Booster seat and seat belt effectiveness among children ages 4-8

Background: Numerous studies have examined booster seat usage among young children or have evaluated interventions to increase booster seat use. Few studies have estimated the effectiveness of booster seat use on injury or fatality risk due to the difficulty in obtaining restraint use data, particularly in the absence of injury.

Methods: We estimated the effectiveness of booster seat use in preventing fatal injury among children ages 4-8 using a matched cohort study of Fatality Analysis Reporting System data for years 1996-2006. Death risk ratios were estimated with conditional Poisson regression, and coefficient standard errors were bootstrapped.

Results: The estimated death risk ratios comparing booster seat use to traveling unrestrained were 0.39 (95% CI 0.32 - 0.47) for children ages 4 or 5 and 0.54 (0.39 - 0.76) for ages 6, 7, or 8. Seat belt risk ratios were 0.40 (0.33 - 0.47) for ages 4 or 5 and 0.46 (0.40 - 0.53) for ages 6, 7, or 8. Both restraints were more effective during rollover collisions and collisions in rural areas. Effectiveness did not appear to vary by model year or calendar year.

Conclusions: This study found that booster seats and ordinary seat belts are approximately equal in their effectiveness in reducing death risk among children ages 4-8 during severe traffic collisions. This analysis did not examine non-fatal injury, but several published studies have reported boosters to be more effective than seat belts in preventing non-fatal injury. Clinical and public health practitioners should advocate for the use of booster seats over seat belts.