Nonadherence to antiepileptic drugs and increased mortality: findings from the RANSOM Study

OBJECTIVES

The primary objective was to investigate whether nonadherence to antiepileptic drugs (AEDs) is associated with increased mortality and the secondary objective to examine whether nonadherence increases the risk of serious clinical events, including emergency department (ED) visits, hospitalizations, motor vehicle accident (MVA) injuries, fractures, and head injuries.

METHODS

A retrospective open-cohort design was employed using Medicaid claims data from Florida, Iowa, and New Jersey from January 1997 through June 2006. Patients aged > or =18 years with > or =1 diagnosis of epilepsy by a neurologist and > or =2 AED pharmacy dispensings were selected. Medication possession ratio (MPR) was used to evaluate AED adherence on a quarterly basis with MPR > or =0.80 considered adherent and <0.80 nonadherent. The association of nonadherence with mortality was assessed using a time-varying Cox regression model adjusting for demographic and clinical confounders. Incidence rates for serious clinical events were compared between adherent and nonadherent quarters using incidence rate ratios (IRRs) with 95% CIs calculated based on the Poisson distribution.

RESULTS

The 33,658 study patients contributed 388,564 AED-treated quarters (26% nonadherent). Nonadherence was associated with an over threefold increased risk of mortality compared to adherence (hazard ratio = 3.32, 95% CI = 3.11-3.54) after multivariate adjustments. Time periods of nonadherence were also associated with a significantly higher incidence of ED visits (IRR = 1.50, 95% CI = 1.49-1.52), hospital admissions (IRR = 1.86, 95% CI = 1.84-1.88), MVA injuries (IRR = 2.08, 95% CI = 1.81-2.39), and fractures (IRR = 1.21, 95% CI = 1.18-1.23) than periods of adherence.

CONCLUSION

These findings suggest that nonadherence to antiepileptic drugs can have serious or fatal consequences for patients with epilepsy.

Monotherapy in adults and elderly persons

Treatment of epilepsy with a single drug has many advantages. Potential benefits of monotherapy vs polytherapy include fewer adverse events and better tolerability, avoidance of drug-drug interactions, reduced treatment costs, and improved compliance. Initial treatment should always be monotherapy. Avoidance of pharmacokinetic interactions is a major advantage. Some patients who have achieved seizure control with polytherapy may be candidates for conversion to monotherapy because there is no conclusive evidence that polytherapy provides better seizure control in the majority of patients. Recently published treatment guidelines that take into account the efficacy and tolerability profiles of new and old antiepileptic drugs (AEDs) provide recommendations for drug selection in adults. Elderly patients with epilepsy face unique treatment challenges, which include age-related reductions in liver or kidney function that may alter drug pharmacokinetics. Older persons are more sensitive to CNS side effects; some drugs may exacerbate preexisting problems such as tremor, ataxia, and cognitive difficulty. Many common conditions in the elderly are treated with drugs that are subject to interactions with AEDs. Complex dosing schedules and high drug costs are often barriers to proper care. For all these reasons, monotherapy is especially attractive for the elderly.

Topiramate in the treatment of partial and generalized epilepsy

Topiramate (TPM) is a widely-used drug for the treatment of epilepsy. It is useful for several types of partial-onset and generalized-onset seizures, and is therefore considered a broad-spectrum agent. It is also effective as a prophylactic against migraine headaches. TPM was first approved for prescription use in 1996. In various countries it is now approved for adjunctive and monotherapy of partial-onset seizures and for therapy of generalized tonic-clonic seizures of nonfocal origin, for children and adults. For initial monotherapy of new-onset seizures, a target dose of 100 mg/day for adults is recommended. Adjunctive use with enzyme-inducing drugs and use for refractory seizures requires higher dosages, though the optimum dose for most patients does not exceed 400 mg/day. Excretion is primarily renal and TPM is not a significant hepatic enzyme inducer. Although it is usually safe and well-tolerated, adverse effects limit use in about 25% of patients. The most salient of these is cognitive dysfunction, especially problems with expressive speech and verbal memory. Weight loss, renal stones, paresthesias and other central nervous system side effects may occur. Tolerability is improved by low initial doses and slow titration to effect.

