Epilepsy is associated with higher subsequent mortality risk in patients after stroke: a population-based cohort study in Taiwan

Pathophysiology, Diagnosis, Prognosis, and Prevention of Poststroke Epilepsy: Clinical and Research Implications

Poststroke epilepsy (PSE) is associated with higher mortality and poor functional and cognitive outcomes in patients with stroke. With the remarkable development of acute stroke treatment, there is a growing number of survivors with PSE. Although approximately 10% of patients with stroke develop PSE, given the significant burden of stroke worldwide, PSE is a significant problem in stroke survivors. Therefore, the attention of health policymakers and significant funding are required to promote PSE prevention research. The current PSE definition includes unprovoked seizures occurring more than 7 days after stroke onset, given the high recurrence risks of seizures. However, the pathologic cascade of stroke is not uniform, indicating the need for a tissue-based approach rather than a time-based one to distinguish early seizures from late seizures. EEG is a commonly used tool in the diagnostic work-up of PSE. EEG findings during the acute phase of stroke can potentially stratify the risk of subsequent seizures and predict the development of poststroke epileptogenesis. Recent reports suggest that cortical superficial siderosis, which may be involved in epileptogenesis, is a promising marker for PSE. By incorporating such markers, future risk-scoring models could guide treatment strategies, particularly for the primary prophylaxis of PSE. To date, drugs that prevent poststroke epileptogenesis are lacking. The primary challenge involves the substantial cost burden due to the difficulty of reliably enrolling patients who develop PSE. There is, therefore, a critical need to determine reliable biomarkers for PSE. The goal is to be able to use them for trial enrichment and as a surrogate outcome measure for epileptogenesis. Moreover, seizure prophylaxis is essential to prevent functional and cognitive decline in stroke survivors. Further elucidation of factors that contribute to poststroke epileptogenesis is eagerly awaited. Meanwhile, the regimen of antiseizure medications should be based on individual cardiovascular risk, psychosomatic comorbidities, and concomitant medications. This review summarizes the current understanding of poststroke epileptogenesis, its risks, prognostic models, prophylaxis, and strategies for secondary prevention of seizures and suggests strategies to advance research on PSE.

Polygenic Risk of Epilepsy and Post-Stroke Epilepsy

Background and Aims

Epilepsy is highly heritable, with numerous known genetic risk loci. However, the genetic predisposition's role in post-acute brain injury epilepsy remains understudied. This study assesses whether a higher genetic predisposition to epilepsy raises post-stroke or Transient Ischemic Attack (TIA) survivor's risk of Post-Stroke Epilepsy (PSE).

Methods

We conducted a three-stage genetic analysis. First, we identified independent epilepsy-associated ( p <5x10 -8 ) genetic variants from public data. Second, we estimated PSE-specific variant weights in stroke/TIA survivors from the UK Biobank. Third, we tested for an association between a polygenic risk score (PRS) and PSE risk in stroke/TIA survivors from the All of Us Research Program. Primary analysis included all ancestries, while a secondary analysis was restricted to European ancestry only. A sensitivity analysis excluded TIA survivors. Association testing was conducted via multivariable logistic regression, adjusting for age, sex, and genetic ancestry.

Results

Among 19,708 UK Biobank participants with stroke/TIA, 805 (4.1%) developed PSE. Likewise, among 12,251 All of Us participants with stroke/TIA, 394 (3.2%) developed PSE. After establishing PSE-specific weights for 39 epilepsy-linked genetic variants in the UK Biobank, the resultant PRS was associated with elevated odds of PSE development in All of Us (OR:1.16[1.02-1.32]). A similar result was obtained when restricting to participants of European ancestry (OR:1.23[1.02-1.49]) and when excluding participants with a TIA history (OR:1.18[1.02-1.38]).

Conclusions

Our findings suggest that akin to other forms of epilepsy, genetic predisposition plays an essential role in PSE. Because the PSE data were sparse, our results should be interpreted cautiously.

External validation and comparison of clinical scores for predicting late seizures after intracerebral hemorrhage in Chinese patients

PURPOSE

Clinical scores have been established to predict the probability of late seizures following intracerebral hemorrhage (ICH) for individual patients, including the CAVE, CAVS and LANE scores. The purpose of this study was to compare these prediction scores in the Chinese population and undertake an independent external validation on them.

