for the main comparison.

Antiepileptic drug (AED) compared with placebo for people with epilepsy and intellectual disability
Patient or population: people with epilepsy and intellectual disability Settings: UK, USA Intervention: AEDs Comparison: placebo
Outcomes	Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
Retention on treatment Duration of retention on treatment was not reported in these studies. The retention on treatment in this analysis is assessed by the number of withdrawals in the intervention and placebo groups The results show a trend in favour of the placebo groups	RR 1.43 (0.76 to 2.69)	310 (3)	⊕⊕⊕⊝ moderate	The included studies assessed different AEDs (topiramate and rufinamide). 1 study did not include participants under 12 years of age, 1 study did not include participants under 4 years of age and 1 study did not include participants under 1 year of age. The duration of intervention was similar across the studies (84 days, 11 weeks and 3 months). 2 studies had low risk of bias and 1 study was unclear
Seizure freedom 1 study reported the incidence of seizure frequency in the intervention and placebo group The results show a trend in favour of the AED group	RR 2.92 (0.32 to 26.77)	73 (1)	⊕⊕⊝⊝ low	The included study had good methodological quality and low risk of bias. However, given that only 1 study was included in this analysis, the overall quality of evidence is low
Responder rate (≥ 50% reduction in overall seizure frequency) 3 studies included data for responder rate for overall seizure reduction in the AED and placebo groups The results show a significant trend in favour of the AED groups	RR 2.58 (1.60 to 4.14)	382 (3)	⊕⊕⊝⊝ low	The included studies assessed different AEDs (lamotrigine, rufinamide, topiramate). Similar age ranges were included in the studies and they had a similar duration of treatment. 2 studies were rated as having unclear risk of bias and 1 study had low risk of bias
Responder rate (≥ 50% reduction in rate of drop seizures) 2 studies reported the frequency of responder rate in the reduction of drop seizures only in the AED and placebo groups The results show a trend in favour of the AED groups	RR 6.04 (0.27 to 133.89)	313 (2)	⊕⊕⊝⊝ low	The 2 studies assessed different AEDs (clobazam, topiramate). They had a similar duration of treatment period (11 weeks, 12 weeks). 1 study was rated as low risk of bias and 1 study was rated as unclear risk of bias
Adverse events 4 studies reported the frequency of self reported adverse events in the AED and placebo groups The results show a trend in favour of the placebo groups	RR 1.13 (0.95 to 1.35)	527 (4)	⊕⊕⊕⊝ moderate	The included studies assessed different AEDs (topiramate, clobazam, rufinamide). They all had similar duration treatment periods (around 3 months). 1 study did not include participants under 12 years of age, 1 study did not include participants under 4 years of age, 1 study did not include participants under 2 years of age and 1 study did not include participants under 1 year of age. 2 studies were rated as having low risk of bias and 2 studies were rated as having unclear risk of bias
CI: confidence interval; RR: risk ratio; AED: antiepileptic drugs
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.