Antenatal Hospital Encounters and Preterm Delivery, MA 2002-2008
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Antenatal Hospital Encounters and Preterm Delivery, MA 2002-2008
Lizzie Harvey, MPHCDC/CSTE Applied Epidemiology FellowMassachusetts Department of Public HealthJune 5, 2012
Background
• MA Infants born <32 weeks gestation made up 1.5% of the birth population but accounted for 63.8% of infant deaths in 2008
• <32 weeks infants have an infant mortality rate (IMR) of 195 deaths/1,000 live births – MA IMR is 5.0 deaths/1,000 live births
Research Priorities
• Prematurity is a research priority– IOM Report: “Preterm Birth:
Causes, Consequences, and Prevention”
– March of Dimes: • Prematurity Research Initiative • “Healthy Babies are worth the wait”
campaign
– ASTHO Presidential Challenge
Infections
Maternal Behaviors
INCREASED RISK OF
PREMATURE DELIVERY
Bacterial vaginosis
Chronic Disease
Chronic Hypertension
Anemia Stress
Diabetes
Family History
Maternal lbw
Black race
Family hx ofPreterm birth
Chorioamnionitis
Trichomonasis
Maternal ObstetricHistory
Prior pretermbirth
Short cervix
Multiplepregnancies
Low BMI
↑ Maternal age
Pre eclampsia
Obesity
Low maternal Weight gain
Maternal smoking
Drug dependency
Asthma poorlycontrolled
Cervicalincompetence
Placental Abruption
Protective
Progesteronefor prior PTD
Neighborhood Factors
Lower SES
Physical Abuse duringpregnancy
Stress
High unemployment
Conceptual Model for Premature Delivery
Research Gaps
• <32 week population– Low percentage of births– High IMR
• Potential for intervention– Course of pregnancy– Hospital encounters
Research Question
• In deliveries <32 weeks, are there patterns among antenatal hospital encounters and adverse pregnancy outcomes?– Demographic characteristics– Timing of hospital encounters – Number of hospital encounters– Diagnosis codes of hospital encounters
Methods
• Definitions:– Adverse outcome: Any delivery with a fetal
death or infant death occurring before 1 year post-delivery
– Hospital Encounters:• Emergency Department (ED)• Observational Stay (OS)• Hospital Discharge (HD)
Methods: PELL Data System
Early Intervention
Linked birth-infant deaths
Child and Mother deaths
Birth Defects Registry
WIC
Birth Certificate
(HD) Birth Mothers
Fetal Death
(HD) Birth Child
Emergency Department
Census 2000 Data
(and 2010 data)
CORE
Geocoded birth data
Observational StaysOther Future Datasets: All
Payers Data, School, NICU, Medicaid
Contextual Data
Pregnancy-associated deaths
Non-birth Hospital Discharge
Newborn Hearing Screening
Vital and Health Status Data
Program Participation Data
Health Services Utilization Data w/ diagnosis codes & charges
1998-2008
875,708 births
Cancer Registry
ART Clinic Data
Databases to be added to system
PRAMS
Methods: PELL Data System
Linked birth-infant deaths
Birth Certificate
Fetal Death
Emergency Department
CORE
Observational Stays
Non-birth Hospital Discharge
Vital and Health Status Data
Health Services Utilization Data w/ diagnosis codes & charges
2002-2008
Methods
• Exclusion criteria:– ≥32 weeks gestation delivery– Missing gestational age– HD, OS, or ED admission date outside
conception and delivery date– Delivery hospitalization records
• Analysis on SAS 9.2:– Frequency distributions– Logistic regressions
Results—Data Merging
567,323Births, FD, ID
11,226 <32 wks
554,603 ≥ 32 weeks1,494 missing GA
9,330 DELIVERIES
Code by adverse deliveryOutcome and delete
multiples
Sorted and merged by child unique identifier
Sorted and merged by mother unique delivery identifier
Results—Data Merging
Final datasets: 1) 9,330 unique deliveries
2) 11,744 duplicate deliveries with every prenatal hospitalization
9,330DELIVERIES
32,360HD
9,330DELIVERIES
252,853ED
9,330DELIVERIES
118,482OS
10,423DEL+ED
9,788OS
9,661HD
7,013NON-ENC.
