The added clinical and economic value of diagnostic testing for epilepsy surgery

Epilepsy center characteristics and geographic region influence presurgical testing in the United States

OBJECTIVE

Persons with drug-resistant epilepsy may benefit from epilepsy surgery and should undergo presurgical testing to determine potential candidacy and appropriate intervention. Institutional expertise can influence use and availability of evaluations and epilepsy surgery candidacy. This census survey study aims to examine the influence of geographic region and other center characteristics on presurgical testing for medically intractable epilepsy.

METHODS

We analyzed annual report and supplemental survey data reported in 2020 from 206 adult epilepsy center directors and 136 pediatric epilepsy center directors in the United States. Test utilization data were compiled with annual center volumes, available resources, and US Census regional data. We used Wilcoxon rank-sum, Kruskal-Wallis, and chi-squared tests for univariate analysis of procedure utilization. Multivariable modeling was also performed to assign odds ratios (ORs) of significant variables.

RESULTS

The response rate was 100% with individual element missingness < 11% across 342 observations undergoing univariate analysis. A total of 278 complete observations were included in the multivariable models, and significant regional differences were present. For instance, compared to centers in the South, those in the Midwest used neuropsychological testing (OR = 2.87, 95% confidence interval [CI] = 1.2-6.86; p = .018) and fluorodeoxyglucose-positron emission tomography (OR = 2.74, 95% CI = = 1.14-6.61; p = .025) more commonly. For centers in the Northeast (OR = .46, 95% CI = .23-.93; p = .031) and West (OR = .41, 95% CI = .19-.87; p = .022), odds of performing single-photon emission computerized tomography were lower by nearly 50% compared to those in the South. Center accreditation level, demographics, volume, and resources were also associated with varying individual testing rates.

SIGNIFICANCE

Presurgical testing for drug-resistant epilepsy is influenced by US geographic region and other center characteristics. These findings have potential implications for comparing outcomes between US epilepsy centers and may inject disparities in access to surgical treatment.

Underutilization of advanced presurgical studies and high rates of vagus nerve stimulation for drug-resistant epilepsy: a single-center experience and recommendations

INTRODUCTION

Epilepsy surgery continues to be profoundly underutilized despite its safety and effectiveness. We sought to investigate factors that may contribute to this phenomenon, with a particular focus on the antecedent underutilization of appropriate preoperative studies.

METHODS

We reviewed patient data from a pediatric epilepsy clinic over an 18-month period. Patients with drug-resistant epilepsy (DRE) were categorized according to brain magnetic resonance imaging (MRI) findings (lesional, MRI-negative, or multifocal abnormalities) and type of epilepsy diagnosis based on semiology and electroencephalography (EEG) (focal or generalized). We then analyzed the rates of diagnostic test utilization, surgical referral, and subsequent epilepsy surgery as well as vagus nerve stimulation (VNS).

RESULTS

Of the 249 patients with a diagnosis of epilepsy, 138 (55.4%) were found to have DRE. Excluding the 10 patients with DRE who did not undergo MRI, 76 patients (59.4%) were found to be MRI-negative (non-lesional epilepsy), 37 patients (28.9%) were found to have multifocal abnormalities, and 15 patients (11.7%) were found to have a single epileptogenic lesion on MRI (lesional epilepsy). Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) were each completed in nine patients (7.0%) and magnetoencephalography (MEG) in four patients (3.1%). Despite the low utilization rate of adjunctive studies, over half (56.3%) ultimately underwent VNS alone, and 8.6% ultimately underwent definitive intracranial resection or disconnection surgery.

CONCLUSIONS

The underutilization of appropriate non-invasive, presurgical testing in patients with focal DRE may in part explain the continued underutilization of definitive, resective/disconnective surgery. For patients without access to a high-volume, multidisciplinary surgical epilepsy center, adjunctive presurgical studies [e.g., PET, SPECT, MEG, electrical source imaging (ESI), EEG-functional magnetic resonance imaging (fMRI)], even when available, are rarely ordered, and this may contribute to excessive rates of VNS in lieu of definitive intracranial surgery.

