1. Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima;
2. Department of Neurological Surgery, Nippon Medical School Hospital, Tokyo;
3. Departments of Health Informatics and
4. Clinical Epidemiology, School of Public Health, Graduate School of Medicine, Kyoto University, Kyoto;
5. Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe;
6. Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka;
7. Department of Neurosurgery, Kyorin University School of Medicine, Tokyo;
8. Department of Neurological Surgery, Okayama University Graduate School of Medicine, Okayama;
9. Department of Neurosurgery, Shiga University of Medical Science, Shiga;
10. Department of Neurosurgery, University of Yamanashi;
11. Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo;
12. Department of Neurosurgery, The University of Tokyo;
13. Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai;
14. Department of Neurosurgery, Yamaguchi University School of Medicine, Ube;
15. Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
16. Department of Neurosurgery, Juntendo University, Tokyo, Japan