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Vehicle characteristics associated with LATCH use and correct use in real-world child restraint installations

Cicchino, Jessica B.; Jermakian, Jessica S.
Insurance Institute for Highway Safety
April 2014

Objective: The purpose of this research was to determine if vehicle features associated with LATCH ease-of-use in laboratory studies with volunteers predict LATCH use and misuse in real-world child restraint installations.
Methods: Vehicle characteristics were extracted from prior surveys of more than 100 top-selling 2010-13 vehicles. Use and correct use of LATCH was determined from records of child restraint installations in these vehicles that were inspected by child passenger safety technicians at Safe Kids car seat checkup events during 2010-12. Logistic regression was used to examine the association between vehicle features and use and correct use of lower anchors and top tethers.
Results: Overall, the lower anchors were used in 78% of the 14,360 installations using either the lower anchors or seat belt alone, and were used correctly in 49%. Controlling for other relevant installation features, the odds of using the lower anchors and of using them correctly were higher when the clearance angle around the lower anchors was greater than 54°, the force required to attach the child restraint to the lower anchors was less than 178 N, and the depth of the lower anchors within the seat bight was less than 4 cm. When child restraints were installed in seating positions with lower anchors meeting all three criteria, the lower anchor use rate was 80% and the correct use rate was 53%; when none of these criteria was met, the lower anchor use rate was 65% and the correct use rate was 41%. Restraints were more likely to be attached correctly when installed with the lower anchors (63%) rather than with the seat belt (34%). The tether was used in 49% of the 2,880 installations of forward-facing restraints, and was used correctly in 38%. If there was not hardware present that could potentially be confused with the tether anchor, the tether use rate was 50% and the correct use rate was 39%; if there was confusing hardware present, the tether use rate was 46% and the correct use rate was 34%. The tether was more likely to be used when the child restraint was attached with lower anchors alone or in combination with the seat belt (62%) than with the seat belt alone (29%). After controlling for lower anchor use and other installation features, the odds of tether use and correct use were higher when there was not confusing hardware present or when the tether anchor was located on the rear deck, which is typical in sedans.
Conclusions: There is converging evidence from laboratory studies with volunteers and real-world child restraint installations that vehicle features are associated with correct LATCH use. Vehicle designs that improve the ease of installing child restraints with LATCH could increase LATCH use rates and reduce child restraint misuse.