Influence of antiepileptic treatment changes on adult patients' clinical outcomes in an outpatient population, North West

Abstract

Background: Epilepsy, being one of the most common neurological conditions, is undertreated in patients worldwide. The primary treatment goal of antiepileptic drugs (AEDs) is to achieve complete limitation of seizures without side-effects, ensuring an optimal quality of life. Medication adherence is a major problem in epilepsy. The clinical outcomes of epilepsy management and prescribing patterns in the public health sector of the Dr Kenneth Kaunda District were unknown. Little prevalence studies have been done on epilepsy in the public health sector of South Africa. This study could contribute to the knowledge about epilepsy in the public health sector of South Africa. Objective: The purpose of this study was to investigate the prescribing patterns of antiepileptic drugs and patients’ clinical outcomes, such as adherence, seizure frequency and therapeutic serum drug levels in the adult outpatient department of a public hospital in Dr Kenneth Kaunda District, North West province, South Africa. Method: A retrospective, quantitative research design was applied to collect data from epileptic patients’ medical files using a pre-developed data collection tool. The inclusion criteria was adult patients (above 18 years) diagnosed with epilepsy and on antiepileptic treatment for six to 24 consecutive months during the study period of 1 January 2014 to 30 June 2016. Patients were excluded if they were diagnosed with medical conditions other than epilepsy for which they received AEDs as treatment. The data collection was conducted from May to August 2016. The medicine possession ratio (MPR) was used to determine adherence status per AED. An MPR ≥ 80% and ≤110% was considered as adherent. Serum drug levels, as measure of therapeutic drug monitoring (TDM), were compared to the therapeutic range per AED and values were classified as therapeutic, subtherapeutic (below the therapeutic range) and supratherapeutic (above the therapeutic range). The prevalence of seizure breakthrough and regimen change were described using descriptive statistics. Results: Forty-six epileptic patients complied with the study criteria. Among them 25 were males and 21 were females. Valproate was the drug mostly prescribed (n=41; 53.24%), followed by lamotrigine (n=24; 31.16%) and carbamazepine (n=8; 10.38%). It is important to remember that patients can be on a regimen with more than one AED, therefore the sum of total number of patients per AED will be more than 46 patients. Adherence, according to the medicine possession ratio, was 64.93% (n=50) and seizures occurred in 84.78% (n=39) of patients. According to the serum drug levels, 61.90% (n=13) of the measurements were subtherapeutic, while 14.28% (n=3) were supratherapeutic. Valproate had the highest rate of seizure breakthrough (n=34; 82.90%) and subtherapeutic serum levels (n=12; 92.31%). More than one regimen changes occurred in 69.56% (n=32) of the population with the change in dose as the most prevalent type of regimen change (n=25; 54.43%). Conclusions and recommendations: The study has attempted to reveal the prescribing patterns and clinical outcomes in the adult outpatient department. Adherence was still poor compared to the ideal of 80%. The number of serum drug levels reported were not sufficient to conclude on the adherence status, although poor adherence and monitoring of patient outcomes, especially in valproate, are suspected. Both sub- and supratherapeutic levels may imply possible non-adherence to antiepileptic treatment. Changes in AED regimen can cause a fluctuation of serum drug levels. Therefore, an expert opinion should be consulted before the initiation of regimen changes. Consequently, the classification of epilepsy, adherence to antiepileptic treatment, the correct documentation of seizure frequency and therapeutic drug level monitoring needs urgent interventions. Therapeutic drug monitoring is fully justified to optimise an individual dosage regimen. Monitoring epilepsy patients, especially patients on valproate, seems to be essential to improve clinical outcomes of anti-epileptic patients in this public hospital. It is recommended that future research projects on this research topic should be implemented in more hospitals and/or other districts in the public health sector of South Africa. The ‘influence’ of regimen change, according to the study title, could not be measured due to the limitations of this study. Therefore, it is suggested that the title of this mini-dissertation should change to: ‘A retrospective analysis of adult epilepsy patients’ clinical outcomes: adherence, seizure frequency and therapeutic drug monitoring in an outpatient department of a public hospital in the North West Province, South Africa.’