Table 1

 Information on design, sample size, duration of follow up, disease duration, and quality criteria of the 17 studies

InformationReference number
328293023113323343427135363738
+, yes; –, no; P, prospective study; R, retrospective study; HQ, study of high quality; MQ, study of medium quality; LQ, study of low quality.
*Participants in the prospective studies must work at the start of the study, onset of RA must occur before work disability for the participants in the retrospective studies; †retrospective studies could not fulfil these criteria; ‡this research involved a population based study.
DesignPPPPPPRRRRPPPRRRR
Sample size (n)14983–‡73827321757206591198649743646916212269
Duration of follow up (years)921061058918
Disease duration (years)
Mean (SD)4 (1)0.5 (–)112 (1)5 (7)7 (–)13 (10)
Median8
Range0–20–10–20.5–10–21–42
Early RA (<5 years, %)10010010010010019251001003934
Late RA (>5 years, %)000008175006166
Quality criteria
1. Were patients diagnosed in line with (revised) ACR criteria?+++++++++++++
2. Was the sample representative?+++++++++++++++
3. Were the patients able to work at baseline?*++++++++++++++++
4. Was baseline response >80% and loss to follow up <30%?+++++++++++
5. Was the follow up >1 year?†+++++++++
6. Was work disability defined as stopping work owing to ill health/RA?++++++++++++
7. Was an external criterion used to assess work disability?+++++++
8. Was recall bias in the work disability assessment avoided?†++++++++
Total quality score (0–8)78788764456553333
Quality labelHQHQHQHQHQHQMQMQMQMQMQMQMQLQLQLQLQ