Prevalence and patterns of anti-epileptic medication prescribing in the treatment of epilepsy in older adults with intellectual disabilities.

BACKGROUND

The prevalence of epilepsy is higher in people with intellectual disability (ID) and increases with the degree of ID. Although life expectancy for people with ID is increasing, people with ID coexisting with epilepsy have a higher mortality rate, particularly those who had recent seizures. There have been few observational studies of the prevalence and patterns of anti-epileptic prescribing among older people with ID and epilepsy. The aim of this study was to investigate prevalence and patterns of anti-epileptic prescribing in the treatment of epilepsy in a representative population of older people with ID and epilepsy.

METHODS

This was an observational cross-sectional study from wave 1 (2009/2010) of Intellectual Disability Supplement to the Irish Longitudinal Study on Aging, a nationally representative sample of 753 persons with ID aged between 41 and 90 years. Participants and/or proxies recorded medicines used on a regular basis and reported doctor's diagnosis of epilepsy; medication data were available for 736 (98%). Prescribing of anti-epileptic drugs (AEDs) for epilepsy in those with a doctor's diagnosis of epilepsy (N = 205) was the primary exposure of interest for this study. Participant exposure to these AEDs was then categorised into AED monotherapy and polytherapy. Participants/carers reported seizure frequency, when epilepsy was last reviewed and which practitioner reviewed epilepsy. In addition, medications that may lower the seizure threshold that were listed in the Maudsley prescribing guidelines in psychiatry were examined.

RESULTS

Of the 736 participants with reported medicines use, 38.9% (n = 287) were exposed to AEDs, and 30.6% (225) had a doctor's diagnosis of epilepsy. Of those with epilepsy (n = 225), 90.9% (n = 205) reported concurrent use of AEDs and epilepsy. Of these 205 participants, 50.3% (n = 103) were exposed to AED polytherapy, and 63 different polytherapy regimes were reported. The most frequently reported AEDs were valproic acid (n = 100, 48.7%), carbamazepine (n = 89, 46.3%) and lamotrigine (n = 57, 27.8%). In total, 13.7% had a concurrent psychotropic, which should be avoided in epilepsy, and 32.6% had a psychotropic where caution is required. Antipsychotics with potential epileptogenic potential accounted for 80% of these medications. Of those with AED polytherapy (n = 103), 29.5% (28) reported being seizure free for the previous 2 years.

CONCLUSIONS

Prevalence of epilepsy was high among older people with ID, and half were exposed to two or more AEDs. Despite the use of AED therapy, over half had seizures in the previous 2 years. As the primary goals of optimal AED treatment are to achieve seizure freedom without unacceptable adverse effects, this was not achievable for many older patients with ID and epilepsy. Our findings indicated that people with ID and epilepsy were often exposed to psychotropic medications that may lower the seizure threshold. Regular review of epilepsy and medicines (including medicines that may interact with AEDs or lower the seizure threshold) by multidisciplinary teams working to agreed standards may improve quality of prescribing. Improved exchange of information and coordination of care between specialists and primary care practitioners in line with expert consensus recommendations could bring substantial benefit.