COPD and microalbuminuria: a 12-year follow-up study

Chronic obstructive pulmonary disease (COPD), low lung function independent of diagnosis and markers of inflammation are all associated with increased morbidity and mortality. Microalbuminuria, reflecting endothelial dysfunction, could be a relevant inflammatory marker of potential systemic effects of COPD. We hypothesised that there was a positive association between microalbuminuria and mortality in individuals with COPD. We conducted a 12-year follow-up study of 3129 participants in the second survey of the Nord-Trøndelag Health Study (HUNT), Norway. At baseline, albuminuria was analysed in three urine samples and spirometry was performed. Among the participants, 136 had COPD and microalbuminuria, defined as a urinary albumin/creatinine ratio between 2.5 and 30.0 mg·mmol(-1). The main outcome measures were hazard ratio of all-cause mortality according to microalbuminuria. Compared to those with COPD without microalbuminuria, the adjusted hazard ratio for all-cause mortality in those with COPD and microalbuminuria was 1.54, 95% CI 1.16-2.04. This result was similar after excluding cardiovascular disease at baseline. Classifying COPD severity by Global Initiative for Chronic Obstructive Lung Disease, there was a positive association trend with increasing severity stages. Microalbuminuria is associated with all-cause mortality in individuals with COPD and could be a relevant tool in identification of patients with poor prognosis.