An analysis of medication adherence among epileptic patients in the private health sector of South Africa
Failure to respond to anti-epileptic (AED) treatment and achieving control over epilepsy has severe clinical consequences. The clinical consequences include an increase in the frequency of seizures and increased work and social impairment, poor treatment outcome, increased treatment costs associated with hospitalisation, over-utilisation of health-care systems and ultimately mortality. The general aim of the study was to measure AED adherence, to determine which factors are closely associated with AED non-adherence and the consequences of prolonged AED non-adherence in the private health sector of South Africa. The empirical study followed a quantitative, descriptive design using longitudinal medicine claims data from 1 January 2008 to 31 December 2013, provided by a nationally representative Pharmaceutical Benefit Management (PBM) company. The study population consisted of all patients registered on the database with an ICD-10 code for epilepsy (G40). The number of epilepsy patients identified over the study period ranged from 6 634 in 2008 to 7 387 in 2013, representing 0.87 to 0.91% of the total number of registered beneficiaries included in the database. Anti-epileptic drugs were prescribed in 0.92% (n= 62 442) to 1% (n= 67 960) of the total number of patients on the database from 2008 to 2013. The mean number of AED items per epilepsy patient ranged from 1.42 ± 0.86 (95% CI 1.40-1.44) in 2008 to 1.55 ± 1.03 (95% CI 1.52-1.57) in 2013. The active ingredient most prescribed was valproate (ranging from 13.24% to 17.02%), followed by lamotrigine (ranging from 12.73% to 17.80%) and carbamazepine (ranging from 15.54% to 13.82%) during the study period. Patients were predominantly female (female-to-male ratio 1.19:1) (p= 0.478; Cramer's V= 0.010). There were no statistical significant associations observed between the average number of AED prescription per patient and gender. The highest average number of AED prescriptions was observed in the 41 to 65 years age group, increasing with 1.91% from 2008 to 2013. A practical significance was observed between the average number of AED prescriptions and the different age groups (p< 0.0001; Cohen's d ≤ 0.314 in 2008; Cohen‟s d ≤ 0.244 in 2013). There were several chronic conditions co-occurring with epilepsy, with hypertension being the most prevalent, followed by hyperlipidaemia and hypothyroidism. The average direct cost per medicine item per patient increased from R237.12 ± R146.93 (95% CI 233.58-240.65) to R522.32 ± R310.62 (95% CI 515.24-529.41) during the study period. A remarkable increase in the average patient contribution was observed during this period (R27.76 ± R46.96 in 2008 to R264.32 ± R162.61 in 2013). Non-substitutable AEDs (those without generics available) were the most prescribed (39.85% over study period), which could be attributed to the increased medical expenditures by the patients (89.50%). The non-substitutable medication use decreased over the study period ranging from 40.06% in 2008 to 26.92% in 2013 Adherence of only 55.14% (n= 26 214) was observed for anti-epileptic treatment. A statistically significant association was found between the active ingredient consumed and adherence status (p= <0.0001), thereby indicating that the use of certain active ingredients resulted in better adherence (Cramer's V= 0.071). Only 5.73% of patients receiving clonazepam were adherent compared to 22.96% and 22.54% in the cases of valproate and lamotrigine, respectively. The current study found that the number of co-morbid conditions and the duration of the treatment period had a statistically significant influence on adherence status (p= <0.0001; Cramer's V= 0.050 and p= <0.0001; Cramer's V= 0.208 respectively). Non-adherence (undersupply and oversupply of medication) contributed to 20.12% of wasted resources (R32 021 575.77). In conclusion, the current study confirms that AED non-adherence is an important concern in developing countries similar to developed countries. Several factors were found to be closely associated with AED treatment non-adherence, which include a short treatment period, certain active ingredients and chronic co-morbid conditions. High direct medicine costs of treatment could further contributed to the poor adherence status, which is especially worrying in a country such as South Africa as we do not have the financial capacity to carry such a burden.
- Health Sciences