In total, 157,423 high school students participated in surveys during 2013, 2015, 2017 and 2019 across 14 states. Approximately 45% (65,044) of total participants reached the minimum intermediate liscense age in their states and reported that they had driven in the past 30 days. Among students who met the inclusion criteria, 53% engaged in CWD at least once during the past 30 days. The prevalence of CWD was highest among older students and lowest for the younger. About 41% of students aged 18 and older sometimes engaged in CWD and 22% of them frequent engaged in CWD, compared to 22% sometimes and 7% frequent among students aged 15 years old. A higher prevalence of White students (60%) at least once engaged in CWD compared to students of other races/ethnicities (42% for Black or African American students, and 45% for Hispanic students). White students had a higher prevalence of engaging in frequent CWD compared to other races. (Table 1, Table 2)
Table 1 Characteristics of study population and prevalence of calling while driving (CWD)a
Variables
|
Unweighted N
|
|
% of CWD (95%CI) b
|
|
Never
(0 day)
|
Sometimes
(1-9 days)
|
Frequent
(10-30 days)
|
Overall
|
65,044
|
|
47(45, 49)
|
36(35, 38)
|
16(15, 18)
|
Survey year
|
|
|
|
|
|
2013
|
12,166
|
|
44(42, 46)
|
37(36, 39)
|
18(17, 20)
|
2015
|
8717
|
|
46(44, 49)
|
39(37, 41)
|
14(13, 16)
|
2017
|
27,168
|
|
50(47, 53)
|
36(33, 38)
|
15(13, 17)
|
2019
|
16,993
|
|
54(52, 55)
|
35(33, 36)
|
12(11, 13)
|
Age (Years)
|
|
|
|
|
|
15
|
2,787
|
|
71(66, 77)
|
22(17, 26)
|
7 (4, 11)
|
16
|
26,256
|
|
60(58, 62)
|
30(28, 33)
|
10 (8, 12)
|
17
|
25,986
|
|
43(40, 46)
|
39(36, 41)
|
18(16, 20)
|
≥18
|
10,015
|
|
37(33, 41)
|
41(38, 44)
|
22(19, 25)
|
Sex
|
|
|
|
|
|
Female
|
31,498
|
|
48(45, 50)
|
37(36, 39)
|
15(13, 16)
|
Male
|
33,230
|
|
47(45, 49)
|
35(33, 38)
|
18(16, 19)
|
Missing
|
316
|
|
|
|
|
Race
|
|
|
|
|
|
White
|
41,452
|
|
40(38, 42)
|
40(38, 42)
|
20(19, 22)
|
Black or African American
|
7,128
|
|
58(53, 63)
|
30(25, 34)
|
12 (9, 15)
|
Hispanic/Latino
|
7,547
|
|
55(51, 59)
|
33(30, 36)
|
12 (9, 15)
|
Other c
|
7,304
|
|
57(52, 62)
|
34(28, 39)
|
9 (7, 12)
|
Missing
|
1,613
|
|
|
|
|
States
|
|
|
|
|
|
AK
|
1,262
|
|
54(50, 58)
|
35(31, 39)
|
11 (8, 13)
|
AR
|
907
|
|
37(33, 42)
|
37(33, 41)
|
26(22, 30)
|
CT
|
3,717
|
|
62(60, 64)
|
29(27, 31)
|
9 (8, 10)
|
MD
|
30,657
|
|
67(66, 68)
|
25(24, 26)
|
8 (7, 8)
|
MA
|
4,201
|
|
54(50, 58)
|
35(32, 37)
|
12(10, 13)
|
MO
|
2,647
|
|
39(36, 41)
|
42(39, 45)
|
19(18, 21)
|
MT
|
10,292
|
|
39(38, 41)
|
43(42, 44)
|
17(16, 19)
|
NE
|
2,325
|
|
33(30, 35)
|
49(46, 51)
|
19(16, 21)
|
NJ
|
617
|
|
46(40, 52)
|
37(33, 42)
|
16(12, 21)
|
ND
|
4,606
|
|
28(26, 30)
|
49(47, 51)
|
23(21, 24)
|
RI
|
859
|
|
49(46, 53)
|
40(34, 46)
|
11 (7, 14)
|
SC
|
1,007
|
|
46(42, 51)
|
33(29, 38)
|
20(17, 23)
|
TX
|
864
|
|
49(44, 54)
|
35(31, 39)
|
16(13, 19)
|
UT
|
1,083
|
|
35(30, 41)
|
48(43, 52)
|
17(15, 19)
|
Notes:
CI: Confidence Interval;
a: Data were from state Youth Risk Behavior Surveys in 14 states (2013, 2015, 2017 and 2019), the United States;
b. Weighted percentage of students that reported talking on a phone while driving during the 30 days before the survey (among students who drove). Percentages may not total 100 due to rounding;
c: Other included: American Indian/Alaskan Native, Asian, Native Hawaiian or Other Pacific Islander, and Multiple- Non-Hispanic/Latino.
