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Determination of a Testing Threshold for Lumbar Puncture in the Diagnosis of Subarachnoid Hemorrhage after a Negative Head Computed Tomography: A Decision Analysis
Author(s) -
Taylor Richard Andrew,
Singh Gill Harman,
Marcolini Evie G.,
Meyers H. Pendell,
Faust Jeremy Samuel,
Newman David H.
Publication year - 2016
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/acem.13042
Subject(s) - medicine , subarachnoid hemorrhage , confidence interval , pre and post test probability , radiology , lumbar puncture , nuclear medicine , surgery , cerebrospinal fluid
Objective The objective was to determine the testing threshold for lumbar puncture ( LP ) in the evaluation of aneurysmal subarachnoid hemorrhage ( SAH ) after a negative head computed tomography ( CT ). As a secondary aim we sought to identify clinical variables that have the greatest impact on this threshold. Methods A decision analytic model was developed to estimate the testing threshold for patients with normal neurologic findings, being evaluated for SAH , after a negative CT of the head. The testing threshold was calculated as the pretest probability of disease where the two strategies ( LP or no LP ) are balanced in terms of quality‐adjusted life‐years. Two‐way and probabilistic sensitivity analyses ( PSA s) were performed. Results For the base‐case scenario the testing threshold for performing an LP after negative head CT was 4.3%. Results for the two‐way sensitivity analyses demonstrated that the test threshold ranged from 1.9% to 15.6%, dominated by the uncertainty in the probability of death from initial missed SAH . In the PSA the mean testing threshold was 4.3% (95% confidence interval = 1.4% to 9.3%). Other significant variables in the model included probability of aneurysmal versus nonaneurysmal SAH after negative head CT , probability of long‐term morbidity from initial missed SAH , and probability of renal failure from contrast‐induced nephropathy. Conclusions Our decision analysis results suggest a testing threshold for LP after negative CT to be approximately 4.3%, with a range of 1.4% to 9.3% on robust PSA . In light of these data, and considering the low probability of aneurysmal SAH after a negative CT , classical teaching and current guidelines addressing testing for SAH should be revisited.