Prevalence of chronic respiratory morbidity, length of stay, inpatient readmissions, and costs among extremely preterm infants with bronchopulmonary dysplasia

Figures & data

Figure 1. Sample selection flowchart of the Truven MarketScan database

Admission to intensive care unit (ICU) or neonatal ICU (NICU) was identified using hospital standard revenue codes. BPD: bronchopulmonary dysplasia; CA: corrected age; CRM: chronic respiratory morbidity; GA: gestational age; PMA: postmenstrual age.

Table 1. Patient characteristics during birth hospitalization

Characteristic	CRM/no CRM cohorts (n = 1782)		BPD/no BPD cohorts (n = 2805)
	Without CRM (n = 1265)	With CRM (n = 517)	Without BPD (n = 1090)	With BPD (n = 1715)
Female, n (%)	601 (47.5)	214 (41.4)	528 (48.4)	762 (44.4)
GA, n (%)^a
<24 weeks	37 (2.9)	39 (7.5)	18 (1.7)	107 (6.2)
24 weeks	102 (8.1)	98 (19.0)	43 (3.9)	268 (15.6)
25–26 weeks	404 (31.9)	212 (41.0)	263 (24.1)	668 (39.0)
27–28 weeks	722 (57.1)	168 (32.5)	766 (70.3)	672 (39.2)
Multiple birth, n (%)	342 (27.0)	130 (25.1)	264 (24.2)	460 (26.8)
Delivery method, n (%)
Vaginal	397 (31.4)	180 (34.8)	352 (32.3)	522 (30.4)
Cesarean	854 (67.5)	348 (67.3)	731 (67.1)	1167 (68.0)
Comorbidities, n (%)
BPD	674 (53.3)	448 (86.7)	–	–
CRM^b	–	–	69 (6.3)	448 (26.1)
Intraventricular hemorrhage^c	334 (26.4)	193 (37.3)	229 (21.0)	582 (33.9)
Retinopathy of prematurity^c	403 (31.9)	229 (44.3)	298 (27.3)	743 (43.3)
Patent ductus arteriosus^c	595 (47.0)	322 (62.3)	383 (35.1)	1060 (61.8)
Necrotizing enterocolitis^c	114 (9.0)	68 (13.2)	55 (5.0)	209 (12.2)

^aGA was determined based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) or ICD-10-CM diagnosis codes; the upper bound of the GA range of each ICD-9-CM code was used to approximate GA

^bCRM was defined as ≥1 of the following events in ≥2 quarters from birth hospitalization discharge through 1 year corrected age: hospital readmission or emergency room visit due to a respiratory cause, use of ≥1 respiratory medication for ≥30 days, or use of home respiratory/oxygen support

^cp < 0.0001 for BPD versus no BPD and CRM versus no CRM cohorts except for p = 0.0088 for necrotizing enterocolitis (BPD vs. no BPD)

BPD: bronchopulmonary dysplasia; CRM: chronic respiratory morbidity; GA: gestational age

Figure 2. Prevalence of events by quarter among 517 infants with chronic respiratory morbidity (CRM) who experienced ≥2 events through 1 year corrected age

Events were tracked individually, and an infant could be counted as having CRM events in >1 quarter. Among 515 infants who survived through 12 months corrected age, 315 (61.2%) had ≥1 CRM event in quarter 4. ER: emergency room; Q: quarter.

