Fig. 4

Associations between risk factors and the odds of receiving a COPD diagnosis using the regression coefficients from studies with multivariable regression modeling† (‘adjusted analysis’) and persistent airflow limitation defined as post-bronchodilator FEV₁/FVC < 0.7. The reference categories were female, the absence of cough, wheeze, dyspnea, phlegm, and GOLD grades 3 and 4, respectively. Squares represent individual study estimates with the size of the square corresponding to their weight in the pooled estimate (represented with diamonds). †Herrera et al. [25] reported prevalence ratios from Poisson regression models. *The reference category was changed from GOLD grade 1 to GOLD grades 3 and 4 by assuming a covariance of 0 between the dummy variables representing GOLD grades 1 and 2.¹ Regression models were adjusted for age (Herrera, Hill, Hvidsten, Miravitlles, Talamo), sex (Herrera, Hill, Hvidsten, Miravitlles, Talamo), ethnicity (Herrera, Talamo), body mass index (Herrera, Hvidsten), education (Herrera, Hvidsten, Miravitlles, Talamo), income (Hvidsten), employment (Talamo), risk factor to dust (Herrera), smoking (Herrera, Hill, Hvidsten, Miravitlles, Talamo), respiratory symptoms, (Herrera, Hill, Hvidsten, Talamo), self-rated health (Hvidsten, Miravitlles), COPD severity (Herrera, Miravitlles, Talamo), comorbidities (Herrera, Hvidsten), prior health-care use (Herrera, Hill), and exacerbations (Herrera)