Long-term mortality of patients with West syndrome.

Objective: To study long-term survival and mortality among patients with West syndrome.

Methods: The study population included all children born in 1960-1976 and treated for West syndrome in three tertiary care hospitals in Helsinki, Finland. The participants were prospectively followed for five decades for survival. Death data were derived from the National Causes of Death Register of the Population Register Center of Statistics Finland.

Results: During follow-up, 102 (49%) of 207 patients had died at the mean age of 19 years. The mean overall annual mortality rate was 15.3 per 1,000 patient-years. The rates ranged from 18.2 per 1,000 after 10 years to 17.2 per 1,000 after 20 years and 15.4 per 1,000 patient-years after 40 years of follow-up. One fourth (25%) had died by 17.2 (95% CI 11.8-22.7) years and 50% by 48.6 (95% CI 38.5-NA) years of follow-up. Etiology at onset was symptomatic in 87% patients and cryptogenic in 13%; 6 of the latter 26 patients later turned out to be symptomatic. The mean annual mortality rate was 3.7 per 1,000 for 4 patients with cryptogenic etiology and 17.6 per 1,000 for those with symptomatic etiology. The hazard of death was fivefold in patients with symptomatic etiology versus cryptogenic etiology. The overall autopsy rate was 73%. Pneumonia was the most frequent cause of death (46%). All patients who died of pneumonia had symptomatic etiology. SUDEP occurred in 10 patients and was the most common epilepsy-related cause of death (10%).

Significance: Risk of excess death of participants with West syndrome is not limited to early age but continues into adulthood, particularly in those with symptomatic etiology, and leads to death in half the cases at around 50 years of age. Measures should be directed to prevent pneumonia, the most common overall cause, and SUDEP, the most frequent seizure-related cause, of death.