Reducing disparities in health outcomes, access to care, and healthcare quality are ongoing priorities in the United States and other countries. As part of the initiatives to achieve health equity, HHS has made a priority in the report, Multiple Chronic Conditions: A Strategic Framework, to assess disparities among the adult MCC population. Most of the existing disparities research focuses on individual chronic conditions, and there has been little research on the extent, causes, and strategies for reducing disparities within the MCC population.
The limited research is a reflection of the complexities involved in analyzing disparities within the MCC population. Disparities research in the MCC population is impeded by several methodological challenges including sample size issues; data quality issues, particularly unreliable sociodemographic variables in many databases; data capture issues regarding patients who do not access the health care system; lack of standard definitions of disparities and MCC; constantly evolving methods; and limited information about the underlying causes of disparities or interventions to reduce disparities. Additionally, meta-analysis is difficult in MCC disparities research due to the lack of standard ways to aggregate socio-demographic categories. For example, researchers use different age cutoffs to investigate disparities by age. Another analytical challenge affecting the potential for meta-analysis is the lack of standardized measures sensitive to MCC disparities.
Despite these methodological challenges, the body of knowledge on MCC disparities is growing. As more studies are published, early results can be tested for replication. Results from our literature review, included in this paper, suggest that
- Women are more likely than men to be classified as having MCC (Ashman et al., 2013; CMS, 2012; Ward et al., 2012; Machlin et al., 2013).
- The number of chronic conditions rises with age (Freid et al., 2012).
- Hispanic patients have the lowest MCC prevalence (Ward et al., 2013; Steiner et al., 2013). Mexican-Americans have lower initial levels of MCC and slower accumulation of comorbidity compared to non-Hispanic White and non-Hispanic Black patients (Quinones et al., 2011).
- MCC prevalence among Asian Americans is lower compared to white or black MCC patients (Machlin et al. 2013), though Asians/Pacific Islanders had the highest mortality and cost per case compared to all other groups (Steiner et al., 2013).
- Patients with dual eligibility status (Medicare and Medicaid) have an elevated prevalence of MCC compared to non-dual-eligible beneficiaries (CMS, 2012).
Numerous papers examine one dimension of disparities among patients with combinations of two conditions. For example, utilization of care is lower for African-American patients with COPD and asthma, compared to non-Hispanic White patients with the same conditions (Shaya et al., 2009); African-Americans with hypertension and chronic kidney disease had more poorly controlled hypertension compared to African-American women and non-Hispanic White patients with the same conditions (Duru et al., 2009); and men with type II diabetes and coronary heart disease were more thoroughly treated compared to women (Kramer et al., 2012). However, the narrow focus of such analyses makes it challenging to identify overall patterns of disparities.
Future research on MCC disparities may be facilitated by efforts to improve reporting on race, ethnicity and other socio-demographic variables, by efforts to identify disparities-sensitive measures of the quality of care, and by the future availability of new databases such as electronic health record based registries, large employer databases, managed care patient registries, practice-based network data, and other data sharing and collection initiatives.
It is important to acknowledge the overlap of persons with MCC and the disabled, dual eligible Medicare/Medicaid beneficiaries, and common combinations of chronic conditions that have been studied (e.g. diabetes, hypertension and hyperlipidemia). There may be disparities research on these groups that can be synthesized to contribute to the body of MCC disparities research.