Characterisation and prognosis of undiagnosed chronic obstructive pulmonary disease patients at their first hospitalisation

Table 3 Association between previous COPD diagnosis and subsequent COPD hospitalisations

	Crude model		Adjusted model*
	HR *(95% CI)*	p-value	HR *(95% CI)*	p-value
Previously diagnosed COPD	1.00		1.00
Newly diagnosed COPD	0.564 (0.380-0.836)	<0.01	0.858 (0.551-1.338)	0.50
Dyspnoea score (mMRC, score 0–4)	--	--	1.234 (1.005-1.515)	0.04
BMI (Kg/m ² )	--	--	0.961 (0.919-1.005)	0.08
RV/TLC (%)	--	--	1.025 (1.000-1.050)	0.04
FEV ₁ post-bronchodilator (% pred)	--	--	0.994 (0.977-1.011)	0.51

HR: hazard ratio; CI: confidence interval; mMRC: modified Medical Research Council; BMI: body mass index; RV/TLC: Residual Volume/Total Lung Capacity; FEV₁: forced expiratory volume in 1 second.
*Final models were adjusted to account for negative confounding, i.e., that the apparently protective effect of undiagnosed COPD is due to a lower clinical severity of the disease. Other potential confounders (see text) were tested but not included because they were not independently related to both the exposure and the outcome, nor did these confounders modify (>10% change in Hazard Ratio) the estimates for the remaining variables.

ISSN: 1471-2466