4,013ED ENC.
7,788NON-ENC.
2,048OS ENC.
Deleted non-prenatal hospitalization encounters by GA, delivery date and hospitalization admission date
7,695NON ENC.
2,064HD ENC.
1,635DEL. w/ HD
1,542DEL. w/ OS
2,317DEL. w/ ED
Merged back to delivery records by unique identifier to capture non-encounters
Demographics by DeliveryCharacteristic % N (9,330)
Race
Hispanic
Non-Hispanic White
Non-Hispanic Black
API
AI/Other
15.1
60.0
17.7
5.7
3.4
1393
5351
1636
527
299
Maternal Age
<20 years
20-34 years
35+ years
9.0
65.7
25.3
835
6124
2358
Nativity
US born
PR
Foreign born
68.9
3.5
27.6
6230
6550
2492
Maternal Education
<HS
HS+
14.4
80.4
1343
8846
Prenatal Care
Adequate Plus
Adequate
Intermediate
Inadequate
80.6
5.4
1.2
3.1
7523
502
112
285
Characteristic % N
Gestational Age
≤20 weeks
21-24 weeks
25-28 weeks
29-31 weeks
6.1
21.6
28.7
43.6
568
2015
2677
4070
Delivery Method
Vaginal
VBAC
Primary C-section
Repeat C-section
50.9
2.6
37.0
9.1
4746
240
3456
848
Plurality
Singletons
Twins
Triplets+
80.9
17.1
2.0
7552
1596
182
Payer
Private
Public
Self-care
Free care
52.0
41.1
1.2
1.2
4849
3837
112
115Note: % and N do not always equal to 9330 due to missing information in some categories
Initial Results
• Exposure: Antenatal hospitalization– 44.0% of deliveries <32 weeks had at least one
non-delivery antenatal hospital encounter
• Outcome: Adverse pregnancy outcome– 31.2% of deliveries <32 weeks with at least one
non-delivery antenatal hospitalizations had an adverse outcome
– 34.4% of all deliveries <32 weeks had an adverse outcome
Results: Demographic Characteristics, Hospital Encounters and Adverse
Outcomes
Univariate Analysis
Demographics by Any Hospitalization
Characteristic % Hosp % Non-Hosp
Race
Hispanic
Non-Hispanic White
Non-Hispanic Black
API
AI/Other
50.3
42.6
48.2
35.5
37.8
49.8
57.4
51.8
64.5
62.2
Maternal Age
<20 years
20-34 years
35+ years
49.8
44.6
40.5
50.2
55.4
59.5
Nativity
US born
PR
Foreign born
45.9
56.9
38.6
54.1
43.1
61.4
Maternal Education
<HS
HS+
49.2
43.6
50.8
56.4
Prenatal Care
Adequate Plus
Adequate
Intermediate
Inadequate
45.6
46.2
41.1
34.7
54.4
53.8
58.9
65.3
Characteristic % Hosp % Non-Hosp
Gestational Age
≤20 weeks
21-24 weeks
25-28 weeks
29-31 weeks
36.3
42.0
44.1
45.9
63.7
58.0
55.9
54.1
Delivery Method
Vaginal
VBAC
Primary C-section
Repeat C-section
41.0
45.0
46.9
49.3
59.0
55.0
53.1
50.7
Plurality
Singletons
Twins
Triplets+
42.9
47.9
52.7
57.1
52.1
47.3
Payer
Private
Public
Self-care
Free care
41.7
52.0
31.3
42.6
58.3
48.0
68.8
57.4
Variations by Type of Hospital Encounter
p<0.0001 p<0.0001 p=0.20 p<0.0001
Variations by Type of Hospital Encounter
p<0.0001 p<0.0001p<0.0001 p<0.0001
Univariate Analysis
Demographics by Adverse Outcome
Characteristic % Adverse % Non-Adverse
Race
Hispanic
Non-Hispanic White
Non-Hispanic Black
API
AI/Other
35.8
31.4
38.3
32.4
41.5
64.2
68.6
64.7
67.9
58.5
Maternal Age
<20 years
20-34 years
35+ years
39.2
34.4
32.5
60.8
65.6
67.5
Nativity
US born
PR
Foreign born
30.7
22.5
38.5
69.3
77.5
61.5
Maternal Education
<HS
HS+
35.0
30.8
65.0
69.2
Prenatal Care
Adequate Plus
Adequate
Intermediate
Inadequate
30.7
25.9
34.8
44.9
69.3
74.1
65.2
55.1
Characteristic % Adverse % Non-Adverse
Gestational Age
≤20 weeks
21-24 weeks
25-28 weeks
29-31 weeks
92.1
79.8
25.7
9.7
7.9
20.2
74.3
90.3
