Epilepsy is a common neurological disease affecting almost 50 million people worldwide (1,2) 5 million of whom have seizures more than once per month (3). Approximately 85% of people afflicted with epilepsy live in developing countries. Two million new cases occur in the world each year. The results of studies suggest that the annual incidence in developed countries is approximately 50 per 100 000 of the general population whereas in developing countries this figure is nearly doubled to 100 per 100 000 (1).
In developing countries few patients with epilepsy receive adequate medical treatment, and an estimated 75 to 90% receive no treatment at all (4). The treatment of epilepsy in developing countries remains far from satisfactory, mainly because of:
- the general lack of medical personnel;
- non-availability of medications; and
- lack of information and/or education on epilepsy for both patients and medical staff (1,4,5).
Epilepsy is characterized by a tendency to recurrent seizures and it is defined by two or more unprovoked seizures (generally within 2 years). Seizures may vary from the briefest lapses or muscle jerks to severe and prolonged convulsions. They may also vary in frequency, from less than one a year to several per day (1). The risks of recurrent seizures include intractable epilepsy, cognitive impairment, physical injury, psychosocial problems and death (6). Children suffer mainly from idiopathic generalized epilepsy and absence, myoclonus and generalized tonic - clonic seizures are the most common forms of seizure seen in children. In adults, symptomatic partial epilepsy is the most common form, and it may cause simple partial, complex partial, or secondarily generalized tonic - clonic seizures (3). Convulsive or tonic - clonic status epilepsy is of major concern as it is associated with a mortality rate of 5 - 15% (7).
The aim of antiepileptic drug (AED) therapy is to achieve freedom from seizures. The treatment goals for patients with epilepsy are to prevent the occurrence of seizures, prevent or reduce drug side-effects and drug interactions, improve the patient's quality of life, provide cost-effective care and ensure patient satisfaction (6,8).Much of the treatment of epilepsy is aimed at creating a balance between prevention of seizures and minimization of side-effects to a level that the patient can tolerate (6,9). Although AED therapy does not offer a permanent cure, successful therapy can eliminate or reduce symptoms. The most commonly used AEDs are (in alphabetical order): carbamazepine, ethosuximide, phenobarbital, phenytoin and valproic acid. New AEDs such as gabapentin, lamotrigine, leviteracetam, felbamate, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide have a role in the management of the 20 - 30% of patients with epilepsy who remain refractory to conventional drug therapy (9). About 25% of patients with epilepsy have intractable seizure disorders, of those between 12 and 25% are candidates for surgery (3).
The direct costs attributable to epilepsy include physician visits, laboratory tests, emergency department visits, antiepileptic drugs and hospitalizations. Indirect costs include working days lost, lost income, decreased quality of life, the cost of failed therapy and side-effects of drugs (6). Garnett et al., referring to the "Epilepsy Foundation of America data", reported that the annual direct and indirect costs of epilepsy exceeded $12.5 billion. The direct costs of epilepsy are significantly lower for patients whose epilepsy is controlled than for those whose disease is not controlled (6).
Recent studies in both developed and developing countries have shown that up to 70% of children and adults newly diagnosed with epilepsy can be successfully treated (i.e. their seizures can be completely controlled for several years) with antiepileptic drugs. After 2 - 5 years of successful treatment, drugs can be withdrawn in about 70% of children and about 60% of adults without relapse occurring (1). In the case of treatment failure it is crucial to establish whether the failure is a result of inappropriate drug selection, inappropriate dosing, refractory disease or poor adherence to the therapeutic regimen (3,6).
Good adherence to treatment and proper health education are fundamental to the successful management of epilepsy (10,11). Poor adherence to prescribed medication is considered to be the main cause of unsuccessful drug treatment for epilepsy (2,3,12 - 18). Nonadherent patients experience an increase in the number and severity of seizures, which leads to more ambulance rides, emergency department visits and hospitalizations (12,19). Nonadherence therefore results directly in an increase in health care costs, and reduced quality of life (19).
The aim of this chapter is to describe the prevalence of adherence (or nonadherence), to treatment for epilepsy, to identify the factors affecting adherence to anti-epilepsy treatment, and to discuss the interventions that have proven effective for improving adherence.
A search on adherence to anti-epilepsy therapies was made using Medline (1990 - 2002). Reviews and reports from international and national organizations were also included. Publications were considered for inclusion if they reported on one of the following: prevalence data on rates of adherence (or nonadherence), factors affecting adherence, interventions for improving adherence, and information on how poor adherence rates affect illness, costs and treatment effectiveness. Of the 99 studies retrieved by the search, 36 were reviewed for this report.