A randomized clinical trial on the efficacy and tolerability of dose reduction and escalation regimen of Trimethoprim/Sulfamethoxazole (TMP/SMX) in patients with rheumatic diseases

INTERVENTION: The 1g group: start TMP/SMX 1g (80 mg/400 mg)/day within 10 days of starting corticosteroid equivalent to/above 0.6 mg/kg/day of prednisolone, continue up to 24 weeks in principle. Continue or stop after 24 weeks on doctor's decision. The 0.5g group: start TMP/SMX 0.5g (40 mg/200 mg)/day within 10 days of starting corticosteroid equivalent to/above 0.6 mg/kg/day of prednisolone, continue up to 24 weeks in principle. Continue or stop after 24 weeks on doctor's decision. The escalation group: start TMP/SMX 0.1g (8 mg/16 mg)/day within 10 days of starting corticosteroid equivalent to/above 0.6 mg/kg/day of prednisolone, increase dose by 0.1g in one week (at least in 2 weeks). When it comes to 0.5g/day, continue it up to 24 weeks. Continue or stop after 24 weeks on doctor's decision. CONDITION: Rheumatic diseases PRIMARY OUTCOME: PCP prevention rate at 24 weeks of the 1g group (1g/day of TMP/SMX, the regular dose) and the escalation group (start 0.1g/day of TMP/SMX and increase gradually up to a half of the regular dose) SECONDARY OUTCOME: 1. PCP prevention rate at 24 weeks of the 1g group and the 0.5g group (0.5g/day of TMP/SMX, a half of the regular dose) ; 2. PCP prevention rate at 24 weeks of the 0.5 g group and the escalation group; 3. PCP prevention rate at 52 weeks of the 1g group, the 0.5g group and the escalation group; 4. Withdrawal rates of TMP/SMX at 24 weeks and 52 weeks; 5. Safety (incidence of adverse events and serious adverse events, side effects and contents of these severe side effects) ; 6. Situations of TMP/SMX administration up to 52 weeks INCLUSION CRITERIA: 1. A patient with rheumatic disease starting corticosteroid equivalent to/above 0.6 mg/kg/day of prednisolone (with or without immunosuppressant) 2. A patient starting treatments mentioned above in a hospital setting 3. A patient who is 20 years old or more and gives written informed consent 4. A patient who has never used TMP/SMX, pentamidine nor diaphenylsulfone 5. A patient with serum creatinine less than maximum of normal range at registration