Table 2 Covariates and outcome of adult bicycle traffic accident helmet users and nonusers before and after propensity score matching (1:1 matching)
Before matching | After matching | |||||||
|---|---|---|---|---|---|---|---|---|
Covariates | Helmet use Yes n = 76 | Helmet use No n = 647 | Odds ratio (95%CI) | P | Helmet use Yes n = 76 | Helmet use No n = 76 | Mean Difference | Standardized Difference |
Age | 48.8 ± 13.7 | 63.1 ± 15.6 | — | <0.001 | 48.8 ± 13.7 | 48.7 ± 13.8 | 0.09211 | 0.67(%) |
Sex | ||||||||
Male | 60(78.9) | 355(54.9) | 3.1(1.74–5.47) | <0.001 | 60(78.9) | 60(78.9) | 1.0(0.46–2.18) | 0.00(%) |
Female | 16(21.1) | 292(45.1) | 0.3(0.18–0.58) | <0.001 | 16(21.1) | 16(21.1) | 1.0(0.46–2.18) | 0.00 (%) |
Comorbidity | ||||||||
DM | 3(3.9) | 86(13.3) | 0.3(0.08–0.87) | 0.019 | 3(3.9) | 3(3.9) | 1.0(0.20–5.12) | 0.00 (%) |
HTN | 12(15.8) | 221(34.2) | 0.4(0.19–0.68) | 0.001 | 12(15.8) | 12(15.8) | 1.0(0.42–2.39) | 0.00 (%) |
CAD | 1(1.3) | 22(3.4) | 0.4(0.05–2.85) | 0.498 | 1(1.3) | 1(1.3) | 1.0(0.06–16.29) | 0.00 (%) |
CHF | 0(0.0) | 4(0.6) | — | 1.000 | 0(0.0) | 0(0.0) | — | — |
CVA | 0(0.0) | 28(4.3) | — | 0.063 | 0(0.0) | 0(0.0) | — | — |
ESRD | 0(0.0) | 2(0.3) | — | 1.000 | 0(0.0) | 0(0.0) | — | — |
Outcome | ||||||||
GCS | 14.5 ± 2.4 | 14.2 ± 2.4 | — | 0.303 | 14.5 ± 2.4 | 14.2 ± 2.6 | — | 0.538 |
≤ 8 | 3(3.9) | 34(5.3) | 0.7(0.22–2.47) | 0.788 | 3(3.9) | 4(5.3) | 0.7(0.16–3.42) | 1.000 |
9–12 | 0(0.0) | 31(4.8) | — | 0.065 | 0(0.0) | 2(2.6) | — | 0.497 |
≥ 13 | 73(96.1) | 582(90.0) | 2.7(0.83–8.87) | 0.085 | 73(96.1) | 70(92.1) | 2.1(0.50–8.67) | 0.494 |
AIS ≥ 3, n (%) | ||||||||
Head/Neck | 9(11.8) | 166(25.7) | 0.4(0.19–0.80) | 0.008 | 9(11.8) | 14(18.4) | 0.6(0.24–1.47) | 0.258 |
Face | 0(0.0) | 1(0.2) | — | 1.000 | 0(0.0) | 0(0.0) | — | — |
Thorax | 4(5.3) | 33(5.1) | 1.0(0.36–3.00) | 1.000 | 4(5.3) | 3(3.9) | 1.4(0.29–6.26) | 1.000 |
Abdomen | 0(0.0) | 7(1.1) | — | 1.000 | 0(0.0) | 0(0.0) | — | — |
Extremity | 20(26.3) | 208(32.1) | 0.8(0.44–1.29) | 0.301 | 20(26.3) | 19(25.0) | 1.1(0.52–2.22) | 0.853 |
ISS, median (IQR) | 5.5(4–9) | 9(4–10) | — | 0.029 | 5.5(4–9) | 7(4–10) | — | 0.808 |
< 16 | 68(89.5) | 523(80.8) | 2.0(0.94–4.30) | 0.065 | 68(89.5) | 63(82.9) | 1.8(0.68–4.51) | 0.240 |
16–24 | 5(6.6) | 88(13.6) | 0.4(0.18–1.14) | 0.084 | 5(6.6) | 11(14.5) | 0.4(0.14–1.26) | 0.113 |
≥ 25 | 3(3.9) | 36(5.6) | 0.7(0.21–2.32) | 0.788 | 3(3.9) | 2(2.6) | 1.5(0.25–9.37) | 1.000 |
Hospital LOS (days) | 7.0 ± 9.5 | 8.9 ± 10.2 | — | 0.116 | 7.0 ± 9.5 | 6.7 ± 6.4 | — | 0.858 |
ICU | ||||||||
Patients, n (%) | 9(11.8) | 139(21.5) | 0.5(0.24–1.01) | 0.049 | 9(11.8) | 11(14.5) | 0.8(0.31–2.04) | 0.631 |
< 16 | 4(5.3) | 38(5.9) | 0.9(0.31–2.57) | 1.000 | 4(5.3) | 1(1.3) | 4.2(0.46–38.17) | 0.367 |
16–24 | 2(2.6) | 69(10.7) | 0.2(0.05–0.94) | 0.026 | 2(2.6) | 8(1.1) | 0.2(0.05–1.12) | 0.050 |
≥ 25 | 3(3.9) | 32(4.9) | 0.8(0.24–2.64) | 1.000 | 3(3.9) | 2(2.6) | 1.5(0.25–9.37) | 1.000 |
ICU LOS (days) | 11.0 ± 20.1 | 7.4 ± 9.5 | — | 0.612 | 11.0 ± 20.1 | 4.3 ± 2.3 | — | 0.346 |
Mortality | 4(5.3) | 24(3.7) | 1.4(0.49–4.27) | 0.524 | 4(5.3) | 3(3.9) | 1.3(0.30–5.96) | 0.706 |