Gustatory dysfunction in multiple sclerosis: a systematic review and meta-analysis

Gustatory dysfunction is an often overlooked symptom in people with multiple sclerosis (PwMS), potentially leading to poor appetite, malnutrition, weight loss, and decreased quality of life. This systematic review and meta-analysis aimed to assess the pooled prevalence of gustatory dysfunction in PwMS and compare their gustatory test scores with healthy controls. An online database search of PubMed, Embase, Scopus, and Web of Science was conducted on 2024 June 29. Observational studies reporting gustatory dysfunction or gustatory test scores in PwMS were included. Pooled prevalence rates were calculated using a random-effects model, with subgroup analyses based on the type of gustatory test used. Standardized mean differences (SMD) were calculated for comparisons between PwMS and healthy controls. A total of 9 studies encompassing 1385 PwMS were included. The pooled prevalence of gustatory dysfunction among PwMS was 16.4% (95% confidence intervals [95% CI]: 8.7% to 24.1%, I² = 90%, P < 0.01). Subgroup analysis showed a prevalence of 18.8% (95% CI: 10.5% to 27.2%, I² = 0%) in 4 studies using the Taste Strip Test (TST), while 3 non-TST studies using liquid tastants or self-reports reported a prevalence of 20.2% (95% CI: 7.2% to 33.3%, I² = 86%). PwMS had significantly lower gustatory test scores compared to healthy controls (SMD: -0.93, 95% CI: -1.20 to -0.65, I² = 0%, P = 0.48). Gustatory dysfunction affects a notable proportion of PwMS, with prevalence rates varying by assessment method. Future studies should assess the possible causes of gustatory dysfunction in PwMS using validated gustatory assessment scales.