Hip Fracture, Comorbidity, and the Risk of Myocardial Infarction and Stroke: A Danish Nationwide Cohort Study, 1995-2015.

We evaluated risks of MI and stroke in elderly patients with hip fracture compared with the general population. We also examined the interaction between hip fracture and comorbidity with respect to risks of MI or stroke, defined as excess of risk explained by combining risks of hip fracture and comorbidity. We conducted a population-based cohort study using Danish health registries, in 1995 to 2015 including 110,563 hip fracture patients and 552,774 members of the comparison cohort from the general population. Thirty-day cumulative incidences of MI were 1.15% among patients with hip fracture and 0.09% in the general population (adjusted hazard ratio [aHR] = 12.97; 95% confidence interval [CI], 11.56 to 14.55). Thirty-day cumulative incidences of stroke were 2.16% for hip fracture patients and 0.21% in the general population (aHR = 9.42; 95% CI, 8.71 to 10.19). During the 31 to 365 days following hip fracture, the aHR for MI was 1.05 (95% CI, 0.97 to 1.14) and remained at this level during the remainder of follow-up (maximum of 20 years). The aHR for stroke was 1.29 (95% CI, 1.22 to 1.35) during the 31 to 365 days following hip fracture, remained elevated for up to 10 years, and then decreased to the general population level. The aHRs for MI and stroke were increased for both men and women, and in all age and comorbidity groups. During the first 30 days, up to 76% of MI and stroke risk was attributable to interaction between hip fracture and comorbidity. Patients with hip fracture are at increased risk of both MI and stroke up to 1 year following the fracture. Risk of stroke, but not of MI, was elevated during up to 10 years postfracture. Although the absolute risks were low, our finding underscores the importance of targeting multimorbidity, including prevention and adequate treatment, to improve the prognosis of hip fracture patients.