Prevalence Of Multimorbidity Between Sexes In Cardiac Rehabilitation Responders Versus Non-responders

PURPOSE: Cardiac rehabilitation (CR) patients often display greater prevalence of chronic conditions (CCs; i.e., multimorbidity). Peak oxygen consumption (VO2 peak) is directly linked to outcomes in patients with cardiovascular disease. While CR has been shown to improve VO2 peak, not all patients respond positively. Further, data suggests that male CR patients have greater improvement in VO2 peak compared to females. This study examined the relationship between VO2 peak in responders/non-responders and the degree of multimorbidity expressed between sexes in CR patients. METHODS: We included male and female (>18 y/o) CR patients (n = 618) who completed cardiopulmonary exercise testing pre- and post- CR. Using the Rochester Epidemiology Project records-linkage system, we assessed the prevalence of 21 chronic conditions defined by the U.S. Department of Health and Human Services. We evaluated change in peak VO2 pre-post CR and grouped patients by responders (≥0% change in peak VO2) or non-responders (<0% change in peak VO2) by sex. Prevalence of CCs by groups was analyzed by Kruskal Wallis test. RESULTS: Of the 618 CR patients (age: 62.9 ± 11.2 y/o; BMI: 29.9 ± 5.4 kg/m2; completed CR sessions: 28.8 ± 12.6 sessions), 469 were male, and 153 were female. There were no differences between groups for the above demographics. Males demonstrated lower prevalence of CCs compared to females (median (IQR): 6.0 (5.0, 8.0) vs. 8.0 (6.0, 9.0); p < 0.05). Similarly, responders demonstrated a lower number of CCs compared to non-responders (median (IQR): 6.0 (5.0, 8.0) vs. 7.0 (5.0, 9.0); p < 0.05). Male responders demonstrated less CCs compared to male non-responders (median (IQR): 6.0 (5.0, 8.0) vs. 7.0 (5.0, 9.0; p < 0.05); however, there was no difference in CCs between female responder and non-responder groups (median (IQR): 8.0 (6.5, 9.0) vs. 8.0 (6.0, 9.0); p = 0.58). CONCLUSION: Our data demonstrate a high burden of multimorbidity in CR patients. Further, CR patients who do not improve VO2 peak demonstrate greater multimorbidity burden. This relationship between multimorbidity and VO2 peak improvement appears to play a more significant role in males compared to females. Larger sample size may be needed to characterize these relationships more fully in female CR patients.