Second update of a systematic review and evidence-based recommendations on texture modified foods and thickened liquids for adults (above 17 years) with oropharyngeal dysphagia

Background & aims: It is well known that oropharyngeal dysphagia (OD) challenges eating, drinking, and swallowing by penetration to the airway. In clinical practice, thickening agents in liquid and texture modified diets are used to reduce pneumonia and secure nutritional status. The scientific evidence on this OD management is, however, limited. In 2016 we updated an original clinical guideline on OD in adults. Based on the strength of the evidence of two randomized control trials (RCTs), we provided a weak clinical recommendation against the use of thickening agents for liquid and none for diet. In the hope of finding new scientific evidence, we aimed to update the clinical guideline by examining the evidence if thickening of liquid and diet 1) improve survival and quality of life, 2) reduce the occurrence of aspiration risk and pneumonia, 3) improve dehydration, nutritional status, and mealtime performance, and 4) relate to patient preferences and intervention adherence.

Methods: We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. We first searched systematic reviews and meta-analyses, and secondly, the primary literature of RCTs. We undertook the search in PubMed, Embase, CINAHL, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials from January 1, 2015, to May 19, 2021. The quality of the evidence was evaluated using the revised Cochrane risk-of-bias tool and the GRADE (Grading of Recommendations: Assessment, Development and Evaluation) approach.

Results: One new study was included, resulting in a total of three RCTs, of which two were already included in our former guideline. The three studies focused on the thickening of liquid, but no change of the former weak recommendation against the thickening of liquid could be made due to the quality of evidence evaluation.

Conclusion: There is no convincing evidence that thickened liquid or texture modified diet prevents death or pneumonia nor improves the quality of life, nutritional status, or oral intake in individuals with OD. There is a need for future studies to examine the effect and discuss outcome measures in OD management with thickening agents.