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Meyer K, Niedermann K, Tschopp A, et al. Is the work ability index useful to evaluate absence days in ankylosing spondylitis patients? A cross-sectional study. BMJ Open 2013;3:e002231.
The affiliations of the fourth author, Andreas Klipstein, should be: Department of Rheumatology University Hospital Zürich, Zurich, Switzerland, and Center of Occupational Health, Zurich, Switzerland.
