Aspects of certainty in patient classification using a health-related quality-of-life instrument in inflammatory bowel disease.

The study has focused on deriving a certainty measure for the classification of disease activity in patients suffering from inflammatory bowel disease (IBD). The aim is to build an Internet-based health-related quality-of-life (HRQoL) questionnaire to continuously monitor a patient's condition. Data from 109 patients was collected four times in intervals of three months, using a standardized disease-specific quality-of-life questionnaire, the Rating Form of IBD Patient Concern (RFIPC), extended with 11 additional questions. Correlation analysis showed that the RFIPC items along with "general wellbeing" were highly correlated (significance < 0.001). Factor analysis confirmed this high correlation and only one factor was identified among those variables. Multivariate discriminant analysis was successful to 78.1% in classifying between cases of remission and relapse. Implementation of a smooth threshold function decreased the classification error. However, discrimination regarding change in disease activity over time has to be further improved.