Recent Findings Highlight new Directions for Researchers in Multi-Morbidity

Jerry Suls, PhD, Multi-Morbidities Special Interest Group (SIG) Chair; Matthew B. Howren, PhD, MPH, Multi-Morbidities SIG Co-chair.

The Multi-morbidities SIG tries to keep its members and the general membership of the Society of Behavioral Medicine informed of the most recent scientific developments in the study of multi-morbidity. This column highlights two recent research programs with strong implications for behavioral medicine research and practice.

Mental Disorders and Subsequent Physical Conditions

Although it has long been known that mental disorders in treatment settings are associated with a higher incidence of chronic physical conditions, whether this is the case in community settings was unknown. To address this gap, Scott et al. (JAMA 2016) published the results from 18 cross-sectional World Mental Health surveys of community-dwelling adults living in 17 countries (47,609 individuals) from January 1, 2001 to December 31, 2011.

Even after adjusting for age, sex, country, smoking and education level, all mental disorder categories, including depression, anxiety disorders and substance abuse, were associated with later physical outcome conditions; chronic lung disease had the highest Odds Ratio (1.70), cancer had the lowest (1.2), and anxiety disorder fell in the middle (1.6) When statistical analyses adjusted for mental disorder co-morbidity (e.g., depression and anxiety), the associations were reduced by about half - suggesting that subsequent physical conditions are more likely if people experience multiple mental problems over the life course. Increasing number of mental disorders over the life-span predicted the subsequent onset and diagnosis of chronic physical conditions.

Scott et al. (2016) conclude that, “…treatment of all mental disorders should optimally incorporate attention to physical health and health behaviors, with this parallel focus on physical health beginning as early in the course of mental disorder as possible,” (p. 157). Also, mental health-physical comorbidity might be better addressed by focusing on the physical health of those with mental disorders rather than current approaches focusing on the mental health of those with chronic physical conditions. This suggestion deserves consideration from the behavioral medicine community, especially those interested in the burdens carried by patients with both primary medical and mental disorders.

Multi-morbidity, Functional Limitations and Geriatric Syndromes

The conventional epidemiological measurement of multi-morbidity relies on disease counts extracted from administrative data, etc. However, Koroukian et al (2015) argue this approach equates multi-morbidity with multiple chronic conditions; researchers should move beyond the traditional approach because most health conditions are multifactorial. Multi-morbidity should be redefined to include the co-occurrence of chronic conditions, functional limitations, and geriatric syndromes. The later two constructs are important because they recognize clinical conditions in older persons that do not fit into discrete disease categories and are strongly associated with disability. We would add that incorporating limitations and syndromes into the definition of multi-morbidity is more in keeping with the intents of behavior medicine Of course, functional limitations are usually considered as outcomes of a medical condition, not a condition in and of itself. Koroukian propose that whether and how a medical condition produces concrete consequences for daily living may be just, if not more, important for understanding long-term health outcomes.

Using data of U.S. adults aged 50 years or older from the longitudinal US Health and Retirement Study, Koroukian et al (2016) tested whether the relative contributions of self-reported fair/poor health, self-reported chronic conditions, functional limitations, and geriatric syndromes to the prediction of self-rated worse health at 2 years, and 2-year mortality. Chronic conditions were identified by whether the respondents was ever told by a physician that they had any medical (conditions) (e.g., heart disease, lung disease, diabetes, stroke, arthritis, cancer, or psychiatric conditions). For functional limitations, the respondent was asked to report difficulties with specific tasks (e.g., pulling/pushing a large object, picking up a dime, walking one block, preparing meals). Geriatric syndrome was assessed by older persons via a series of questions about visual and hearing impairment, depressive symptoms, urinary incontinence; low cognitive performance; persistent dizziness or; severe pain. Analyses using a novel machine-learning method identified combinations of predictors associated with health outcomes. The most important “splitting” variables were age, functional limitations, and geriatric syndromes, rather than chronic conditions. Hence, functional limitations and geriatric syndromes appeared to drive health outcomes in older individuals.

This study’s results highlight the importance of characterizing multi-morbidity in broader terms with general symptoms (rather than disease-specific) and limitations also being critical for identifying subgroups that are most vulnerable to experience adverse outcomes. Whether functional limitations and geriatric syndrome consistently predict future mortality better than occurrence of medical conditions needs further study. In addition to these “lessons,” Kourukian’s research illustrates how the US Health and Retirement Study (available to all researchers) can serve as a valuable resource to explore questions relating to multi-morbidity.

References

Koroukian SM, Warner DF, Owusu C, Given CW. Multimorbidity Redefined: Prospective Health Outcomes and the Cumulative Effect of Co-Occurring Conditions. Prev Chronic Dis 2015;12:140478. DOI: http://dx.doi.org/10.5888/pcd12.140478

Koroukian, SM, Schiltz, N., Warner, DF, Sun, J., Bakaki, PM, Smyth, KA, Stange, KC, & Given, CW. Combinations of Chronic Conditions, Functional Limitations, and Geriatric Syndromes that Predict Health Outcomes. J Gen Intern Med 31(6):630–7 DOI: 10.1007/s11606-016-3590-9

Scott KM, Lim C, Al-Hamzawi A, et al. Association of mental disorders with subsequent chronic physical conditions. JAMA Psychiatry. 2016; 73(2):150-158.