Identifying risk factors for adverse events of pyridoxal phosphate in infantile epileptic spasms syndrome.

Introduction: Infantile epileptic spasms syndrome (IESS) is characterized by epileptic spasms, regardless of hypsarrhythmia on electroencephalogram or neurodevelopmental delay. In Japan, pyridoxal 5'-phosphate (PLP) is often used as the first-line treatment for IESS because it is effective in a certain number of patients. Although several studies have reported serious adverse events following PLP treatment, no study has investigated the risk factors for such occurrences.

Objective: To investigate adverse events associated with PLP therapy for the treatment of IESS and to identify the associated risk factors.

Materials And Methods: We retrospectively evaluated adverse events in 59 patients with IESS at Tottori University Hospital between January 1995 and September 2022. We subsequently collected and analyzed their clinical data and analyzed the risk factors associated with each adverse event. The cutoff values and relative risk (RR) were analyzed for items with significant associations with adverse events.

Results: Twenty-seven (51.9%) participants experienced adverse events, including vomiting in 16 participants (59.3%), elevated liver enzyme levels in 15 participants (55.6%), and rhabdomyolysis in two participants (3.4%). No significant differences were observed between the non-adverse events group and the overall adverse events group, as well as between the non-adverse events group and the vomiting group, in terms of the factors examined. However, when comparing the non-adverse events group with the group with elevated liver enzyme levels, age at PLP treatment showed a negative correlation, whereas PLP dose showed a positive correlation with elevated liver enzyme levels. The cutoff dose was 40 mg/kg/day (73.3% sensitivity and 60.7% specificity), and the cutoff age was 9 months (100% sensitivity and 40.0% specificity). RRs of doses ≥40 mg/kg/day and age <9 months were 2.6 and 3.6, respectively.

Conclusions: Adverse events of PLP therapy, including vomiting, elevated liver enzymes, and rhabdomyolysis, were observed in approximately half of the participants. Age under 9 months and a dose ≥40 mg/kg/day were identified as risk factors for elevation of liver enzymes on PLP treatment in infants with IESS, with rhabdomyolysis can occur in the younger or higher dose cases.