Evaluation of the long term effect of antirheumatic drugs with the survey rate method

: In the long term study of antirheumatic drugs, drop out of patients (for failure of effect or side effects) can analysed with "survey rate" methods. Survey rates become in drug tests "treatment continuation rates". With this method D-penicillamine and levamisole have been compared. Penicillamine has better "continuation rate" not because of better tolerance, but because of better long term effectiveness compared with levamisole.