Fair and poor seizure control are associated with a significantly lower quality of life and a higher prevalence of depression, anxiety, and stress in patients with epilepsy [17]. Also, DRE is reported to have serious physical and emotional consequences and it poses a great burden on the family as well as on social, educational, and health services [18]. Furthermore, these patients are at higher risk of some potentially life-threatening events, arising as a result of uncontrolled seizures including aspiration, electrolyte imbalance, brain edema, refractory status epilepticus, renal failure, cardiac arrhythmias, and unexplained sudden death [15]. It should be noted that the prevalence of DRE is considerably high. In the current study, 22% of adults with epilepsy admitted during six years had DRE. According to a systematic review and meta-analysis on 19 studies, the pooled incidence of DRE in epilepsy patients was 20% (95% CI 14–27%). Though there was a great heterogeneity among the included studies in this review (ranging from a prevalence of 6–51%) [11]. Another systematic review and meta-analysis on 15 studies estimated that the prevalence of DRE is 25% (95% CI 17–32%) [19]. The heterogeneity among studies is partially due to the different DRE definitions. In the current study, we applied the most updated definition of DRE which was established by the consensus of ILAE [12]. In the systematic review by Kalilani et al. of 15 included studies, only 4 studies (10.5%) used a case definition of DRE that complied with the ILAE definition of DRE [19]. Some investigators defined DRE with higher the number of failed antiepileptic medications [15, 20–23]. While other studies only required failure of one antiepileptic medication [24–26]. Furthermore, the discrepancy among different studies is attributable to the differences in the genetic/ethnicity predisposition [27]. As far as we investigated, our study is the first study on the Iranian population, evaluating the prevalence and associated factors of DRE in adults.
In the current study in a relatively large number of epileptic patients, we identified a positive history of CP/developmental disorders as an independently associated factor with DRE. However, age and sex were not associated with DRE. Likewise, Farghaly et al. by evaluation of 437 patients with epilepsy also reported that age and sex were not associated with DRE but mental retardation significantly increased the risk of DRE [26]. These results were in concordance with the results of Chawla et al. and Eriksson and Koivicco, who reported that perinatal problems were the leading cause of DRE [28, 29]. The association of CP/developmental disorders with DRE may be attributed to the pathophysiology and brain structural abnormalities of these diseases. However, due to the intellectual disabilities of these patients, there is a possibility of a lack of adequate adherence to the prescribed antiepileptic medications. Therefore, first, perinatal care should receive more attention to reduce the possibility of developing these anomalies. Second, these patients should be encouraged and helped out to use their medications accurately.
Some studies postulated that the rate of partial epilepsy is significantly higher in DRE patients [26, 30, 31]. However, we did not find any significant association between seizure type and DRE. Similarly, Kalilani et al. by a meta-analysis of 15 studies data, failed to detect any significant relationship between seizure type and DRE [19]. However, it should be noted that the number of patients with partial seizure was relatively low in our study. This is because we conducted this study on the admitted patients and patients with partial seizures are rarely get admitted to the wards. Therefore, the results of our study on the relationship between seizure type and DRE may hardly generalizable for the whole population. Thus, it is warranted that this issue gets investigated in future population-based studies.
As like other retrospective studies, the main limitation of our study was the lack of recorded data ascertainment, which meant that the data on the cause of epilepsy could not be ascertained. Nonetheless, the patients were admitted to a teaching hospital and were under observation by attending neurologists. Moreover, the number of used antiepileptic medications and characteristics of the seizures was recorded based on the patient’s/components’ claims.