Outcomes
Outcomes evaluate the impact of disease. In rheumatology they span measures of disease activity, end-organ damage, and quality of life. Some outcomes are categorical, such as the presence or absence of remission. Other outcomes involve extended numeric scales such as joint counts, radiographic scores, and quality of life measures. Outcomes can be measured in the short term—weeks and months—or over years and decades. Short-term outcomes, though readily related to treatment, may have less relevance for patients. Clinical trials focus on short-term outcomes whereas observational studies explore longer-term outcomes. The matrix of rheumatic disease outcomes is exemplified by rheumatoid arthritis. Its outcomes span disease activity assessments like joint counts, damage assessed by erosive scores, quality of life evaluated by disease-specific measures like the Health Assessment Questionnaire (HAQ) or generic measures like the Short Form 36 (SF-36), overall assessments like remission, and end result such as joint replacement or death. Outcome measures are used to capture the impact of treating rheumatic diseases, and are influenced by both disease severity and the effectiveness of treatment. However, they are also influenced by a range of confounding factors. Demographic factors like age, gender, and ethnicity can all have crucial impacts. Deprivation is important, as poverty invariably worsens outcomes. Finally, comorbidities affect outcomes and patients with multiple comorbid conditions usually have worse quality of life with poorer outcomes for all diseases. These multiple confounding factors mean comparing outcomes across units without adjustment will invariably show major differences.