Background
Methods
Design, setting and participants
Crash outcome data
Insurance claims
Hospital discharge and mortality data
Police reports
Follow-up survey
Analyses
Capture- recapture analysis
Comparison with self-reports
Results
Baseline Characteristics | N | % |
---|---|---|
Total
|
2590
| |
Age (years)
| ||
16-35 | 579 | 22.4 |
36-50 | 1351 | 52.2 |
51+ | 660 | 25.5 |
Gender
| ||
Male | 1874 | 72.4 |
Female | 715 | 27.6 |
Ethnicity
| ||
Māori | 104 | 4.0 |
Non-Māori | 2486 | 96.0 |
Level of education
| ||
High school (secondary) or less | 535 | 20.7 |
Polytechnic | 654 | 25.3 |
University | 1395 | 53.9 |
Missing | 6 | 0.2 |
NZDep2006 scores*
| ||
1-3 | 1292 | 49.9 |
4-7 | 919 | 35.5 |
8-10 | 343 | 13.2 |
Missing | 36 | 1.4 |
Urbanity of residence
| ||
Main urban area | 2013 | 77.7 |
Others | 541 | 20.9 |
Missing | 36 | 1.4 |
Region of residence
| ||
Auckland | 919 | 35.5 |
Wellington | 534 | 20.6 |
Others | 1101 | 42.5 |
Missing | 36 | 1.4 |
Bicycle crashes reported at the follow-up survey
No. of crashes (No. of participants) | |||
---|---|---|---|
All crashes | On-road crashes | Collisions | |
Total crashes experienced in the preceding year | 784 (432) | 450 (324) | 140 (106) |
Crashes claimed to ACC | 228 (173) | 49 (41) | |
Crashes requiring hospital admission | 29 (29) | 10 (10) | |
Crashes reported to police | 51 (48) | 46 (44) |
Bicycle crashes identified through record linkage
ACC | NMDS | CAS | No. of crashes | % of total crashes |
---|---|---|---|---|
All crashes
| ||||
1 | 1 | 1 | 18 | 1.3 |
0 | 1 | 1 | 0 | 0.0 |
1 | 0 | 1 | 19 | 1.4 |
0 | 0 | 1 | 9 | 0.7 |
1 | 1 | 0 | 104 | 7.8 |
0 | 1 | 0 | 16 | 1.2 |
1 | 0 | 0 | 1170 | 87.6 |
Total
| 1336 | |||
On road crashes
| ||||
1 | 1 | 1 | 18 | 2.4 |
0 | 1 | 1 | 0 | 0.0 |
1 | 0 | 1 | 19 | 2.5 |
0 | 0 | 1 | 9 | 1.2 |
1 | 1 | 0 | 72 | 9.5 |
0 | 1 | 0 | 11 | 1.5 |
1 | 0 | 0 | 626 | 82.9 |
Total
| 755 | |||
Collisions with a motor vehicle
| ||||
1 | 1 | 1 | 18 | 15.0 |
0 | 1 | 1 | 0 | 0.0 |
1 | 0 | 1 | 17 | 14.2 |
0 | 0 | 1 | 7 | 5.8 |
1 | 1 | 0 | 7 | 5.8 |
0 | 1 | 0 | 3 | 2.5 |
1 | 0 | 0 | 68 | 56.7 |
Total
| 120 |
Completeness of the linked data
Model | Variables included | Estimate | SE | AIC | AIC weight | Weighted estimate | Unconditional SE |
---|---|---|---|---|---|---|---|
All crashes
| |||||||
1 | ACC NMDS CAS | 5.23 | 0.22 | 84.87 | 0.00000003 | 0.00000014 | 0.00000001 |
2 | ACC NMDS CAS ACC*NMDS | 5.75 | 0.37 | 84.48 | 0.00000003 | 0.00000019 | 0.00000001 |
3 | ACC NMDS CAS ACC*CAS | 5.06 | 0.27 | 85.32 | 0.00000002 | 0.00000011 | 0.00000001 |
4 | ACC NMDS CAS NMDS*CAS | 5.33 | 0.22 | 54.87 | 0.09009773 | 0.48066236 | 0.03346642 |
5 | ACC NMDS CAS ACC*NMDS NMDS*CAS | 6.32 | 0.41 | 50.37 | 0.85614943 | 5.40872405 | 0.07995839 |
6 | ACC NMDS CAS ACC*CAS NMDS*CAS | 5.19 | 0.27 | 55.90 | 0.05375276 | 0.27913806 | 0.02753761 |
Model-averaged estimate | 6.17 | ||||||
Unconditional SE | 0.14 | ||||||
On-road crashes
