Table 3: Association of Physical Accident with risk factors by logistic regression Variable ORa 95% CI Age Year 0.96 0.98-٠0.93 Sex Female 1 Male 1.57 2.77-0.9 Fastening seat belt Yes 1 No 2.23 3.52-1.42 Falling out of the car No 1 Yes 6.83 14.52-3.2 Trapping in the car No 1 Yes 2.33 4.04-1.35 listening to music No 1 Yes 1.22 1.91-078 Car Model No 1 Yes 1.17 1.82-0.75 Combustion No 1 Yes 20.6 87.8-4.84 Smoking No 1 Yes 1.81 1.03-0.39 Using hand phone No 1 Yes 0.71 1.3-0.39 Time of accident 8-12 1 12-18 0.44 0.79-0.25 18-24 1.81 3.2-1.1 Direction of contact Behind 1 Front 3.08 5.25-1.81 Next 1.31 2.40-0.71 a Adjusted odds ratio Relative risk on car accidents P value <0.001 0.114 <0.001 <0.001 0.002 0.369 0.487 <0.001 0.046 <0.275 0.006 0.021 <0.001 0.38 nificance in the injuries (p>0.05). Combustion in the case group was approximately 21% which was 1.3% in the control group, indicating that the chance of combustion in the case group was 20 times more than the control group in a single vari- able analysis. This variable in comparison to the other influencing variables significantly was correlated with the degree of injuries and risks caused by the accidents. The results indicated that 30.5% of the cas- es were trapped at the time of the accident; this num- ber in the control group was approximately 15.8%. This model both in the single and multiple model were significantly correlated with the amount of inju- ries and its risk (p<0.002). Of course, this variable along with the model of the car had a weaker correlation in the case and con- trol group which was again significant after the omis- sion of the model of the car. Trapping in the car in both case and control groups was significantly higher in the less modern cars, (p<0.05). Based on this vari- able as well, falling out of the car was significantly different in two groups (p<0.001). The relationship indicated in the multiple variable groups beside not using seat belts, it was significantly higher and after precise investigations indicated that only 4.2% of the people with seat belts were fallen out of the car dur- ing the accident, mentioning that this number was 32% among the ones not fastening seat belts. Results indicated that the chance of falling out of the car dur- ing the accident in case of not using seat belts was 10.2 times more (p<0.001). Smoking was also significantly correlated in the case group with the time of accident (p<0.05). In the multiple-variable model, this variable along with the sex indicated a non- significant correlation, other var- iables such as listening to music or talking with a hand phone did not have a significant correlation with the extent of injuries. After entering all variables into the multiple lo- gistic regression model, 3 variables, include age, not fastening seat belt and combustion, were identified as more dangerous risk factors. Comparing Table 3 and this finding indicates that smoking and the time and direction of the accident were among the variables which were shown to have a significant correlation in the single variable model, but were not considered significant in the presence of other variables. Of course, it is worth mentioning that in a basic multi- variable model, falling out of the car and being trapped at the time of accident were remained in the WWW.ircmj.com Vol 13 August 2011 533