Patient Recruitment and Retention are Major Challenges for Clinical Trials in CNS


Applied Clinical Trials

Applied Clinical TrialsApplied Clinical Trials-01-01-2012
Volume 21
Issue 1

Often CNS trial subjects face unique obstacles like mental dependency

Recruitment and retention of patients in clinical trials for central nervous system (CNS) diseases has become a major challenge for pharmaceutical companies and the clinical research organizations (CROs) who conduct clinical trials.

The reason for this is the complicated and lengthy nature of these trials and the unique features of CNS diseases such as the mental dependency of patients suffering with neurodegenerative diseases. Even though the CNS market has reached a stage of maturity, there is still high scale research and development taking place, especially in the field of drug delivery.

The expiration of numerous drug patents by 2011-2012 is placing immense pressure on manufacturers to develop alternative and novel therapeutic agents.


GBI Research has evaluated that CNS attracted 7,751 trials from 2005 to 2010, which was the highest among the non-oncology group of therapy areas. The high number of trials indicated that CNS is a therapy area that is greatly focused on by the pharmaceutical companies. There are many pipeline molecules, along with large patient populations for indications such as Alzheimer's disease, Parkinson's disease, epilepsy, schizophrenia, and depression.

The average number of patients recruited per trial depends on the protocol specifications and the phase of the trial. The number of patients required for a particular trial to justify an intervention is based on the phase of the trial.

The average number of patients per phase of trial illustrates the status of the patients recruited for CNS trials in the recent past.


The major challenge for clinical trials in CNS is patient recruitment and retention due to the smaller population of patients compared to other indications. The doctors participating in the clinical trials face difficulty in recruiting patients as there is poor public awareness about such diseases, resulting in delayed diagnosis.

The patient recruitment can be enhanced by providing additional support, training, and education to the investigators by helping them to comply with global requirements and provide high-quality data for the clinical trial analysis.

The other reasons which affect the patient recruitment in clinical trials are a lack of neuroimaging facilities at trial sites, along with clinical logistics hurdles.

Patients suffering with brain-based diseases often have impairment in their thinking processes due to the conditions. They need extra care and assistance when making decisions such as participation in clinical trials and need assistance with their medication, which causes difficulty in gaining their consent for participation.

Each neurological condition presents a unique feature with distinct and specific behaviors and preferences. The most difficult processes in patient recruitment are the initial-screening visits and the informed-consent process. Most of the trials have lengthy diagnostic or evaluation tools to ensure that the subject recruited falls within the inclusion/exclusion criteria.

Along with the possibility of impaired cognitive abilities in patients with CNS disorders, the physical immobility of some patients tends to be a major hurdle to those taking part in studies for long periods of time. Frequent hospital visits and the exhaustive evaluation processes of the clinical trials restrict patient compliance.

— Saloni Gupta is an Analyst, Clinical Trials, at GBI Research.

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