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In clinical practice with people with learning disability we are left with something of a clinical
effectiveness dilemma. To practice purely by gold-standard approaches leaves us with
precious few interventions, and almost zero comparative studies. We therefore apply
knowledge on interventions gained in the general population to this special population, but
the validity of this approach in this population remains unproven, in particular for assessment
of side effects. The latter course of action is, of course, a clinical necessity.

Clinical effectiveness data in people with learning disability
Studies looking at this population have been divided into assessing practice, usually
antiepileptic drug (AED) reductions through cohort or intervention studies, and
pharmacological interventions to control seizures.

Cohort studies and drug reduction
Cohort studies looking at practice over several years have been performed in institutional21,22
and clinic populations23,24. Pellock and Hunt22 reviewed ten years of treatment in an American
institution using an open methodology and showed a trend towards reduction in polytherapy
(19%), with a relative increase in monotherapy and a large decrease in patients receiving
three anticonvulsants (a decrease of 47.6%), and a decrease in the use of barbiturate
anticonvulsants. Poindexter and colleagues21 showed a similar trend towards medication
rationalisation and in particular reduction of barbiturate anticonvulsants. Singh and Towle23
followed 100 patients with learning disability over a mean duration of 7.5 years in an
outpatient referral setting. This survey is an interesting reflection on clinical practice with
60% of patients maintained on one, 38% on two, and 2% on three AEDs. Tobias and
colleagues24 audited the practice of a large British outpatient epilepsy service through 1000
consecutive referrals. Again, essentially through a cohort study, it enabled comparison
between people with and without handicap and shows that there was a trend toward
withdrawal of barbiturate anticonvulsants in the general population over this period.

Several intervention studies have assessed drug reduction or ‘rationalisation’. Fischbacher25
showed in an uncontrolled or randomised study that reduction of at least one AED was
feasible for many patients and could have an associated behavioural improvement. Beghi and
colleagues26, using a similar uncontrolled non-randomised approach, were able to show a
reduction in AEDs from 1.84 to 1.05 per patient over a mean of 12.5 months. A further non-
controlled, open, non-randomised study from the UK27 showed that out of 172 patients
remaining over three years (from a population of 215 patients) the mean number of AEDs
reduced from 1.41 to 1.05 per patient. This was associated with an increase in dosage of
remaining drugs and a less than clear effect on seizure frequency, with a reduction in 48% of
patients, an increase in 33% and no change in 19%. Unfortunately for the practising clinician,
while there appears to be a groundswell of support for ‘rationalisation’, aspects of the
methodology used in all of the above studies, crucially lack of control and randomisation,
leave the issue unproved.

Some guidance for the clinician intending to discontinue medication when a patient has been
seizure free can be gained from the work of Alvarez28. In a non-randomised, controlled, but
well described study the author showed, with an impressive eight-year follow-up period, that
following a seizure-free period of at least two years an attempt at reduction could be made.
In this population of 50 patients seizures recurred in 26 (52%); 11 of these occurred during
discontinuation and 30% after discontinuation. A total of 80% of recurrences occurred less
than three years after the start of discontinuation. Predictors of successful discontinuation are
(1) few documented seizures in a lifetime, (2) no gross neurological abnormalities, (3) low
drug levels at initial discontinuation, and (4) persistently normal EEGs before and after
discontinuation.