Developing Measures of Approval for Myositis

• Activity Number: 101
• Type: Topic Contributed
• Date/Time: Monday, August 9, 2004 : 10:30 AM to 12:20 PM
• Sponsor: WNAR
• Author(s): Peter A. Lachenbruch*+ and Lisa Rider and Frederick Miller
• Companies: U.S. Food and Drug Administration and National Institutes of Health and National Institutes of Health
• Keywords: myositis ; index development ; CART

Abstract

The myositis syndromes are a group of autoimmune diseases characterized by chronic inflammation of muscle resulting in muscle weakness. We obtained consensus rating of improvement from a panel of clinicians. They obtained consensus in 204 of 222 patients. We then selected the variables to develop the index based on the clinician's evaluation of the variable's usefulness.The clinicians ranked the variables on their importance in defining improvement, the number of the variables required for improvement, the amount of improvement in each variable that was needed, and how much worsening could be permitted. Six candidate variables were selected. Third, we developed candidate rules. These were similar to indices used in rheumatoid arthritis and lupus or from exploratory statistical analyses of the data. Fourth, we examined the sensitivity, specificity, positive predictive value, negative predictive value and Area Under the Curve (AUC) of the rules. Fifth, a panel of experts in the field selected promising candidate rules for improvement from a set of candidates that excluded poorly performing rules.