| Risk factor | Participants () | ESS >10 OR (95 CI) | Sleepy at the wheel OR (95 CI) | Fatigue-related clinical error OR (95 CI) |
| Gender | ||||
| Male | 51.5 | 1.00 | 1.00 | 1.00 |
| Female | 48.5 | 1.34 (1.02 to 1.78) | 1.18 (0.90 to 1.57) | 1.02 (0.79 to 1.33) |
| Ethnicity | ||||
| Non-Maori New Zealanders | 70.0 | 1.00 | Univariate NS | 1.00 |
| New Zealand Maori | 3.6 | 1.43 (0.70 to 2.94) | 0.94 (0.47 to 1.87) | |
| Other | 26.4 | 1.74 (1.27 to 2.37) | 0.59 (0.43 to 0.81) | |
| Age (years) | ||||
| 2026 | 24.3 | Univariate NS | 1.00 | 1.00 |
| 2729 | 27.9 | 0.96 (0.62 to 1.48) | 0.75 (0.51 to 1.10) | |
| 3033 | 25.1 | 0.76 (0.46 to 1.23) | 0.62 (0.39 to 0.97) | |
| 3457 | 22.7 | 0.59 (0.35 to 1.00) | 0.62 (0.38 to 1.04) | |
| Living with dependants | ||||
| No | 72.7 | Univariate NS | 1.00 | 1.00 |
| Yes | 27.3 | 0.91 (0.63 to 1.31) | 1.20 (0.83 to 1.73) | |
| Career status | ||||
| Registrar | 60.7 | 1.00 | 1.00 | 1.00 |
| House officer | 39.3 | 1.29 (0.97 to 1.72) | 1.48 (1.04 to 2.11) | 1.78 (1.28 to 2.46) |
| Commuting time (min) | ||||
| 115 | 49.2 | Univariate NS | 1.00 | Univariate NS |
| 1630 | 40.8 | 1.89 (1.41 to 2.53) | ||
| >30 | 10.1 | 3.13 (1.86 to 5.28) | ||
| Days worked, past 2 weeks (n) | ||||
| 010 | 40.3 | Univariate NS | 1.00 | Univariate NS |
| >10 | 59.7 | 1.10 (0.83 to 1.47) | ||
| Hours worked, past 2 weeks | ||||
| No excess | 39.7 | 1.00 | Univariate NS | Univariate NS |
| Small excess | 41.5 | 0.96 (0.69 to 1.34) | ||
| Large excess | 18.8 | 1.54 (1.02 to 2.33) | ||
| 2 Shifts/week >14 hours | ||||
| No | 59.3 | Univariate NS | 1.00 | 1.00 |
| Yes | 40.7 | 1.10 (0.82 to 1.48) | 1.11 (0.79 to 1.54) | |
| Night duty, past 2 weeks | ||||
| 1 Night in both weeks | 64.1 | 1.00 | 1.00 | 1.00 |
| 2 in at least 1 week | 8.0 | 1.51 (0.90 to 2.52) | 1.08 (0.63 to 1.86) | 0.96 (0.57 to 1.61) |
| 3 in one or both weeks | 27.9 | 1.53 (1.02 to 2.33) | 1.53 (1.11 to 2.12) | 1.37 (1.03 to 1.84) |
| Breaks <10 hours, past 2 weeks (n) | ||||
| None | 36.5 | 1.00 | Univariate NS | 1.00 |
| 1 a week | 27.9 | 1.21 (0.84 to 1.76) | 0.96 (0.69 to 1.43) | |
| >1 in at least 1 week | 35.6 | 1.47 (0.97 to 2.22) | 1.27 (0.87 to 1.85) | |
| Schedule changes, past 2 weeks | ||||
| No changes | 53.9 | 1.00 | 1.00 | 1.00 |
| Change in one week | 17.3 | 1.35 (0.92 to 1.96) | 1.60 (1.08 to 2.35) | 1.33 (0.93 to 1.88) |
| Change in both weeks | 28.8 | 1.81 (1.31 to 2.50) | 1.78 (1.28 to 2.48) | 0.99 (0.73 to 1.34) |
| Adequate supervision | ||||
| Never/rarely/sometimes | 28.4 | 1.00 | 1.00 | 1.00 |
| Often/always | 71.6 | 0.67 (0.50 to 0.91) | 0.60 (0.43 to 0.82) | 0.68 (0.51 to 0.91) |
| Total risk score, past week | ||||
| Lower | 36.9 | 1.00 | 1.00 | 1.00 |
| Significant | 31.4 | 1.85 (1.30 to 2.63) | 1.53 (1.10 to 2.13) | 1.31 (0.95 to 1.80) |
| Higher | 31.7 | 3.54 (2.51 to 4.98) | 2.33 (1.65 to 3.30) | 1.85 (1.35 to 2.53) |
The house officer category includes both house surgeons and senior house officers.