To what extent are comorbidity profiles associated with referral and uptake to cardiac rehabilitation

Introduction: Given the high proportion of comorbidities in patients with coronary heart disease (CHD) and low participation rates in cardiac rehabilitation (CR), a better understanding of how comorbidity interacts with the CR pathway is needed. We investigated associations between comorbidity profiles and referral and uptake in everyday clinical CR across UK. Method: Patients (>= 18 years) diagnosed with a CHD between 1st of January 2014 and 31st of December 2019 registered in the National Audit of Cardiac Rehabilitation (NACR) database were eligible. Self-reported comorbidities from 15 disease categories were conceptualized into similar or dissimilar based on overall related pathophysiologic profile and care management as CHD. Regression models were conducted with four comorbidity profiles; similar conditions, dissimilar conditions, similar and dissimilar and no comorbidity. Results: 399,348 (61.8%) patients were eligible for referral from 198 programmes. The majority were males (70%), mean age of 67 (+/- 12 SD) years. A non-significant association was found between comorbidity profiles and referral. Odds ratios (OR) for CR uptake were higher in patients with dissimilar (OR = 1.38 (95% CI 1.26-1.54)) and dissimilar and similar comorbidities profiles (OR = 1.35 (95% CI 1.21-1.43)) compared to patients with similar comorbidities. No significant differences in uptake were found between patients with similar comorbidities and those without comorbidities (OR = 0.985 (95% CI 0.854-1.125). Conclusion: Using routine practice data, comorbidity profiles were not significantly associated with CR referral suggesting equality in referral. Dissimilar comorbidity profiles were associated with uptake. To increase the likelihood of starting CR, services should consider developing tailored participation strategies that include comorbidity profiles.