Underutilization of epilepsy surgery: Part I: A scoping review of barriers

One-third of persons with epilepsy have seizures despite appropriate medical therapy. Drug resistant epilepsy (DRE) is associated with neurocognitive and psychological decline, poor quality of life, increased risk of premature death, and greater economic burden. Epilepsy surgery is an effective and safe treatment for a subset of people with DRE but remains one of the most underutilized evidence-based treatments in modern medicine. The reasons for this quality gap are insufficiently understood. In this comprehensive review, we compile known significant barriers to epilepsy surgery, originating from both patient/family-related factors and physician/health system components. Important patient-related factors include individual and epilepsy characteristics which bias towards continued preferential use of poorly effective medications, as well as patient perspectives and misconceptions of surgical risks and benefits. Health system and physician-related barriers include demonstrable knowledge gaps among physicians, inadequate access to comprehensive epilepsy centers, complex presurgical evaluations, insufficient research, and socioeconomic bias when choosing appropriate surgical candidates.

Antibody Prevalence in Epilepsy before Surgery (APES) in drug-resistant focal epilepsy

OBJECTIVE

There is a growing recognition of immune-mediated causes in patients with focal drug-resistant epilepsy (DRE); however, they are not systematically assessed in the pre-surgical diagnostic workup. Early diagnosis and initiation of immunotherapy is associated with a favorable outcome in immune-mediated seizures. Patients with refractory focal epilepsy with neuronal antibodies (Abs) tend to have a worse surgical prognosis when compared to other etiologies.

METHODS

We studied the prevalence of serum Abs in patients ≥18 years of age with DRE of unknown cause before surgery. We proposed and calculated a clinical APES (Antibody Prevalence in Epilepsy before Surgery) score for each subject, which was modified based on Dubey's previously published APE² score. RESULTS`: A total of 335 patients were screened and 86 subjects were included in final analysis. The mean age at the time of recruitment was 44.84 ± 14.86 years, with age at seizure onset 30.89 ± 19.88 years. There were no significant differences among baseline clinical features between retrospective and prospective sub-cohorts. The prevalence of at least one positive Ab was 33.72%, and central nervous system (CNS)-specific Abs was 8.14%. APES score ≥4 showed slightly better overall prediction (area under the curve [AUC]: 0.84 vs 0.74) and higher sensitivity (100% vs 71.4%), with slightly lower but similar specificity (44.3% vs 49.4%), when compared to APE² score ≥4. For subjects who had available positron emission tomography (PET) results and all components of APES score (n = 60), the sensitivity of APES score ≥4 yielded a similar prediction potential with an AUC of 0.80.

SIGNIFICANCE

Our findings provide persuasive evidence that a subset of patients with focal DRE have potentially immune-mediated causes. We propose an APES score to help identify patients who may benefit from a workup for immune etiologies during the pre-surgical evaluation for focal refractory epilepsy with unknown cause.

Cost-effectiveness analysis of invasive EEG monitoring in drug-resistant epilepsy

PURPOSE

Our aim was to determine the cost-effectiveness of two intracranial electroencephalography (iEEG) interventions: 1) stereoelectroencephalography (SEEG) and 2) placement of subdural grid electrodes (SDGs) both followed by resective surgery in patients with drug-resistant, partial-onset epilepsy, compared with medical management (MM) in Hungary from payer's perspective.

METHODS

The incremental health gains and costs of iEEG interventions have been determined with a combination of a decision tree and prevalence Markov process model over a 30-year time horizon in a cost-utility analysis (CUA). To address the effect of parameter uncertainty on the incremental cost-effectiveness ratio (ICER), deterministic and probabilistic sensitivity analyses were performed.