Valproate protein binding following rapid intravenous administration of high doses of valproic acid in patients with epilepsy

OBJECTIVE

To characterize protein binding in patients with epilepsy who achieve transient high (>150 mg/L) total plasma concentrations following rapid valproate infusion at very high doses.

METHODS

Patients with epilepsy (n = 40) were administered 20 or 30 mg/kg loading doses (6 or 10 mg/kg/min) of undiluted valproate sodium injection. Total and unbound valproic acid (VPA) concentrations were used to assess VPA binding to plasma albumin. One- and two-binding site models were explored in a nonlinear mixed effects population analysis framework. The relative importance of weight, age, sex, race and enzyme-inducing comedications on the binding site association constant (K) was examined using the likelihood ratio test. Intersubject and intrasubject variabilities were characterized using exponential or proportional error models.

RESULTS

Optimal characterization of the data was achieved using the one-binding site model. Population binding parameter estimates (standard error) for number of binding sites (N) and K were 1.98 (0.0865) and 15.5 [2.28 (1/mM)], respectively. No significant covariates were identified for VPA protein binding. The intersubject and intrasubject coefficients of variation were 32% and 14%, respectively.

CONCLUSIONS

A one-binding site model without any significant covariates for binding constants optimally described VPA protein binding. As the estimated dissociation constant (1/K, 64.5 microm or 9.3 mg/L) was within the therapeutic range (5-15 mg/L) for unbound VPA concentrations, protein binding was nonlinear. Although the range of unbound fraction and VPA concentrations were much higher than previous studies, the dissociation constant was consistent with historical data in normal healthy adults and epilepsy patients receiving lower doses.

Safety of rapid intravenous loading of valproate

BACKGROUND

The introduction of IV valproic acid (VPA) has facilitated its use in situations where oral administration is not feasible. The present study was designed to evaluate the safety of administration of undiluted VPA (20 or 30 mg/kg/min) administered intravenously at rates of 6 or 10 mg/kg/min.

METHODS

Forty patients received a VPA loading dose (20 or 30 mg/kg) at 6 or 10 mg/kg/min. Heart rate (HR), mean arterial pressure (MAP), oxygen saturation, respiratory rate, and three lead ECG measurements were taken at baseline. Following dose administration the measurements were repeated at 2.5-min intervals for the first 20 min, then at 30, 45, 60 min, and 4 h. Local tolerance was defined as absence of irritation or phlebitis at the site of injection. Systemic tolerability was defined as absence of significant changes in vital signs and level of consciousness (LOC). Changes in vital signs and local intolerance scores were compared across time using repeated measures analysis of variance.

RESULTS

Rapid administration was well tolerated with no significant changes in HR (p=0.9) or MAP (p=0.7). Complaints of local irritation were transient, lasting less than 3 min in all patients with no indication of redness, irritation, or phlebitis. No patient exhibited a decline in the LOC.

CONCLUSIONS

Rapid administration of undiluted valproate is safe and well tolerated at infusion rate up to 10 mg/kg/min and doses of up to 30 mg/kg. The lack of serious cardiovascular, neurological, hepatic, or local adverse effects supports the use of VPA in emergent situations.

Medical decision-making abilities in older adults with chronic partial epilepsy

Little is known about the medical decision-making abilities of older adults with chronic partial epilepsy, although these patients are often faced with medical decisions that impact their health care. Twenty-one older adults with epilepsy and 21 healthy older adults completed the Capacity to Consent to Treatment Instrument (CCTI) and Dementia Rating Scale II (DRS-II). Older adults with epilepsy performed significantly below controls on the CCTI standards Evidencing Choice, Appreciation, and Understanding and the DRS-II Total Score. DRS-II was positively associated with performance on the standards Appreciation and Understanding. Number of antiepileptic drugs, duration of epilepsy, and age at seizure onset were related to performance on Understanding. Older adults with epilepsy demonstrated deficits in their capacity to give informed consent for medical treatment that appear to be associated with cognition and seizure variables. Physicians should consider the decisional abilities of their older adult patients with epilepsy when presenting treatment options.

