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Purpose: To study the course and outcome of childhood-onset epilepsy during 15-year follow-up (FU).
Methods: We extended FU in 413 of 494 children with new-onset epilepsy recruited in a previously described prospective hospital-based study by questionnaire.
Results: Mean FU was 14.8 years (range 11.6–17.5 years). Five-year terminal remission (TR) was reached by 71% of the cohort. Course during FU was favorable in 50%, improving in 29%, and poor or deteriorating in 16%. Mean duration of seizure activity was 6.0 years (range 0–21.5 years), strongly depending on etiology and epilepsy type. Duration was <1 year in 25% of the cohort and exceeded 12 years in another 25%. Antiepileptic drugs (AEDs) were used by 86% during a mean of 7.4 years: one-third had their last seizure within 1 year of treatment, and one-third continued treatment at the end, although some had a 5-year TR. At last contact, 9% of the cohort was intractable. In multivariate analysis, predictors were nonidiopathic etiology, febrile seizures, no 3-month remission, and early intractability. Eighteen patients died; 17 had remote symptomatic etiology. Standardized mortality ratio for remote symptomatic etiology was 31.6 [95% confidence interval (CI) 18.4–50.6], versus 0.8 [95% CI 0.02–4.2] for idiopathic/cryptogenic etiology.
Discussion: In most children with newly diagnosed epilepsy, the long-term prognosis of epilepsy is favorable, and in particular, patients with idiopathic etiology will eventually reach remission. In contrast, epilepsy remains active in ∼30% and becomes intractable in ∼10%. AEDs probably do not influence epilepsy course; they merely suppress seizures. Mortality is significantly higher only in those with remote symptomatic etiology.
Knowledge of the long-term outcome of epilepsy is of the utmost importance in the treatment of children with epilepsy. Many investigators have studied cohorts with the purpose of describing epidemiology, prognosis, and mortality, as well as social and educational outcomes (Camfield et al., 1993; Berg et al., 1999b; Wakamoto et al., 2000; Sillanpaa & Schmidt, 2009). Next to methodology and cohort size, length of follow-up (FU) determines the significance of the results of these studies, especially when it comes to aspects such as course of epilepsy, intractability, terminal remission, and mortality. A lifelong FU of cohorts would be ideal to cover all aspects; however, although this has not yet been realized, studies with prolonged FU are valuable.
Whereas outcome in terms of remission or death can be determined easily, the course of epilepsy during FU is more difficult to describe. This can be done in terms of success or failure of antiepileptic drugs (AEDs), or in terms of remission and relapse (Camfield et al., 1993; Sillanpaa & Schmidt, 2006). The course of epilepsy is in our view important to investigate, because intra- and interindividual variation may be considerable (Berg et al., 2006; Sillanpaa & Schmidt, 2006). Periods of remission and relapse may interchange. Such a dynamic course might influence our interpretation of the results of prognostic studies, advice to patients, treatment strategies, and timing of referral for surgery. Moreover, it is still largely unknown whether the long-term outcome of epilepsy is determined by its natural course or whether it can be modified by treatment. Long-term FU studies may be helpful to solve this dispute.
Between 1988 and 1992 we consecutively recruited children who attended hospital with new-onset epilepsy. Results at 2 and 5 years after diagnosis have already been published (Arts et al., 1999, 2004). We extended the FU of 413 children to a mean of 15 years. To date, there have been no reports of studies with cohorts of this size combined with this length of FU. The main purpose of this study was to investigate course and outcome of childhood epilepsy and its determinants, treatment, and mortality.
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Table S1. Significant variables for active epilepsy (TRE < 5 year) and final intractability, and odds ratios for intractability (OR) for each value as compared with the reference value of that variable.
Table S2. Characteristics of nine subjects who died after more than 5 years of follow-up (FU). The causes of death of those who died in the first 5 years have been described in detail previously (Callenbach et al., 2001).
Figure S1. Cumulative proportion reaching a 2-year terminal remission (TRE) during follow-up.
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Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.