RESULTS

Our results showed that both SEEG and SDG interventions represent a more expensive but more effective strategy than MM representing the current standard of care. The total discounted cost of SEEG and SDG were € 32,760 and € 25,028 representing € 18,108 and € 10,375 additional cost compared with MM, respectively. However, they provide an additional 3.931 (in SEEG group) and 3.444 quality-adjusted life years (QALYs; in SDG group), correspondingly. Thus, the ICER of SEEG is € 4607 per QALY gain, while the ICER for SDG is € 3013 per QALY gain, compared with MM. At a cost-effectiveness threshold of € 41,058 per QALY in Hungary, both subtypes of iEEG interventions are cost-effective and provide good value for money.

SIGNIFICANCE

Because of the high cost of implanting electrodes and monitoring, the invasive EEG for patients with refractory epilepsy is currently not available in the Hungarian national healthcare system. Our study demonstrated that these procedures in Hungary are cost-effective compared with the MM. As a result, the introduction of iEEG interventions to the reimbursement list of the National Health Insurance Fund Administration was initiated.

Deciphering the surgical treatment gap for drug-resistant epilepsy (DRE): A literature review

Patients with drug-resistant epilepsy (DRE) rarely achieve seizure freedom with medical therapy alone. Despite being safe and effective for select patients with DRE, epilepsy surgery remains heavily underutilized. Multiple studies have indicated that the overall rates of surgery in patients with DRE have stagnated in recent years and may be decreasing, even when hospitalizations for epilepsy-related problems are on the rise. Ultimately, many patients with DRE who might otherwise benefit from surgery continue to have intractable seizures, lacking access to the full spectrum of available treatment options. In this article, we review the various factors accounting for the persistent underutilization of epilepsy surgery and uncover several key themes, including the persistent knowledge gap among physicians in identifying potential surgical candidates, lack of coordinated patient care, patient misconceptions of surgery, and socioeconomic disparities impeding access to care. Moreover, factors such as the cost and complexity of the preoperative evaluation, a lack of federal resource allocation for the research of surgical therapies for epilepsy, and difficulties recruiting patients to clinical trials all contribute to this multifaceted dilemma.

Cost-Effectiveness of Advanced Imaging Technologies in the Presurgical Workup of Epilepsy

The cost-effectiveness and benefit of many diagnostic tests used in the presurgical evaluation for persons with epilepsy is for the most part uncertain as is their influence on decision-making. The options we have at our disposal are ever increasing. Advanced imaging modalities aim to improve surgical candidacy by helping us better define the epileptogenic zone and optimize surgical planning. However, judicious use is important. Randomized controlled trials delineating which mode of investigation is superior are lacking. Presurgical tests do have incremental value by increasing surgical candidacy and refining surgical planning. The yield of additional imaging will increase with complex localization. However, every case must be tailored by hypothesis, cost, and accessibility. Future studies using a quantitative cost–benefit framework are needed to determine the cost-effectiveness of advanced diagnostic tests (beyond magnetic resonance imaging) in the presurgical evaluation of those with epilepsy.

Early economic evaluation of MRI-guided laser interstitial thermal therapy (MRgLITT) and epilepsy surgery for mesial temporal lobe epilepsy

Background

MRI-guided laser interstitial thermal therapy (MRgLITT) is a new minimally invasive treatment for temporal lobe epilepsy (TLE), with limited effectiveness data. It is unknown if the cost savings associated with shorter hospitalization could offset the high equipment cost of MRgLITT. We examined the cost-utility of MRgLITT versus surgery for TLE from healthcare payer perspective, and the value of additional research to inform policy decision on MRgLITT.

Methods

We developed a microsimulation model to evaluate quality adjusted life years (QALYs), costs, and incremental cost-effectiveness ratio (ICER) of MRgLITT versus surgery in TLE, assuming life-time horizon and 1.5% discount rate. Model inputs were derived from the literature. We conducted threshold and sensitivity analyses to examine parameter uncertainties, and expected value of partial perfect information analyses to evaluate the expected monetary benefit of eliminating uncertainty on probabilities associated with MRgLITT.

