Motor Vehicle Occupant Injury and Related Hospital Expenditures in Children Aged 3 to 8 Yrs Covered vs. Uncovered by Booster Seat Laws Joyce C. Pressley, PhD, MPH, Tiffany Kendig, MSPT, Barbara Barlow, MD, Lisa Trieu Columbia University November 7, 2007

Methods-Data Source(s)  Health Care Cost and Utilization Project - Kids Inpatient Database (KID-HCUP) 2003  Acute care hospital discharges for ages 3 to 8 yrs  36 states reported data  80% sample of acute care hospitals based on the Nationwide Inpatient Sample (NIS) sampling strata  Acute care hospitalizations for the majority of U.S. children (excludes rehab hospitals)  Data completeness varied by state (Texas reported 73%, Minnesota, 88%)  This study assumed that completeness of MVO vs. nonMVO injury was similar within a state and age range  Analyses are unweighted

Methods-Data Source(s)  Variables available in KIDHCUP  Demographics: age, race, ethnicity, zip code level income (quartiles), state of residence  Clinical: source/type of admission, E-coded injury mechanisms (4), ICD-9-CM diagnosis codes (15), month of injury, weekend/weekday injury, length of stay, hospitalization charges, discharge disposition, and others  ICD-9-CM codes allowed for injury severity scoring using ICDMAP-90 and ICISS  CDC’s WISQARS database used for comparison of mortality by state and age

Booster Seat Law Coverage Classification  States were classified as either having or not having a booster seat law in effect during calendar year 2003  Eight states had laws and had data in KID-HCUP  For 2 states with coverage during part of 2003 (CO, MD), classification was determined using effective date of the law and month of injury  Coverage determination was at the individual level based on whether the law covered the age and state of residence  Variables not available at the state level in KIDHCUP  Height, weight or vehicle class data necessary to assess exclusions to age-based laws  Data on booster seat usage at the time of injury  Weight variables for inflating to full state population

States in KID-HCUP 2003 with Booster Seat Law Coverage StateAges coveredEffective Date California Up to 61/1/2002 Colorado Up to 68/1/2003 Maryland Up to 610/1/2003 Nebraska Up to 67/20/2002 New Jersey Up to 812/1/2001 Oregon Up to 61/1/2002 Rhode Island Up to 71/1/2002 South Carolina Up to 67/1/2001

Methods (cont’d) Comparisons were made for states with and without coverage for: –Proportion of hospitalizations : MVO injury All injury –Proportion of expenditures : MVO injury hospital charges All injury hospital charges –Distribution and types of injury –Injury severity Scores used ICD-MAP90 and ICISS (USFs International classification of injury severity scores) In-hospital mortality –Statistical analysis used SAS 9.1 Chi-square, Fisher’s Exact tests, ANOVA Wilcoxon rank sum

States in KID-HCUP 2003 with and without Booster Seat Law Coverage (as of 2003) KID-HCUP state with booster seat law in 2003 KID-HCUP state without booster seat law States not reporting to KID-HCUP Map and HCUP Data source: HCUP KID 2003 (01/30/2006) Documentation, Design of the HCUP KID, 2003 Booster Seat Law Data source: Advocates for Highway and Auto Safety, Booster Seat Law Chart, February 24, 2007

- 16% (p =.12) - 10% (p =. 34) - 27% (p <.01) - 22% (p <.10) SES Differences in Proportion of Motor Vehicle Occupant Injury/All Injury by Booster Seat Law Coverage Median Household Income of Residence Zip Code -13% (p=.0717) Below the median -26% (p=.0011) Above the median

26% lower (p =.0026) 10% lower (p =.5398) 38% lower (p <.0001) Racial Differences in the Proportion of Motor Vehicle Occupant/All Injury by Booster Seat Law Coverage

28% lower (p =.0005) 14% lower (p=.0980) 20% lower (p =.2800) Age Differences in the Proportion of Motor Vehicle Occupant Injury/All Injury by Booster Seat Law Coverage

Distribution of Injury in Children Hospitalized for MVO by Booster Seat Law Coverage UncoveredCoveredTotalChi-Square n (%)Χ² (p-value) Population1725(84.8)310(15.2)2035(100.0) Types of Injury Coma/stupor /brain damage 43(2.5)6(1.9)49(2.4) 0.3(0.5557) Intracranial580(33.6)97(31.3)677(33.3)0.6(0.4222) Spinal cord23(1.3)2(0.6)25(1.2) --(0.4110) Crushing/internal467(27.1)67(21.6)534(26.2) 4.0(0.0443) Fractures Skull/Face246(14.3)56(18.1)302(14.8) 3.0(0.0828) Upper extremity223(12.9)32(10.3)255(12.5) 1.6(0.2021) Lower extremity233(13.5)45(14.5)278(13.7) 0.2(0.6339) Neck of femur26(1.5)1(0.3)27(1.3) --(0.1083) Other187(10.8)22(7.1)209(10.3) 4.0(0.0456) Superficial691(40.1)147(47.4)838(41.2)5.9(0.0153)

Injury Severity Score and Length of Stay by Booster Seat Coverage Status for MV Occupant Injury UncoveredCovered Injury Severity Score N = 1676N = 297 Mean (± SD) Median (± IQR) 8.42 (± 9.3) 5.00 (± 12.0) 7.53 (± 8.5) 5.00 (± 9.0) Length of Stay (days) Mean (± SD) Median (± IQR) 4.29 (± 6.9) 2.00 (± 4.0) 3.70 (± 6.3) 2.00 (± 3.0)

