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Mortality Among Very Low Birthweight Infants in Hospitals Serving Minority Populations Support Provided by: UCLA-Drew EXCEED Program (AHRQ), RWJ Minority.

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Presentation on theme: "Mortality Among Very Low Birthweight Infants in Hospitals Serving Minority Populations Support Provided by: UCLA-Drew EXCEED Program (AHRQ), RWJ Minority."— Presentation transcript:

1 Mortality Among Very Low Birthweight Infants in Hospitals Serving Minority Populations Support Provided by: UCLA-Drew EXCEED Program (AHRQ), RWJ Minority Medical Faculty Development Program, and UCLA-RCMAR Center (NIA) Leo Morales, M.D., Ph.D. Assistant Professor, UCLA AcademyHealth June 7, 2004

2 Morales-2 03/18/04 Key Collaborators Jeanette Rogowski, Ph.D., University of Medicine and Dentistry of New Jersey and RAND Douglas Staiger, Ph.D., Dartmouth University Jeffery Horbar, M.D., The Vermont Oxford Network (VON) Joe Carpenter, M.S., VON Mike Kenny, M.A., VON Jeff Geppert, M.A., National Bureau of Economic Research

3 Morales-3 03/18/04 I. BACKGROUND

4 Morales-4 03/18/04 Hospital Characteristics and Patient Outcomes Worse outcomes are associated with: –Rural hospitals (Kahn, 1994) –Non-teaching hospitals (Kuhn, 1994; Polanczyk, 2002; Taylor, 1999; Kahn, 1994) –For-profit hospitals (Hartz, 1989; Haas, 2003) –Lower expenses per admission (Burstin, 1993) –Minority-serving hospitals (Brennan, 1991) –Low volume and lower level of care (Phibbs, 1996) Little is known about the relationship of minority- serving hospital status to infant mortality

5 Morales-5 03/18/04 Trends in Infant Mortality Overall, infant mortality is decreasing for black and white infants However, the disparity between black and white infant mortality remains constant and maybe increasing (MacDorman, 2002) –Black infant mortality 14.1 per 1,000 live births –White infant mortality 5.7 per 1,000 live births Eliminating the racial disparity in infant mortality is one of six target areas in the Health People 2010 initiative

6 Morales-6 03/18/04 Very Low Birthweight Infants Definitions –Low birthweight (LBW): <2500 grams –Very low birthweight (VLBW): <1500 grams Small but high risk infant population –LBW infants account for 7.6% of live births but 66% of all infant deaths (MacDorman, 2002) –VLBW infants account for 1.4% of live births but 52% of all infant deaths (MacDorman, 2002)

7 Morales-7 03/18/04 Research Questions Do VLBW infants treated by minority-serving hospitals have similar neonatal mortality as those treated by other hospitals? Do hospital characteristics and process of care variables explain differences in neonatal mortality between minority-serving hospitals and other hospitals? Are black and white infants treated by minority- serving hospitals at similar risk for neonatal mortality?

8 Morales-8 03/18/04 II. METHODS

9 Morales-9 03/18/04 Primary Data Source 1995-2000 Vermont Oxford Network (VON) –332 hospitals –40% of US hospitals with NICUs –50% of VLBW infants in US Abstracted medical records –Mortality outcomes –Case-mix variables –Process of care Institutional survey of participating hospitals –NICU level of care

10 Morales-10 03/18/04 Additional Data Sources American Hospital Association Annual Survey of Hospitals –Hospital characteristics 1990 United States Census –Maternal income and education

11 Morales-11 03/18/04 Study Subjects VLBW infants between 500g and 1500g –White infants (n= 49,132) –Black (n=24,918) Inborn infants only

12 Morales-12 03/18/04 Outcome Variable Neonatal mortality –Mortality in the first 28 days after birth –Mortality ascertained through transfers until discharge home

13 Morales-13 03/18/04 Main Explanatory Variable: Hospital Minority-Serving Status Hospitals assigned to 1 of 3 categories based on the proportion of infants treated between 1995 and 2000 who were Black % VLBW black infants = VLBW black infants / VLBW black and white infants Category Number of Hospitals Proportion of Hospitals <15% Black Infants11334% 15%-35% Black Infants12136% >35% Black Infants9830%

14 Morales-14 03/18/04 Explanatory Variables: Case-Mix Variables Gestational age (+ gestational age squared)* Birthweight* Small for gestational age Congenital malformation Multiple birth Any prenatal care 1-minute APGAR Sex Race Vaginal delivery Maternal income and education based on census

