Multimorbidity is common to family practice: is it commonly researched?

Family physicians often have to care for patients with several concurrent chronic conditions (multimorbidity or comorbidity). Consequently, they need to inform themselves by reading indexed publications on multimorbidity. This study aimed to assess how well the concept of multimorbidity was covered in the medical literature. Objectives were first, to quantify the literature on multimorbidity (or comorbidity) and to compare the number of publications on it with the number of publications on three common chronic conditions (asthma, hypertension, and diabetes), and second, to describe the articles on multimorbidity.

Bibliometric study.

We consulted MEDLINE for the reference period 1990 to the end of 2002. The term "multimorbidity" and its various spellings was used as the search term. Comorbidity, asthma, hypertension, and diabetes were searched for using their respective MeSH terms. For comparison purposes, prevalence data were taken from published sources. Abstracts of articles relating to multimorbidity were reviewed and their content analyzed.

Number and type of articles.

Multimorbidity has a prevalence of 60% among people aged 55 to 74. This prevalence is much higher than that of asthma (6.5%), hypertension (29.6%), and diabetes (8.7%). Few articles in the medical literature deal specifically with multimorbidity (or comorbidity), however. For each article on multimorbidity, there are 74 on asthma, 94 on hypertension, and 38 on diabetes. Content analysis of abstracts of articles on multimorbidity revealed a high proportion of epidemiologic studies (50.0%) followed by validation studies (22.4%) and opinion pieces (11.8%). The few experimental studies on multimorbidity were not done in primary care settings.

This study shows that the prevalence of multimorbidity is not matched by the number of indexed publications on it in the medical literature. To date, the number and diversity of articles on multimorbidity are both insufficient to provide scientific background for strong evidence-based care of patients affected by multiple concurrent chronic conditions. Research is needed to increase knowledge and understanding of this important clinical topic.