Microalbuminuria in patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis

Background and objectives We conducted this systematic review and meta-analysis to determine the prevalence of microalbuminuria in patients with chronic obstructive pulmonary disease (COPD) and its association with COPD severity. Methods We conducted a literature search in PubMed, Embase, Scopus, Web of Science, Cochrane Library, and the Virtual Health Library from inception to December 31th, 2024. The search strategy was: ('chronic obstructive pulmonary disease' OR COPD OR 'chronic airflow obstruction' OR emphysema OR 'chronic bronchitis') AND (microalbuminuria OR albuminuria OR proteinuria OR 'urinary albumin creatinine ratio' OR 'urinary albumin excretion'). We included studies recruiting patients diagnosed by spirometry and providing data of microalbuminuria prevalence. We excluded studies in patients with other respiratory diseases associated with COPD, and studies published in predatory journals. The pooled prevalence of microalbuminuria was calculated using the DerSimonian-Laird binary random effects method, and the association of microalbuminuria with COPD and its severity was assessed using the Mantel-Haenszel random effects method. Results Twenty-five articles were included. The prevalence of microalbuminuria in patients with COPD was 49.3% [95% confidence interval (CI) 34.3-64.4%], which was higher than in the control population, with an estimated odds ratio of 3.94 (95% CI 2.25-6.60). In patients with severe to very severe COPD, it was higher than in those with mild to moderate COPD, with an estimated odds ratio of 4.55 (95%IC 2.85-7.28). Patients with COPD and microalbuminuria had an estimated decrease in PaO2 of 9.98 mmHg (95% CI 13.94-6.02) and an increase in PaCO2 of 8.08 mmHg (95% CI: 4.87-11.29). Interpretations and conclusions Microalbuminuria is highly prevalent in patients with COPD, with a much higher frequency than in the general population. It is more common in patients with more severe airflow obstruction and is associated with hypoxia and hypercapnia.