Evaluation of laboratory disturbance risk when adding low-dose cotrimoxazole for PJP prophylaxis to regimens of high-grade glioma patients taking RAAS inhibitors

Background Cotrimoxazole is associated with the development of hyponatremia, hyperkalemia and elevated serum creatinine, especially when combined with inhibitors of the renin–angiotensin–aldosterone system (RAAS). Pneumocystis jirovecii pneumonia (PJP) prophylaxis is the standard of care for high-grade glioma (HGG) patients receiving temozolomide concurrently with radiotherapy, low-dose cotrimoxazole being the preferred agent. Many of these patients are also taking renin–angiotensin–aldosterone system inhibitors, however the risk of significant laboratory disturbance in these patients remains undescribed. Objective We evaluated whether high-grade glioma patients taking renin–angiotensin–aldosterone system inhibitors receiving low-dose cotrimoxazole for Pneumocystis jirovecii pneumonia prophylaxis are at additional risk of laboratory disturbances in comparison with their non-renin–angiotensin–aldosterone system counterparts. Methods We conducted a retrospective chart review of adult neuro-oncology patients treated for WHO Grade III or IV glioma between 2013 and 2016. Patient serum Na, K, creatinine, and eGFR were compared (renin–angiotensin–aldosterone system vs. non-renin–angiotensin–aldosterone system) using the chi-square test. Binary logistic regression analysis was then performed to account for differences between cohorts. Results Of 63 patients (35 non-renin–angiotensin–aldosterone system, 28 renin–angiotensin–aldosterone system), patients in the renin–angiotensin–aldosterone system cohort were more likely to experience a laboratory disturbance (odds ratio=3.17, p = 0.03). Overall, these disturbances were moderate, but were slightly more common and slightly more severe in the renin–angiotensin–aldosterone system cohort. Conclusion Adding low-dose cotrimoxazole for Pneumocystis jirovecii pneumonia prophylaxis to the regimens of patients with high-grade glioma taking renin–angiotensin–aldosterone system inhibitors increases the risk of laboratory disturbances. While these are generally moderate, some patients are at risk of significant electrolyte abnormalities requiring intervention.