Incidence rates and hazard ratios for driver injury during the total follow up period, by indicators of socioeconomic status
| Hazard ratio (95% CI), Adjusted for:† | ||||||
|---|---|---|---|---|---|---|
| Socioeconomic status | Cases (n) | Person years | Incidence rate* | Age and sex | Age, sex, cohort, alcohol, and driving exposure | Age, sex, cohort, alcohol, driving exposure, area of residence, marital status, BMI, and either educational level or occupational status‡ |
| *Cases per 10 000 person years. | ||||||
| †Age and occupational status were fitted as continuous variables, while the following were fitted as categorical variables: sex (two levels), cohort (two levels), maximum daily alcohol intake (four levels), driving exposure (two variables: driving exposure estimated from the New Zealand Household Travel Survey, five levels; work related driving exposure, four levels), area of residence (three levels), marital status (three levels), body mass index (BMI, five levels) and educational level (four levels). p Values are for linear trend. | ||||||
| ‡The educational and neighbourhood income models were adjusted for occupational status, whereas the occupational status model was adjusted for educational level. | ||||||
| Educational level | ||||||
| University/polytechnic | 38 | 40 398 | 9.4 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Secondary >3 years | 35 | 24 222 | 14.4 | 1.42 (0.90 to 2.25) | 1.24 (0.75 to 2.03) | 0.87 (0.51 to 1.49) |
| Secondary 2–3 years | 38 | 20 788 | 18.3 | 2.15 (1.37 to 3.37) | 2.05 (1.27 to 3.30) | 1.41 (0.84 to 2.39) |
| Secondary <2 years | 25 | 19 829 | 12.6 | 2.26 (1.34 to 3.81) | 1.73 (0.96 to 3.14) | 1.30 (0.69 to 2.46) |
| Missing | 3 | 3 504 | 8.6 | (p for trend =0.007) | (p for trend =0.02) | (p for trend =0.22) |
| Occupational status | ||||||
| ISEI 60–85 | 14 | 23 220 | 6.0 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| ISEI 40–59 | 23 | 29 144 | 7.9 | 1.32 (0.67 to 2.59) | 1.04 (0.50 to 2.20) | 0.94 (0.44 to 1.99) |
| ISEI 30–39 | 27 | 26 804 | 10.1 | 1.50 (0.79 to 2.87) | 1.14 (0.57 to 2.29) | 1.12 (0.56 to 2.24) |
| ISEI 20–29 | 61 | 17 043 | 35.8 | 4.17 (2.31 to 7.55) | 3.55 (1.92 to 6.56) | 2.81 (1.49 to 5.31) |
| Missing | 14 | 12 530 | 11.2 | (p for trend <0.0001) | (p for trend <0.0001) | (p for trend =0.002) |
| Neighbourhood income | ||||||
| NZ$40000–NZ$69700 | 15 | 25 555 | 5.9 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| NZ$35000–NZ$39999 | 31 | 22 492 | 13.9 | 2.04 (1.10 to 3.78) | 1.44 (0.75 to 2.76) | 0.95 (0.44 to 2.04) |
| NZ$27500–NZ$34999 | 31 | 26 587 | 11.7 | 1.58 (0.85 to 2.93) | 1.23 (0.65 to 2.34) | 0.92 (0.45 to 1.89) |
| NZ$15000–NZ$27499 | 33 | 22 481 | 14.7 | 1.81 (0.98 to 3.35) | 1.34 (0.70 to 2.55) | 0.97 (0.47 to 2.01) |
| Missing | 29 | 11 626 | 24.9 | (p for trend =0.12) | (p for trend =0.48) | (p for trend =0.91) |