Age representation in antiepileptic drug trials: A systematic review and meta-analysis

To analyze age representation trends over time in antiepileptic drug (AED) trials and to assess trial design elements as possible barriers to enrollment of elderly patients.

We searched MEDLINE, EMBASE, and PsycINFO, and meta-analyzed demographic data of cohorts enrolled in randomized controlled trials (RCTs) of AEDs published since 1991. Data analysis included trends of age representation over time and trial design elements associated with average age of enrolled cohorts.

We identified 187 studies (n = 48,077); 184 studies were included in the meta-analysis. The mean age of participants enrolled increased steadily from a mean age of 27.0 years (SD 5.7, range 21.0-38.4) in 1991-1992, to a mean age of 41.9 years (SD 11.4, range 28.8-71.4) in 2015-2016 (r = 0.868, p < 0.0001). Maximum age limit for inclusion of participants was present in 83 trials (44%). There was no significant decrease in the use of upper age limit over time (r = 0.072, p = 0.8161). Among the eligibility criteria assessed, only the exclusion of neurological conditions other than epilepsy was associated with a significant reduction of the average age of enrolled cohorts (-2.1 years, 95% CI -4.1 to -0.1).

Despite a progressive increase in the average age of participants enrolled in AED trials over time, elderly patients are still largely underrepresented. Successful strategies to increase representation of elderly patients in these trials will likely need to involve more than minimal protocol modifications of eligibility criteria.