Figure 2
![Figure 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2F1756-0500-7-227/MediaObjects/13104_2013_Article_2741_Fig2_HTML.jpg)
Mean RMDQ over time using all available paper-only data and CATI-only data. Bars indicate 95% confidence interval. RMDQ: modified Roland Morris Disability Questionnaire (0-23 where higher scores reflect worse back pain-related function); CATI: computer assisted telephone interview.