Acknowledgements
The authors thank M. Szymaniak-Vits, P. Otte, Dr. J. Waldschmidt, Prof. Dr. M. Hug, Dr. M. Ruch, PD Dr. M. Boeker, M. Naegele and S. Müller, all UKF for their significant support, fruitful discussion, and valuable suggestions. We are highly obliged to the DSMM, GMMG, EMN, and IMWG experts for their insightful comments that have inspired us to further improve the manuscript, to Daniel Textor for diligent data management using our MM database, and to Dr. Patrique Wolfrum for IT support.
Potential conflict of interest
Disclosure forms provided by the authors are available with the full text of this article online at https://doi.org/10.1080/10428194.2018.1448084.