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Smoking and attitudes to seat belt usage
PubL Hlth, Load. (t982), 96, 48-52
Smoking and Attitudes to Seat Belt Usage K. S. Cliff
Senior Lecturer F.F.C.M., D.P.H.
P. Grout
Medical Student and D. Machin
Sen~or Lecturer in Medica/ Statistics M.gc.
Community Medicine, South Block, Southampton Genera/Hospital Southampton S09 4XY An evaluation of a health education programme promoting the use o f seat belts as an injury protection measure in vehicle collision accidents, was carried out using a postal questionnaire to a random sample of people drawn from the electoral rolls of a local authority. The questionnaire asked respondents to provide information about their habits and opinions on a number of aspects including scat'belt wearing habits: cigarette consumption, age, sex, driver or non-driver of a motor vehicle, opinion on legislation to enforce ,seat belt wearing, and opinion on a reduction in ear insurance premium for seat belt wearers. Allowing for age and sex amongst drivers, self-reported seat belt wearing declined as cigarette consumption rose (P < 0-01). Analysis o f / h e data related to "opinions on legislation to enforce seat belt wearing" by means oflogit-linear models indicated that age was the only variable which, when considered alone, was found to influence the response (P < 0.05). If the two variables, cigarette consumption and drivers were added in an interactive mode, then there was a significant improvement in the fit as compared to age alone (P < 0-05). This improvement was not found in respect of "' opinions relating to insurance premium reduction", age-sex being the only interaction which was significantly associated with response ( P < 0"05).
Introduction The use o f seat belts as a n effective measure to reduce injury arising from vehicle collision accidents, has been well d o c u m e n t e d . ~-~ The use o f seat belts by front seat o c c u p a n t s has been m a n d a t o r y for some years in a n u m b e r o f countries, for example: Belgium, N e w Zealand, Australia and Switzerland. In the U n i t e d K i n g d o m , five a t t e m p t s to introduce legislation t o enforce seat belt wearing have failed, t h o u g h currently a Bill introduced into the H o u s e o f Lords h a s passed its second reading. Present G o v e r n m e n t policy remains one o f persuasion through education, rather than legislation. W i t h this p o l i c y in mind a study was carried out b y the Wessex positive health t e a m (led by one oT us K.S.C.) during the period N o v e m b e r 1 9 7 9 - M a r c h 1980. 8 The s t u d y involved a health e d u c a t i o n p r o g r a m m e p r o m o t i n g the use of seat bett wearing as an effective preventive m e a s u r e in reducing injury a m o n g s t front seat occupants arising f r o m vehicle 0033-3506/82/010048 +05 $01.00/0
c~) 1982 The Society of Community Medicine
Smokhzg and Attitudes to Seat Belt Usage
49
collision accidents and was established particularly to test the hypothesis: "persuasion through education can increase the seat belt wearing amongst front seat car occupants". During the course o f a pilot study concerned with the feasibility of measuring the seat belt wearing rate amongst front seat car occupants, observations suggested that non-users of seat belts were more commonly smoking cigarettes compared to seat belt users. Whilst the overall aim of the questionnaire was concerned with evaluating the effectiveness of the health education programme, fhe findings reported in this paper are confined to a consideration o f the relationships which the variables: age, sex, driver or non-driver, and cigarette smoking might have individually, or jointly on the following: (i) seat belt wearing habits; (ii) opinion on legislation to enforce seat belt wearing; (iii) opinion on reduction in car insurance premiums for seat belt wearing. Methods
A postal questionnaire was sent to a random sample of people drawn from the electoral roll of the local authority district in which a health education programme had been promoted. Information sought from respondents included: age, sex, seat belt wearing habits, cigarette consumption, opinion on reduction in car insurance premiums for seat belt wearers and whether the respondents were qualified drivers of motor cars or light vans. A total of 670 people, representing a 1% sample, was drawn randomly from the electoral roll of the district: 386 people responded but 0nly 374 questionnaires were suitable for data analysis, giving an effective response rate of 56%. Non-responders were not contacted again. Information was coded, punched and analysed using the regional health authority's computer. The questions related to the three areas of interest outlined in the introduction are set out below: Smoking habit
Do you smoke cigarettes? YES... N O . . . I f YES, please indicate approximately the number/'day: 0-5, 6--10, 11-15, 16-20, 20 or more. Legislation to enforce seat belt wearing
Please indicate your personal opinion about seat belt wearing being made compulsory in Great Britain. (a) I agree that a law should be passed to enforce seat belt wearing at all times. (b) I do NOT agree that a law should be passed to enforce seat belt wearing. (e) No definite opinion. (Respondents were asked to tick one of the three opinions) Opinion related to insurance premium reduction for seat belt wearers
Do you think that motorists who wear seat belts should pay less motor insurance? YES... N O . . . The analysis to examine the data in relation to seat belt wearing; opinion to enforceseat belt wearing;and opinion to reduce insurance premiums.for Seat belt wearing, has been
