The present and future of comprehensive outcome measures for rheumatic diseases

In recent years, outcome, or health status, measurement has received wide attention in rheumatology. These measures are based on the concept of maintaining or improving health as the goal of medical care, the World Health Organization (WHO) definition of health, and measurement of those factors that directly impact the patient rather than the traditional measures of disease process. Within this framework, outcomes important to the patient with rheumatic diseases have been identified. They have been conceptualized in general terms of physical, psychological and social functioning or specifically by dimensions of death, disability, discomfort, side effects and economic costs. Two widely used outcome measures, the health assessment questionnaire (HAQ) and the arthritis impact measurement scales (AIMS), are described. Outcomes are measured by patient self-reported questionnaires which have been rigorously tested to establish the measurement properties of reliability and validity. Results show that patient self-report is valid, outcomes are accurately measured, correlate with traditional endpoints, and are sensitive to change over time. These measures are particularly suited for use in follow-up studies because of their simplicity, ease of administration, and cost. Future directions include additional study to define clinically meaningful change, extension of validations to many of the rheumatic diseases, the design of special purpose questionnaires and the development of the cumulative outcome concept.