Socioeconomic status and outpatient follow-up in children with bronchopulmonary dysplasia

To the Editor,

Approximately 10% of infants in the U.S. are born prematurely¹. Bronchopulmonary dysplasia (BPD), the primary respiratory complication of preterm birth, is associated with significant morbidity and mortality, especially in the first few years of life². Previous studies have demonstrated that low socioeconomic status (SES) is associated with an increased risk of mortality, emergency department visits, and hospital admissions in this population ^3–6. However, the underlying mechanism of how SES affects outcomes and the pattern of outpatient follow-up in this population are poorly understood. We sought to investigate whether the number of outpatient subspecialty visits, a proxy for care received, is associated with SES in a population of infants and young children with BPD, and thus might partially explain the difference in outcomes by SES.

METHODS:

A retrospective chart review was performed for subjects (n=361) born in Maryland, discharged home from NICUs across the state between 7/1/2013 and 6/30/2019, and followed in an outpatient BPD clinic. All subjects were born at ≤ 32 weeks gestation and diagnosed with BPD based on the 2001 NHLBI consensus statement². Electronic medical record data was reviewed for outpatient subspecialty visits (pulmonary, cardiology, otolaryngology, and gastroenterology) for a two-year period following initial NICU discharge. Individual household income was estimated based on residential zip code. Median income in the state of Maryland at the time of this study was $84,805. Insurance status, defined as public or private, was determined based on coverage at first outpatient visit following NICU discharge. Race/ethnicity were self-reported. Caregivers were consented per protocol as approved by the Johns Hopkins University IRB. Descriptive features of subpopulations were compared using chi-square and t-tests.

RESULTS:

Of the 361 subjects, 185 (51.2%) had public insurance and 240 (66.5%) had estimated household incomes below the state median, and these measures of SES were closely aligned (p<0.001) (Supplemental Table 1 and 2). Both markers of low SES were also associated with self-reported Black race, and insurance was associated with Hispanic ethnicity (Supplemental Table 3). Lower birth weights were seen with those with public insurance and self-reported Black subjects and earlier gestational ages were seen with self-reported Black and Hispanic subjects.

On average, subjects had a total of 5.5 outpatient subspecialty visits with 3.2 pulmonary visits, 1.2 cardiology visits, 0.2 otolaryngology visits, and 0.9 gastroenterology visits in the first two years after discharge. There was no difference in the overall number of completed appointments based on insurance coverage, median household income, or race/ethnicity (Tables 1 and 2, Supplemental Tables 4 and 5). However, in the sub-group of the population requiring home mechanical ventilation, there were significantly fewer completed pulmonary appointments among those public insurance as compared to those with private insurance (4.1 ± 2.9 compared to 8.9 ± 5.0, Table 1). Of note, public insurance, household income below the state median, and self-reported Black race were associated with a greater number of no-show appointments.

Table 1.

Clinic Visits by Health Insurance Coverage

Mean ± S.D. [Range]		Number of Clinic Visits within 2 years of Initial Discharge			P Value
		Entire Study Population (n = 361)	Private Insurance (n = 176)	Public Insurance (n = 185)
Completed Pulmonary Visits	All	3.2 ± 3.0	3.2 ± 2.7	3.2 ± 3.3	0.89
	Severe BPD	3.7 ± 3.6 (n = 205)	3.5 ± 3.1 (n = 104)	4.0 ± 4.1 (n = 101)	0.29
	Nasal Cannula Oxygen	3.9 ± 3.6 (n = 140)	3.4 ± 2.4 (n = 75)	4.4 ± 4.6 (n = 65)	0.08
	Home Ventilator	6.1 ± 4.5 (n = 19)	8.9 ± 5.0 (n = 8)	4.1 ± 2.9 (n = 11)	0.017
Completed Cardiology Visits	All	1.2 ± 3.1	1.2 ± 2.8	1.2 ± 3.4	0.87
	Pulmonary Hypertension	4.2 ± 4.1 (n = 72)	4.0 ± 3.1 (n = 34)	4.3 ± 4.9 (n = 38)	0.72
Completed Otolaryngology Visits	All	0.2 ± 0.8	0.2 ± 0.8	0.2 ± 0.9	0.85
	Tracheostomy	1.2 ± 1.7 (n = 22)	1.0 ± 1.6 (n = 9)	1.6 ± 1.8 (n = 13)	0.45
Completed Gastroenterology Visits	All	0.9 ± 2.3	0.9 ± 1.9	1.0 ± 2.6	0.79
	Gastrostomy	2.1 ± 3.3 (n = 124)	1.9 ± 2.6 (n = 52)	2.3 ± 3.8 (n = 72)	0.51
	Nissen	2.6 ± 4.0 (n = 72)	2.6 ± 3.1 (n = 27)	2.6 ± 4.5 (n = 45)	0.95
All Visits	Completed	5.5 ± 6.7	5.5 ± 5.9	5.5 ± 7.5	0.95
	Cancelled	2.5 ± 3.7	2.2 ± 3.2	2.8 ± 4.1	0.16
	No Show	0.7 ± 1.5	0.3 ± 0.9	1.1 ± 1.8	<0.001

^*Bronchopulmonary severity defined by NHLBI consensus statement.

