Early shunt surgery improves survival in idiopathic normal pressure hydrocephalus

Abstract

Background and purpose: To examine the effect of delayed compared to early planning of shunt surgery on survival, in patients with idiopathic normal pressure hydrocephalus (iNPH), a long-term follow-up case–control study of patients exposed to a severe delay of treatment was performed. Methods: In 2010–2011 our university hospital was affected by an administrative and economic failure that led to postponement of several elective neurosurgical procedures. This resulted in an unintentional delay of planning of treatment for a group of iNPH patients, referred to as iNPHDelayed (n = 33, waiting time for shunt surgery 6–24 months). These were compared to patients treated within 3 months, iNPHEarly (n = 69). Primary outcome was mortality. Dates and underlying causes of death were provided by the Cause of Death Registry. Survival was analysed by Kaplan–Meier plots and a Cox proportional hazard model adjusted for potential confounders. Results: Median follow-up time was 6.0 years. Crude 4-year mortality was 39.4% in iNPHDelayed compared to 10.1% in iNPHEarly (p = 0.001). The adjusted hazard ratio in iNPHDelayed was 2.57; 95% confidence interval 1.13–5.83, p = 0.024. Causes of death were equally distributed between the groups except for death due to malignancy which was not seen in iNPHDelayed but in 4/16 cases in iNPHEarly (p = 0.044). Conclusions: The present data indicate that shunt surgery is effective in iNPH and that early treatment increases survival.