MCC prevalence across racial/ethnic groups varies according to the population included in the study. Non-Hispanic whites had the highest MCC prevalence rates in the Medicare and Adult Civilian populations (Lochner et al. 2013, Machlin et al. 2013), while Freid, et al. found that non-Hispanic Blacks had the highest MCC prevalence rates in the adult civilian population (Freid et al. 2012) while differences between racial/ethnic groups in Medicare were minimal (CMS 2012). These varying results point to the need to for research on subsamples that are hypothesized to be disparate. However, one commonality across studies is that Hispanic patients had lower MCC prevalence rates when compared to white and black populations (See Exhibit 5). Ward and colleagues found that among the same gender and age group, non-Hispanic white (33.6%) and non-Hispanic Black men (38.4%) were more likely to have two or more MCC compared to Hispanic men (23.4%) (Ward et al. 2013). Steiner and colleagues also found that the proportion of adults discharged with four or more MCC was lowest among Hispanic patients when analyzing the Nationwide Inpatient Sample (Steiner et al. 2013). Other race/ethnic groups, such as Asian/Pacific Islander or Native Americas, have not been as well studied. Although some evidence suggests that MCC prevalence estimates in these populations are also smaller compared to white or black MCC patients (Machlin et al. 2013).
Although only supported by one study in the literature review, the accumulation of chronic conditions over time may vary across different race/ethnic groups. In an 11-year longitudinal study of Health & Retirement Study data, Quinones and colleagues examined the trajectory of multimorbidity across different race/ethnic groups and found that Mexican Americans had lower initial levels and slower accumulation of comorbidity than white and black MCC patients (Quinones et al. 2011). In addition, blacks were found to have an elevated level of multimorbidity at baseline, but slower rate of increase in multimorbidity over the study period relative to white patients. Prevalence rates among black and white MCC patients appeared to converge over time. There was a clear difference in MCC prevalence between Hispanic/Mexican and white/black individuals, but less between white and black groups.
Exhibit 5: MCC Prevalence by Race/Ethnic Group in Four Studies from 2010 to 2013*
*Note: although the studies include different age groups, the relative trends are consistent.
Differences in chronic condition clusters among race/ethnic groups were examined by one study to-date. Using ICD-9 codes to create a Phenotypic Disease Network, Hidalgo and colleagues were able to examine differences in the strengths of disease comorbidities between white and black males (Hidalgo et al., 2009). Although not reported here, their analysis suggests that significantly different disease networks may exist among different race/ethnic groups. However, their investigation is their first of its kind and cannot be compared with other evidence at this time.
Only one study investigated healthcare utilization, cost and outcomes across different race/ethnic groups. Steiner and colleagues found that Asian/Pacific Islanders had the highest mortality and cost per case compared to all other groups, including Native Americans (Steiner et al., 2013).