Association between Phosphate Binders and Constipation in Patients Undergoing Chronic Hemodialysis: A Cross-sectional Study.

Objective Constipation, a clinical form of gut dysbiosis, is highly prevalent in patients undergoing hemodialysis. Patients with chronic kidney disease experience uremia-related changes in the gut environment. Dysbiosis reportedly leads to an atherosclerosis pathogenesis, and constipation is associated with several adverse clinical outcomes including cardiovascular disease and mortality. Phosphate binders, commonly prescribed to patients with end-stage renal disease, bind to non-phosphate molecules and may alter the gut microbiota, potentially leading to systemic effects unrelated to phosphate control, although the clinical evidence is limited. Methods This cross-sectional study included 293 outpatients undergoing hemodialysis at Masuko Memorial Hospital, Japan. Information about patient characteristics and medication usage was collected, and constipation was assessed using the original diagnostic criteria, incorporating both the Rome IV criteria and a history of laxative use. Results Of 293 participants, 152 (51.9%) were diagnosed with constipation and 60 (20.5%) had severe constipation. Lanthanum carbonate use was independently associated with a lower risk of constipation [adjusted odds ratio (aOR) 0.55, 95% confidence interval (CI) 0.32-0.94, p=0.029] and a lower risk of severe constipation (aOR 0.41, 95%CI 0.19-0.86; p=0.018), while precipitated calcium carbonate use was associated with a lower risk of severe constipation, independent of age and sex (aOR 0.48, 95%CI 0.26-0.89, p=0.021). Conclusion Our study highlights the association between specific phosphate binders and a lower risk of constipation. Accordingly, phosphate binders could be selected based on their positive effects on constipation in this patient population.