METHODS

At one tertiary hospital in China, we retrospectively recruited consecutive inpatients who had been diagnosed with ICH. Medical records and tele interviews with a modified standardized questionnaire were used to identify late seizures. All the predictors of the prediction scores were collected from patient charts and databases by a standardized data collection protocol. The external validation of the prediction scores was quantified by the area under the curve (AUC), sensitivity, specificity, Youden index (YI), positive predictive value (PPV), and negative predictive value (NPV).

RESULTS

69 (5.4%) of 1276 patients experienced late seizures after ICH. There was no significant difference in the CAVE, CAVS, and LANE scores, which had AUCs of 0.75 (95% CI = 0.70-0.81), 0.74 (95% CI = 0.68-0.80), and 0.76 (95% CI = 0.70-0.82), respectively. At the optimal cutoff score, the LANE score had a lower sensitivity but a higher specificity than the CAVE and CAVS scores. Among the three prediction scores, the LANE score had a higher PPV than the others (0.145 vs. 0.088, 0.083), while the NPV was similar among the three prediction scores (0.989, 0.989, and 0.972).

CONCLUSION

Our study showed that the CAVE, CAVS and LANE scores had similar AUCs for the occurrence of late seizures, but the LANE score had a relatively high PPV at the optimal cutoff score. Due to low evidence for using prophylactic antiseizure medications (ASM) in patients with ICH and poor availability of specialist stroke care in China, the LANE score with a cutoff score of 3 could be an applicable prediction tool in Chinese patients with ICH.

Post-stroke epilepsy and risk of all-cause mortality: A systematic review and meta-analysis of cohort studies

OBJECTIVE

Post-stroke epilepsy (PSE) has been suggested as a predictor of poor prognosis. We aimed to evaluate the association between PSE and all-cause mortality via a meta-analysis.

METHODS

Relevant cohort studies were identified by search of electronic databases including PubMed, Embase, and Web of Science. Two authors independently performed database search, data collection, and study quality evaluation. A randomized-effect model incorporating the possible between-study heterogeneity was used to pool the results.

RESULTS

Overall, ten cohort studies including 177,929 patients with stroke contributed to the meta-analysis. Of them, 15,836 (8.9%) had PSE during a mean follow-up of 4 years. Compared to stroke survivors without PSE, patients with PSE had a significantly increased risk of all-cause death (odds ratio [OR]: 1.68, 95% confidence interval: 1.51-1.87, p < 0.001; I² = 80%). Subgroup analyses showed consistent association in patients with ischemic and hemorrhagic stroke, in prospective and retrospective studies, in PSE diagnosed as unprovoked seizure occurred more than 7 days and 14 days after stroke, in studies with follow-up durations within or over 5 years, and in studies with different quality scores (p for subgroup effect all < 0.05). The Galbraith plot identified three outlier studies which may contribute to the heterogeneity of the meta-analysis, and all of the three studies were database-linked studies. The between-study heterogeneity was significantly reduced after removing the three database-linked studies (OR: 1.39, 95% CI: 1.18-1.62, p < 0.001; I² = 0%).

CONCLUSION

PSE was associated with a higher risk of all-cause mortality.

Effects of long-term anti-seizure medication monotherapy on all-cause death in patients with post-stroke epilepsy: a nationwide population-based study in Taiwan

OBJECTIVE

We aim to compare the effect of long-term anti-seizure medication (ASM) monotherapy on the risk of death and new ischemic stroke in patients with post-stroke epilepsy (PSE).

PATIENTS AND METHODS

We identified all hospitalized patients (≥ 20 years) with a primary diagnosis of ischemic or hemorrhagic stroke from 2001 to 2012 using the National Health Insurance Research Database in Taiwan. The PSE cohort were defined as the stroke patients (1) who had no epilepsy and no ASMs use before the index stroke, and (2) who had epilepsy and ASMs use after 14 days from the stroke onset. The patients with PSE receiving ASM monotherapy were enrolled and were categorized into phenytoin, valproic acid, carbamazepine, and new ASM groups. We employed the Cox regression model to estimate the unadjusted and adjusted hazard ratios (HRs) with 95 % confidence intervals (CIs) of death and new ischemic stroke within 5 years across all groups, using the new ASM group as the reference.

