Impact of prophylaxis choice on risk of pneumocystis pneumonia in children with cancer: A case-control study

Abstract

Background: Pneumocystis jirovecii pneumonia (PJP) is a life-threatening opportunistic infection. Prophylaxis is recommended for patients with malignancies and trimethoprim-sulfamethoxazole (TMP-SMX) is the recommended first-line agent. Many paediatric patients receive second-line agents due to perceived adverse reactions from TMP-SMX.

Objective: The objective of the study is to determine the risk of PJP in patients receiving TMP-SMX vs. second-line medications for prophylaxis.

Methods: We conducted a retrospective, single centre, case-control study of paediatric oncology patients. Cases included children diagnosed with PJP by microscopy between 2000 and 2018 while being treated for a malignancy. Controls were matched by age, oncologic diagnosis, treatment protocol, phase of treatment and oncologic diagnosis date. For each case, up to 5 controls were randomly selected. The index date was the date of the PJP diagnosis for cases and the equivalent dummy date for controls.

Results: Eleven cases with PJP were identified and matched with 50 controls. Six (55%) cases and 42 (84%) controls were on prophylaxis with TMP-SMX. The remaining patients received inhaled pentamidine (3 cases, 4 controls), dapsone (2 cases, 3 controls), or atovaquone (1 control). Myelosuppression was the most common reason to stop TMP-SMX. Cases with PJP were less likely to have been taking TMP-SMX in the 3 months before diagnosis when compared with controls (odds ratio: 0.15, 95% confidence interval: 0.01-0.97, p = 0.02).

Conclusion: TMP-SMX prophylaxis was associated with a lower risk of developing PJP compared with second-line treatments. Although alternate agents may be required in certain situations, efforts should be made to rechallenge with TMP-SMX when possible.

Keywords: Neoplasm; Pneumocystis pneumonia; Sulfamethoxazole; Trimethoprim.