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Abstract

Objective To evaluate diagnostic criteria for idiopathicnormal pressure hydrocephalus (INPH) among patientswith memory impairment, and to estimate the incidenceof INPH.Design Prospective observational cross-section andcohort study of diagnostic accuracy.Setting Memory Disorders Clinic following referral by themedical practitioners.Participants 408 consecutive patients enrolled 2010–2014.Outcome measures Reference diagnostic test was theclinical judgement of an experienced specialist basedon the presence of cognitive impairment and/or balanceand gait disorders in the presence of dilated ventricles.Mini-Mental State Examination (MMSE), Tinetti balanceand gait tests were performed before and 12 monthsafter ventriculoperitoneal shunt surgery. The associationbetween reference diagnosis, clinical and brain CT scanmeasurements was estimated by multivariate Poissonregression. Triage index diagnostic test scores werecalculated from the regression coefficients, with diagnosticthresholds selected using receiver operating characteristicanalysis.Results The presence of balance and/or gait disorders,especially fear of falling, difficulty standing on toes/heals, urinary disturbances, ventriculomegaly withEvans ratio greater than Combined Diagnostic Threshold(0.377-{Maximum width of posterior horns*0.0054}),strongly predict the diagnosis of INPH; while hallucinationsand/or delusions and forgetfulness reduce the likelihoodof the diagnosis. This triage index test had high sensitivity(95.2%) and specificity (91.7%). 62 of 408 (15%)participants with cognitive impairment had INPH, anincidence of 11.9/100 000/year and 120/100 000/yearover 75 years. 96% of participants following shunting,compared with 45% of the non-shunted, improved by over25% of available measurable improvement in either MMSEor balance/gait scores (51% difference; 95%CI 28% to74%; p<0.001), and 56% vs 5% improved by over 50% ofmaximum in both (51% difference; 95%CI 30% to 73%;p<0.001).

Item Type:	Article
Authors/Creators:	Razay, G and Wimmer, M and Robertson, I
Journal or Publication Title:	BMJ Open
Publisher:	B M J Group
ISSN:	2044-6055
DOI / ID Number:	https://doi.org/10.1136/bmjopen-2018-028103
Copyright Information:	© Author(s) (or their employer(s)) 2019. This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the useis non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
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