Recruitment and retention in clinical trials of the elderly

The recruitment and retention of elderly patients in clinical trials provide many challenges. Factors affecting recruitment, retention, and cost of recruitment are discussed in this chapter. Various methods are described that were used in recruiting and retaining elderly patients in a Veterans Affairs (VA) Administration clinical trial that compared two newer antiepileptic drugs (AEDs), gabapentin and lamotrigine, to the established standard AED, carbamazepine. Various strategies were utilized in the VA study to improve recruitment, and each strategy's overall effectiveness was monitored. Modification of the patient inclusion criteria, by lowering the age of eligibility from 65 to 60 years, added approximately 100 patients to the study. Replacing five trial sites that had poor recruiting records, extending the patient recruitment period by 3 months, and conducting site visits also improved patient recruitment rates, such that 82.4% of target enrollment (720 patients) was achieved. The main reasons that screened patients were excluded from the study included: lack of seizures during the prior 3 months, unstable medical condition, adequate treatment with an AED, satisfaction with current treatment, and the inability to give informed consent. Retaining patients for 1 year was the primary outcome measure of this trial, with 46.8% of patients completing the year. The most common reasons for early termination were study drug-related adverse events (43.0%) and lack of seizure control (10.8%). Comorbidities and polypharmacy occurred more frequently in the elderly, and both had a negative influence on recruitment and retention.