Table 2.

Clinic Visits by Median Household Income

Mean ± S.D. [Range]		Number of Clinic Visits within 2 years of Initial Discharge			P Value
		Entire Study Population (n = 361)	Above Maryland State Median (n = 121)	Below Maryland State Median (n = 240)
Completed Pulmonary Visits	All	3.2 ± 3.0	3.1 ± 3.4	3.2 ± 2.8	0.73
	Severe BPD	3.7 ± 3.6 (n = 205)	3.6 ± 4.0 (n = 76)	3.8 ± 3.4 (n = 129)	0.68
	Nasal Cannula Oxygen	3.9 ± 3.6 (n = 140)	3.5 ± 3.8 (n = 54)	4.0 ± 3.5 (n = 86)	0.42
	Home Ventilator	6.1 ± 4.5 (n = 19)	8.0 ± 7.0 (n = 6)	5.2 ± 2.7 (n = 13)	0.22
Completed Cardiology Visits	All	1.2 ± 3.1	1.7 ± 4.4	0.9 ± 2.1	0.029
	Pulmonary Hypertension	4.2 ± 4.1 (n = 72)	4.6 ± 5.1 (n = 25)	3.9 ± 3.5 (n = 47)	0.50
Completed Otolaryngology Visits	All	0.2 ± 0.8	0.2 ± 0.8	0.2 ± 0.8	0.97
	Tracheostomy	1.2 ± 1.7 (n = 22)	1.0 ± 1.9 (n = 7)	1.3 ± 1.6 (n = 15)	0.67
Completed Gastroenterology Visits	All	0.9 ± 2.3	1.2 ± 2.4	0.8 ± 2.3	0.15
	Gastrostomy	2.1 ± 3.3 (n = 124)	2.5 ± 3.2 (n = 41)	1.9 ± 3.4 (n = 83)	0.31
	Nissen	2.6 ± 4.0 (n = 72)	2.7 ± 3.7 (n = 23)	2.6 ± 4.1 (n = 49)	0.94
All Visits	Completed	5.5 ± 6.7	6.2 ± 8.6	5.2 ± 5.5	0.18
	Cancelled	2.5 ± 3.7	2.7 ± 3.8	2.4 ± 3.6	0.41
	No Show	0.7 ± 1.5	0.5 ± 1.1	0.9 ± 1.6	0.022

^*Bronchopulmonary severity defined by NHLBI consensus statement.

DISCUSSION:

In relative contrast with other chronic pediatric diseases, we found that surrogate markers of SES as well as race/ethnicity were not generally associated with the number of outpatient subspecialty appointments in the two years following discharge for infants and young children with BPD. Our findings suggest that the mechanism leading to poorer outcomes seen in patients with lower SES may not necessarily be access to subspecialty care.

There are a few possible explanations for our findings. The case management services provided by the NICU, including caregiver education, home nursing, and developmental services, may provide a degree of outpatient support during the first few years of life that may aid access to subspecialty care. Additionally, the frequent primary care appointments for immunizations and RSV prophylaxis may also contribute to improved coordination of care. We would note that the two surrogate markers of SES used in this analysis do not address geographic disparities that are an integral part of a subject’s SES. It is possible that these geographic disparities may more strongly contribute to inequities in accessing subspecialty health care through adverse environmental exposures⁷, chronic stress, social isolation, and transportation barriers.

Although the number of completed subspecialty visits was generally not associated with SES markers or race/ethnicity, we did find that lower SES and self-reported Black subjects were more likely to have no-show appointments. This may suggest the presence of last-minute events or barriers that preclude coming to clinic visits. Additionally, in the subgroup of the population requiring home mechanical ventilation, those with public insurance had significantly fewer completed pulmonary appointments in the first two years after NICU discharge compared with those with private insurance. This group is likely to have longer and more protracted initial admissions given severity of a subject’s condition as well as caregiver training required prior to transition home which may contribute to lower SES status and use of public insurance. This disparity among ventilated subjects is especially important to note given the vulnerability of this group and may provide insight into a potential window for intervention.

Our study was limited to patients at a single center, but did include patients who were discharged from NICUs across the state and resided in urban and rural areas. We did not account for geographic distance from various clinics as a potential barrier to care and did not have data on subjects’ personal means of transportation. Furthermore, our analysis did not include data on the frequency or duration of acute care use or hospital admissions, which may have prevented outpatient visits. Additionally, it is possible that there are patients whose SES prevented them from ever establishing subspecialty care and are therefore not included in our study population.

Future longitudinal research is needed to understand the mechanisms through which SES impacts outcomes in infants and children with a history of prematurity and BPD to better address potential barriers. It is possible that increased frequency of visits may improve outcomes in lower SES groups, in which case, interventions such as combined primary care-subspecialty appointments or multidisciplinary appointments and home visits may be more effective in reaching this population.