An easily customized, random allocation system using the minimization method for multi-institutional clinical trials

In a randomized clinical trial, random allocation of patients to treatment groups should be done to balance in the distribution of prognostic factors. Random allocation in a multi-institutional randomized clinical trial is conducted by a coordinating center, independent of the medical institution the attending doctor uses for his/her practice. This study provides a sophisticated system for doing an exact random allocation of patients to treatment groups. The minimization method proposed by Pocock was applied to this system to balance the distribution of prognostic factors between two treatment groups, even when the number of registered patients is relatively small (S.J. Pocock, Allocation of patients to treatment in clinical trial, Biometrics 35 (1979) 183-197). Furthermore, Zelen's method is used to balance the number of patients allocated to the two groups within each institution (M. Zelen, The randomization and stratification of patients to clinical trials, J. Chron. Dis. 27 (1974) 365-375.). This system was created by the 'PERL’ language for writing common gateway interface (CGI) script, and can therefore, be easily extended to include data entry function by attending doctors as well as the random allocation function. This system is being used effectively in thirteen multi-institutional randomized clinical trials for stomach, colon-rectum and breast cancers in Japan.