Table 2

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 statusCases (n)Person yearsIncidence rate*Age and sexAge, sex, cohort, alcohol, and driving exposureAge, 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/polytechnic3840 3989.41.00 (reference)1.00 (reference)1.00 (reference)
Secondary >3 years3524 22214.41.42 (0.90 to 2.25)1.24 (0.75 to 2.03)0.87 (0.51 to 1.49)
Secondary 2–3 years3820 78818.32.15 (1.37 to 3.37)2.05 (1.27 to 3.30)1.41 (0.84 to 2.39)
Secondary <2 years2519 82912.62.26 (1.34 to 3.81)1.73 (0.96 to 3.14)1.30 (0.69 to 2.46)
Missing33 5048.6(p for trend =0.007)(p for trend =0.02)(p for trend =0.22)
Occupational status
ISEI 60–851423 2206.01.00 (reference)1.00 (reference)1.00 (reference)
ISEI 40–592329 1447.91.32 (0.67 to 2.59)1.04 (0.50 to 2.20)0.94 (0.44 to 1.99)
ISEI 30–392726 80410.11.50 (0.79 to 2.87)1.14 (0.57 to 2.29)1.12 (0.56 to 2.24)
ISEI 20–296117 04335.84.17 (2.31 to 7.55)3.55 (1.92 to 6.56)2.81 (1.49 to 5.31)
Missing1412 53011.2(p for trend <0.0001)(p for trend <0.0001)(p for trend =0.002)
Neighbourhood income
NZ$40000–NZ$697001525 5555.91.00 (reference)1.00 (reference)1.00 (reference)
NZ$35000–NZ$399993122 49213.92.04 (1.10 to 3.78)1.44 (0.75 to 2.76)0.95 (0.44 to 2.04)
NZ$27500–NZ$349993126 58711.71.58 (0.85 to 2.93)1.23 (0.65 to 2.34)0.92 (0.45 to 1.89)
NZ$15000–NZ$274993322 48114.71.81 (0.98 to 3.35)1.34 (0.70 to 2.55)0.97 (0.47 to 2.01)
Missing2911 62624.9(p for trend =0.12)(p for trend =0.48)(p for trend =0.91)