Table 2. Length of stay during birth hospitalization, and hospital readmissions after discharge through 1 year corrected age, among extremely preterm infants in the CRM/no CRM cohorts

	CRM/no CRM cohorts (n = 1782)
	Without CRM (n = 1265)	With CRM (n = 517)	Adjusted p-value^a
Birth hospitalization
Mean ± SD length of stay, days	78 ± 31	98 ± 33	<0.0001
Hospital readmission, all cause, n (%)	180 (14.2)	209 (40.4)	<0.0001
Incidence rate of readmissions per person-year	0.18	0.64	<0.0001
Length of stay among infants with ≥1 readmission after discharge
Days per person-year	7.53	10.40	0.0480
Median, days	4.00	5.00	–
Infants with >1 readmission, n (%)	32 (2.5)	69 (13.3)	<0.0001
Hospital readmission, respiratory cause, n (%)	82 (6.5)	160 (30.9)	<0.0001
Incidence rate of readmissions per person-year	0.07	0.44	<0.0001
Length of stay among infants with ≥1 readmission
Days per person-year	7.62	10.01	0.0877
Median, days	4.00	5.00	–
Infants with >1 readmission, n (%)	3 (0.2)	48 (9.3)	<0.0001

^aAdjusted for sex, gestational age, postmenstrual age at discharge, cesarean delivery, birth year, multiple birth, comorbidities (intraventricular hemorrhage, retinopathy of prematurity, periventricular leukomalacia, necrotizing enterocolitis, bacterial sepsis, and spontaneous intestinal perforation).

Note: Reported outcomes are observed and unadjusted.

CRM: chronic respiratory morbidity; SD: standard deviation

Figure 3. Comparison of total health care costs by presence of chronic respiratory morbidity (CRM) through 1 year corrected age in extremely preterm infants

Health care costs were inflated to 2017 US dollars (USD) using the US Medical Service Consumer Price Index. ^aAdjusted for sex, gestational age, postmenstrual age at discharge, cesarean delivery, birth year, multiple birth, and comorbidities (intraventricular hemorrhage, retinopathy of prematurity, periventricular leukomalacia, necrotizing enterocolitis, bacterial sepsis, and spontaneous intestinal perforation). ^bTotal does not sum due to rounding.

Figure 4. Total health care costs by presence of bronchopulmonary dysplasia (BPD) through 1 year corrected age in extremely preterm infants

Health care costs were inflated to 2017 US dollars (USD) using the US Medical Service Consumer Price Index. ^aAdjusted for sex, gestational age, postmenstrual age at discharge, cesarean delivery, birth year, multiple birth, and comorbidities (intraventricular hemorrhage, retinopathy of prematurity, periventricular leukomalacia, necrotizing enterocolitis, bacterial sepsis, and spontaneous intestinal perforation). ^bTotal does not sum due to rounding.

Table 3. Length of stay during birth hospitalization, and hospital readmissions after discharge through 1 year corrected age, among extremely preterm infants in the BPD/no BPD cohorts

	BPD/no BPD cohorts (n = 2805)
	Without BPD (n = 1090)	With BPD (n = 1715)	Adjusted p-value^a
Birth hospitalization
Mean ± SD length of stay, days	68 ± 23	95 ± 33	0.4308
Hospital readmission, all cause, n (%)	131 (12.0)	447 (26.1)	<0.0001
Number of readmissions per person-year (incidence rate)	0.14	0.39	<0.0001
Length of stay among infants with ≥1 readmission after discharge
Days per person-year	7.35	11.33	0.0110
Median, days	4.00	5.00	–
Infants with >1 readmission, n (%)	20 (1.8)	129 (7.5)	<0.0001
Hospital readmission, respiratory cause, n (%)	70 (6.4)	290 (16.9)	<0.0001
Number of readmissions per person-year (incidence rate)	0.07	0.22	<0.0001
Length of stay among infants with ≥1 readmission
Days per person-year	6.05	12.10	<0.0001
Median, days	4.00	5.00	–
Infants with >1 readmission, n (%)	8 (0.7)	65 (3.8)	<0.0001

^aAdjusted for sex, gestational age, postmenstrual age at discharge, cesarean delivery, birth year, multiple birth, comorbidities (intraventricular hemorrhage, retinopathy of prematurity, periventricular leukomalacia, necrotizing enterocolitis, bacterial sepsis, and spontaneous intestinal perforation).

Note: Reported outcomes are observed and unadjusted.

BPD: bronchopulmonary dysplasia; SD: standard deviation

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.