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. Author manuscript; available in PMC: 2016 Jul 1.
Published in final edited form as: J Adolesc Health. 2015 Jul;57(1 0):S24–S35.e6. doi: 10.1016/j.jadohealth.2015.03.010

Table 3.

Risk estimates with one or more passengers, compared with solo driving, for teenage or young drivers versus older drivers (Question 2)

Type of crash and study Driver age group
Passenger agea,c Measure Younger drivers
Older drivers
Younger versus older driver age group with one or more passengers
Detail on type of crash
Youngera Oldera,b Est. 95% CI Est. 95% CI Est. 95% CI
Fatal
 Bédard et al., 2004 <201 40–493 Any ORd 1.32 1.28–1.36 .59 .55–.64 — — With unsafe versus safe action
<204+ 20–292 2.15 2.00–2.31 1.18 1.15–1.22
 Chen et al., 2000 16 30–59 Any RR 1.65 1.53–1.78 .72 .71–.74 2.28 2.11–2.47 Per 10 million trips
161 30–591 1.39 1.24–1.55 .78 .76–.79 — —
162 30–592 1.86 1.56–2.20 .61 .60–.62 — —
163+ 30–593+ 2.82 2.27–3.50 .70 .67–.71 — —
17 30–59 1.84 1.72–1.97 — — 2.54 2.37–2.74
171 — 1.48 1.35–1.62 — — — —
172 — 2.58 2.24–2.95 — — — —
173+ — 3.07 2.50–3.77 — — — —
16–17 30–59 1.78 1.69–1.87 — — 2.47 2.34–2.60
 Doherty et al., 1998 16–19m 25–59m Any RRe 2.50 p < .10 1.50 p < .05 — — Per 100 million driver-km
16–19f 25–59f 3.55 p < .10 .62 p < .05 — —
20–24m 25–59m 1.23 p > .10 — — — —
20–24f 25–59f 1.75 p > .10 — — — —
 Geyer and Ragland, 2004 15–19m 55–59md Any AORf .98 .93–1.03 .68 .57–.81 — — At fault versus not at fault
20–24m 25–29m 1.13 1.08–1.19 1.15 1.08–1.23 — —
15–19f 40–44f .71 .66–.77 .60 .53–.68
20–24f 30–34f .86 .79–.95 .75 .61–.84
 Preusser et al., 1998 16–19 30–59 Any OR — — 2.13 1.07–2.19 At fault versus not at fault
16w/ 30–59w/ — — 4.72 4.32–5.15
16w/o 30–59w/o — — 2.28 2.05–2.53
17w/ 30–59w/ — — 3.52 3.26–3.80
17w/o 30–59w/o — — 1.77 1.63–1.92
18w/ 30–59w/ — — 3.66 3.40–3.93
18w/o 30–59w/o — — 1.77 1.65–1.90
19w/ 30–59w/ — — 3.23 3.01–3.47
19w/o 30–59w/o — — 1.61 1.50–1.72
20–24 30–59 — — 1.81 1.76–1.86
20–24w/ 30–59w/ — — 2.54 2.45–2.64
20–24 w/o 30–59w/o — — 1.50 1.45–1.55
Nonfatal and combined fatal/nonfatal crashes
 Doherty et al., 1998 16–19m 25–59m Any RRe 2.29 p < .10 1.15 p > .10 — — Injury; per million driver-km
16–19f 25–59f 1.91 p < .10 .43 p < .05 — —
20–24m — .70 p < .05 — — — —
20–24f — 1.37 p > .10 — — — —
16–19m 25–59m 1.87 p < .10 .86 p > .10 — — Material; per million driver-km
16–19f 25–59f 1.58 p < .05 .38 p < .05 — —
20–24m — .53 p < .10 — — — —
20–24f — 1.12 p > .10 — — — —
 Engstrom et al., 2008 18–24 25–64 Any RRg .39 .38–.40 .26 .26–.27 1.47 1.42–1.52 Injury-fatal; per 10 million km
18–241 25–641 .41 .40–.43 .34 .33–.35 — —
18–242 25–642 .31 .29–.34 .17 .17–.18 — —
18–243+ 25–643+ .21 .19–.24 .08 .08–.09 — —
 Lam et al., 2003 ≤24 >24 Same age group OR — — — — 3.14 2.19–4.50 Injury-fatal; cases versus controls
≤241 >241 2.59 1.26–5.33 .96 .58–1.59 — —
≤242+ >242+ 5.77 2.32–14.33 1.06 .34–3.30 — —
≤241 >241 AOR 2.39 .91–6.29 .78 .42–1.46 — —
≤242+ >242+ 15.55 5.76–42.02 .30 .06–1.44 — —
 Lee et al., 2008 16–24 25–59 Any OR .58 .42–.79 .36 .29–.45 1.59 1.16–2.18 Police-reported; at fault versus not at fault
 Orsi et al., 2013 ≤24 >24 Any OR 1.63 1.19–2.22 1.15 .98–1.33 1.42 1.13–1.79 Injury-fatal; with injury versus without injury
AOR 1.42 1.00–2.02h 1.07 .90–1.26 — —
 Rueda-Domingo et al., 2004 18–24m 25–34mi 16–24m OR 1.15 1.08–1.23 1.10 .99–1.22 — — Injury-fatal; at fault versus not at fault
18–24m 25–34m 16–24f .60 .56–.63 .59 .54–.63 — —
18–24f 25–34f 16–24m .99 .84–1.17 .95 .79–1.15 — —
18–24f 25–34f 16–24f .86 .78–.96 .85 .75–.95 — —
— 55–64m 16–24m — — .62 .45–.86 — —
— 55–64m 16–24f — — .42 .31–.57 — —
— 55–64f 16–24m — — .54 .37–.77 — —
— 55–64f 16–24f — — .61 .45–.84 — —
18–24m 25–34m 16–24m AOR .95 .87–1.04 .98 .84–1.14 — —
18–24m 25–34m 16–24f .63 .58–.68 .60 .54–.66 — —
18–24f 25–34f 16–24m .88 .70–1.11 .91 .70–1.18 — —
18–24f 25–34f 16–24f .94 .82–1.07 .88 .75–1.04 — —
— 55–64m 16–24m — — .66 .42–1.04 — —
— 55–64m 16–24f — — .55 .37–.81 — —
— 55–64f 16–24m — — .61 .37–1.02 — —
— 55–64f 16–24f — — .81 .54–1.23 — —

