Table 2

 Approaches to studying work disability as a clinical endpoint in ankylosing spondylitis

Work statusStudy designEndpoint
Stably employedControlled trialNumber of sick days
Change in work hours
Change in type of work
Need for help at work
Employed but withControlled trialMaintenance of
threatened workCohort studyemployment
disability
Recently work disabledCohort studyReturn to work
Long-term workTime seriesSecular trend in rates of
disabledpermanent work disability