Table 2 Associations between cellphone laws and calling while driving (CWD) a
Variables
|
CWD b (95%CI)
|
|
Prevalence Ratios (95%CI)
|
|
Crude
|
Adjusted c
|
Overall
|
53 (51, 55)
|
|
|
|
Cellphone laws
|
|
|
|
|
No ban
|
57 (55, 60)
|
|
Reference
|
Reference
|
Young driver ban
|
54 (51, 57)
|
|
0.94 (0.87, 1.00)
|
1.05 (1.00, 1.10)
|
Concurrent bans d
|
44 (41, 47)
|
|
0.76 (0.71, 0.83)
|
0.81 (0.76, 0.86)
|
Age (Years)
|
|
|
|
|
15
|
29 (23, 34)
|
|
0.72 (0.59, 0.88)
|
0.65 (0.56, 0.75)
|
16
|
40 (38, 42)
|
|
Reference
|
Reference
|
17
|
57 (54, 60)
|
|
1.42 (1.32, 1.52)
|
1.54 (1.47, 1.60)
|
≥18
|
63 (59, 67)
|
|
1.57 (1.46, 1.70)
|
1.68 (1.61, 1.77)
|
Sex
|
|
|
|
|
Female
|
52 (50, 55)
|
|
Reference
|
Reference
|
Male
|
53 (51, 55)
|
|
1.02 (0.96, 1.07)
|
1.01 (0.97, 1.04)
|
Race
|
|
|
|
|
White
|
60 (58, 62)
|
|
Reference
|
Reference
|
Black or African American
|
42 (37, 47)
|
|
0.70 (0.63, 0.77)
|
0.67 (0.61, 0.74)
|
Hispanic/Latino
|
45 (41, 49)
|
|
0.75 (0.70, 0.81)
|
0.77 (0.72, 0.82)
|
Other e
|
43 (38, 48)
|
|
0.71 (0.64, 0.79)
|
0.74 (0.69, 0.80)
|
|
|
|
|
|
Percent of students in rural areas
|
|
|
1.01 (1.01, 1.01)
|
1.01 (1.01, 1.01)
|
Year
|
|
|
|
|
2013
|
57 (54, 59)
|
|
Reference
|
Reference
|
2015
|
54 (52, 57)
|
|
0.93 (0.88, 0.97)
|
0.93 (0.88, 0.97)
|
2017
|
50 (47, 54)
|
|
0.94 (0.89, 1.01)
|
0.94 (0.89, 1.01)
|
2019
|
44 (43, 46)
|
|
0.95 (0.90, 1.01)
|
0.95 (0.90, 1.01)
|
Notes:
CI: Confidence Interval;
a. Data were from state Youth Risk Behavior Surveys in 14 states (2013, 2015, 2017 and 2019), the United States;
b. Weighted percentage of calling while driving (CWD): Percentage of students that reported talking on a phone while driving at least once during the 30 days before the survey (among students who drove);
c. Model adjusted for cellphone laws, age, sex, race, percent of students in rural area, and survey year;
d. Concurrent bans both a handheld calling ban and a young driver ban;
e. Other included: American Indian/Alaskan Native, Asian, Native Hawaiian or Other Pacific Islander, and Multiple- Non-Hispanic/Latino.