Felbamate: Consensus of current clinical experience

An expert panel convened to evaluate data and review current clinical practices regarding the novel antiepileptic drug (AED) felbamate. Felbamate has demonstrated efficacy against a variety of refractory seizures types, including seizures associated with Lennox-Gastaut syndrome, but postmarketing experience revealed serious idiosyncratic adverse effects that were not observed during clinical trials. Although felbamate is not indicated as first-line antiepileptic therapy, its utility in treating seizures that are refractory to other AEDs is undisputed, as shown by the number of patients who continue to use it. New exposures to felbamate number approximately 3200-4200 patients annually, and it is estimated that over the past 10 years, approximately 35,000 new starts have occurred. Recommendations by the American Academy of Neurology and a review of felbamate literature were evaluated in conjunction with the clinical experience of the expert panel to determine current medical opinion and practice regarding felbamate. The past 10 years of clinical experience have demonstrated that when used in accordance with existing recommendations and close clinical monitoring, felbamate is an effective treatment for some patients with seizures refractory to other AEDs. This review of clinical data and discussion of the current understanding of the risk:benefit of felbamate therapy supports its use as an important therapeutic option for some patients with refractory epilepsy.

Race/ethnicity, sex, and socioeconomic status as predictors of outcome after surgery for temporal lobe epilepsy

BACKGROUND

Several risk factors have been attributed to seizure recurrence after surgery. It is unknown whether race/ethnicity plays a role in outcome.

OBJECTIVE

To evaluate whether race/ethnicity plays a role in seizure recurrence after surgery.

DESIGN

Cohort study.

SETTING

We evaluated data obtained from the epilepsy centers at the University of Alabama at Birmingham and New York University, New York, NY.

PATIENTS

All patients included had a diagnosis of mesial temporal sclerosis and underwent temporal lobectomy.

MAIN OUTCOME MEASURES

Occurrence of seizure after surgery was registered 1 year after surgery. We used multiple logistic regression analysis to model the presence of seizure recurrence after surgery and generated odds ratios (ORs) for seizure recurrence after surgery for African American and Hispanic patients relative to white patients. An unadjusted model incorporated only race/ethnicity as the independent variable, and an adjusted model included socioeconomic status, age, duration of epilepsy, education, history of febrile seizures, sex, handedness, lateralization of epileptogenic focus, and number of antiepileptics as the independent variables.

RESULTS

Two hundred fifty-two patients underwent surgical treatment with pathological confirmation of mesial temporal sclerosis. No differences were found between racial/ethnic groups in terms of seizure recurrence in any models. For African American patients, the ORs were 0.9 (95% confidence interval [CI], 0.4-2.1) for the unadjusted model and 0.8 (95% CI, 0.3-2.0) for the adjusted model; for Hispanic patients, the ORs were 1.6 (95% CI, 0.8-3.2) for the unadjusted model and 1.1 (95% CI, 0.5-2.6) for the adjusted model, relative to white patients.

CONCLUSION

Our data suggest that although sex appears to play a role in the outcomes of surgery for temporal lobe epilepsy, race and socioeconomic status do not.

Epilepsy Case Studies

Epilepsy is a common disorder affecting all age groups. Diagnosis depends on accurate eyewitness description and electroencephalography. Many genetic, metabolic, and structural perturbations of cortical function can cause seizures. MRI is the most important test for etiology. Medication selection is based on classification of seizure type and epilepsy syndrome, with consideration of patient age, gender, and comorbidities. Surgery is a good treatment for some patients who have medically refractory partial-onset seizures.

Global/local scoring modifications for the Rey-Osterrieth Complex Figure: relation to unilateral temporal lobe epilepsy patients

Observation of figural reproductions of right temporal lobe epilepsy (RTLE) patients have revealed overall configuration errors, whereas in left temporal lobe epilepsy (LTLE) patients, the global aspect of performance is generally preserved. This study compared performance of individuals with temporal lobe epilepsy (LTLE, n=83; RTLE, n=63) on a global/local modification of the Rey-Osterrieth Complex Figure Test (RCFT). In Phase I, neuropsychologists (n=6) and neuropsychology fellows (n=3) completed a survey identifying the global and local aspects of the RCFT. Questionnaire responses were used to categorize a list of global and local items (five global, five local) for re-scoring the protocols of TLE patients during study Phase II. Results showed that the RTLE and LTLE groups were not differentiated according to the global or local indices F(1,141) = .385; p = not significant. There were lower local scores for both groups in the copy F(1,142) = 5.23; p = .024, immediate F(1,142) = 445.26; p < .001, and delay trials F(1,142) = 427.82; p < .001, indicating less retention of local information over time. Results suggest general declines in figural memory for local stimulus properties in both unilateral TLE groups. However, this relationship was weakened after controlling for global and local item verbalizability.