RESULTS

Of 6962 patients with PSE using ASM monotherapy, 3917 (56 %) were on phenytoin, 1623 (23 %) on valproic acid, 457 (7 %) on carbamazepine, and 965 (14 %) on new ASMs. After adjusting for confounders, compared with new ASM users, phenytoin users had a higher risk of death in 5 years (HR: 1.64; 95 % CI: 1.06-2.55). On the other hand, all ASM groups showed a similar risk of new ischemic stroke in 5 years.

CONCLUSIONS

Among patients with PSE on first-line monotherapy, compared to new ASMs, use of phenytoin was associated with a higher risk of death in 5 years.

Gout and the risk of epilepsy: A population-based cohort study

Gout is a chronic disease related to uric acid metabolism. It involves crystals of uric acid accumulating in the joints, causing joint pain and releasing cytokines that trigger inflammation. Inflammation is a key component in the pathogenesis of epilepsy. Thus, we conducted a cohort study to investigate if epilepsy is associated with gout and determine the risk of epilepsy in patients with gout.The gout cohort was obtained from the Registry of Catastrophic Illnesses Patient Database (RCIPD). We identified 104,238 patients who were aged 20 years or more and newly diagnosed with gout between 2000 and 2011 and 3 outpatient visits or history of gout-specific hospitalization between 2000 and 2011. Patients without gout were frequency matched with the gout cohort at a 2:1 ratio according to age, sex, comorbidities, and year of gout diagnosis.The gout cohort showed a 1.27-fold higher overall crude hazard ratio (HR) for epilepsy compared with the control cohort. After we adjusted the analyses by age, sex, and comorbidities the gout patients displayed an increased risk of epilepsy compared with the control group (adjusted HR = 1.25, 95% confidence interval = 1.15-1.36).This study revealed a significantly higher risk of epilepsy in patients with gout. It provides further evidence for the debate around the effect of gout on brain health.

Subsequent Development of Epithelial Ovarian Cancer After Ovarian Surgery for Benign Ovarian Tumor: A Population-Based Cohort Study

Purpose

The goal of the current study is to determine the risk of subsequent development of epithelial ovarian cancer (EOC) in women after ovarian surgery for benign ovarian tumors.

Patients and Methods

We conducted the nationwide population-based historic cohort study using the National Health Insurance Research Database (NHIRD) of Taiwan. Eleven thousand six hundred twenty women who underwent ovarian surgery for ovarian benign diseases were analyzed. The collected data included age, types of ovarian surgery, medical history by Charlson comorbidity index (CCI), infertility (yes/no), pelvic inflammatory disease (PID) (yes/no), tubal ligation (yes/no), total/subtotal hysterectomy (TH/STH) (yes/no), and endometrioma (yes/no). We used the Kaplan-Meier method and the Log-rank test to evaluate the risk factors. Cox proportional hazard methods were used to evaluate risk factors for the subsequent development of EOC. Multivariate analysis using Cox stepwise forward regression was conducted for the covariate selected in univariate analysis. Hazard ratio (HR) and 95% confidence interval (CI) were calculated using the Wald test.

Results

Subsequent EOC incidence rate (IR, incidence per 10,000 person-years) of women after ovarian surgery for benign ovarian tumors was 2.98. Separating into four groups based on different age, IR of EOC was 1.57 (<30 years), 4.71 (30-39 years), 3.59 (40-49 years) and 0.94 (≥50 years), respectively. Univariate and multivariate analyses identified only high level of CCI (≥2 or more) as an independent risk factor for subsequent development of EOC in women after ovarian surgery for benign ovarian tumors (HR 59.17, 95% CI 7.50-466.80 in women with CCI level of 2 and HR 190.68, 95% CI 24.33-2494.19, in women with CCI level ≥3, respectively).

Conclusion

Our results, if confirmed, suggest that women with other comorbidities (CCI) should be well informed that they may have a higher risk of subsequent development of EOC when ovarian surgery is planned even though the final pathology showed a benign ovarian tumor.