Finalisation and validation of the rheumatoid arthritis impact of disease score, a patient-derived composite measure of impact of rheumatoid arthritis: a EULAR initiative - Gossec, L.; Paternotte, S.; Aanerud, G. J.; Balanescu, A.; Boumpas, D. T.; Carmona, L.; de Wit, M.; Dijkmans, B. A.; Dougados, M.; Englbrecht, M.; Gogus, F.; Heiberg, T.; et al. (Ann Rheum Dis, 2011)