Discrepancy between self‐perceived mycophenolic acid‐associated diarrhea and stool water content after kidney transplantation

BACKGROUND: Diarrhea is a well‐known side effect of mycophenolic acid (MPA) use in kidney transplant recipients (KTRs). It is unknown whether self‐reported diarrhea using the Modified Transplant Symptom Occurrence and Symptom Distress Scale (MTSOSD‐59R) corresponds to stool water content and how both relate to MPA usage. METHODS: MTSOSD‐59R questionnaires filled out by 700 KTRs from the TransplantLines Biobank and Cohort Study (NCT03272841) were analyzed and compared with stool water content. Stool samples (N = 345) were freeze‐dried, and a water content ≥80% was considered diarrhea. RESULTS: Self‐perceived diarrhea was reported by 46%, while stool water content ≥80% was present in 23% of KTRs. MPA use was not associated with self‐perceived diarrhea (odds ratio(OR) 1.32; 95% confidence interval(CI), 0.87–1.99, p = .2), while it was associated with stool water content ≥80% (OR 2.88; 95%CI, 1.41–5.89, p = .004), independent of potential confounders. Adjustment for prior MPA discontinuation because of severe diarrhea, uncovered an association between MPA use and self‐perceived diarrhea (OR 1.80; 95%CI, 1.13–2.89, p = .01). CONCLUSIONS: These results suggest that reporting bias could add to the discrepancy between both methods for diarrhea assessment. We recommend use of objective biomarkers or more extensive questionnaires which assess information on stool frequency and stool consistency, to investigate post‐transplantation diarrhea.