Prediction of primary non-response to methotrexate therapy using demographic, clinical and psychosocial variables: results from the UK Rheumatoid Arthritis Medication Study (RAMS) oleh Jamie C. Sergeant, Kimme L. Hyrich, James Anderson, Kamilla Kopec-Harding, Holly F. Hope, Deborah P. M. Symmons, RAMS Co-Investigators, Anne Barton, Suzanne M. M. Verstappen