| |||||||
1 | ACC NMDS CAS | 4.61 | 0.24 | 75.99 | 0.0000010926 | 0.0000050416 | 0.0000005142 |
2 | ACC NMDS CAS ACC*NMDS | 5.15 | 0.37 | 75.19 | 0.0000016262 | 0.0000083754 | 0.0000002457 |
3 | ACC NMDS CAS ACC*CAS | 4.38 | 0.32 | 76.40 | 0.0000008888 | 0.0000038942 | 0.0000006566 |
4 | ACC NMDS CAS NMDS*CAS | 4.74 | 0.25 | 53.42 | 0.0870396250 | 0.4128898692 | 0.0311739533 |
5 | ACC NMDS CAS ACC*NMDS NMDS*CAS | 5.69 | 0.41 | 48.83 | 0.8633010530 | 4.9139959238 | 0.0796703971 |
6 | ACC NMDS CAS ACC*CAS NMDS*CAS | 4.56 | 0.33 | 54.54 | 0.0496557143 | 0.2264598505 | 0.0271116407 |
Model-averaged estimate | 5.55 | ||||||
Unconditional SE | 0.14 | ||||||
Collisions with a motor vehicle
| |||||||
1 | ACC NMDS CAS | 2.45 | 0.36 | 60.47 | 0.0002105079 | 0.000514923 | 0.0000677993 |
2 | ACC NMDS CAS ACC*NMDS | 2.75 | 0.43 | 61.24 | 0.0001433835 | 0.000393918 | 0.0000255905 |
3 | ACC NMDS CAS ACC*CAS | 2.40 | 0.62 | 62.46 | 0.0000777519 | 0.000186721 | 0.0000374729 |
4 | ACC NMDS CAS NMDS*CAS | 2.78 | 0.37 | 45.81 | 0.3216029517 | 0.895471259 | 0.0453152851 |
5 | ACC NMDS CAS ACC*NMDS NMDS*CAS | 3.33 | 0.47 | 44.94 | 0.4970883194 | 1.656397698 | 0.0609100608 |
6 | ACC NMDS CAS ACC*CAS NMDS*CAS | 3.37 | 0.70 | 46.96 | 0.1808770856 | 0.609953708 | 0.0483519920 |
Model-averaged estimate | 3.18 | ||||||
Unconditional SE | 0.15 |
Agreement between the linked and self-reported data
Agreement N (%) | Disagreement N (%) | % Total agreement | Kappa (95% CI) | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | |||
---|---|---|---|---|---|---|---|---|---|---|
Both yes | Both no | SR yes LD no | SR no LD yes | |||||||
All crashes
| ||||||||||
At least one crash claimed to ACC | 114 (7.8) | 1201 (82.5) | 59 (4.1) | 82 (5.6) | 90.3 | 0.56 (0.50, 0.63) | 65.9 (58.3, 72.8) | 93.6 (92.1, 94.9) | 58.2 (50.9, 65.1) | 95.3 (94.0, 96.4) |
At least one crash requiring overnight hospital admission | 10 (0.7) | 1415 (97.8) | 18 (1.3) | 12 (0.2) | 98.5 | 0.47 (0.28, 0.66) | 34.5 (18.6, 54.3) | 99.8 (99.3, 100.0) | 76.9 (50.0, 93.8) | 98.7 (97.9, 99.2) |
At least one crash requiring attention
|
118 (8.1)
|
1187 (81.5)
|
69 (4.7)
|
82 (5.6)
|
89.6
|
0.55 (0.49, 0.61)
|
63.1 (55.7, 69.9)
|
93.5 (92.0, 94.8)
|
59.0 (51.8, 65.8)
|
94.5 (93.1, 95.7)
|
Collisions with a motor vehicle
| ||||||||||
At least one collision claimed to ACC | 20 (1.4) | 1412 (97.0) | 21 (1.4) | 3 (0.2) | 98.4 | 0.62 (0.48, 0.76) | 48.8 (33.2, 64.6) | 99.8 (99.3, 100.0) | 87.0 (65.3, 96.6) | 98.5 (97.7, 99.1) |
At least one collision requiring overnight hospital admission | 2 (0.1) | 1443 (99.1) | 8 (0.6) | 3 (0.2) | 99.3 | 0.26 (−0.03, 0.56) | 20.0 (3.5, 55.8) | 99.8 (99.3, 100.0) | 40.0 (7.3, 83.0) | 99.5 (99.0, 99.7) |
At least one collision reported to police | 10 (0.7) | 1412 (97.0) | 34 (2.3) | 0 (0.0) | 97.7 | 0.36 (0.20, 0.53) | 22.7 (12.0, 38.2) | 100.0 (99.7, 100.0) | 100.0 (65.6, 100.0) | 97.7 (96.7, 98.3) |
