Cameron K. Fong

Seat belt use and fit among drivers aged 75 years and older in their own vehicles

ABSTRACT Objective: This article aims to describe seat belt wearing patterns and quality of seat belt fit among drivers aged 75 years and older. A secondary aim is to explore associations between body shape, comfort, and seat belt use patterns. Methods: This is an observation and survey study of a cohort of 380 drivers aged 75 years and over. During home visits, photographs were taken of the drivers in their vehicles for later analysis of belt fit and a short survey was also administered to collect demographic data and information about seat belt use and comfort. Seat belt fit and use of belt and seat accessories were analyzed from the photographs. Results: Data from 367 participants with photographs were analyzed. Whereas 97% reported using a seat belt and 90% reported their seat belt to be comfortable, 21% reported repositioning their seat belt to improve comfort. Good sash and lap belt fit were achieved in 53 and 59% of participants, respectively, but only 35% achieved overall good fit. Both poor sash and lap belt fit were observed in 23% of participants. Drivers who were in the obese category had over twice the odds (95% confidence interval [CI], 1.2–4.1) of having a poor lap belt fit than those in the normal body mass index [BMI] range, and drivers who were overweight had 1.8 times the odds (95% CI, 1.1–2.9) of having poor lap belt fit. Older females also had twice the odds (95% CI, 1.3–3.5) of poor lap belt fit compared to older males, regardless of BMI. Sash belt fit did not vary significantly by BMI, stature, or gender. However older drivers who reported that they had not made any adjustments to the D-ring height had 1.7 times the odds of having poor sash belt fit than those who made adjustments (1.2–2.9). Females were 7.3 times more likely to report comfort problems than males (95% CI, 3.2, 16.3) but there was no association between reported comfort and BMI or seat belt fit. Drivers who reported comfort problems had 6 times the odds (3.2–13.6) of also reporting active repositioning of the belt. Conclusions: The results suggest that older drivers face challenges in achieving comfortable and correct seat belt fit. This may have a negative impact on crash protection. Belt fit problems appear to be associated with body shape, particularly high BMI and gender. There is a need for further investigation of comfort accessories; in the interim, older drivers and occupants should be encouraged to use features such as D-ring adjusters to improve sash belt fit.

A novel method for quanitifying comfort in child passengers demonstrates an association between child restraint comfort and errors in use of booster seats

ABSTRACT Objective: Misuse of child restraint systems is a widespread and long-standing problem impacting risk of injury and death in car crashes. Discomfort has been suggested as a causative factor for misuse, particularly in errors introduced by children while they use the restraints. However, the relationship between comfort and errors in use has never been studied. In this study we examine the reliability and sensitivity of a newly developed observational method for assessing comfort in children in vehicles. We then use this method to examine the relationship between comfort and errors in use of booster seats. Methods: A novel method was developed for assessing comfort by counting fidgeting and postural adjustment behaviors to derive a Discomfort Avoidance Behavior (DAB) score. The sensitivity of the DAB score was examined by observing children in four different seating conditions designed as “comfortable” and “uncomfortable” (Part 1). Paired-samples t-tests were used to compare differences in DAB between seating conditions. The reliability of the DAB score was assessed by calculating the intraclass correlation coefficient (ICC) between DAB scores recorded by different researchers. The association between comfort and correctness of use was examined by observing children using booster seats (Part 2). The association between DAB score and number of usage errors was tested using linear regression analysis. Participants were children ages 4–8 years. Fourteen children participated in Part 1 and 15 children in Part 2. Results: The DAB score was sensitive to changes in seat condition (p < 0.01), and was repeatable between different researchers (ICC 0.98, 95% confidence interval [CI] 0.954–0.991). Increases in DAB were associated with increases in the number of use errors among children using booster seats (errors in use = 3.89 × DAB − 2.18, p < 0.0001). Conclusion: The DAB score is a reliable and valid measure of comfort of children in child restraints but could be improved by incorporating a measurement of postural positioning. Comfort, as characterized by fidgeting and postural adjustment behaviors, is associated with correct use of child restraints. The broader implication is that this confirms ergonomic design of child restraints as important for minimizing errors in use. There is a need for further study of the impact of specific restraint design features on comfort experienced by children.

Seat belt repositioning and use of vehicle seat cushions is increased among older drivers aged 75 years and older with morbidities

Good seat belt fit and positioning is important for crash protection. Older drivers experience problems in achieving good seat belt fit and often reposition seat belts and/or use seat cushions. Comfort influences these behaviours. This work examines the impact of functional morbidities on belt positioning and accessory use and whether comfort mediates this relationship

Child restraint use and parental perceptions of comfort

ABSTRACT Objective: Suboptimal child restraint use includes incorrect and/or inappropriate restraint use and increases the risk of injury. Comfort has been suggested as an important factor impacting on optimal use of restraints by children. This article aims to examine the relationships between parent reported comfort and restraint misuse and age-appropriate restraint choice. Methods: This is an analysis of data from a cross sectional observation study of child restraint use in New South Wales. Logistic regression was used to model the relationship between parent-reported comfort and restraint misuse and age-appropriate restraint choice. Results: There was no significant relationship between either parent-reported comfort and restraint misuse or parent-reported comfort and age-appropriate restraint choice. Conclusions: Parent perceptions of comfort of children in child restraints do not appear to be associated with incorrect child restraint use or age appropriate restraint choice. It is possible that the actual comfort of the child may be related to incorrect use but this remains to be tested. Further investigation of the relationship between parent-perceived comfort and the actual comfort of the child, as well as the impact of child comfort on optimal child restraint use is warranted.

173 Seat belt fit and use behaviours observed among drivers aged 75+ years in their own vehicles [abstract]

Background Older occupants are at increased risk of serious injury in a crash compared to younger occupants. While seatbelts reduce injury risk, effectiveness relies on good belt fit and positioning. Laboratory research indicates increased likelihood of poor belt fit with increasing age, however little is known about seat belt use in this age group. The aims of this work are to (i) describe belt fit and use among drivers aged 75+ years in their own vehicles, and (ii) examine the influence of body mass index (BMI), comfort and comorbidities on belt fit and use. Methods Photographs were taken of drivers in their vehicles to assess belt fit and accessory use. Surveys of comorbidities and belt use, and measurements of height and weight were made. Logistic regression and mediation analysis examined associations between BMI, comfort, comorbidities and belt fit, belt repositioning behaviour, and accessory use. Results 367 drivers were photographed, mean age 80 years, 23% used an accessory, 47% had poor sash and 41% poor lap belt fit. While 90% reported their belt as comfortable, 21% reported repositioning their belt. Poor lap belt fit was more likley in obese (OR2.2, 95% CI: 1.2–4.0) and overweight drivers (OR 1.8, 95% CI: 1.1–3.0), and females (2.2,95% CI: 1.3–3.5). Comfort pads were associated with shorter stature (OR 1.1 95% CI: 1.02–1.1), and cushions with belt discomfort (OR 2.5, 95% CI: 1.1–5.6). Musculoskeletal comorbidities increased belt repositioning (OR 1.3, 95% CI: 1.1–1.6), and comfort partially mediated this relationship (p = 0.03). General comorbidities, increased the odds of accesory use (OR 1.2 95% CI: 1.04–1.3). Conclusions Older drivers face challenges achieving comfortable and correct belt fit, and many reposition belts and use comfort accesories. This may negatively impact crash protection.Older drivers need to be aware of the importance of good belt positioning, particularly those with comorbidities.The impact of accesories on injury risk needs examination.