K. S.
50
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0,2 0
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20
Doily eigoretle consumption
Figure 1. Proportion of drivers always wearing seat belts in relation to daily cigarette consumption. Logit P = -0.011-0.056 (cigarette consumption).
made by means of logit-linear models as described by Little.5 These models include the four explanatory variables: age, sex, cigarette consumption, and driver or non-driver. The use of models helps to clarify the inter-relationships between the explanatory variables and to help distinguish significant features from insignificant detail. Results
Seat belt wearing by drivers Forty-three ~ of males and 48 ~ of females in the sample always wore seat belts. Using the three age groups 18-44, 45-64 and 65 + there appeared no significant differences in the proportion wearing seat belts on analysis of the data by logit-linear models. In contrast the cigarette consumption of drivers after grouping into non-smokers, 1-10 cigarettes and 11 or more cigarcttes/day was a significant variable (X~= 8-85, d.f. = 2; P < 0.02). The proportion of drivers wearing seat belts decreases approximately linearly with increasing cigarette consumption, as indicated in Figure 1. Opinion relating to legislation to enforce seat belt wearing Of the 353 responding to this particular question, 42~o agreed with the need for legislation, 11 ~ did not have any opinion and 4 7 ~ opposed legislation. Forty-one ~ of males and 4 3 ~ of females agreed with legislation. Analysis of the data indicated that age was the only variable which, when taken alone was found to influence the response (X~ = 6:83, d.f. = 2; P < 0-05). Forty-seven ~o of the two older age groups accepted the idea of compulsory legislation compared with 31 ~ for the 18--44 age group. Adding the variables: cigarette consumption; driver or non-driver, to age did not alter the model significantly. If the interaction between these two variables was also included,
51
Smoking and Attitudes to Seat Belt Usage TABLE 1. Percentage of law enforeemeat opinion by cigarette consumption
Drivers Agree (~) No opinion (%) Sample size Non.drivers Agree (%) No opinion (~o) Sample size Total Agree (~o) No opinion (~) Sample size
0
Cigarette consumption/day 1-10
> 11
47 9 209
42 8 24
21 11 47
42 2t 53
29 14 7
62 15 13
46 11 262
39 10 31
30 12 60
TABLE 2. Insurance opinion by.age and sex
Male Agree (~) Sample size Female Agree (~) Sample size
t8--44
Age 45-64
> 65
55 40
55 87
54 41
28 29
36 58
65 17
however, then the model gave a significant improvement in fit over age alone (,yz = 12-69, d.f. = 5; P < 0.05). Table 1 summarizes the data for opinion on legislation by cigarette smoking for drivers and non-drivers combined and emphasizes the lowering response of drivers with increasing cigarette consumption. Opinion related to reduced motor insurance premium for seat belt wearers
Analysis of the data suggested that cigarette consumption and whether or not the respondent wasa driver had little influence on their insurance opinion. A model including age, sex and age--sex interaction was however appropriate (,y~= 12.73, d.f. -----5; P < 0"05), as indicated in Table 2 by the differing responses by age group of the males and females. Discussion
Work by Helsing and Comstocke in the U.S.A. identified a number of factors associated with the non-wearing of seat belts. Their analysis indicated no association between cigarette consumption and seat belt wearing habit. They suggested however that in heavy smokers, over 35 cigarettes/day, there might be some association but they thought this was probably due to chance because of small numbers in their sample.
52
K . S . Cliff et al.