Delivery Method
Vaginal
VBAC
Primary C-section
Repeat C-section
51.9
53.8
13.8
13.7
48.1
46.3
86.2
86.3
Plurality
Singletons
Twins
Triplets+
35.1
32.4
24.6
64.9
67.6
75.4
Payer
Private
Public
Self-care
Free care
34.7
34.9
61.6
40.0
65.3
65.1
38.4
60.0
Bivariate Analysis
p=0.004 p<0.0001 p<0.0001 p<0.0001
Adjusted models controlled for: race/ethnicity, education, maternal age, gestational age at delivery, plurality, payer source, method of delivery, prenatal care, nativity
Odds Ratios
Other Demographic aORs for Adverse Outcomes
• Race/Ethnicity: – Black: 0.79 (0.66-0.93) vs. NH white
• Gestational age:– <25 weeks: 33.9 (29.1-39.5) vs. 29-31 weeks– 25-28 weeks: 3.61 (3.13-4.15) vs. 29-31 weeks
• Plurality:– Twins: 1.61 (1.37-1.90) vs. Singletons
• Payer:– Self-care: 1.81 (1.08-3.02) vs. Private
• Delivery Method:– Vaginal: 4.34 (3.78-5.00) vs. Primary c-section– VBAC: 4.61 (3.26-6.53) vs. Primary c-section
• Nativity:– PR 0.72 (0.59-0.87) vs. US-born– Foreign 1.06 (1.01-1.12) vs. US-born
Results: Timing of Hospital Encounters and Adverse
Outcomes
Variation in Timing of Encounters
Timing Indicators of Adverse Outcomes
Results: Number of Hospital Encounters and Adverse
Outcomes
Number and Duration of Visits: HD Encounters
P<0.0001
Mean # visits= 1.26
Mean Length of Stay/visit= 4.07 days
Number and Duration of Visits: OS Encounters
P<0.0001
Mean # visits= 1.33
Mean Length of Stay/visit= 0.39 days
Number and Duration of Visits: ED Encounters
P=0.0095
Mean # visits= 1.73
Mean Length of Stay/visit= 3.40 hours
No Increased Odds of Adverse Outcomes with Increased ED
Encounters
Results: Diagnosis Codes and Adverse Outcomes
HD Diagnosis Codes
Top 10 Principal Diagnosis Codes with No Adverse Outcomes
1. Threatened premature labor
2. Cervical incompetence
3. Hemorrhage from placenta previa
4. Other conditions, mother, complicating preg/childbirth
5. Mild/NOS pre-eclampsia
6. Premature separation of placenta
7. Premature rupture of membranes
8. Other congenital or acquired abnormality of the cervis
9. Transient hypertension
10. Delayed delivery after spontaneous rupture of membranes
Top 10 Principal Diagnosis Codes with Adverse Outcomes
1. Cervical incompetence
2. Threatened premature labor
3. Premature rupture of membranes
4. Threatened abortion
5. Hemorrhage from placenta previa
6. Other conditions, mother, complicating preg/childbirth
7. Delayed delivery after spontaneous rupture of membranes
8. Premature separation of placenta
9. Hyperemesis gravidum with metabolic disturbance
10. Unspecified hemorrhage in early pregnancy
OS Diagnosis Codes
Top 10 Principal Diagnosis Codes with No Adverse Outcomes
1. Threatened premature labor
2. Other conditions, mother, complicating preg/childbirth
3. Premature rupture of membranes
4. Unspecified antepartum hemorrhage
5. Cervical incompetence
6. Mild/NOS pre-eclampsia
7. Hemorrhage from placenta previa
8. Transient hypertension
9. Other threatened labor
10. Severe pre-eclampsia
Top 10 Principal Diagnosis Codes with Adverse Outcomes
1. Threatened premature labor
2. Cervical incompetence
3. Other conditions, mother, complicating preg/childbirth
4. Premature rupture of membranes
5. Unspecified hemorrhage in early pregnancy
6. Threatened abortion
7. Unspecified antepartum hemorrhage
8. Twin pregnancy
