Increasing burden of multiple long-term conditions and mortality risk following COVID-19 diagnosis: a national cohort study of one million adults with cardiovascular disease in England.

BACKGROUND: Individuals with cardiovascular disease (CVD) experienced high mortality during coronavirus disease 2019 (COVID-19), yet most live with multiple long-term conditions (MLTCs). We examined the association between MLTCs burden and mortality following COVID-19 among people with CVD. METHODS: In this population-based cohort study, linked national electronic health records from England were analysed. Adults aged ≥18 years with CVD and a positive COVID-19 test between 31 January 2020 and 31 October 2022 were included. MLTCs burden was defined as the number of additional long-term conditions beyond CVD (0, 1, 2, or ≥3). One-year mortality was assessed using adjusted flexible parametric Royston-Parmar models. RESULTS: In 1 081 695 individuals with CVD and COVID-19, 89.7% had at least one long-term condition (LTC) and 67.9% had two or more. Increasing MLTC burden showed a dose-response association with mortality. Compared to individuals without additional LTCs, mortality risk was doubled for those with one LTC (adjusted hazard ratio: 1.86, 95% CI: 1.76-1.96), tripled among those with two LTCs (3.00, 2.85-3.16), and five-fold higher in those with ≥3 LTCs (5.00, 4.75-5.27). Associations were consistent across CVD subtypes. CONCLUSIONS: MLTCs burden was a stronger determinant of mortality risk than CVD subtype alone. Findings support moving beyond single-disease models towards integrated, MLTC-informed care, and pandemic preparedness.