TABLE 5

Change of lung function and risk of hospital/emergency room (ER) admission for breathing problems over follow-up, for subjects with current asthma, chronic obstructive pulmonary disease (COPD) or both, compared with healthy subjects

Asthma aloneACOSCOPD alonep-value heterogeneity#
FEV1 change mL·year−10.69 (−1.65–3.02)1.62 (−2.76–5.99)−7.64 (−12.6– −2.66)**0.007
FEV1 change % of baseline·year−10.004 (−0.07–0.07)0.05 (−0.08–0.18)−0.37 (−0.52– −0.22)***<0.001
FVC change mL·year−1−0.92 (−3.79–1.96)−4.84 (−10.23–0.54)−13.83 (−19.96– −7.70)***<0.001
FVC change % of baseline·year−1−0.01 (−0.08–0.05)−0.11 (−0.23–0.01)−0.30 (−0.43– −0.16)***<0.001
Hospital/ER admission for breathing  problems OR (95% CI) with respect  to the healthy category3.76 (2.84–4.99)***5.12 (3.24–8.10)***2.10 (1.06–4.13)*0.080
  • Data are presented as mean difference (95% CI) with respect to the healthy category, unless otherwise stated. Regression coefficients were obtained using linear regression models, with forced expiratory volume in 1 s (FEV1) or forced vital capacity (FVC) change as dependent variables, sex, age, height, body mass index (BMI), education level, occupational exposure to vapours, gas, dust or fumes, disease status at baseline or lifetime smoking exposure (five-level variable coded as follows. 0: lifetime nonsmoker; 1: past smoker <15 pack-years; 2: past smoker ≥15 pack-years; 3: current smoker <15 pack-years; or 4: current smoker ≥15 pack-years) and change in BMI over follow-up as independent variables, and a random intercept term for European Community Respiratory Health Survey (ECHRS) centre and sample. A negative value represents a greater decline with respect to the healthy reference category. Odds ratios were obtained using a logistic regression model, with hospital/emergency room (ER) admissions as dependent variables, sex, age, BMI, education level, occupational exposure to vapours, gas, dust or fumes, disease status at baseline, lifetime smoking exposure and change in BMI over follow-up as independent variables, and a random intercept term for ECRHS centre and sample. ACOS: asthma–COPD overlap syndrome. #: p-value for the heterogeneity of the association across the groups, obtained by testing the difference across regression coefficients using Wald test; p<0.05 indicates that at least one of the regression coefficients is significantly different from the others, i.e. that the change in lung function (or risk of hospital/ER admissions) with respect to the reference healthy category differs for at least one disease group compared to the others; : present if a subject answered positively to one or both of “Since the last survey, have you spent a night in hospital?” or “Have you visited a hospital casualty department or ER because of breathing problems?” *: p<0.05; **: p<0.01; ***: p<0.001 for the comparison of the disease group with the healthy category.