Table 1. Odds ratios (ORs) and 95% confidence intervals (CIs) for ossification of the posterior longitudinal ligament of the spine according to life style in the prime of life (between 30 and 50 years).
| Factors | Crude OR (95% CI) | Adjusted OR (95% CI) | |
| Sleeping hours | |||
| Moderate (6-8 h/d) / Short (5h/d or less) and long ( 9h/d or more) | 0.24 (0.09, 0.59)*1 | 0.18 (0.06, 0.54)*7 | |
| Had regular sleeping habits | Yes/ No | 0.48 (0.27, 0.88)*2 | 0.44 (0.22, 0.90)*8 |
| Had | Insufficient sleep/ Sufficient sleep | 3.10 (1.31, 7.01)*2 | 1.85 (0.70, 4.91)*8 |
| Moderate physical exercise | |||
| Once a week and more/ Less than once a week | 0.86 (0.44, 1.70)*3 | 0.97 (0.42, 2.26)*9 | |
| Smoking habit | Current smokers/Never smokers, ex-smokers | 1.37 (0.74, 2.54)*4 | 1.41 (0.67, 2.97)*10 |
| Drinking habit | Once a week and more/ Less than once a week | 1.03 (0.57, 1.88)*5 | 1.08 (0.53, 2.20)*11 |
| Had a hangover | Once a week and more/ Less than once a week | 6.86 (1.37, 32.24)*6 | 1.12 (0.43, 2.94)*12 |
Adjusted OR: adjusted for high body mass index (25.0 or greater) and diabetes mellitus.
* The number of cases and controls used for analysis.
*1:68 cases and 127 controls, *2: 68 cases and 133 controls, *3: 65 cases and 121 controls, *4:63 cases and 121 controls, *4: 67 cases and 127 controls, *5: 67 cases and 121 controls, *6: 57 cases and 104 controls, *7: 66 cases and 119 controls, *8: 66 cases and 122 controls, *9: 64 cases and 112 controls, *10: 60 cases and 114 controls, *11: 64 cases and 112 controls, *12: 57 cases and 98 controls