The organization of cooperative effort by multiple hospitals, exemplified by testing of therapeutic agents in rheumatoid arthritis.

The advantage of a multi-center clinical investigation lies in the possibility of obtaining conclusive results on the basis of relatively few numbers of patients from each of the participating institutions. It has the disadvantage of a lack of uniformity of methods among centers, which must be overcome by careful advance planning, including the institution of a central coordinating unit, the biometrical unit. Its functions include (1) participation in the planning of all phases of the investigation, (2) editing and processing of the data, and (3) analysis of the data and evaluation of results. Three devices for promoting uniformity of methods are: (1) the protocal, (2) specially designed record forms, and (3) visits to participating centers by a team of observers, including the statistician. The protocol is the document which contains all important specification for the conduct of the investigation, including statement of purpose of the study, definition of the study population, and explicit instructions on methods of patient assessment. In a clinical trial, the biometrical unit prepares the random allocation of treatments to patients. Stratification may be used to make comparisons between strata, and/or increase the sensitivity of the experiment. Stratification by exclusion may increase sensitivity at the cost of restricting the generality of results. A well-planned multi-center study, in which the members really cooperate, may achieve objectives exceeding the scope of single-center studies and provide a setting for the fruitful exchange of knowledge and ideas.