9. Intrauterine death
10. Mild/NOS pre-eclampsia
ED Diagnosis Codes
Top 10 Principal Diagnosis Codes with No Adverse Outcomes
1. Other conditions, mother, complicating preg/childbirth
2. Threatened abortion
3. Unspecified hemorrhage in early pregnancy
4. Mild hyperemesis gravidarum
5. Other specified complications of pregnancy
6. Abdominal pain; unspecified site
7. Infections of genitourinary tract in pregnancy
8. Headache, Facial pain, Pain in head NOS
9. Unspecified antepartum hemorrhage
10. Asthma (bronchial) (allergic NOS)
Top 10 Principal Diagnosis Codes with Adverse Outcomes
1. Other conditions, mother, complicating preg/childbirth
2. Threatened abortion
3. Unspecified hemorrhage in early pregnancy
4. Mild hyperemesis gravidarum
5. Other specified complications of pregnancy
6. Infections of genitourinary tract in pregnancy
7. Unspecified antepartum hemorrhage
8. Abdominal pain
9. Headache, Facial pain, Pain in head NOS,
10. Sprains/strains; neck, Anterior longitudinal (ligament), cervical, Atlanto-axial (joints), Atlanto-occipital (joints), Whiplash injury
• 44% of all <32 wk deliveries had ≥1 hospital encounter– Of these deliveries, almost 1/3 will have an adverse
outcome
• Type of hospital encounter matters:– Deliveries with ≥ 1 ED encounter have a 16% greater
risk of adverse outcomes than those with no encounter
– OS and HD encounters are protective against adverse outcomes, with 29% and 32% decreased risk, respectively
Conclusions
• Demographic:– Gestational age is the driver of poor outcomes– Black mothers and PR born mothers have decreased odds of adverse outcomes– Twins, Self-care payment, and vaginal delivery have increased odds of adverse
outcomes• Timing:
– Deliveries with adverse outcomes will present sooner in pregnancy with each type of hospital encounter than those without
– Women present sooner in the ED than OS or HD• Number:
– HD and OS both have decreased odds of adverse outcomes with each additional visit
– No increased risk of adverse outcomes with each additional ED visit• Diagnosis:
– HD: Cervical incompetence, threatened premature labor, PROM – OS: Cervical incompetence, hemorrhage, threatened abortion– ED: Infections, hemorrhage, sprains/strains
Conclusions
• Expand study population
• Further refinement of diagnosis coding
• Consult with clinicians – Share data by type of hospitalization– Feedback on potential interventions
• Exploration of costs associated with hospital utilization
Next Steps
Acknowledgements
• Hafsatou Diop, MD, MPH• Xiaohui Cui, PhD• Milton Kotelchuck, PhD, MPH• Maria Vu, MPH• Emily Lu, MPH• Karin Downs, RN, MPH
• CDC/CSTE Fellowship
References• CDC Premature Birth:
– http://www.cdc.gov/Features/PrematureBirth/• IOM Report:
– National Research Council. Preterm Birth: Causes, Consequences, and Prevention. Washington, DC: The National Academies Press, 2007.
• PELL Data System:– https://sph.bu.edu/index.php/Maternal-a-Child-Health/Pregnancy-to-Early-Life-
Longitudinal-Linkage-bPELLb/menu-id-452.html• MA Death Statistics:
– http://www.mass.gov/eohhs/docs/dph/research-epi/death-report-08.pdf• March of Dimes:
– http://www.marchofdimes.com• ASTHO Presidential Challenge:
– http://www.astho.org/t/pres_chal.aspx?id=6484
Thank you
Contact Information:[email protected]