The association between polypharmacy and malnutrition(risk) in older people: A systematic review

Malnutrition adversely influences a broad range of physical and psychological symptoms. Although polypharmacy is often mentioned to be associated with malnutrition, especially in older people it is unclear to what extent. The aim of this systematic review was to investigate the extent of the association between polypharmacy and malnutrition in older people.

The methodology followed the guidelines of the Cochrane Collaboration. Literature search was performed in PubMed, CINAHL and Embase. The population of interest for this systematic review were people of 65 years and older with polypharmacy. Because there is ambiguity with regard to the actual definition of malnutrition and polypharmacy, in this systematic review all articles describing malnutrition prevalence rates were included, regardless of the criteria used. Both observational and intervention studies were screened for eligibility. Selection and quality assessment of the included full text studies was assessed by two reviewers independently. A level of evidence and methodological quality score was adjudged to each article based on this assessment.

A total of 3126 studies were retrieved by the literature search, of which seven studies were included in this systematic review. There was considerable variation in the definition of polypharmacy between studies. Two studies defined polypharmacy as the use of five or more drugs, two studies as the use of six or more drugs, two studies provided a mean and standard deviation that corresponded to the minimum of five drugs, and one study distinguished between polypharmacy (five or more drugs) and excessive polypharmacy (ten or more drugs). However, all studies showed a statistically significant association between (the risk) of becoming malnourished and polypharmacy regardless the instrument or criterion used to define risk of malnutrition. Studies presented the associations respectively as OR ≥ 1.177, p-value ≤ 0.028, β ≥ -0.62 and r  ≥ -0.31.

This review demonstrated a statistically significant association between polypharmacy and malnutrition. Further research is required to determine the magnitude of the effect by increased number of drugs in combination with the type of drugs, on the risk of malnutrition.