# Presentation: 053565

## Are Children Too Heavy for Age-appropriate Child Passenger Safety Seats?

- William Basco, Paul Hletko*, Lynn West, and Paul Darden
- AHRQ National PBRN Research Conference
- May 16-18, 2007

## SCPPRNSouth Carolina Pediatric Practice Research Network

- www.musckids.com/scpprn

## Funding

- Supported in part by:
- HRSA – Grant # D54HP05448
- Agency for Healthcare Research and Quality – Grant # 1KO8 HS015679-01A1

## SCPPRN Members

- Charleston Pediatrics
- Seacoast Pediatrics
- MUSC Children’s Care, N. Charleston
- MUSC Pediatric Primary Care

- MUSC Children’s Care, Moncks Corner
- Barnwell Pediatrics
- Georgetown Pediatrics
- Beaufort Pediatrics

## Background:

- Motor vehicle related injury (MVA) is the number one cause of unintentional injury death in children under 19 years old in South Carolina and the US.
- Improper use of child automobile restraints is an important contributor to risk of death if involved in a MVA

## Background, MVA Injury:

- Arbogast (2004): review of 1998-2002 US crash data
- proper use of child restraints for children 12-47 months old reduced the risk of serious injury by 78% (OR 0.22, 95% CI 0.11-0.45) compared to seat belts
- Durbin (2005): 1998-2002 US crash data
- Children not properly restrained had an increased risk of injury (OR 1.8, 95% CI 1.4-2.3) compared to properly restrained children.
- Unrestrained children had an OR for severe injury of 3.2 (95% CI 2.5-4.1).
- Elliott (2006): Proper use of child passenger restraints reduces the risk of DEATH in motor vehicle crashes by 28%.

## 1999 - 2004, US and South Carolina Unintentional, Overall Motor Vehicle Deaths and Rates per 100,000 All Races, Both Sexes, Ages 0 to 19

**Source: **WISQARSTM (Web-based Injury Statistics Query and Reporting System),
- Centers for Disease Control and Prevention

## There ought to be a (SC) law!

- Children from birth to 1 year old, or who weigh less than 20 pounds, must be secured in a rear-facing child safety seat.
- Children 1 through 5 years old weighing 20 to 40 pounds must be restrained in a forward-facing child seat.
- Children 1 through 5 years old weighing 40 to 80 pounds must be secured in a belt-positioning booster seat.
- Children under the age of 6 are not required to be in booster seats if they weigh more than 80 pounds or if they can sit with their backs against the car's seat and bend their legs over the seat edge without slouching.
- Children under 6 may not sit in the front passenger seat. However, this restriction does not apply if the vehicle has no rear passenger seats or if all other rear passenger seats are occupied by children less than 6 years old.

## Usual Restraint cutoffs:

- Infant carrier: at least 20 lb AND 12 months
- Toddler seat: at least 40 lb AND 5 years
- Booster seat: at least 80 lb
- Front seat (air bag): > 12 years (SC law > 6 years)

- _[http://www.aap.org/family/carseatguide.htm](http://www.aap.org/family/carseatguide.htm)_

## Background, Obesity:

- Ogden (2003), Hedley (2004), and Freedman (2006): rates of obesity have been increasing in US children, especially among low-income children.
- Trifiletti (2006): 1999-2000 data from the National Health and Nutrition Examination Survey (NHANES)
- modeled the potential impact of weight changes on proper restraint selection.
- Generous in their selection of an upper bound for infants (35 lbs – the typical infant carrier is rated to only 20-22 lbs).
- Ages 2-3 years old appeared to be the most problematic strata with significant numbers of children in those strata too heavy for age-appropriate restraints.

## Objective:

- To determine what percentages of children in critical age strata are too heavy for their age-appropriate child passenger restraint.

## Hypotheses:

**Hypothesis #1:** Significant numbers of children in this sample will be too heavy for age-appropriate car restraints.
**Hypothesis #2**: Minority children will be too heavy for age-appropriate car restraints at higher rates than the comparison, non-minority children.
**Hypothesis #3:** There will be significant variation in the percentages of children too heavy for age-appropriate car restraints among practices.
**Hypothesis #4:** Is location (urban vs rural).