More recent work by Eiser et aL~ showed after allowing for age, sex and social class a statistically significant association between smokers and the self reported non-use of seat belts (P < 0-001). The results o f the present study support this finding for drivers after allowing for an adjustment of age and sex. Social class data was not available to us. In respect o f opinion towards seat belt legislation, Eiser et al. found that wearers were, after controlling for age, sex and social class, significantly in favour o f compulsory legislation. The present study found that amongst drivers, those who were non-smokers were more in favour o f legislation when compared to those who smoke more than 11 cigarettes/day. In addition we have suggested that smokers are less likely to wear seat belts. Thus the present study would support albeit indirectly the findings o f Eiser et aL
Acknowledgements We wish to acknowledge the financial help given to K.S.C. by the Wessex Regional Health Authority, which enabled the study to be undertaken. We also wish to acknowledge the financial support from the Health Education Council to continue the work into the relationship between smoking, road traffic accidents and seat belt wearing. We also wish to acknowledge the hel'p and encouragement given by Professor W. E. Waters, Professor of Community Medicine, University of Southampton.
References 1. Hobbs, C. A. (1978). The effectiveness of seat belts in reducing injuries to car occupants. TRRL Report; LR 811 (Department of Transport, Crowthorne, U.K.). 2. Grime, G. (1979). The protection afforded by seat belts. TRRL Report; SR 449. (Department of Transport, Crowthorne, U.K.). 3. McDermott, F. (1978). Control of road trauma epidemic in Australia. Annals of the Royal College of Surgeons (England) 60, 437-50. 4. Cliff, K. S., Catford, J., Dillow, I. &Swann, C. (1980). Promoting the use of seat belts. British Medical Journal ii, 1477-8. 5. Little, R. J. A. (1978). Generalised linear models for cross-classified data from the WFS. World Fertility Survey Technical Bulletin 5/Tech. 834, 68. 6. Helsing, J. K. & Comstock, G. W. (1977). What kinds of people do not use seat belts. American Journal of Public Health 67, 1043-50. 7. Eiser, J. R., Sutton, S. R. & Wober, M. (1979). Smoking, seat belts and beliefs about health. Addictive Behaviour 4, 331-8.
Smoking and Attitudes to Seat Belt Usage K. S. Cliff
Senior Lecturer F.F.C.M., D.P.H.
P. Grout
Medical Student and D. Machin
Sen~or Lecturer in Medica/ Statistics M.gc.
Community Medicine, South Block, Southampton Genera/Hospital Southampton S09 4XY An evaluation of a health education programme promoting the use o f seat belts as an injury protection measure in vehicle collision accidents, was carried out using a postal questionnaire to a random sample of people drawn from the electoral rolls of a local authority. The questionnaire asked respondents to provide information about their habits and opinions on a number of aspects including scat'belt wearing habits: cigarette consumption, age, sex, driver or non-driver of a motor vehicle, opinion on legislation to enforce ,seat belt wearing, and opinion on a reduction in ear insurance premium for seat belt wearers. Allowing for age and sex amongst drivers, self-reported seat belt wearing declined as cigarette consumption rose (P < 0-01). Analysis o f / h e data related to "opinions on legislation to enforce seat belt wearing" by means oflogit-linear models indicated that age was the only variable which, when considered alone, was found to influence the response (P < 0.05). If the two variables, cigarette consumption and drivers were added in an interactive mode, then there was a significant improvement in the fit as compared to age alone (P < 0-05). This improvement was not found in respect of "' opinions relating to insurance premium reduction", age-sex being the only interaction which was significantly associated with response ( P < 0"05).
