Sulfonamide allergy label and the risk of opportunistic infections in solid organ transplant recipients – A retrospective matched cohort study

Background: While a penicillin allergy label has been linked to various negative clinical outcomes, limited studies have specifically characterized the implication of sulfonamide allergy labels (SAL) on clinical outcomes. We examined the impact of SAL on clinical outcomes of solid organ transplant recipients. Methods: In this retrospective matched cohort study, we utilized the TriNetX US collaborative Network, a multicenter de-identified US database, and identified solid organ transplant recipients with and without SAL. The 1-year probability of developing Pneumocystis jirovecii pneumonia (PJP), toxoplasmosis, and nocardiosis was estimated and contrasted between the two study groups. The hazard ratio (HR) and the 95% confidence interval (CI) quantified the strength and direction of the association between SAL and these outcomes. Results: When comparing 1571 solid organ transplant recipients with SAL to an equal number of matched controls, patients with SAL had a higher probability of developing nocardiosis (HR 3.85; 95% CI, 1.44–10.30; p =.004; corrected p =.04), and toxoplasmosis (HR, 1.87; 95% CI, 1.10–3.17; p =.019; corrected p =.19), but no difference in the risk of developing PJP (HR, 1.64; 95% CI, 0.68–3.95; p =.27). There was no mortality difference (HR, 1.31; 95% CI, 0.99–1.75; p =.061; corrected p =.6). SAL influenced antibiotic prescription with overutilization of dapsone, atovaquone, and pentamidine and underutilization of trimethoprim and sulfamethoxazole. Conclusion: SAL is associated with an increased risk of opportunistic infections following solid organ transplantation. Measures to evaluate and de-label sulfonamide allergy prior to transplantation or desensitizing shortly after transplantation are advisable. (Figure presented.).