## Anthropometrics:Method

- 6 practices collected data on consecutively-seen patients.
- Each practice collected data on 20 patients per age stratum, in the units they typically used (lbs or kg, etc.)
- Data converted to kg and cm by research staff

## Anthropometrics:Age Strata

- Age categories (12)
- 0-6 months, recorded in months
- 7-12 months, recorded in months
- 13-24 months, recorded in months
- 25-35 months, recorded in months,
- Two-year groupings: 3-4 year olds, 5-6 year olds, 7 and 8 year olds, 9 and 10 year olds, 11 and 12 year olds, 13 and 14 year olds, 15 and 16 year olds, and 17 and 18 year olds.

## Analyses:

- 1. Descriptive analysis of the SC cohort as well as by practice.
- 	a. Mean Weight and mean Height by age stratum
- 	b. Mean Weight and mean Height by Gender
- 	c. Mean Weight and mean Height by Ethnicity/Race
- 	d. Mean Weight and mean Height by Practice Site
- 2. Compare mean weight and mean heights among practices to determine if any adjustment should be made for clustering of observations within a practice.

## Analyses, 2:

- Percentage of children be misclassified by seat type based on weight vs age.
- For example, children less than 12 months old should be in an infant carrier, but weight cutoff should be ~ 22lbs.
- Percentage of children 13 months to < 6 years who are too heavy for a forward facing toddler seat (> 40 pounds).
- Percentage of children age 13 months to < 6 years who are too heavy for a belt-positioning booster seat (> 80 pounds).
- Compare rates determined in #3 by ethnicity/race breakdown of the children, comparing percentages overweight for age restraint in African-American and Hispanic children to White children.
- Adjust all comparisons by site if children are found to vary a significant amount by site.

## Results:	

- 6 practices provided data on 1,390 subjects
- 717 subjects < 6 years old
- Male = 56%
- N per age stratum:
- < 12 months, 267 subjects
- 12 months to < 6 years, 450 subjects
- Race/ethnicity
- White, 42%
- Black, 42%
- Hispanic, 15%
- Other, 1%

## Results: < 12 months and above 20-lb cutoff

- 24% - 63 of 267 subjects

## Results: < 12 months and above 20-lb cutoff – race/ethnicity

- 24% - 63 of 267 subjects

|  | < 20 lbs (%) | > 20 lbs (%) |
| --- | --- | --- |
| white | 77 | 23 |
| black | 77 | 23 |
| Hispanic | 75 | 25 |

## Results: < 12 months and above 20-lb cutoff - practice

- 24% - 63 of 267 subjects
- Range by practice 16-41%

| Practice | < 20 lbs (%) | > 20 lbs (%) |
| --- | --- | --- |
| 1 | 82 | 18 |
| 2 | 82 | 18 |
| 3 | 78 | 22 |
| 4 | 84 | 16 |
| 5 | 78 | 22 |
| 6 | 59 | 41 |

- P=.04

## Results: < 6 years and above 40-lb cutoff

- 21% - 96 of 450 subjects

## Results: < 6 years and above 40-lb cutoff – race/ethnicity

- 21% - 96 of 450 subjects

|  | < 20 lbs (%) | > 20 lbs (%) |
| --- | --- | --- |
| white | 79 | 21 |
| black | 80 | 20 |
| Hispanic | 77 | 23 |

## Results: < 6 years and above 40-lb cutoff - practice

- 21% - 96 of 450 subjects
- Range by practice 13-26%

| Practice | < 20 lbs (%) | > 20 lbs (%) |
| --- | --- | --- |
| 1 | 79 | 21 |
| 2 | 76 | 24 |
| 3 | 86 | 13 |
| 4 | 76 | 24 |
| 5 | 80 | 20 |
| 6 | 74 | 26 |

- P>.05

## Results: < 6 years and above 80-lb cutoff

- 0.22% - 1 of 450 subjects

## Conclusions:	

- Substantial percentages of children in this SC cohort were too heavy for their age-appropriate child automobile restraint.
- Substantial variation in % overweight by practice site greater variation at younger ages.
- Less variation than expected by race/ethnicity.

## Implications:

- Changing weights of US children will have an adverse effect on proper automobile restraint selection.
- This will place increased numbers of children at risk for injury if involved in an MVA.
- Providers should stress both age AND weight when advising parents about selection of proper child automobile restraint.