A systematic review on the epidemiology of normal pressure hydrocephalus

Background: The aim of this systematic review is to gather all available studies reporting prevalence and incidence rates of iNPH and to assess their methodological quality and consistency. Methods: All available studies published up to June 2019 were retrieved searching the databases PubMed, ISI Web of Science, and the Cochrane Database of Systematic Reviews. All included studies were qualitatively assessed by two independent reviewers using the MORE Checklist for Observational Studies of Incidence and Prevalence. Key results: Bibliographic searches and other sources yielded 659 records. A total of 28 studies were selected and applied the predefined inclusion and exclusion criteria. Fourteen studies were further excluded, and 14 studies (10 on prevalence and 6 on incidence) were included in the qualitative analysis. Results from the prevalence studies reported crude overall rates ranging from 10/100 000 to 22/100 000 for probable iNPH and 29/100 000 for possible iNPH, and age-specific rates ranging from 3.3/100 000 in people aged 50-59 to 5.9% in people aged ≥ 80 years. Results from incidence studies reported overall crude rates ranging from 1.8/100 000 to 7.3/100 000 per year, and age-specific rates ranging from 0.07/100 000/year in people aged < 60 years to 1.2/1000/year in people aged ≥ 70 years. Conclusions & Inferences: The high methodological and clinical heterogeneity of included studies does not allow drawing adequate conclusions on the epidemiology of iNPH. Further, high-quality, population-based studies should be carried out to allow for a better understanding of the epidemiology of this condition. Moreover, the implementation in current clinical practice of guidelines on the diagnosis and management of iNPH should also be endorsed.