Patient characteristics
In all, 210,414 patients who were hospitalized in our facility during the study period were screened. Of those, 39 patients met all the inclusion criteria (Fig. 1). Fifteen (38.5%) and 23 (59.0%) patients were diagnosed as P. jirovecii-positive based on PCR results of BALF and sputum samples, respectively. Fluorescent staining of BALF samples was positive for four patients (10.3%) including one patient with a negative PCR result. The patients’ baseline characteristics are shown in Table 1. The median patient age was 70 years (range: 27–92 years), and 18 patients (46.2%) were female. Twenty-one patients (53.8%) had autoimmune diseases and 13 patients (33.3%) had malignancies; seven of the 13 patients had had hematologic malignancies. Thirty-two (82.1%) and 14 (35.9%) patients were being treated with corticosteroids and immunosuppressants, respectively, and among them, 11 (28.2%) received both corticosteroids and immunosuppressants at the time of PCP development. Among the 32 patients who were being treated with corticosteroids, the daily corticosteroid dose converted to the PSL equivalent dose ranged from 2 to 60 mg, with the median dose being 14 mg. Further, 24 (61.5%), 11 (28.2%), and six (15.4%) patients were treated with a dose of 20 mg or less, 10 mg or less, and 5 mg or less, respectively (Fig. 2). The corticosteroid administration period ranged from 27 to 2,084 days, with the median period being 121 days. None of 39 patients was being administered TMP-SMX for prophylaxis when PCP developed. Aerosolized pentamidine was administered to only four patients; in three of the patients, it was administered from the beginning of prophylactic treatment, and in the remaining patient, it was administered after TMP-SMX discontinuation. The remaining 35 patients were not being administered any prophylactic drug when PCP developed; 25 of these patients never received prophylaxis, while the remaining 10 had discontinued TMP-SMX before PCP development. Seventeen patients (43.6%) died at the hospital.
Comparison of the characteristics of patients who were never administered and those who discontinued the prophylactic TMP-SMX treatment
Twenty-five patients were never administered TMP-SMX as prophylaxis for PCP and 11 other patients discontinued TMP-SMX before PCP development (Table 2). There were no significant differences between the two groups in age, sex, underlying diseases, initial laboratory findings, corticosteroid use or dose, immunosuppressant use, diagnostic methods, and in-hospital mortality. The duration of corticosteroid treatment was significantly longer in the patients who discontinued prophylactic TMP-SMX than in those who were never administered TMP-SMX (542 [range: 0-2084] days vs 64.5 [range: 0-728] days, p < 0.01). This significant difference existed even after excluding patients who were not being administered corticosteroids at the time of PCP development (739 [range: 116–2084] days vs 155 [range: 27–728] days, p < 0.01).
Patients who discontinued prophylactic TMP-SMX
The detailed characteristics of the 11 patients who discontinued prophylactic TMP-SMX before PCP development are shown in Table 3. Only one patient was administered prophylactic aerosolized pentamidine after TMP-SMX discontinuation due to its side effects. A lymphoma patient was never administered corticosteroid therapy, while the remaining 10 patients had been administered corticosteroids for more than 116 days. The daily corticosteroid dose at the time of PCP development, which was converted to the PSL equivalent dose, ranged from 2 to 30 mg, with the median dose was 10 mg. Four patients (36.4%) were administered a dose of 5 mg or less. All of the patients who died at the hospital were administered a dose of 10 mg or higher. The period from TMP-SMX discontinuation to PCP development ranged from 44 to 175 days, with the median duration being 95 days, and in nine patients (81.8%), PCP developed 14 ± 2 weeks after TMP-SMX discontinuation (Table 3 and Fig. 3).