Cardiovascular disease and subsequent risk of psychiatric disorders: a nationwide sibling-controlled study

Background The association between cardiovascular disease (CVD) and selected psychiatric disorders has frequently been suggested while inadequate control of familial factors and comorbidities has halted causal inferences. Methods We identified 869 056 patients newly diagnosed with CVD from 1987 to 2016 in Sweden while no history of psychiatric disorders, and 910 178 full siblings of these patients and 10 individually age- and sex-matched unrelated population controls (N=8 690 560). Adjusting for multiple comorbid conditions, we used flexible parametric models and Cox regression to estimate the association of CVD with risk of all subsequent psychiatric disorders, comparing rates of first incident psychiatric disorder among CVD patients with rates among unaffected full siblings and population controls. Results The median age at diagnosis was 60 years for patients with cardiovascular disease and 59.2% were male. During up to thirty years of follow-up, the crude incidence rates of psychiatric disorder were 7.1, 4.6 and 4.0 per 1000 person-years for patients with cardiovascular disease, their siblings and population controls. In the sibling comparison, we observed an increased risk of psychiatric disorder during the first year after cardiovascular diagnosis (hazard ratio [HR], 2.74; 95% confidence interval [CI], 2.62-2.87) and thereafter (1.45; 95% CI, 1.42-1.48). Increased risks were observed for all types of psychiatric disorders and among all diagnoses of cardiovascular disease. We observed similar associations in the population comparison. Cardiovascular patients who developed a comorbid psychiatric disorder during the first year after diagnosis were at increased risk of subsequent cardiovascular death compared to patients without such comorbidity (HR 1.55; 95% CI 1.44-1.67). Conclusions Patients diagnosed with cardiovascular disease are at an elevated risk for subsequent psychiatric disorders independent of familial factors and comorbid conditions. Cardiovascular patients with comorbid psychiatric disorders are at increased risk of cardiovascular mortality suggesting that surveillance and treatment of psychiatric comorbidities should be considered as an integral part of clinical management of newly diagnosed patients with cardiovascular disease. Funding this work was supported by the EU Horizon 2020 Research and Innovation Action Grant (CoMorMent, Grant nr. 847776 to UV, PFS and FF), Grant of Excellence, Icelandic Research Fund (grant no. 163362-051 to UV), ERC Consolidator Grant (StressGene, grant no: 726413 to UV), Swedish Research Council (Vetenskapsrådet, award D0886501 to PFS) and US NIMH R01 MH123724 (to PFS).