The prevalence and risk factors of refractory partial seizure Thai patients at Prasat Neurological Institute

The prevalence of refractory partial seizure Thai patients at Prasat Neurological Institute was retrospectively from patient charts from January 1995-December 1996 and further prospectively analysed. All epileptic patients were screened by direct questions regarding the anti-epileptic drugs (AEDs) regimen, the frequency, nature of seizure attacks and risk factors of seizure. The criteria of clinical refractory partial seizure was defined as partial seizure which cannot be controlled by a combination of at least two AEDs for four weeks. The results were 3,018 cases of total epileptic patients out of 300,008 visits. These were classified as 2,802 cases of generalized seizures (92.8%), 184 cases of partial seizures (6.1%), and 32 cases of unclassified seizures (1.1%). In the partial seizures group, the number of clinical refractory partial seizures was found to be 48 cases (26.1% of partial seizure). We found that the major risk factor of refractory partial seizures was lack of therapeutic AEDs blood level monitoring (64.5% of cases) and the other risk factors were lack of compliance, loss of follow-up but continued medication, concomitant medication, and improper drug storage. AEDs dosage was adjusted until the blood levels were in the therapeutic range, and correction of other risk factors and patient counseling was given. The number of true refractory partial seizures was reduced to 10 cases (5.4% of partial seizure). This procedure revealed that AED blood level monitoring and correction of other risk factors were essential in controlling seizure frequency. Thus, the prevalence of true refractory partial seizure in our study was 3.3 cases of refractory partial seizure per 1,000 cases of the seizure population. We recommend that AEDs blood level monitoring and exclusion of other risk factors should be added to the criteria for the definition of refractory partial seizures. This criteria should be applied when considering the use of new AEDs as an add-on therapy in refractory Thai patients.