Risk of Hospitalization for Serious Adverse Gastrointestinal Events Associated With Sodium Polystyrene Sulfonate Use in Patients of Advanced Age

Key PointsQuestionIs the use of sodium polystyrene sulfonate associated with a higher risk of hospitalization for adverse gastrointestinal events? FindingsIn this population-level cohort study of 20020 matched individuals, sodium polystyrene sulfonate use was associated with a 1.9-fold higher risk of hospitalization within 30 days of initial prescription for adverse gastrointestinal events compared with nonuse. MeaningThe use of sodium polystyrene sulfonate was associated with a high risk of hospitalization for serious adverse gastrointestinal events. This population-based cohort study assesses the risk of hospitalization or emergency department visit for adverse gastrointestinal events associated with sodium polystyrene sulfonate use in patients of advanced age. ImportanceSodium polystyrene sulfonate is commonly prescribed for the treatment of hyperkalemia. Case reports of intestinal injury after administration of sodium polystyrene sulfonate with sorbitol resulted in a US Food and Drug Administration warning and discontinuation of combined 70% sorbitol-sodium polystyrene sulfonate formulations. There are ongoing concerns about the gastrointestinal (GI) safety of sodium polystyrene sulfonate use. ObjectiveTo assess the risk of hospitalization for adverse GI events associated with sodium polystyrene sulfonate use in patients of advanced age. Design, Setting, and ParticipantsPopulation-based, retrospective matched cohort study of eligible adults of advanced age (>= 66 years) dispensed sodium polystyrene sulfonate from April 1, 2003, to September 30, 2015, in Ontario, Canada, with maximum follow-up to March 31, 2016. Initial data analysis was conducted from August 1, 2018, to October 3, 2018; revision analysis was conducted from February 25, 2019, to April 2, 2019. Cox proportional hazards regression models were used to examine the association of sodium polystyrene sulfonate use with a composite of GI adverse events compared with nonuse that was matched via a high-dimensional propensity score. Additional analyses were limited to a subpopulation with baseline laboratory values of estimated glomerular filtration rate and serum potassium level. ExposureDispensed sodium polystyrene sulfonate in an outpatient setting. Main Outcomes and MeasuresThe primary outcome was a composite of adverse GI events (hospitalization or emergency department visit with intestinal ischemia/thrombosis, GI ulceration/perforation, or resection/ostomy) within 30 days of initial sodium polystyrene sulfonate prescription. ResultsFrom a total of 1853866 eligible adults, 27704 individuals were dispensed sodium polystyrene sulfonate (mean [SD] age, 78.5 [7.7] years; 54.7% male), and 20020 sodium polystyrene sulfonate users were matched to 20020 nonusers. Sodium polystyrene sulfonate use compared with nonuse was associated with a higher risk of an adverse GI event over the following 30 days (37 events [0.2%]; incidence rate, 22.97 per 1000 person-years vs 18 events [0.1%]; incidence rate, 11.01 per 1000 person-years) (hazard ratio, 1.94; 95% CI, 1.10-3.41). Results were consistent in additional analyses, including the subpopulation with baseline laboratory values (hazard ratio, 2.91; 95% CI, 1.38-6.12), and intestinal ischemia/thrombosis was the most common type of GI injury. Conclusions and RelevanceThe use of sodium polystyrene sulfonate is associated with a higher risk of hospitalization for serious adverse GI events. These findings require confirmation and suggest caution with the ongoing use of sodium polystyrene sulfonate.