Can we develop simple response criteria for slow acting antirheumatic drugs?

The conventional assessment of response to slow acting antirheumatic drugs depends on multiple clinical and laboratory measures. Each measure is analysed separately. For clinical practice and therapeutic trials a single unified classification of response is preferable, based on the most sensitive and simple current measures. Whether or not this was practical was determined in a prospective study of two cohorts of patients: 145 given penicillamine 250-500 mg daily in a single dose; 98 sulphasalazine at an initial dose of 500 mg rising after one month to 2 g daily. Both groups were followed up for 12 months. A panel of 11 clinical and laboratory measures were evaluated every three to six months. Most changes had occurred by six months, and this was the optimum time to classify response. Four measures were used to devise a five point (0-4) classification of response from no change to remission. The objective was to evaluate if this approach is appropriate; the best level of each measure to use was not determined. The response index was based on: erythrocyte sedimentation rate less than 30 mm/h; articular index less than 3; morning stiffness less than 15 min; greater than 50% reduction in joint pain. Similar results were obtained with both drugs. The other clinical and laboratory measures gave limited information. This response index is simple and appropriate. It is suitable for use in clinical practice and drug studies, though the optimal values for dividing each clinical and laboratory variable need to be determined.