Quantification of the effect of chemotherapy and steroids on risk of P neumocystis jiroveci among hospitalized patients with adult T ‐cell leukaemia

Summary This study aimed to quantify the risks of Pneumocystis pneumonia ( PCP ) among adult T‐cell leukaemia ( ATL ) patients without prophylaxis. We used hospital administrative data collected nationwide in Japan over 4 years. The research design was a retrospective cohort study. Subjects were 4369 patients diagnosed with ATL aged 18 years or older. The subjects were categorized into four treatment groups: no agent, chemotherapy, chemotherapy + steroids and steroids. We described the risks of PCP among ATL patients without prophylaxis. Risks of PCP were 3·2% for the no agent group, 9·7% for the chemotherapy group, 10·0% for the chemotherapy + steroids group and 16·6% for the steroids group. Logistic regression analyses showed that the chemotherapy, chemotherapy + steroids and steroids groups had significantly higher risk of PCP than did the no agent group [adjusted odds ratio ( AOR ) 3·30 (1·55–7·02), P  = 0·002 for the chemotherapy group; AOR 3·35 (2·18–5·17), P  < 0·001 for the chemotherapy + steroids group; AOR 6·12 (3·99–9·38), P  < 0·001 for the steroids group]. In conclusion, the chemotherapy, chemotherapy + steroids and steroids groups had significantly higher risks of PCP . Prophylaxis for PCP among ATL patients being treated with chemotherapy, chemotherapy + steroids and steroids is highly recommended.