Magnetic source imaging versus intracranial electroencephalogram in epilepsy surgery: A prospective study

OBJECTIVE

Noninvasive brain imaging tests can potentially supplement or even replace the use of intracranial electroencephalogram (ICEEG), an invasive, costly procedure used in presurgical epilepsy evaluation. This study prospectively examined the agreement between magnetic source imaging (MSI) and ICEEG localization in epilepsy surgery candidates.

METHODS

Patients completing video monitoring with scalp EEG who had intractable partial epilepsy based on ictal electro-clinico-anatomical features were screened. Forty-nine enrolled patients (mean age, 27 years; range, 1-61 years) completed MSI and ICEEG studies. Decisions about ICEEG and surgery were made at a consensus conference where MSI could only influence ICEEG coverage by indicating supplemental coverage to that already planned by an original hypothesis.

RESULTS

The positive predictive value of MSI for seizure localization was 82 to 90%, depending on whether computed against ICEEG alone or in combination with surgical outcome. The kappa score of agreement for MSI with ICEEG was 0.2744 (p < 0.01)

INTERPRETATION

MSI yields localizing information with a high positive predictive value in epilepsy surgery candidates who typically require ICEEG. This finding suggests that enough clinical validity exists for MSI to potentially replace ICEEG for seizure localization.

Step therapy is not appropriate for antiepileptic drugs

We read with interest the article by Payakachat and colleagues, comparing the clinical practice guidelines for treatment of new-onset epilepsy in adults.1 While we appreciate their efforts to provide a careful review of available treatment guidelines and consideration of how these guidelines might be applied in managed care, we strongly disagree with their conclusion that older agents (i.e., phenobarbital, carbamazepine, phenytoin, and valproate) are the preferred first-line treatments for new-onset epilepsy. Their conclusions appear to be based upon a rather narrow consideration that only accounts for efficacy in controlling seizures. As the authors correctly note, broader data on the effectiveness, outcomes, tolerability, and quality of life are lacking in the published literature. However, the authors underemphasize important aspects of epilepsy as a disorder and characteristics of antiepileptic drugs that must be a part of therapeutic and formulary decision making. Indeed, the guidelines that are included in the article make specific statements about drug selection in epilepsy contrary to the conclusion of Payakachat et.al. The following are important factors, essential to therapeutic decisions in new-onset epilepsy, that had they been included would probably have led to a different conclusion.

Determining empirically based self-reported cognitive change: development of reliable change indices and standardized regression-based change norms for the multiple abilities self-report questionnaire in an epilepsy sample

PURPOSE

Reliable change indices (RCIs) and standardized regression-based (SRB) change score norms were calculated for a measure of self-reported cognitive function, the Multiple Abilities Self-Report Questionnaire (MASQ), in patients with complex partial seizures. Establishment of such standardized change scores could be useful in determining the magnitude and direction of self-appraised cognitive change after epilepsy surgery or other treatment interventions. The primary study objective was to calculate RCI and SRB values for the MASQ. A secondary objective was to report SRB change scores in patients who had undergone anterior temporal lobectomy (ATL) and to assess relationships between self-reported cognitive change, seizure outcome, objective memory test performance, and mood.

METHODS

The MASQ was administered to 36 patients with complex partial seizures on two occasions (mean test-retest interval, 6 months). This group did not have major psychopathology and were on stable antiepileptic drugs. RCI and SRB change scores were calculated. Adjustments for baseline ratings, age, education, gender, age at seizure onset, and seizure duration were made with the SRB method. A confidence interval cutoff score (90% level) was calculated for the five MASQ cognitive domains (Language, Visual Perception, Verbal Memory, Visual-Spatial Memory, Attention/Concentration). MASQ SRB scores were computed for a second sample of 50 patients who had undergone ATL.