CWD prevalence varied across states, from 33% in Maryland to 72% in North Dakota (Table 1). States with no ban had a higher percentage of students who sometimes or frequent engaged in CWD (57%) compared to states with concurrent bans (44%) (Figure 1). Students in states with a young driver ban had a lower prevalence of CWD compared to states with no ban (54% vs 57%), though this difference was not statistically significant in the adjusted model. (Table 2)
Multivariable analysis showed that students in states with concurrent bans were 19% less likely to report CWD compared to students in states with no ban (adjusted PR=0.81, 95% CI: 0.76-0.86) (Table 2). Similarly, students in states with concurrent bans were 23% less likely to engage in CWD compared to students in states with only a young driver ban. (adjusted PR=0.77, 95% CI: 0.73-0.83)
The association between law and CWD stratified by subgroups were presented in Table 3. Adjusted PRs by demographics were similar to the main analysis without interactions. Young driver ban was not associated with a lower prevalence of CWD across subgroups. Black/African American or Hispanic/Latino students who in states with a young driver ban had a slightly, but not statistically significant, lower prevalence of CWD. The association between concurrent bans and CWD was stronger among younger drivers (15 and 16 years) (adjusted PR=0.54, 95% CI: 0.49-0.60), or those of Hispanic/Latino race (adjusted PR=0.66, 95% CI: 0.57-0.77) compared to the estimation without interaction (adjusted PR=0.81, 95% CI: 0.76-0.86).
Table 3: Adjusted prevalence ratios and 95%CI stratified by student demographics
Variables
|
Young driver ban
|
Concurrent bans
|
No ban
|
P-values&
|
Age#
|
|
|
|
<0.0001
|
15-16 years
|
1.02(0.94, 1.11)
|
0.54(0.49, 0.60)
|
Reference
|
|
≥ 17 years
|
1.08(1.03, 1.14)
|
0.90(0.84, 0.96)
|
Reference
|
|
Sex$
|
|
|
|
0.0151
|
Female
|
1.02(0.96, 1.08)
|
0.76(0.70, 0.82)
|
Reference
|
|
Male
|
1.07(1.01, 1.14)
|
0.86(0.80, 0.93)
|
Reference
|
|
Race*
|
|
|
|
0.0229
|
White
|
1.06(1.01, 1.10)
|
0.83(0.78, 0.89)
|
Reference
|
|
Black or African American
|
0.97(0.77, 1.22)
|
0.74(0.62, 0.89)
|
Reference
|
|
Hispanic/Latino
|
0.93(0.82, 1.06)
|
0.66(0.57, 0.77)
|
Reference
|
|
Other a
|
1.08(0.92, 1.26)
|
0.89(0.78, 1.02)
|
Reference
|
|
Notes:
CI: Confidence Interval;
&: p-valuse for the interaction terms of age*law, sex*law, and race*law.
#: model adjusted for age, and interaction between age and cellphone laws, sex, race, the state’s percent of students in rural areas, and survey year;
$: model adjusted for sex, and interaction between sex and cellphone laws, age, race, the state’s percent of students in rural areas, and survey year;
*: model adjusted for race, and interaction between race and cellphone laws, age, sex, the state’s percent of students in rural areas, and survey year.
a. Other included: American Indian/Alaskan Native, Asian, Native Hawaiian or Other Pacific Islander, and Multiple- Non-Hispanic/Latino.
Results of the sensitivity analyses were similar to the main analysis (Additional File Table 4 and Table 5). When categorizing CWD as a three-level nominal outcome, students in states with concurrent bans had a lower risk of sometimes engaging in CWD compared to students in states with no ban (adjusted PR=0.80, 95% CI: 0.74-0.87). Additionally, concurrent bans were associated with a 30% lower prevalence of frequent CWD compared to no bans. (adjusted PR =0.70, 95% CI: 0.60-0.80) (Additional File Table 5).