Impact of Sulfonamide Allergy Label on Clinical Outcomes in Patients with Pneumocystis jiroveciiPneumonia

Introduction: The presence of antibiotic allergy labels can have harmful impacts on clinical outcomes, particularly among immunosuppressed patients, in whom there have been associations with increased complications, readmission rates, and mortality. We explore the effects of a sulfonamide allergy label (SAL) on clinical outcomes in adult patients with Pneumocystis jiroveciipneumonia (PJP). Methods: In this retrospective matched cohort study, we utilized TriNetX, a multicenter national database, to match 535 adult patients with PJP and SAL to an equal number of controls. We identified cases indexed between 01/01/2010 and 01/01/2023 utilizing ICD-10 codes for PJP and allergy status to sulfonamides and through detection of P. jiroveciiantigen with immunofluorescence or PCR. Propensity score matching was performed in a 1:1 fashion for demographics and comorbidities, and our analysis included clinical outcomes that occurred within 30 days after the occurrence of the index event. Results: While hospitalization risk tended to be lower among patients with SAL as compared to controls (RR: 0.90; 95% CI 0.81–1.01), there were no major differences in the risk of respiratory failure (RR: 0.94; 95% CI 0.84–1.05), prednisone use (RR: 1; 95% CI 0.91–1.10), intensive level of care requirement (RR: 0.85; 95% CI 0.69–1.06), intubation (RR: 0.85; 95% CI 0.61–1.19), or mortality (RR: 0.98; 95% CI 0.68–1.42). The presence of SAL did however impact antibiotic prescription patterns, with an underutilization of trimethoprim (RR: 0.50; 95% CI 0.43–0.59) and sulfamethoxazole (RR, 0.47; 95% CI 0.40–0.56) and overuse of alternative agents by patients with SAL as compared to controls. Yet, there was no difference in the occurrence of adverse outcomes such as hepatotoxicity (RR: 1.09; 95% CI 0.49–2.45) or acute kidney injury (RR: 0.94; 95% CI 0.78–1.14) between patients with SAL and controls. Conclusions: The presence of SAL alters antibiotic prescription patterns among adults with Pneumocystisinfection but has no clinically significant impact on outcomes.