RESULTS

Test-retest reliabilities for the MASQ domains ranged from a low of 0.63 (Attention/Concentration) to a high of 0.87 (total score). Baseline MASQ score was the single largest contributor to the regression equations. Left and right ATL groups demonstrated similar magnitudes of self-reported cognitive change across all five MASQ domains. Individual base rate change distributions were similar across four of the five domains. with a higher proportion of right ATL patients reporting worsening attention function. Both postoperative mood and SRB-based verbal memory outcome were significantly correlated to self-reported cognitive change in the patients who had undergone ATL.

CONCLUSIONS

SRB methodology provides a standardized technique with which to establish patient perception of cognitive change and may be of use when examining change across individual- and group-level ratings of cognitive functioning in clinical and research settings. These techniques also provide a common metric for direct comparison between subjective self-report ratings of cognitive function and objective cognitive test instruments.

Older adults with epilepsy demonstrate cognitive impairments compared with patients with amnestic mild cognitive impairment

Little is known about the cognitive effects of chronic epilepsy in older adults. To better characterize cognitive impairment in seniors with epilepsy, we compared cognitive performance of 26 seniors with epilepsy with that of 26 well-matched patients with mild cognitive impairment (MCI) and 26 well-matched healthy older adults. Participants completed neuropsychological testing with the Dementia Rating Scale (DRS), Logical Memory, and CFL Word Fluency. There were no significant demographic group differences, although seniors with epilepsy had higher self-reported depression. Seniors with epilepsy performed below controls on virtually all neuropsychological tests, and performed below patients with MCI on DRS Total score, Initiation/Perseveration, and CFL Fluency. Seniors with epilepsy on antiepileptic drug (AED) polytherapy had the most severe cognitive deficits, whereas seniors with epilepsy on AED monotherapy were comparable to cholinesterase inhibitor-naïve patients with MCI. This study emphasizes the clinical importance of cognitive impairment in seniors with epilepsy and highlights the need for future studies addressing causes and treatment of cognitive impairment.

Efficacy of rapid IV administration of valproic acid for status epilepticus

Although not approved by the US Food and Drug Administration for the treatment of status epilepticus (SE), valproic acid (VPA) is an emerging option for this purpose. The authors reviewed 63 patients (30 men) with SE treated with IV VPA (average dose, 31.5 mg/kg). Analysis of demographic, clinical, and treatment information indicated an overall efficacy of 63.3% and favorable tolerance of rapid administration.

What are the concerns of older adults living with epilepsy?

PURPOSE

The goal of this work was to examine the concerns of living with recurrent seizures as expressed by older adults with epilepsy (OAE).

METHODS

Thirty-three community-dwelling adults over the age of 60 (mean age=65, range 60-80) were surveyed as to their concerns living with epilepsy. All patients were being treated for intractable partial epilepsy (mean age at seizure onset=37, range 1-77) and all were receiving antiepileptic drugs (AEDs). Patients were given a blank sheet of paper and asked to list any concerns they had about living with epilepsy. Each patient listed his or her concerns in order of importance.

RESULTS

Twenty-eight different areas of concern were listed by the OAE (range 1-6 per patient). Concerns about driving/transportation (64%) and medication side effects (64%) were the most frequently listed concerns. Other concerns listed by >20% of patients included personal safety (39%), AED costs (29%), employment (26%), social embarrassment (21%), and memory loss (21%). Driving/transportation and AED side effects were the two most important concerns.

CONCLUSIONS

Quality-of-life issues in OAE appear similar in content to those of younger epilepsy groups. Driving/transportation, role restriction (i.e., grandparenting role), employment, social embarrassment, and safety are major concerns expressed by older adults. However, medication side effects appear more concerning to older adults as compared with earlier studies with younger patients. This study highlights the substantial burden of living with epilepsy in older adults and points to the challenges clinicians have when addressing them.

