Cost‐effectiveness Analysis of Follow‐up Strategies for Thunderclap Headache Patients With Negative Noncontrast CT

Abstract

Objectives: Accurate diagnosis of acute subarachnoid hemorrhage (SAH) is critical in thunderclap headache patients due to high morbidity and mortality associated with missed aneurysmal bleeds. The objective of this study was to determine the utility of computed tomography angiography (CTA) in managing patients with acute, severe headaches and negative noncontrast CT and assess the costeffectiveness of three different screening strategies-no follow up, CTA, and lumbar puncture (LP).Methods: A modeling-based economic evaluation was performed with a time horizon of 1 year for thunderclap headache patients in the emergency department with negative noncontrast CT for SAH. Sensitivity analyses were performed to determine the effect of sensitivity of CT and the prevalence of SAH on cost-effectiveness.Results: Lumbar puncture follow-up has the lowest cost and the highest utility in the mathematical model. The Monte Carlo simulation shows noncontrast CT with LP follow-up to be the most costeffective strategy in 85.3% of all cases even at a $1 million/quality-adjusted life-years willingness-to-pay. Sensitivity analyses demonstrate that LP follow-up should be performed, except for when CT sensitivity exceeds 99.2% and the SAH prevalence is below 3.2%, where no follow-up may be considered.Conclusions: Although CTA is frequently used for evaluation of thunderclap headache patients, its utility is not clearly defined. LP follow-up is shown to be the most cost-effective strategy for evaluation of thunderclap headache patients in most clinical settings.ACADEMIC EMERGENCY MEDICINE 2016;23:243-250 © 2016 by the Society for Academic Emergency Medicine S evere, acute headache remains a common cause for presentation to the emergency department (ED) and exclusion of subarachnoid hemorrhage (SAH) in these patients is a critical part of the workup.1,2 Nontraumatic SAH is caused by vascular lesions, such as aneurysms or ateriovenous malformation, in 85% cases and false-negative diagnosis can have increased morbidity and mortality.3,4 The conventional workup for thunderclap headache, or for a patient presenting with an acute onset of "the worst headache of his life," is a noncontrast CT. 5,6 In the case of a negative CT for acute SAH, a lumbar puncture (LP) is performed which is sensitive to small amounts of blood and xanthochromia in cerebrospinal fluid. However, LP is invasive with risks for complications and is also operator-dependent.7 Recent ED literature has proposed using a strategy of CT followed by CT angiography (CT/CTA) instead of CT/LP based on mathematical probabilities and CTA has been increasingly used in evaluating thunderclap headache patients with negative initial CTs. 7,8 Computed tomography angiography has become highly accurate for diagnosis of intracranial aneurysms, with 64-detector CTA having over 98% sensitivity and 100% specificity for aneurysm detection in setting of SAH.9 It is particularly sensitive in detection of aneurysms greater than 3 mm. 10 The tiny aneurysms possibly missed by CTA have a very l...

Determination of a Testing Threshold for Lumbar Puncture in the Diagnosis of Subarachnoid Hemorrhage after a Negative Head Computed Tomography: A Decision Analysis

“…This results are also supported by a recent cost-effectiveness study that demonstrated when the CT sensitivity is >99% (i.e., CT on newer-generation scanner performed less 6 hours from onset of symptoms) no further testing is warranted. 58 For carefully selected patients (those with a high probability of disease [>20%] and who present late > 2 days) the likelihood of SAH may exceed testing thresholds in the lowest range of our intervals, suggesting that LP may be a beneficial approach for such patients presuming the most conservative estimates for all input variables (Figure 3). Because of the declining performance of CT for SAH over time and the complicated aspect of determining a pre-CT probability of disease, we believe that decision aids such as Figure 3 coupled with clinical decision rules that estimate pre-CT probabilities of disease will be helpful in making shared decisions with patients under uncertainty.…”

Management of thunderclap headache in the emergency room: A retrospective cohort study

“…Some researchers argue that CT might be sufficient to rule out subarachnoid bleeding if the scan is normal and is done within 6 h of the TCH onset (19,20,27,34). However, other secondary headache disorders can be responsible for the TCH, and even in those studies, 4.0% (19) to 9.3% (27) of patients showed a cause of TCH different from SAH, half of them diagnosed only by LP (25).…”

Other primary headaches—thunderclap-, cough-, exertional-, and sexual headache

“…In those with negative CT, examination of cerebrospinal fluid (CSF) for altered blood products remains positive from 12 h to 2 weeks in 100% of cases [15][16][17]. The risk of angiography in lieu of CSF examination, or in late presentations, is detection of an incidental aneurysm and potential unnecessary and cost-ineffective intervention [18,19]. It has been argued that using third generation CT scans to image patients within 6 h of ictus, the sensitivity and specificity for detecting aneurysmal subarachnoid haemorrhage is 100%.…”