A systematic review and meta-analysis of pneumonia associated with thin liquid vs. thickened liquid intake in patients who aspirate

Objective: To investigate whether drinking thin liquids with safety strategies increases the risk for pneumonia as compared with thickened liquids in patients who have demonstrated aspiration of thin liquids. Data sources: Seven electronic databases, one clinical register, and three conference archives were searched. No language or publication date restrictions were imposed. Reference lists were scanned and authors and experts in the field were contacted. Review methods: A blind review was performed by two reviewers for published or unpublished randomized controlled trials and prospective non-randomized trials comparing the incidence of pneumonia with intake of thin liquids plus safety strategies vs. thickened liquids in adult patients who aspirated on thin liquids. The data were extracted from included studies. Odds ratios (OR) for pneumonia were calculated from the extracted data. Risk of bias was also assessed with the included published trials. Results: Seven studies out of 2465 studies including 650 patients met the inclusion criteria. All of the seven studies excluded patients with more than one known risk factor for pneumonia. Six studies compared thin water protocols to thickened liquids for pneumonia prevention. A meta-analysis was done on the six studies, showing no significant difference for pneumonia risk (OR = 0.82; 95% CI = 0.05–13.42; p = 0.89). Conclusions: There was no significant difference in the risk of pneumonia in aspirating patients who took thin liquids with safety strategies compared with those who took thickened liquids only. This result, however, is generalizable only for patients with low risk of pneumonia.