The Influence of Age on the Morbidity and Mortality of Pedestrian Victims

Objectives. The present study examined the influence of age on the morbidity and mortality of pedestrian victims while controlling for confounding factors.

Methods. The Pedestrian Crash Data Study (PCDS) database was used for a cross-sectional study to compare the outcome of senior (age ≥60 years) and adult (age 19 to 50 years) pedestrian victims. The outcome measures were the Injury Severity Score (ISS), Maximum Abbreviated Injury Score (MAIS), Abbreviated Injury Scale (AIS), and Mortality. Logistic regression models were used to estimate age-associated risks while controlling for confounders such as vehicle type, impact speed, and pedestrian height, weight, and gender.

Results. Compared to the adult victims, the seniors had a higher average ISS (23 vs. 16, p = 0.018) and higher mortality (30 percent vs. 11 percent, p ≤ 0.001). The seniors were also more likely to have an ISS ≥9 (odds ratio = 2.72; 95 percent CI: 1.31–5.68) and to die (odds ratio = 6.68; 95 percent CI: 2.37–19.88). The seniors were approximately twice as likely to have higher AIS scores to almost every body region.

Conclusions. The adjusted age-dependent risks indicated by the current study should be considered when calculating or projecting pedestrian morbidity and mortality. Adjustment in statistical models is essential to achieve precise risk estimates and in turn to appropriately allocate public health rescores.

Keywords:

• Pedestrian Victim
• Crash
• Adult
• Senior
• Age
• Injury

Notes

¹ Abbreviations: N: frequency; %: percentage; SD: standarddeviation.

² Percentages are presented by column (each column sums to 100%). Numbers and Percentages of observations may differ from variable to another because of the missing and unknown values.

³ p-value for the test of significance of differences between the two age groups. t-test was used to test differences in group means while Chi-2 to test differences in rates.

¹ Abbreviations: N: frequency; %: percentage; SEM: standard error for the mean.

²Percentages are presented by column (each column sums to 100%). Numbers and percentages of observations may differ from variable to another because of the missing and unknown values.

³SE = 0 because all the observations in this category (AIS < 2) are equal to “1”. Hence, there is no variation within this category.

⁴p-value for the test of significance of differences between the two age groups. t-test was used for differences in means and Chi-2 for differences in rates.

⁵By definition: AIS is an outcome measure for injuries and not for pedestrian cases (one pedestrian may have more than one injury). Unlike MAIS and ISS, the SEM values for the AIS outcome were rounded to the nearest two digits because of the small SEM values associated with AIS.

¹Abbreviations: N/n: frequency; %: percentage; M: mean; SD: standard deviation.

² p-values are for t-test of significance for the differences between two group means except for mortality where Chi-2 was used.

³AIS is calculated for injuries (1,879 male injuries and 1,207 female injuries).

^{a 1}Abbreviations: OR: odds ratio.

^{a 2}Adjusted for impact speed.

¹Abbreviations: OR: odds ratio; 95% CI: 95% confidence interval.

²Adjusted for pedestrian weight, height, and gender, vehicle type and impact speed.

³p-value = .055.

⁴p-value > .050 but <.100.

⁵p-value > .100.

¹Abbreviations: OR: odds ratio.

²Adjusted for pedestrian weight, height, and gender, vehicle type, and impact speed within each speed group.

¹Abbreviations: OR: odds ratio; 95% CI: 95% confidence interval.

²Adjusted for impact speed, vehicle body type, and pedestrian height and weight.