摘要BACKGROUND The current understanding of the magnitude and consequences of multimorbidity in Chinese older adults with coronary heart disease(CHD)is insufficient.We aimed to assess the association and population-attributable fractions(PAFs)between multimorbidity and mortality among hospitalized older patients who were diagnosed with CHD in Shenzhen,China.METHODS We conducted a retrospective cohort study of older Chinese patients(aged≥65 years)who were diagnosed with CHD.Cox proportional hazards models were used to estimate the associations between multimorbidity and all-cause and cardi-ovascular disease(CVD)mortality.We also calculated the PAFs.RESULTS The study comprised 76,455 older hospitalized patients who were diagnosed with CHD between January 1,2016,and August 31,2022.Among them,70,217(91.9％)had multimorbidity,defined as the presence of at least one of the predefined 14 chronic conditions.Those with cancer,hemorrhagic stroke and chronic liver disease had the worst overall death risk,with adjus-ted HRs(95％CIs)of 4.05(3.77,4.38),2.22(1.94,2.53),and 1.85(1.63,2.11),respectively.For CVD mortality,the highest risk was observed for hemorrhagic stroke,ischemic stroke,and chronic kidney disease;the corresponding adjusted HRs(95％CIs)were 3.24(2.77,3.79),1.91(1.79,2.04),and 1.81(1.64,1.99),respectively.All-cause mortality was mostly attributable to cancer,heart failure and ischemic stroke,with PAFs of 11.8,10.2,and 9.1,respectively.As for CVD mortality,the leading PAFs were heart fail-ure,ischemic stroke and diabetes;the corresponding PAFs were 18.0,15.7,and 6.1,respectively.CONCLUSIONS Multimorbidity was common and had a significant impact on mortality among older patients with CHD in Shenzhen,China.Cancer,heart failure,ischemic stroke and diabetes are the primary contributors to PAFs.Therefore,prioritizing improved treatment and management of these comorbidities is essential for the survival prognosis of CHD patients from a holist-ic public health perspective.