What do we mean by multimorbidity? An analysis of the literature on multimorbidity measures, associated factors, and impact on health services organization

Background: Multimorbidity is a consequence of both epidemiological and demographic transition. Unlike comorbidity, it currently has no consensus definition, making it difficult to assess its epidemiological and socioeconomic burden, to organize healthcare services rationally, and to determine the skills needed for patient self-reliance. The aim of this study is to define the spectrum of multimorbidity and to discuss current implications for the organization of care.

Methods: Two independent readers analyzed the literature indexed in PubMed, Embase, CINAHL, and Scopus.

Results: The bibliographic search conducted on July 16, 2013, retrieved 2287 articles (670 in PubMed, 666 in Embase, 582 in Scopus, and 369 in CINAHL). Of these, 108 articles were retained. Multimorbidity is designated by a variety of terms, none of them being MeSH terms. There is no single measure of multimorbidity, as this entity is usually studied for its functional or economic impact, rather than its causes. The prevalence varies considerably, depending on the measure used and the population studied. Factors associated with multimorbidity are age, gender, and socioeconomic characteristics of the populations studied. Studies evaluating the organization-of-care are inconclusive or insufficient.

Conclusions: Multimorbidity serves as an avatar for the fundamental, recurrent problems of modern medicine and the organization-of-care. It may be defined by its causes or its consequences and reflects our concept of both individual health and its collective management. Tools that would allow a more appropriate measurement of this entity are available; we should use them to match medical reality to the needs of patients.