At least one collision requiring attention
|
22 (1.5)
|
1399 (96.1)
|
33 (2.3)
|
2 (0.1)
|
97.6
|
0.55 (0.41, 0.68)
|
40.0 (27.3, 54.1)
|
99.9 (99.4, 100.0)
|
91.7 (71.5, 98.5)
|
97.7 (96.7, 98.4)
|
Participants' characteristics | N | Agreement N (%) | Disagreement N (%) | % Total agreement | Kappa (95% CI) | ||
---|---|---|---|---|---|---|---|
Both yes | Both no | SR yes LD no | SR no LD yes | ||||
Age
| |||||||
16-35 | 158 | 16 (10.1) | 125 (79.1) | 5 (3.2) | 12 (7.6) | 89.2 | 0.59 (0.42, 0.77) |
36-50 | 715 | 64 (9.0) | 590 (82.5) | 26 (3.6) | 35 (4.9) | 91.5 | 0.63 (0.54, 0.71) |
51+ | 583 | 38 (6.5) | 472 (81.0) | 38 (6.5) | 35 (6.0) | 87.5 | 0.44 (0.33, 0.55) |
Gender
| |||||||
Male | 1069 | 93 (8.7) | 865 (80.9) | 49 (4.6) | 62 (5.8) | 89.6 | 0.57 (0.49, 0.64) |
Female | 387 | 25 (6.5) | 322 (83.2) | 20 (5.2) | 20 (5.2) | 89.7 | 0.50 (0.36, 0.63) |
Ethnicity
| |||||||
Maori | 46 | 3 (6.5) | 40 (87.0) | 1 (2.2) | 2 (4.4) | 93.5 | 0.63 (0.25, 1.00) |
Non-Maori | 1410 | 115 (8.2) | 1147 (81.4) | 68 (4.8) | 80 (5.7) | 89.5 | 0.55 (0.48, 0.61) |
Level of education
| |||||||
High school (secondary) or less | 240 | 13 (5.4) | 193 (80.4) | 15 (6.3) | 19 (7.9) | 85.8 | 0.35 (0.18, 0.52) |
Polytechnic | 370 | 31 (8.4) | 305 (82.4) | 14 (3.8) | 20 (5.4) | 90.8 | 0.59 (0.47, 0.72) |
University | 846 | 74 (8.8) | 689 (81.4) | 40 (4.7) | 43 (5.1) | 90.2 | 0.58 (0.50, 0.66) |
NZDep 2006 scores*
| |||||||
1-3 | 752 | 61 (8.1) | 600 (79.8) | 43 (5.7) | 48 (6.4) | 87.9 | 0.50 (0.41, 0.59) |
4-7 | 516 | 44 (8.5) | 426 (82.6) | 19 (3.7) | 27 (5.2) | 91.1 | 0.61 (0.50, 0.71) |
8-10 | 174 | 13 (7.5) | 149 (85.6) | 6 (3.5) | 6 (3.5) | 93.1 | 0.65 (0.46, 0.83) |
Urbanity of residence
| |||||||
Main urban area | 1165 | 98 (8.4) | 943 (80.9) | 58 (5.0) | 66 (5.7) | 89.4 | 0.55 (0.48, 0.62) |
Others | 277 | 20 (7.2) | 232 (83.8) | 10 (3.6) | 15 (5.4) | 91.0 | 0.56 (0.41, 0.72) |
Region of residence
| |||||||
Auckland | 531 | 37 (7.0) | 431 (81.2) | 30 (5.7) | 33 (6.2) | 88.1 | 0.47 (0.36, 0.58) |
Wellington | 313 | 27 (8.6) | 251 (80.2) | 14 (4.5) | 21 (6.7) | 88.8 | 0.54 (0.41, 0.68) |
Others | 598 | 54 (9.0) | 493 (82.4) | 24 (4.0) | 27 (4.5) | 91.5 | 0.63 (0.54, 0.72) |
Pre-existing medical condition
ƚ
| |||||||
Yes | 296 | 23 (7.8) | 237 (80.1) | 21 (7.1) | 15 (5.1) | 87.8 | 0.49 (0.35, 0.63) |
No | 1160 | 95 (8.2) | 950 (81.9) | 48 (4.1) | 67 (5.8) | 90.1 | 0.57 (0.50, 0.64) |
Hours spent cycling a week
| |||||||
0-2 | 237 | 12 (5.0) | 212 (89.5) | 3 (1.3) | 10 (4.2) | 94.5 | 0.62 (0.43, 0.81) |
3-5 | 552 | 47 (8.5) | 444 (80.4) | 31 (5.6) | 30 (5.4) | 88.9 | 0.54 (0.44, 0.64) |
6+ | 667 | 59 (8.8) | 531 (79.6) | 35 (5.2) | 42 (6.3) | 88.5 | 0.54 (0.45, 0.63) |
Confidence of reporting having crashes
| |||||||
Sure or very sure | 1413 | 117 (8.3) | 1150 (81.4) | 68 (4.8) | 78 (5.5) | 89.7 | 0.56 (0.49, 0.62) |
Others | 43 | 1 (2.3) | 37 (86.1) | 1 (2.3) | 4 (9.3) | 88.4 | 0.23 (−0.20, 0.68) |