Incidence of depression in patients with cardiovascular disease and type 2 diabetes: a nationwide cohort study.BACKGROUND
 Estimating how type 2 diabetes (T2D) affects the rate of depression in cardiovascular disease (CVD) can help identify high-risk patients.  The aim is to investigate how T2D affects the rate of depression according to specific subtypes of CVD.


 Incident CVD patients, free of psychiatric disease, with and without T2D, were included from nationwide registries between 2010 and 2020.  We followed patients from CVD diagnosis until the first occurrence of depression, emigration, death, 5 years, or end of study (December 31, 2021).  We used time-dependent Poisson regression to estimate the incidence rates and rate ratios (IRR) of depression following subtypes of CVD with and without T2D.  The model included age, sex, comorbidities, calendar year, T2D duration, educational level, and living situation as covariates.


 A total of 165,096 patients were included; 45,845 had a myocardial infarction (MI), 63,691 had a stroke, 19,959 had peripheral artery disease (PAD), 35,568 had heart failure (HF), and 979 were diagnosed with 2 or more CVD subtypes (= > 2 CVD's).  Baseline T2D in each CVD subtype ranged from 11 to 17%.  The crude incidence rate of depression per 1000 person-years (95% confidence intervals) was: MI + T2D: 131.1 (109.6;155.6), MI: 82.1 (65.3;101.9), stroke + T2D: 287.4 (255.1;322.6), stroke: 222.4(194.1;253.6), PAD + T2D: 173.6 (148.7;201.4), PAD:137.5 (115.5;162.5), HF + T2D: 244.3 (214.6;276.9), HF: 199.2 (172.5;228.9), =  > 2 CVD's + T2D: 427.7 (388.1;470.2), =  > 2 CVD's: 372.1 (335.2;411.9).  The adjusted IRR of depression in MI, stroke, PAD, HF, and =  > 2 CVD's with T2D compared to those free of T2D was: 1.29 (1.23;1.35), 1.09 (1.06;1.12), 1.18 (1.13;1.24), 1.05 (1.02;1.09), and 1.04 (0.85;1.27) (p-value for interaction < 0.001).


 CONCLUSION
 The presence of T2D increased the rate of depression differently among CVD subtypes, most notable in patients with MI and PAD.
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