By Kathryn Nicholson
Answering an invitation to contribute with an article to a special issue of the journal Health Psychology, we wrote the article entitled “The measurement of multimorbidity” that was recently published [1]. The article was written with the purpose of providing a review of the literature published between 1974 and 2018 that have utilized measures for multimorbidity and to provide guidance on measures to consider when conducting a research study on multimorbidity. The article introduces the reader to the two main groups of measures of multimorbidity that can be distinguished. The first group of measures is constituted by a simple count from various lists of chronic conditions. The second group of measures introduces weighting for included chronic conditions thus creating a “weighted index” of multimorbidity. These two main groups are not mutually exclusive as the list of medical conditions in some weighted indexes can be used as a list of conditions without weighting. This classification does not include measures of multimorbidity which are not based on lists of medical conditions, such as the Cumulative Illness Rating Scale, which includes areas or domains that are grouped under body systems instead of medical conditions. The article shows the variety of existing measurements, highlighting their differences, to provide an overview of the possibilities that are available to a researcher intending to measure multimorbidity. Finally, the article outlines some guidelines for the choice of a measurement of multimorbidity for research studies. We hope that this review of the existing literature will help inform the careful use of these tools by researchers moving forward. In addition to this review, it is advised that readers attempt to keep updated on the ever-increasing multimorbidity literature.
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1. Nicholson K, Almirall J, Fortin M: The measurement of multimorbidity. Health Psychol 2019. Apr 25. doi: 10.1037/hea0000739. [Epub ahead of print]