Mean and Median Charges in U.S. Dollars per MVO Hospitalization by Coverage Status and In-hospital Patient Disposition UncoveredCovered LivedN = 1676N = 297 Mean $ (± SD) Median $ (± IQR) $23,707 (± 39,438) $13,162 (± 18,241) $34,572 (± 63,760) $18,205 (± 24,388) DiedN = 36 (0.02)N = 12 (0.04) Mean $ (± SD) Median $ (± IQR) $41,856 (± 53,191) $24,683 (± 33,471) $93,031 (± 91,582) $62,984 (±134,263)

* Unweighted approximations are underestimated by %sampled and/or not reporting within category) Percent MVO/All Injury Hospital Charges Proportion of Expenditures (MVO/All Injury) Covered and Uncovered Children by Payor

HCUP-Captured ~80% Approximations* of MVO Hospitalization Incidence (per 100,000) in Uncovered and Covered Children by Race * Unweighted approximations are underestimated by %sampled and/or not reporting within category)

Study Limitations  This study did not have data on whether a booster seat was in use, correct use, or type of booster seat  Non-age based exclusions to the law were not available for analysis (child height and weight, vehicle type)  Data completeness and quality assumed to be similar across uncovered and covered children  Limited ability to evaluate true incidence at state level  Weights to the national level based on hospital vs. population characteristics precluded using weighted data at state level  Incidence and charges based on these approximations are known to be an underestimate of the true absolute MVO injury burden  Lack of e-codes on a significant proportion of injuries  Lack of consistently included professional fee charges  Sampling without state level weights

Booster Seat Law Coverage by State (2007) States with booster seat law in effect by end of 2003 States with booster seat law in effect after 2003 States without booster seat law Map source: HCUP KID 2003 (01/30/2006) Documentation, Design of the HCUP KID, 2003 Data source: Advocates for Highway and Auto Safety, Booster Seat Law Chart, February 24, 2007

Conclusions  States with booster seat laws had a lower proportion of MVO injury in booster seat aged children compared to states without legislation  States with legislation tended to have a lower proportion of injury dollars spent for MVO in booster seat aged children  Assuming that covered and uncovered states capture an unbiased and similar proportion of the population, this study suggests expenditure patterns are a reflection of lowered incidence and not lowered cost per case  In 2003, legislative and regulatory measures for prevention of MVO injury in booster seat aged children were grossly under utilized  Not implemented universally  Not all states with booster seat laws follow “best practices” covering the full age of vulnerable children

Conclusions  Observed disparities by race, median income, and/or payor are consistent with other studies that suggest affordability and access to quality booster seats impede legislative effectiveness  Further examination of the distribution of injury and expenditures using other data sets should be conducted  HCUP should weigh the pros and cons of using demographers to develop state specific weights  Improve the capacity of the HCUP series to be used to investigate the true effectiveness of state-level legislative and regulatory initiatives

Back up slides

States Reporting KID-HCUP 2003 Data (n=36)  Arizona  California  Colorado  Connecticu t  Florida  Georgia  Hawaii  Illinois  Indiana  Iowa  Kansas  Kentucky  Maryland  Ohio  Oregon  Rhode Island  South Carolina  South Dakota  Tennessee  Texas  Utah  Vermont  Virginia  Washington  West Virginia  Wisconsin  Massachusetts  Michigan  Minnesota  Missouri  Nebraska  Nevada  New Hampshire  New Jersey  New York  North Carolina Maine and Pennsylvania, included in previous versions of KID-HCUP, did not report in 2003

Population Characteristics by Covered and Not Covered by Booster Seat Law Covered Not CoveredTotal N6,95430,29237,246 Median Income (%) $1 – 35,999 $36,000 – 44,999 $45,000 – 59,999 $60, Race (%) White Black Hispanic Other

Unweighted 80%Approximations of Incidence in Covered and Uncovered States by Age * Approximations are dependent upon completeness of reporting/sampling within each state

22% lower (p =.0011) 7% lower (p =.4740) 22% lower (p =.0010) Sensitivity Analysis: Difference in All Motor Vehicle injury in Uncovered and Covered States by Race

Difference in All Motor Vehicle injury in covered and uncovered states by median income 7% decrease (p =.2962) 3% increase (p =.6589) 16% decrease (p =.0377) 14% decrease (p =.1439)

Difference in non-pedestrian-related Motor Vehicle injury in covered and uncovered states by race 29% decrease (p =.0002) 0.3% decrease (p =.9865) 38% decrease (p <.0001)

18% decrease (p =.0545) 12% decrease (p =.2241) 29% decrease (p =.0019) 20% decrease (p =.0891) Difference in non-pedestrian-related Motor Vehicle injury in covered and uncovered states by median income

Difference in Motor Vehicle Occupant Injury between income strata by coverage status p <.0001p =.0006

Study Population Characteristics Age3 – 8 years N37,246 Median Income $1 – 35,999 $36,000 – 44,999 $45,000 – 59,999 $60, % % 25.10% % Race White Black Hispanic Other % % % %

Study Population Characteristics for MV Occupant Injury Age3 – 8 years N2066 Median Income $1 – 35,999 $36,000 – 44,999 $45,000 – 59,999 $60, % 27.5 % 24.3 % 14.5 % Race White Black Hispanic Other 38.2 % 11.5 % 15.3 % 34.9 %

Median Household Income (US $) for Patients Zip Code of Residence (%) Income ($)WhiteBlackHispanicTotal* <25, $25K - $34, $35K - $44, < $50, *Includes other and unspecified Source: Pressley JC and Barlow B. Injury Prevention 2005;11(5):267-73

UncoveredCovered All injuryMVOAll injuryMVO $ % $ % All Injury$ Private$ Gov't$ Self-Pay$ Other$ Total$ Cost ($ in millions) Due to MV Occupant and All Injury for Covered and Uncovered by Payor % of all injury in that payor category

Cost due to Motor Vehicle Occupant and All Injury for covered and uncovered states by payor UncoveredCovered