Factorial rating system for comparative efficacy of antiasthmatic medication: a multicentric study report

Faced with 1-year daily medication diaries from over 300 patients, each documenting the use of from one to five medications a day, we found it was necessary to devise a system which would reduce this data into a form which would allow a meaningful interpretation of changes of medications in a single patient or group of patients. Since the medications were principally steroids, beta agonists, or xanthines, representative agents were chosen as the standard for each class and the other medications were rated against them. A conversion factor was then determined to allow comparison between classes. Each medication taken by a patient could now be expressed as a single number and the sum of all the medications would be the individual's Asthma Medication Index. The AMI allowed (i) evaluation of a single patient over time, (ii) comparison of different patients at any single point or over a period of time, and (iii) evaluation of entire groups of patients over time as was the case in our evaluation of Zaditen. Application of the system allowed the differentiation of two therapeutic agents versus placebo during a 1-year study, revealing excellent correlation with the physician's global assessment of the patient's improvement. With proper modification of the basic drug groups and intergroup factor relationship, the Index can be adapted to any disease state where a change in concomitant medication is an indicator of therapeutic effect.