Nighttime Post-Transplant Cyclophosphamide Associated With Higher Haemorrhagic Cystitis Risk

A retrospective, single-centre study published in the European Journal of Haematology examined whether post-transplant cyclophosphamide (PTCy) infusion timing was associated with haemorrhagic cystitis after allogeneic haematopoietic stem cell transplantation. The cohort included 178 adults transplanted between January 2014 and December 2022. All received PTCy 50 mg/kg/day for two consecutive days and were classified by first-dose timing: daytime (06:00–17:59) or nighttime (18:00–05:59). The primary endpoint was Grade II–IV haemorrhagic cystitis.

Grade II–IV cystitis occurred in 16.4% of daytime recipients and 31.2% of nighttime recipients. The unadjusted association was not statistically significant (OR 2.31, 95% CI 0.97–5.49; p = 0.079), but nighttime administration was associated with higher odds after adjustment for potential confounders (adjusted OR 2.82, 95% CI 1.12–7.10; p = 0.028). Grade III–IV cystitis occurred in 4.8% versus 15.6%, respectively (OR 3.68, 95% CI 1.09–12.45; p = 0.043). No significant differences in transplant outcomes were observed.

These findings identify infusion timing as a potentially modifiable factor warranting prospective evaluation, rather than establishing that daytime dosing prevents cystitis. The retrospective, single-centre design limits causal interpretation, and confidence intervals were wide. Only the abstract was available; the specific adjustment variables could not be assessed.