10-year mortality, causes of death and cardiovascular comorbidities in idiopathic normal pressure hydrocephalus.

OBJECTIVE: The objective was to investigate 10-year mortality, causes of death and cardiovascular comorbidity in idiopathic normal pressure hydrocephalus (iNPH) and to evaluate their mutual associations.

METHODS: This prospective cohort study included 176 CSF-shunted iNPH patients, and 368 age- and sex-matched controls. At inclusion, participants were medically examined, had blood analyzed and answered a questionnaire. The vascular comorbidities investigated were smoking, diabetes, body mass index, blood pressure (BP), hyperlipidemia, kidney function, atrial fibrillation and, cerebro- and cardiovascular disease.

RESULTS: Survival was observed for a mean period of 10.3 ± 0.84 years. Shunted iNPH patients had an increased risk of death compared to controls (hazard ratio (HR) = 2.5, 95% CI 1.86-3.36; p < 0.001). After 10 years, 50% (n = 88) of iNPH patients and 24% (n = 88) of the controls were dead (p < 0.001). The risk of dying from cardiovascular disease, falls and neurological diseases were higher in iNPH (p < 0.05). The most common cause of death in iNPH was cardiovascular diseases (14% vs 7% for controls). Seven out of nine iNPH dying from falls had subdural hematomas. Systolic BP (HR = 0.985 95% CI 0.972-0.997, p = 0.018), atrial fibrillation (HR = 2.652, 95% CI 1.506-4.872, p < 0.001) and creatinine (HR = 1.018, 95% CI 1.010-1.027, p < 0.001) were independently associated with mortality for iNPH.

DISCUSSION: This long-term and population-matched cohort study indicates that in spite of CSF-shunt treatment, iNPH has shorter life expectancy. It may be important to treat iNPH in supplementary ways to reduce mortality. Both cardiovascular comorbidities and lethal falls are contributing to the excess mortality in iNPH and reducing these preventable risks should be an established part of the treatment plan.