Introduction The use o f seat belts as a n effective measure to reduce injury arising from vehicle collision accidents, has been well d o c u m e n t e d . ~-~ The use o f seat belts by front seat o c c u p a n t s has been m a n d a t o r y for some years in a n u m b e r o f countries, for example: Belgium, N e w Zealand, Australia and Switzerland. In the U n i t e d K i n g d o m , five a t t e m p t s to introduce legislation t o enforce seat belt wearing have failed, t h o u g h currently a Bill introduced into the H o u s e o f Lords h a s passed its second reading. Present G o v e r n m e n t policy remains one o f persuasion through education, rather than legislation. W i t h this p o l i c y in mind a study was carried out b y the Wessex positive health t e a m (led by one oT us K.S.C.) during the period N o v e m b e r 1 9 7 9 - M a r c h 1980. 8 The s t u d y involved a health e d u c a t i o n p r o g r a m m e p r o m o t i n g the use of seat bett wearing as an effective preventive m e a s u r e in reducing injury a m o n g s t front seat occupants arising f r o m vehicle 0033-3506/82/010048 +05 $01.00/0
c~) 1982 The Society of Community Medicine
Smokhzg and Attitudes to Seat Belt Usage
49
collision accidents and was established particularly to test the hypothesis: "persuasion through education can increase the seat belt wearing amongst front seat car occupants". During the course o f a pilot study concerned with the feasibility of measuring the seat belt wearing rate amongst front seat car occupants, observations suggested that non-users of seat belts were more commonly smoking cigarettes compared to seat belt users. Whilst the overall aim of the questionnaire was concerned with evaluating the effectiveness of the health education programme, fhe findings reported in this paper are confined to a consideration o f the relationships which the variables: age, sex, driver or non-driver, and cigarette smoking might have individually, or jointly on the following: (i) seat belt wearing habits; (ii) opinion on legislation to enforce seat belt wearing; (iii) opinion on reduction in car insurance premiums for seat belt wearing. Methods
A postal questionnaire was sent to a random sample of people drawn from the electoral roll of the local authority district in which a health education programme had been promoted. Information sought from respondents included: age, sex, seat belt wearing habits, cigarette consumption, opinion on reduction in car insurance premiums for seat belt wearers and whether the respondents were qualified drivers of motor cars or light vans. A total of 670 people, representing a 1% sample, was drawn randomly from the electoral roll of the district: 386 people responded but 0nly 374 questionnaires were suitable for data analysis, giving an effective response rate of 56%. Non-responders were not contacted again. Information was coded, punched and analysed using the regional health authority's computer. The questions related to the three areas of interest outlined in the introduction are set out below: Smoking habit
Do you smoke cigarettes? YES... N O . . . I f YES, please indicate approximately the number/'day: 0-5, 6--10, 11-15, 16-20, 20 or more. Legislation to enforce seat belt wearing
Please indicate your personal opinion about seat belt wearing being made compulsory in Great Britain. (a) I agree that a law should be passed to enforce seat belt wearing at all times. (b) I do NOT agree that a law should be passed to enforce seat belt wearing. (e) No definite opinion. (Respondents were asked to tick one of the three opinions) Opinion related to insurance premium reduction for seat belt wearers
Do you think that motorists who wear seat belts should pay less motor insurance? YES... N O . . . The analysis to examine the data in relation to seat belt wearing; opinion to enforceseat belt wearing;and opinion to reduce insurance premiums.for Seat belt wearing, has been
K. S.
50
B
P 0"5
Cliff et aL
I
O
g
0"4
"8 ¢J
0.3
,o
er
0,2 0
5
I0
15
20
Doily eigoretle consumption
Figure 1. Proportion of drivers always wearing seat belts in relation to daily cigarette consumption. Logit P = -0.011-0.056 (cigarette consumption).
