Characteristics of diagnosed normal pressure hydrocephalus in routinely‐collected data from memory assessment services in a large South London catchment area

Our findings could reflect under-diagnosis of NPH in memory services. Recorded diagnosis of NPH in our population was rare, with a 17-year case proportion of 0.28%. Other studies have estimated the point prevalence of NPH in the general population above 60 years old to be 0.45% and, though our measure is not directly comparable, we expected a higher number of cases in this clinical population with cognitive symptoms. We focussed on recorded diagnosis of G91.2, which may have limited our results due to inconsistent diagnostic code use. These findings warrant further work including investigating the chronology of diagnosis with memory clinic referral and investigation of alternative ICD10 codes used for NPH in this population.