spectrum of disease activity, previous treatment and comorbid- ity, unmeasured confounders might include patient preferences and compliance. In summary we have demonstrated the importance of time to ﬁrst DMARD/S treatment, response to ﬁrst DMARD/S and total duration of DMARD treatment over a 10-year time period in patients with early IP using state-of-the-art statistical methods to adjust for time varying confounding. Acknowledgements We are grateful to the general practitioners and rheumatologist in the Norwich area for their continuing support of NOAR and acknowledge the con- tribution of the NOAR metrologists in the collection of the clinical data, and database manager Stephanie Manning. Funding All work was funded by the Arthritis Research Campaign, UK, arc grant reference no: 17552. Competing interests None. Ethics approval This study was conducted with the approval of the Norwich Research Ethics Committee. Provenance and peer review Not commissioned; externally peer reviewed. 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