Xerostomia and hyposalivation in association with oral candidiasis: a systematic review and meta-analysis

Introduction Several studies reported that hyposalivation was associated with a higher prevalence of oral Candida colonisation and oral candidiasis, and despite the correlation between these conditions, no previous systematic review was conducted to examine this relationship in its utmost depth.Objectives This study aims to investigate the relationship between xerostomia, hyposalivation and oral candidiasis.Search methods This systematic review and meta-analysis was conducted in February 2021 through an electronic search.Data sources The electronic search was performed on PubMed, Scopus, Web of Science through Clarivate, Medline through Clarivate and Cochrane Library.Data selection This systematic review and meta-analysis included cohort, observational nested case-control cohort studies, and studies of other designs providing the number of patients with and without xerostomia or hyposalivation crossed with the number of patients with and without oral candidiasis or oral Candida growth. Studies included were conducted on adult populations with no restriction to sex or race. Included studies should use a reliable diagnostic method for all conditions of interest.Data extraction Results were obtained from the implementation of the search strategy and managed using the EndNote Web and Rayyan Qatar Computing Research Institute (QCRI). Quantitative data synthesis was performed using the Review Manager 5.4 software.Results A total of 429 studies were identified by searching the databases, of which nine studies were included for qualitative and quantitative data synthesis. The analysis included 590 xerostomic patients and 697 controls subgrouped into two categories: Candida growth (207 patients and 195 controls) and oral candidiasis (383 patients and 502 controls). The Candida growth subgroup analysis shows that the xerostomic patients are at higher risk for oral Candida growth than controls (OR [95% CI] = 3.13 [2.02-4.86]) and the oral candidiasis subgroup analysis yields that xerostomic patients are at higher risk for developing manifest oral candidiasis than controls (OR [95% CI] = 2.48 [1.83-3.37]).Conclusion Our study concludes that patients with xerostomia have a higher risk than non-xerostomic control groups of developing oral candidiasis and oral fungal growth. Major inter-study heterogeneity, however, may restrict confidence in the accuracy of our results, and caution should therefore be taken in interpreting the evidence. In caring for patients with hyposalivation, we recommend healthcare professionals consider the possible association between both conditions. Furthermore, we recommend further research with improved methodological qualities and more valid diagnostic methods.