15 Morales-15 03/18/04 Explanatory Variables: Hospital Variables Geography –Region –Urban setting of >1,000,000 NICU characteristics –Level of care –Volume Hospital characteristics –Ownership –Teaching status –Percent Medicaid admissions –Expenditures per admission –Average maternal income and education based on census

16 Morales-16 03/18/04 Explanatory Variables: Process of Care Variables Indicator variables: –Treatment with surfactants –Treatment with antenatal steroids

17 Morales-17 03/18/04 Statistical Models Descriptive analysis –Infants by case-mix, hospital, and process of care variables Stratified regression by race –%black + case-mix Pooled regression –Model 1: %black + case-mix –Model 2: %black + case-mix + hospital –Model 3: %black + case-mix + hospital + process of care

18 Morales-18 03/18/04 Estimation Methods Maximum-likelihood logistic regression models Robust standard errors Clustering of infants within hospitals STATA 8.0

19 Morales-19 03/18/04 III. RESULTS

20 Morales-20 03/18/04 Infants by Case-Mix Variables All Infants (n=74,050) Neonatal Infant Morality11% Birth Weight (grams)1048.5 Gestational Age (weeks)28.5 1-Minute APGAR Score5.4 Male Sex51% Small for Gestational Age21% Multiple Birth29% Congenital Malformation4% Vaginal Delivery38% Maternal Black Race34% Had Prenatal Care96% Maternal Education (years)12.41 Maternal Income ($1000s)36.01 Antenatal Steroids74% Surfactants60%

21 Morales-21 03/18/04 Infants by Hospital Variables

22 Morales-22 03/18/04 Stratified Logistic Regressions: Neonatal Mortality on Case-Mix Variables Note. Models include year dummies. *p<0.05 **p<0.01

23 Morales-23 03/18/04 Pooled Regressions: Neonatal Mortality on Hospital and Case-Mix Variables Note. Models include case-mix model and year dummies. *p<0.05 **p<0.01

24 Morales-24 03/18/04 Thought Experiment-1 What if black infants were treated by the three categories of hospitals we studied (e.g., 35% black) in the same proportions as white infants? –Black infant mortality would drop by 8.5%

25 Morales-25 03/18/04 Thought Expereiment-2 What if neonatal mortality at hospitals where 15% or more of the treated infants were black were the same as hospitals where <15% of the infants treated were black? –10% lower for white infants –22% lower for black infants

26 Morales-26 03/18/04 IV. CONCLUSIONS

27 Morales-27 03/18/04 Conclusions Minority-serving hospitals had higher neonatal mortality than other hospitals The difference in neonatal mortality between minority-serving and other hospitals was not explained by the hospital variables or process of care variables Neonatal morality was similarly elevated for black and white VLBW infants treated by minority-serving hospitals

28 Morales-28 03/18/04 Implications Minority-serving hospitals may provide worse quality of care than other hospitals Hospital-level factors may be more important in understanding disparities in care than individual characteristics such as infant race per se, at least among VLBW infants Disparities in infant mortality nationally might be reduced by improving care for VLBW infants at minority-serving hospitals

29 Contact Information: or 310-794-2296

30 Morales-30 03/18/04 Potential Explanations for Results Staffing patterns –Nurse-to-patient ratio –Board-certified specialists Maternal characteristics: smoking, drug and alcohol use –Mediated by infant severity of illness –Infant characteristics in minority-serving similar to other hospitals –Maternal income and education had no effect Unmeasured severity of illness –VON risk adjustment ROC=0.88 –SNAP ROC=0.73 to 0.91

31 Morales-31 03/18/04 Study Generalizability Compared with all US hospitals, VON hospitals are: –More likely to be private non-profit –Teaching hospitals –Childrens hospitals –More NICU beds Compared with all VLBW infants in US, VLBW infants treated by VON hospitals are: –Differed in terms of birthweight but not gestational age

32 Morales-32 03/18/04 Hospital Characteristics

33 Morales-33 03/18/04 Secondary Analyses Do the effects of risk-adjustment vary by race? –Insignificant case-mix*race interactions Do the effects of minority-serving status vary by race? –Insignificant percent black*race interactions Do the effects of hospital variables vary by percentage black infants treated? –Insignificant percent black*hospital characteristic interactions

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