Table 3

Spearman’s r for correlations between days of lost productivity and age, FEV1% predicted values, comorbidities and exacerbations of respiratory symptoms in hospital-recruited COPD cases, population recruited-COPD cases and population-recruited control subjects

AgeFEV1, % of predictedNumber of comorbid conditionsNumber of events, exacerbations of respiratory symptoms
Hospital-recruited COPD cases, Spearman’s rr=0.154; p=0.12r=−0.390; p<0.001r=0.341; p<0.001r=0.071; p=0.478
Population-recruited COPD cases, Spearman’s rr=0.035; p=0.80r=−0.214; p=0.124r=0.28; p=0.039r=0.246; p=0.075
Population-recruited controls, Spearman’s rr=0.023; p=0.81r=−0.136; p=0.163r=0.156, p=0.108r=0.20, p=0.038
  • The significance of bold is P<0.05.

  • COPD, here defined by FEV1/FVC<0.7 postbronchodilation and FEV1 <80% of predicted values.

  • COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.