**5. Conclusions**

This study is the first prospective multicenter cross-sectional comparison of subjective outcomes in patients with cervical OPLL according to the presence or absence of DISH. There were no significant correlations between DISH grade and clinical scores. However, there was a significant difference in the prevalence of neck pain among the three grades, albeit not in the prevalence of back pain or LBP. Interestingly, DISH localized in the thoracic spine (grade 1) could create overload at the cervical spine and lead to neck pain in patients with cervical OPLL.

**Author Contributions:** Conceptualization, T.H., S.N., T.Y., K.M. (Kanji Mori), S.U., S.M., K.K., N.N. (Narihito Nagoshi) and Y.K.; Methodology, T.H.; Software, T.H., S.U. and N.N. (Narihito Nagoshi); Validation, T.H., T.Y., K.M. (Kazuma Murata), S.U., S.M., K.K., N.N. (Narihito Nagoshi); Formal Analysis, T.H. and N.N. (Narihito Nagoshi); Investigation, K.M. (Kanji Mori), T.Y., T.H., N.N. (Narihito Nagoshi), S.N., K.T. (Kazuhiro Takeuchi), S.M. and K.K.; Resources, M.M., M.Y. (Masashi Yamazaki) and A.O.; Data Curation, T.H., T.Y., K.M. (Kanji Mori), S.U., S.M., K.K., N.N. (Narihito Nagoshi), M.M., M.N., K.W. (Kota Watanabe) and Y.K.; Conceptualization, T.H., T.Y., S.U., J.H., K.M. (Kanji Mori), S.M., K.K., N.N. (Narihito Nagoshi), K.T. (Katsushi Takeshita), T.F., K.W. (Kei Watanabe), N.N. (Norihiro Nishida), K.W. (Kota Watanabe), T.K., S.K., K.N., M.K., H.I., S.I., Y.M. (Yuji Matsuoka), K.W. (Kanichiro Wada), A.K., T.O., H.K., H.O., Y.M. (Yu Matsukura), H.I. and Y.K.; Writing—Original Draft Preparation, T.H., S.N., H.H., Y.M. (Yukihiro Matsuyama), K.T. (Katsushi Takeshita), H.O., A.O. and Y.K.; Writing—Review and Editing, T.H., S.N., T.Y., S.U., K.M. (Kanji Mori), S.M., K.K., N.N. (Norihiro Nishida), K.T. (Kazuhiro Takeuchi), T.F., K.W. (Kei Watanabe), N.N. (Norihiro Nishida), K.W. (Kota Watanabe), T.K., S.K., K.N., M.K., H.N., S.I., Y.M. (Yukihiro Matsuyama), K.W. (Kanichiro Wada), A.K., T.O., H.K., H.O. and Y.K.; Visualization, T.H., N.N. (Narihito Nagoshi), K.M.(Kazuma Murata) and S.U.; Supervision, M.M., M.W., M.N., M.Y., A.O. and Y.K.; Project Administration, T.H and Y.K.; Funding Acquisition, M.M., M.Y. and A.O. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was funded by a Health and Labour Science Research gran<sup>t</sup> (number 201610008B) and a gran<sup>t</sup> from the Japan Agency for Medical Research and Development (number 16ek0109136h0002).

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the institutional review board of each participating institution (protocol code 28-34; 14 March 2017).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study. **Data Availability Statement:** The data generated and analyzed in this study are available from the corresponding author upon reasonable request.

**Acknowledgments:** We thank Nobuko Nakajima, Tomomi Kobayashi, Namiko Katayama, and Yukiko Oya for data collection.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
