Long-term predictors of developmental outcome and disease burden in SCN1A-positive Dravet syndrome

Dravet syndrome is a severe infantile onset developmental and epileptic encephalopathy associated with mutations in the sodium channel alpha 1 subunit gene SCN1A. Prospective data on long-term developmental and clinical outcomes are limited; this study seeks to evaluate the clinical course of Dravet syndrome over a 10-year period and identify predictors of developmental outcome. SCN1A mutation-positive Dravet syndrome patients were prospectively followed up in the UK from 2010 to 2020. Caregivers completed structured questionnaires on clinical features and disease burden; the Epilepsy & Learning Disability Quality of Life Questionnaire, the Adaptive Behavioural Assessment System-3 and the Sleep Disturbance Scale for Children. Sixty-eight of 113 caregivers (60%) returned posted questionnaires. Developmental outcome worsened at follow-up (4.45 [SD 0.65], profound cognitive impairment) compared to baseline (2.9 [SD 1.1], moderate cognitive impairment, P < 0.001), whereas epilepsy severity appeared less severe at 10-year follow-up (P = 0.042). Comorbidities were more apparent at 10-year outcome including an increase in autistic features (77% [48/62] versus 30% [17/57], χ2 = 19.9, P < 0.001), behavioural problems (81% [46/57] versus 38% [23/60], χ2 = 14.1, P < 0.001) and motor/mobility problems (80% [51/64] versus 41% [24/59], χ2 = 16.9, P < 0.001). Subgroup analysis demonstrated a more significant rise in comorbidities in younger compared to older patients. Predictors of worse long-term developmental outcome included poorer baseline language ability (P < 0.001), more severe baseline epilepsy severity (P = 0.003) and a worse SCN1A genetic score (P = 0.027). Sudden unexpected death in epilepsy had not been discussed with a medical professional in 35% (24/68) of participants. Over 90% of caregivers reported a negative impact on their own health and career opportunities. Our study identifies important predictors and potential biomarkers of developmental outcome in Dravet syndrome and emphasizes the significant caregiver burden of illness. The negative impact of epilepsy severity at baseline on long-term developmental outcomes highlights the importance of implementing early and focused therapies whilst the potential impact of newer anti-seizure medications requires further study.

Comorbidities and predictors of health-related quality of life in Dravet syndrome: A 10-year, prospective follow-up study

OBJECTIVE

Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy, leading to reduced health-related quality of life (HRQOL). Prospective outcome data on HRQOL are sparse, and this study investigated long-term predictors of HRQOL in DS.

METHODS

One hundred thirteen families of SCN1A-positive patients with DS, who were recruited as part of our 2010 study were contacted at 10-year follow-up, of which 68 (60%) responded. The mortality was 5.8%. Detailed clinical and demographic information was available for each patient. HRQOL was evaluated with two epilepsy-specific instruments, the Impact of Pediatric Epilepsy Scale (IPES) and the Epilepsy & Learning Disabilities Quality of Life Questionnaire (ELDQOL); a generic HRQOL instrument, the Pediatric Quality of Life Inventory (PedsQL); and a behavioral screening tool, the Strength and Difficulties Questionnaire (SDQ).

RESULTS

Twenty-eight patients were 10-15 years of age (0-5 years at baseline) and 40 were ≥16 years of age (≥6 years at baseline). Patients 0- to 5-years-old at baseline showed a significant decline in mean scores on the PedsQL total score (p = .004), physical score (p < .001), cognitive score (p = .011), social score (p = .003), and eating score (p = .030) at follow-up. On multivariate regression, lower baseline and follow-up HRQOL for the whole cohort were associated with worse epilepsy severity and a high SDQ total score (R²  = 33% and 18%, respectively). In the younger patient group, younger age at first seizure and increased severity of epilepsy were associated with a lower baseline HRQOL (R²  = 35%). In the older age group, worse epilepsy severity (F = 6.40, p = .016, R²  = 14%) and the use of sodium-channel blockers were independently associated with a lower HRQOL at 10-year follow-up (F = 4.13, p = .05, R²  = 8%).

SIGNIFICANCE

This 10-year, prospective follow-up study highlights the significant HRQOL-associated cognitive, social, and physical decline particularly affecting younger patients with DS. Sodium channel blocker use appears to negatively impact long-term HRQOL, highlighting the importance of early diagnosis and disease-specific management in DS.