors