Morbidity - Comorbidity and multimorbidity. What do they mean?

This Practice Question has been published with the kind permission of the Royal College of Nursing.

These terms are often used by healthcare professionals in clinical practice and in health policy documents. Used in medical settings, morbidity means illness or disease and is not to be confused with mortality, which means death, and is frequently used in statistical reports. Comorbidity simply means more than one illness or disease occurring in one person at the same time and multimorbidity means more than two illnesses or diseases occurring in the same person at the same time.

Due to an ageing population and improved detection and treatment of disease, many older people now have more than one illness. Common comorbid conditions in older people include heart disease, hypertension, respiratory disease, mental health problems (including dementia), cerebrovascular disease, joint disease, diabetes and sensory impairment.

Alongside comorbidity and multimorbidity comes polypharmacy, or the prescription of many medications. An audit I carried out a few years ago in an acute admission ward for older people revealed the average number of prescribed medications per patient was seven. Polypharmacy brings its own difficulties, particularly the potential for drug interactions and complicated medication regimens which can be hard to follow. In my clinical work I frequently meet older people who cannot tell me why they are taking certain medications, as well as individuals who have had medications prescribed for many years without a review.