Results

MRgLITT yielded 0.08 more QALYs and cost $7,821 higher than surgery, with ICER of $94,350/QALY. Influential parameters that could change model outcomes include probabilities of becoming seizure-free from disabling seizures state and returning to disabling seizures from seizure-free state 5 years after surgery and MRgLITT, cost of MRgLITT disposable equipment, and utilities of disabling seizures and seizure-free states of surgery and MRgLITT. The cost-effectiveness acceptability curve showed surgery was preferred in more than 50% of iterations. The expected monetary benefit of eliminating uncertainty for probabilities associated with MRgLITT was higher than for utilities associated with MRgLITT.

Conclusions

MRgLITT resulted in more QALYs gained and higher costs compared to surgery in the base-case. The model was sensitive to variations in the cost of MRgLITT disposable equipment. There is value in conducting more research to reduce uncertainty on the probabilities and utilities of MRgLITT, but priority should be given to research focusing on improving the precision of estimates on effectiveness of MRgLITT.

Refractory seizures: Prediction of outcome of surgical intervention based on results from PET-CT, PET-MRI and electroencephaolography

PURPOSE

The purpose of this article is to evaluate the effectiveness of fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) and PET-magnetic resonance imaging (MRI) with scalp and intracranial electroencephalogram (EEG) in predicting surgical outcomes in patients with refractory seizures.

METHODS

Patients who underwent PET-CT and MRI fusion, scalp and intracranial EEG, and subsequent surgical intervention were retrospectively included. PET-CT were fused with MRI and interpreted by an experienced blinded reader. An area of hypometabolism on PET was identified as the location of the epileptic focus. The site of seizure focus was correlated with scalp and intracranial EEG findings. Surgical outcomes were evaluated. Thirty-six patients were included; all had presurgical PET-CT, scalp EEG, and PET-MRI fusion, and 28 of these patients had intracranial EEGs.

RESULTS

PET-CT showed concordance of epileptic foci with scalp EEG in 7/36 patients (19%) and with intracranial EEG in 9/28 patients (32%). PET-MRI was concordant with scalp EEG in 6/36 patients (17%) and with intracranial EEG in 8/28 patients (29%). All patients with concordance of epileptic foci between PET-CT and PET-MRI and scalp EEG had improvement or resolution of seizures postintervention, and 89% of patients had concordance between intracranial EEG and PET studies. However, 45% of patients with discordant PET-CT and scalp EEG, 37% with discordance PET-CT and intracranial EEG, 43% with discordant PET-MRI and scalp EEG, and 35% of patients with discordant PET-MRI and intracranial EEG did not improve postsurgically.

CONCLUSION

Concordance of epileptic foci localization between PET imaging and EEG yields favorable postoperative outcome in nearly all patients, whereas discordance has an equal probability of favorable vs unfavorable outcomes.

Cost-utility analysis of magnetoencephalography used to inform intracranial electrode placement in patients with drug resistant epilepsy: a model based analysis

OBJECTIVES

We estimated the cost-effectiveness of adding magnetoencephalography to a standard assessment for epilepsy surgery consisting of neuropsychology, magnetic resonance imagining, scalp electroencephalography, video electroencephalography and intracranial electroencephalography, in the capacity of informing intracranial electroencephalography electrode placement.

METHODS

We used Microsoft Excel (2007) to construct a decision model. Discounted costs and quality adjusted life years are aggregated to calculate incremental cost-effectiveness ratios. Sensitivity analyses are conducted to assess robustness of findings.

RESULTS

Our base case analysis yielded a result of $14 300 per quality adjusted life year gained. A total of 82.7% of probabilistic sensitivity analysis iterations resulted in incremental cost-effectiveness ratios below $100 000 in 2014 Canadian dollars.

CONCLUSIONS

Our findings demonstrate that the inclusion of Magnetoencephalography in the assessment for epilepsy surgery in the capacity of informing intracranial electroencephalography electrode placement is likely not cost saving but does represent a reasonable allocation of resources from a value for money perspective.