Major issues in the organization and implementation of the National Cooperative Gallstone Study (NCGS).

The National Cooperative Gallstone Study (NCGS) was a cooperative, randomized, controlled trial of a drug, chenodiol, for the medical dissolution of gallstones. The design and procedures of the NCGS were complex, having developed as a result of extensive involvement of many experts in the field of gallstone disease and biliary lipids. During the design and implementation of the protocol, many important issues required consideration and resolution.

Recruitment for the National Cooperative Gallstone Study.

The National Cooperative Gallstone Study (NCGS) recruitment experience is reported, and the factors determining recruitment performance at a center are evaluated. Recruitment performance was grouped into four major areas: coordinating center, protocol, patient population, and treatment center. At the treatment centers, no relationship was found between performance and the prior experience of the clinic staff in clinical trials or expertise in gallstone research, lack of institutional support was not initially apparent, and ancillary studies did not appear to stimulate performance.