Screening tests for normal-pressure hydrocephalus: sensitivity, specificity, and cost.
OBJECTIVE
Many tests have been proposed to help choose candidates for shunt insertion in cases of suspected normal-pressure hydrocephalus (NPH). It is unclear what sensitivity and specificity a prospective test must have to improve outcomes, compared with the results of automatic shunt insertion.


METHODS
The authors adapted the decision analysis model used in a companion article to allow for application of a screening test. Using the reported sensitivities and specificities of several such tests, they evaluated the effects such tests would have on the expected outcome of an average 65-year-old patient with moderate dementia. They also evaluated the cost-effectiveness of a theoretical screening test with superior sensitivity and specificity.


CONCLUSIONS
Although external lumbar drainage comes quite close, none of the screening tests reported to date have sufficient sensitivity and specificity to improve expected outcome in an average candidate, compared with the results of automatic shunt placement in cases of suspected NPH. In addition, even a theoretically improved test would need to be considerably less expensive than prolonged lumbar drainage to be cost-effective in clinical practice.
Burnett
Mark G
MG
Department of Neurosurgery and Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Sonnad
Seema S
SS
Stein
Sherman C
SC
D000368:Aged; D003362:Cost-Benefit Analysis / Q000191:economics; D003704:Dementia / Q000175:diagnosis / Q000191:economics* / Q000401:mortality / Q000601:surgery*; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis / Q000191:economics* / Q000401:mortality / Q000601:surgery*; D008403:Mass Screening / Q000191:economics*; D009010:Monte Carlo Method; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D019057:Quality-Adjusted Life Years; D016019:Survival Analysis; D014481:United States