Verbal memory outcome in patients with normal preoperative verbal memory and left mesial temporal sclerosis

PURPOSE

Previous studies have shown that structural integrity (i.e., presence/absence of mesial temporal sclerosis (MTS)) of the left mesial temporal lobe is associated with verbal memory outcome following left anterior temporal lobectomy (ATL). However, the functional integrity of the left temporal lobe, as exemplified by preoperative verbal memory performance, has also been associated with verbal memory outcome following surgery. We investigated the risk of verbal memory loss in patients with known structural abnormality (i.e., left mesial temporal sclerosis by MRI) and normal preoperative verbal memory performance who undergo left ATL.

METHODS

Seventeen patients with left temporal lobe epilepsy, MRI-based exclusive left MTS, and normal preoperative verbal memory were identified. Normal verbal memory was defined as performance on both Acquisition (learning across trials 1-5) and Retrieval (long delayed free recall) portions of the California Verbal Learning Test (CVLT) above a T score of 40 (>16%ile). Postoperative verbal memory outcome was established by incorporating standardized regression-based (SRB) change scores.

RESULTS

Postoperative declines across both CVLT Retrieval T scores and Acquisition T scores (average 20% and average 15% declines from baseline scores, respectively) were measured for the group. The average CVLT Retrieval SRB change score was -2.5, and the average CVLT Acquisition SRB change score was -1.0. A larger proportion of patients demonstrated postoperative declines on Retrieval scores than Acquisition scores (64.7% vs 17.6%, respectively).

CONCLUSIONS

Even in the presence of left MTS, patients exhibiting normal presurgical verbal memory are at risk for verbal memory declines following ATL. These results suggest that the functional integrity of the left mesial temporal lobe may play an important role in the verbal memory outcome in this patient group.

Cognitive functioning in community dwelling older adults with chronic partial epilepsy

PURPOSE

To examine cognitive functioning in community-dwelling older adults with chronic partial epilepsy and demographically matched healthy older adults.

METHODS

Standardized measures of neurocognitive function were collected as part of an ongoing study investigating health-related quality-of-life issues in older adults with epilepsy. Cognitive tests consisted of the Mattis Dementia Rating Scale (subscales include attention, initiation/perseveration, construction, conceptualization, memory), Logical Memory subtest from the WMS-III (immediate and delayed recall scores), and word fluency. Mood was measured with the Geriatric Depression Scale. Older adults with epilepsy (n=25) and healthy older adults (n=27) completed testing. All participants were at least 60 years old, living independently in the community, and had no history of drug/alcohol abuse or life-threatening medical conditions. All older adults with epilepsy had been diagnosed as having medically intractable partial complex seizures, including those with histories of secondary generalization.

RESULTS

Older adults with epilepsy demonstrated impairments across all cognitive measures compared with the healthy controls. Seizure onset (age) and seizure duration (years) were not statistically associated with neurocognitive function or self-reported mood. Older adults with epilepsy who were receiving antiepileptic drug (AED) polytherapy (n=11) displayed worse performance on the attention, initiation/perseveration, and memory subscales of the DRS and Logical Memory delayed recall score compared with those older adults with epilepsy receiving monotherapy (n=14). The number of AEDs taken was not associated with seizure frequency.

CONCLUSIONS

Negative effects on cognitive function are experienced by older adults with chronic partial epilepsy. AED polytherapy may increase the risk for negative cognitive dysfunction.

Review of United States and European clinical trials of zonisamide in the treatment of refractory partial-onset seizures

Zonisamide is an antiepilepsy drug (AED) with both sodium and calcium channel-blocking properties. This dual mechanism may predict efficacy in some refractory patients, and a broad spectrum of action against different seizure types. Zonisamide has been commercially available in Japan since 1989, and became available in the United States for treatment of adults over the age of 12 with partial-onset seizures in March 2000. Several multicenter clinical trials have been conducted in the United States over the past 15 years. These have included three double-blind, placebo-controlled trials as well as long-term open-label studies. Zonisamide was characterized in these studies as a safe and effective adjunctive treatment for partial-onset seizures. Zonisamide has not yet been studied in the United States as an initial monotherapy, but in one long-term study, some patients were able to discontinue other AEDs and successfully transition to monotherapy. The most frequently reported adverse events were somnolence, dizziness, and anorexia. Current United States labeling states that 12 patients with epilepsy receiving zonisamide had symptomatic kidney stones; however, after more than a dozen years of zonisamide use in Japan, the incidence of kidney stones associated with zonisamide remains low.