made by means of logit-linear models as described by Little.5 These models include the four explanatory variables: age, sex, cigarette consumption, and driver or non-driver. The use of models helps to clarify the inter-relationships between the explanatory variables and to help distinguish significant features from insignificant detail. Results
Seat belt wearing by drivers Forty-three ~ of males and 48 ~ of females in the sample always wore seat belts. Using the three age groups 18-44, 45-64 and 65 + there appeared no significant differences in the proportion wearing seat belts on analysis of the data by logit-linear models. In contrast the cigarette consumption of drivers after grouping into non-smokers, 1-10 cigarettes and 11 or more cigarcttes/day was a significant variable (X~= 8-85, d.f. = 2; P < 0.02). The proportion of drivers wearing seat belts decreases approximately linearly with increasing cigarette consumption, as indicated in Figure 1. Opinion relating to legislation to enforce seat belt wearing Of the 353 responding to this particular question, 42~o agreed with the need for legislation, 11 ~ did not have any opinion and 4 7 ~ opposed legislation. Forty-one ~ of males and 4 3 ~ of females agreed with legislation. Analysis of the data indicated that age was the only variable which, when taken alone was found to influence the response (X~ = 6:83, d.f. = 2; P < 0-05). Forty-seven ~o of the two older age groups accepted the idea of compulsory legislation compared with 31 ~ for the 18--44 age group. Adding the variables: cigarette consumption; driver or non-driver, to age did not alter the model significantly. If the interaction between these two variables was also included,
51
Smoking and Attitudes to Seat Belt Usage TABLE 1. Percentage of law enforeemeat opinion by cigarette consumption
Drivers Agree (~) No opinion (%) Sample size Non.drivers Agree (%) No opinion (~o) Sample size Total Agree (~o) No opinion (~) Sample size
0
Cigarette consumption/day 1-10
> 11
47 9 209
42 8 24
21 11 47
42 2t 53
29 14 7
62 15 13
46 11 262
39 10 31
30 12 60
TABLE 2. Insurance opinion by.age and sex
Male Agree (~) Sample size Female Agree (~) Sample size
t8--44
Age 45-64
> 65
55 40
55 87
54 41
28 29
36 58
65 17
however, then the model gave a significant improvement in fit over age alone (,yz = 12-69, d.f. = 5; P < 0.05). Table 1 summarizes the data for opinion on legislation by cigarette smoking for drivers and non-drivers combined and emphasizes the lowering response of drivers with increasing cigarette consumption. Opinion related to reduced motor insurance premium for seat belt wearers
Analysis of the data suggested that cigarette consumption and whether or not the respondent wasa driver had little influence on their insurance opinion. A model including age, sex and age--sex interaction was however appropriate (,y~= 12.73, d.f. -----5; P < 0"05), as indicated in Table 2 by the differing responses by age group of the males and females. Discussion
Work by Helsing and Comstocke in the U.S.A. identified a number of factors associated with the non-wearing of seat belts. Their analysis indicated no association between cigarette consumption and seat belt wearing habit. They suggested however that in heavy smokers, over 35 cigarettes/day, there might be some association but they thought this was probably due to chance because of small numbers in their sample.
52
K . S . Cliff et al.
More recent work by Eiser et aL~ showed after allowing for age, sex and social class a statistically significant association between smokers and the self reported non-use of seat belts (P < 0-001). The results o f the present study support this finding for drivers after allowing for an adjustment of age and sex. Social class data was not available to us. In respect o f opinion towards seat belt legislation, Eiser et al. found that wearers were, after controlling for age, sex and social class, significantly in favour o f compulsory legislation. The present study found that amongst drivers, those who were non-smokers were more in favour o f legislation when compared to those who smoke more than 11 cigarettes/day. In addition we have suggested that smokers are less likely to wear seat belts. Thus the present study would support albeit indirectly the findings o f Eiser et aL
Acknowledgements We wish to acknowledge the financial help given to K.S.C. by the Wessex Regional Health Authority, which enabled the study to be undertaken. We also wish to acknowledge the financial support from the Health Education Council to continue the work into the relationship between smoking, road traffic accidents and seat belt wearing. We also wish to acknowledge the hel'p and encouragement given by Professor W. E. Waters, Professor of Community Medicine, University of Southampton.
References 1. Hobbs, C. A. (1978). The effectiveness of seat belts in reducing injuries to car occupants. TRRL Report; LR 811 (Department of Transport, Crowthorne, U.K.). 2. Grime, G. (1979). The protection afforded by seat belts. TRRL Report; SR 449. (Department of Transport, Crowthorne, U.K.). 3. McDermott, F. (1978). Control of road trauma epidemic in Australia. Annals of the Royal College of Surgeons (England) 60, 437-50. 4. Cliff, K. S., Catford, J., Dillow, I. &Swann, C. (1980). Promoting the use of seat belts. British Medical Journal ii, 1477-8. 5. Little, R. J. A. (1978). Generalised linear models for cross-classified data from the WFS. World Fertility Survey Technical Bulletin 5/Tech. 834, 68. 6. Helsing, J. K. & Comstock, G. W. (1977). What kinds of people do not use seat belts. American Journal of Public Health 67, 1043-50. 7. Eiser, J. R., Sutton, S. R. & Wober, M. (1979). Smoking, seat belts and beliefs about health. Addictive Behaviour 4, 331-8.