The PerPAIN trial: a pilot randomized controlled trial of personalized treatment allocation for chronic musculoskeletal pain—a protocol oleh E. Beiner, D. Baumeister, D. Buhai, M. Löffler, A. Löffler, A. Schick, L. Ader, W. Eich, A. Sirazitdinov, C. Malone, M. Hopp, C. Ruckes, J. Hesser, U. Reininghaus, H. Flor, J. Tesarz, PerPAIN consortium