Estimates and CIs that were extracted from articles are not in italics; those that were calculated to answer the specific research questions are in italics. Estimates and CIs were only calculated when there were raw data addressing the specific research questions. Calculations of estimates and CIs might be affected by both rounding to a few decimals in source articles and adjustment based on sampling, which may results here in narrower intervals that should be interpreted with caution.

+ = or more; 1 = 1 passenger; 2 = 2 passengers; 3 = 3 passengers; 4 = 4 passengers; CI = confidence interval; AOR = adjusted odds ratio; Est. = Estimate; f = female; m = male; OR = odds ratio (or crude odds ratio); RR = relative risk; w/= with passengers; w/o = without passengers.

a

Sections about driver and passenger age can also include details about gender and number of passenger if the data were only reported as such in articles.

b

Some articles have estimated risk for drivers older than the age of 65 years. In the present article, we try to provide comparable estimates between studies by focusing on drivers younger than the age of 65 years.

c

“Any” describes studies including passengers of any age. When the information about passenger age was not provided, it was assumed that any passenger age was included.

d

Only smaller to higher estimates are presented here for passengers of different age groups.

e

This study presented crash rates for male and female drivers separately. We calculated estimates, but significance was provided in the article.

f

Estimates and CIs for male and female drivers were extracted from figures in the article.

g

This article compared solo driving versus passenger presence; so, estimates and CIs were extracted from the article, and scores were inverted to answer the current research question.

h

This CI was reported significant in the article.

i

Estimates for 35- to 54-year-old drivers are not presented here.