Antiseizure medication withdrawal risk estimation and recommendations: a survey of American Academy of Neurology and EpiCARE members
Authors: Terman Samuel W , van Griethuysen Renate , Rheaume Carole E , Slinger Geertruida , Haque Anisa S , Smith Shawna N , Kerr Wesley T , van Asch Charlotte , Otte Willem M , Ferreira-Atuesta Carolina , Galovic Marian , Burke James F , Braun Kees PJ 
Published: November 2022

Background

Choosing candidates for antiseizure medication (ASM) withdrawal in well- controlled epilepsy is challenging. We evaluated 1) the correlation between neurologists’ seizure risk estimation (“clinician predictions”) versus calculated predictions, 2) how viewing calculated predictions influenced recommendations, and 3) barriers to using risk calculation.

Methods

We asked neurologists to predict two-year seizure risk after ASM withdrawal for hypothetical vignettes. We compared withdrawal recommendations ASMs before versus after viewing calculated predictions using generalized linear models.

Results

Three-hundred forty-six responded. There was moderate correlation between clinician and calculated predictions (Spearman coefficient 0.42). Clinician predictions varied widely, e.g., predictions ranged 5%-100% for a two-year seizure-free adult without epileptiform abnormalities. Mean clinician predictions exceeded calculated predictions for vignettes with epileptiform abnormalities (e.g., childhood absence epilepsy: clinician 65%, 95% confidence interval [CI] 57%-74%; calculated 46%) and surgical vignettes (e.g., focal cortical dysplasia six-months seizure-free mean clinician 56%, 95% CI 52%-60%; calculated 28%). Clinicians overestimated the influence of epileptiform EEG findings on withdrawal risk (26%, 95% CI 24%-28%) compared with calculators (14%, 95% 13%-14%). Viewing calculated predictions slightly reduced willingness to withdraw (−0.8/10 change, 95% CI -1.0 to -0.7), particularly without epileptiform abnormalities. The greatest barrier to calculator use was doubting its accuracy (44%).

Conclusions

Clinicians overestimated the influence of abnormal EEGs particularly for low-risk patients and overestimated risk and the influence of seizure-free duration for surgical patients, compared with calculators. These data may question widespread ordering of EEGs or time-based seizure-free thresholds for surgical patients. Viewing calculated predictions reduced willingness to withdraw particularly without epileptiform abnormalities.

What is already known on this topic

For the two-thirds of patients with epilepsy who become seizure-free on antiseizure medications (ASMs), a key question is whether ASMs are necessary indefinitely after attaining seizure-freedom. An individualized post-withdrawal seizure risk calculator exists,[1,2] which has demonstrated moderate external validity, and one 1993 study suggested that viewing results from an older version of such a calculator slightly reduced patients’ willingness to withdraw.

What this study adds

Before our study, it was unknown how closely clinicians’ intuitive estimates of post-withdrawal seizure risk (“clinician predictions”) align with model (“calculated”) predictions, and no study had previously evaluated the influence of viewing calculated risk on clinician recommendations. We found 1) moderate correlation between clinician and calculated predictions (Spearman coefficient 0.42), 2) clinician predictions and recommendations varied widely, 3) clinicians tended to overestimate risk compared with calculators for vignettes with epileptiform abnormalities and surgical cases, 4) viewing calculated predictions slightly reduced willingness to withdraw particularly without epileptiform abnormalities, and 5) the greatest endorsed barrier to calculator use was doubting its accuracy.

How this study might affect research, practice or policy

Our study suggests patient scenarios in which viewing calculator results may be most useful or be most likely to change clinical practice. These data may also question widespread ordering of EEGs or time-based seizure-free thresholds for surgical patients given calculated risk differences were smaller than clinician predictions. We also provide preliminary data guiding future work to improve calculator implementation such as targeting educational efforts to improve knowledge of its development, improving its accuracy, and integrating it into the electronic medical record.