Organizing the Metro Firm System for research

During the mid-1970s, four similar groups of patients and providers were created with the institution of the Firm System at Cleveland Metropolitan General Hospital (Metro). In the early 1980s, ongoing randomization was initiated for patients and physicians, setting the stage for the performance of randomized controlled trials. Techniques such as stratification and blocking are used with randomization to ensure that equivalent numbers and characteristics of patients and physicians are distributed among the firms. Comparability of key patient and physician features across firms has been documented during the baseline periods of several recent firm studies. Dissimilarities among firms can occur secondary to differential drop-out of patients (residue cohort effect), or to administrative decisions that adversely affect the structural or operational integrity of the system. Prestudy evaluations of equivalence and vigilant system maintenance programs are methods to identify and minimize important differences among firms.