Disproportionately raised risk of adverse outcomes in patients with COPD and comorbid type 2 diabetes or depression: Swedish register-based cohort study.

Background: We aimed to examine if patients with COPD and comorbid type 2 diabetes, or COPD with comorbid depression or anxiety, had disproportionally raised excess risks of subsequent cardiovascular disease and mortality.

Methods: This general population-based cohort study used data from Swedish national registers, with follow-up during 2005-2018. Cox regression estimated risks of cardiovascular disease or mortality, producing hazard ratios (HR) with (95% confidence intervals). Interaction testing quantified disproportionally increased excess risks.

Results: Among 5,624,306 individuals, 332,549 had a COPD diagnosis. Compared with individuals who did not have COPD or type 2 diabetes, all-cause mortality risk was higher for individuals who had either COPD or type 2 diabetes, with HR 2.68 (2.66-2.69) and 1.70 (1.69-1.71), respectively. Having both conditions produced an HR of 3.72 (3.68-3.76). Among cardiovascular outcomes, the highest risks were found for chronic heart failure: COPD only, HR 2.87 (2.84-2.90); type 2 diabetes only, 1.86 (1.84-1.88); and both, 4.55 (4.46-4.64). Having both COPD and type 2 diabetes was associated with disproportionally higher excess risks than expected from the sum of the individual diseases, except for cerebrovascular disease or ischemic heart disease. For COPD and depression/anxiety, all-cause mortality risk was associated with COPD only, HR 2.74 (2.72-2.76); depression/anxiety only, 2.39 (2.38-2.40); and both 4.72 (4.68-4.75). Chronic heart failure was associated with COPD only, HR 2.74 (2.71-2.78); depression/anxiety only, 1.31 (1.30-1.32); and both, 3.45 (3.40-3.50). This disease combination was associated with disproportionally higher excess risks than expected, except for atrial fibrillation.

Conclusions: Type 2 diabetes or depression/anxiety in COPD patients were associated with disproportionally excess risks for cardiovascular disease and mortality. It is important for clinicians to be aware of these greater than expected risks, to prevent further cardiovascular morbidity and mortality.