Multicenter trial

A multicenter research trial is a clinical trial conducted at more than one medical center or clinic. Most large clinical trials, particularly Phase III trials, are conducted at several clinical research centers. The benefits of multicenter trials include a larger number of participants, different geographic locations, the possibility of inclusion of a wider range of population groups, and the ability to compare results among centers, all of which increase the generalizability of the study. In many cases, efficacy will vary significantly between population groups with different genetic, environmental, and ethnic or cultural backgrounds ("demographic" factors); normally only geographically dispersed trials can properly evaluate this.

Competitive enrollment
Enrollment should be competitive. If the subject recruitment rate is lower than expected at one centre and higher than expected at another, planned allocation numbers should be transferred from the centre with low subject recruitment to a centre with high recruitment where subject inclusion is expected to be completed earlier than planned. This will be done to help ensure that subject enrollment is completed as planned.

Set up costs
The low set up costs should be negotiated in order to enable to sign agreements with larger number of sites.

Expected subject recruitment rate
Expected subject recruitment rate should be evaluated. Subject enrollment ends when the planned number of subjects is reached. The recruitment rates estimate should be based on retrospective data provided by the investigator(s) from previous studies, i.e., on the number of subjects who would have satisfied the proposed  inclusion/exclusion criteria in the past. The investigator(s) should make every effort to ensure that the planned accrual rate is maintained, that CRF’s are completed promptly and completely, and that data quality is maintained at all times. The investigator(s) should discuss with the monitor any anticipated problems with recruitment or delays in study completion.

Number of sites for the study depends on estimated recruitment rates.

Although, without outside assistance, the typical site may recruit as few as one-fifth of the patients it promised to deliver originally. Some may recruit none, taking their setup money and contributing nothing more, or recruit only one patient so that there is no offsetting control.

Additional reading
Role of ICH GCP and Recruitment Strategies Training of Clinical Sites Staff in Successful Patient Recruitment Rates By Marithea Goberville, Ph.D.IBPA Publications 2005