Added value of combining methotrexate with a biological agent compared to biological monotherapy in rheumatoid arthritis patients: A systematic review and meta-analysis of randomis... by Tarp, S, Jørgensen, TS, Furst, DE, Dossing, A, Taylor, PC, Choy, EH, Suarez-Almazor, ME, Lyddiatt, A, Kristensen, LE, Bliddal, H, Christensen, R