Summary
The main objective of our study was to use the NHIS to examine the prevalence of MCC by select sociodemographic groups and the prevalence of MCC dyads and triads. The results showed that more than one-quarter of US adults have MCC. Among certain subgroups (such as women and older adults), the prevalence of MCC was generally higher, and for others (Hispanic adults and those with private insurance) the prevalence was generally lower. Not surprisingly, the prevalence rates of our study vary from those of others because of differing populations of interest and the specific definition of MCC used. However, some of the general patterns found in our study, such as higher prevalence among older adults, have also been found in past research. The arthritis/hypertension dyad and the arthritis/diabetes/hypertension triad were 2 of the most prevalent MCC combinations, differing from the most common MCC combinations found by other studies examining adults aged 65 or older. Our trend analyses showed significant increases in MCC for all adults since 2001.
Although MCC prevalences presented in this study are generalizable to the US adult noninstitutionalized civilian population, use of the NHIS has limitations. Only 10 conditions detailed in the HHS Interagency Workgroup definition were able to be captured, leaving certain conditions unaccounted for. Of the conditions captured, their measurement using NHIS could potentially be further debated (eg, including all cancers as opposed to only noncurable cancers). The NHIS also captured only conditions that were confirmed by a doctor or health professional, potentially leading to the underreporting of conditions that remain undiagnosed or were not recalled by the respondent during the NHIS interview. Finally, this research was exploratory in nature and used multiple comparisons, which could increase the likelihood of type I error.
In spite of these limitations, examining the prevalence of MCC among subgroups of adults allows for the identification of MCC patterns in the US adult population. Our research serves as a platform from which additional research using the NHIS can build. It would be beneficial for future studies to seek to explain why differences in the prevalence of MCC among subgroups exist. This might entail examining topics such as how different health insurance types influence service use and the likelihood of being diagnosed with a chronic condition, how educational attainment may affect MCC, or what behavioral risk factors are most common among adults with MCC.
Our study shows that the increasing trend in the prevalence of MCC among US adults is a cause for concern, and the NHIS can be a useful data source for identifying patterns of MCC at the national level and assessing which population subgroups are most likely to have MCC. This information can be useful in helping clinicians develop prevention strategies tailored to population subgroups with greater prevalence of MCC and subgroups that are most at risk for complications resulting from specific dyads and triads, consequently reducing health care costs among these subgroups.