Prognostic Factors for Mortality in Patients With Autoimmune Diseases Complicated by Pneumocystis Pneumonia

Objectives Pneumocystis pneumonia (PCP) has a poor prognosis in patients with autoimmune diseases. Additionally, the mortality of PCP in autoimmune diseases is higher than that of human immunodeficiency virus-PCP. Therefore, this study aimed to assess the risk factors associated with mortality in patients with autoimmune diseases complicated with PCP. Methods We conducted a retrospective observational study involving 38 patients treated for PCP at Showa University School of Medicine from January 2010 to August 2014. Diagnoses were established based on clinical symptoms, imaging, and laboratory tests, including hypoxemia (partial pressure of oxygen (PaO2) < 70 mmHg), chest computed tomography findings, elevated (1,3)-β-D-glucan, and positive Pneumocystis jiroveciipolymerase chain reaction tests from sputum samples. Data regarding patient demographics, underlying diseases, therapeutic interventions, and laboratory findings were collected. Statistical comparisons between survivors and non-survivors were performed using Fisher's exact probability test and Mann-Whitney U test for independence test with Stata/SE version 17.0 (StataCorp LLC, College Station, TX). Results The median age of the study group was 72.4 years old, with the majority having rheumatoid arthritis. Mortality occurred in 18% (seven out of 38) of cases. Factors associated with increased mortality include males, higher serum creatinine and C-reactive protein levels, lower albumin and immunoglobulin A levels, and lower PaO2/fraction of inspired oxygen (FiO2) ratio. No significant difference was observed in the rate of intratracheal intubation, ICU management, and hospitalization period. Prophylactic administration of trimethoprim-sulfamethoxazole (TMP-SMX) was not performed in any of the cases. Conclusions This study examined the risk of mortality for PCP in patients with autoimmune diseases. The male gender, low IgA and albumin levels, low PaO2/FiO2 ratio, as well as high creatinine and CRP levels, were identified as significant factors for poor prognosis. These factors can help identify patients at high risk for PCP and guide the consideration of prophylactic TMP-SMX administration. They may also provide insights into when to discontinue prophylactic treatment. Future studies should investigate the administration of prophylactic TMP-SMX. Additionally, the risk of mortality for PCP under the administration of new biological agents, such as anifrolumab, belimumab, and rituximab, or immunosuppressants, such as mycophenolate mofetil and voclosporin, should be evaluated. These findings can contribute to improving PCP prevention and treatment strategies in patients with autoimmune diseases, ultimately leading to better patient outcomes.