By Thomas Lehnert

In almost all developed countries the proportion of elderly people is steadily increasing. Many elderly persons suffer from multimorbidity (multiple chronic conditions), which has been linked to poor outcomes in various dimensions of health and health care (1, 2). In trying to meet the care demands of more and more patients with multiple chronic diseases, health care systems originally designed to handle acute and episodic illnesses are faced with substantial organizational and possibly additional financial challenges.

Multimorbidity has not been extensively researched as of yet (3). We know particularly little about health care utilization (patterns) and health care costs of (elderly) patients with multiple chronic conditions (4, 5). Considering this gap in knowledge, we conducted a systematic literature review with studies that investigated the relationship between multimorbidity and health care utilization outcomes (physician use, hospital use, medication use) and cost outcomes (medication costs, out-of-pocket costs, total health care costs) for elderly general populations. This study was published in Medical Care Research and Review 2011, 68(4) 387-420 [PubMed abstract].

Although synthesis of studies was complicated (e.g. because of ambiguous definitions and measurements of multiple chronic conditions), almost all included studies observed a positive association between multimorbidity and utilization/cost outcomes, many of which found that utilization/costs significantly increased with each additional condition. In terms of health care utilization, most of the evidence points to more complex in- and outpatient care scenarios. For instance, the more co-existing conditions an elderly patient had, the more physicians he/she saw (more pronounced increases for specialists) and the more medications he/she took (polypharmacy). Polypharmacy constitutes a risk factor for adverse drug events, while adverse drug events pose a significant cost to health care systems. It is therefore not surprising that multimorbid individuals had substantially increased health care costs as well. Several included studies indicate a curvilinear, near exponential relationship between multiple chronic conditions and costs.

In light of the rising prevalence of multimorbidity, substantial (additional) costs attributable to patients with co-existing diseases, and the fear that current care arrangements/guidelines may be inappropriate for at least some (elderly) multimorbid patients (6), we point out and discuss a variety of implications for health care policy and research.    

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2.         Marengoni A, Angleman S, Melis R, Mangialasche F, Karp A, Garmen A, et al. Aging with multimorbidity: A systematic review of the literature. Ageing Res Rev2011 Sep;10(4):430-9.
3.         Fortin M, Lapointe L, Hudon C, Vanasse A. Multimorbidity is common to family practice: is it commonly researched? Can Fam Physician2005 Feb;51:244-5.
4.         Vogeli C, Shields AE, Lee TA, Gibson TB, Marder WD, Weiss KB, et al. Multiple chronic conditions: prevalence, health consequences, and implications for quality, care management, and costs. J Gen Intern Med2007 Dec;22 Suppl 3:391-5.
5.         Gijsen R, Hoeymans N, Schellevis FG, Ruwaard D, Satariano WA, van den Bos GA. Causes and consequences of comorbidity: a review. J Clin Epidemiol2001 Jul;54(7):661-74.
6.         Fortin M, Contant E, Savard C, Hudon C, Poitras ME, Almirall J. Canadian guidelines for clinical practice: an analysis of their quality and relevance to the care of adults with comorbidity. BMC Fam Pract2011;12:74.