A case-control study comparing rates and diagnoses of hospital readmission in infants affected by neonatal abstinence syndrome

Figures & data

Table 1. Comparison of infant demographic and clinical characteristics between infants diagnosed with NAS and controls.

	Case (n = 2248)	Control (n = 2248)	p
	n (%) or median (IQR)	n (%) or median (IQR)
Gender			.069
Male	1226 (54.5%)	1163 (51.8%)
Female	1022 (45.5%)	1081 (48.2%)
Race/ethnicity			<.001
White, non-Hispanic	1999 (92.4%)	1732 (81.7%)
Black, non-Hispanic	120 (5.5%)	212 (10.0%)
Other race/ethnicity	45 (2.1%)	177 (8.3%)
County designation			<.001
Urban	735 (32.9%)	1070 (48.4%)
Non-urban	1499 (67.1%)	1141 (51.6%)
Preterm			<.001
Yes	609 (27.1%)	127 (5.6%)
No	1639 (72.9%)	2121 (94.4%)
Hospital readmission			<.001
Yes	939 (41.8%)	311 (13.8%)
No	1309 (58.2%)	1987 (86.2%)

Table 2. Generalized estimated equations modeling hospital readmission (n = 4241).

	Estimated relative risk (RR)	95% CI for RR	p
Sex			.17
Male	1.06	0.97–1.16
Female	1.00
Race/ethnicity
White, non-Hispanic	1.50	1.12–2.01	.007
Other race/ethnicity	1.31	0.86–2.01	.21
Black, non-Hispanic	1.00
County designation			<.001
Non-urban	1.85	1.64–2.08
Urban	1.00
Preterm birth			.11
Yes	0.92	0.83–1.02
No	1.00
Cohort			<.001
Case	2.74	2.44–3.07
Control	1.00

Table 3. Diagnoses among case and control infants readmitted to the hospital.

CCSR category description	% Total sample of readmitted neonates	Case (n = 939) n (%)	Control (n = 311) n (%)	p
Newborn affected by maternal conditions or complications of labor/delivery	76.1%	897 (95.5%)	54 (17.4%)	<.001
Other specified and unspecified perinatal conditions	64.1%	704 (75.0%)	97 (61.2%)	<.001
Neonatal digestive and feeding disorders	52.1%	589 (62.7%)	62 (19.9%)	<.001
Exposure, encounters, screening, or contact with infectious disease	44.6%	480 (51.1%)	78 (25.1%)	<.001
Respiratory perinatal condition	37.4%	408 (43.4%)	59 (19.0%)	<.001
Encounter for observation and examination for conditions ruled out (excludes infectious disease, neoplasm, mental disorders)	34.7%	316 (33.7%)	118 (37.9%)	.17
Hemolytic jaundice and perinatal jaundice	34.5%	378 (40.3%)	53 (17.0%)	<.001
Abnormal findings without diagnosis	33.1%	305 (32.5%)	109 (35.1%)	.40
Implant, device or graft related encounter	32.5%	332 (35.4%)	74 (23.8%)	<.001
Short gestation; low birth weight; and fetal growth retardation	31.0%	359 (38.2%)	28 (9.0%)	<.001
Socioeconomic/psychosocial factors	28.5%	340 (36.2%)	16 (5.1%)	<.001
Septicemia	27.0%	270 (28.8%)	67 (21.5%)	.013
Other general signs and symptoms	26.6%	238 (25.4%)	95 (30.6%)	.072
Other specified male genital disorders	25.9%	301 (32.1%)	23 (7.4%)	<.001
Cardiac and circulatory congenital anomalies	24.4%	256 (27.3%)	49 (15.8%)	<.001
Respiratory distress syndrome	23.1%	258 (27.5%)	31 (10.0%)	<.001
Personal/family history of disease	22.2%	214 (22.8%)	64 (20.6%)	.42
Neonatal acidemia and hypoxia	20.9%	227 (24.2%)	34 (10.9%)	<.001
Fluid and electrolyte disorders	20.6%	175 (18.6%)	83 (26.7%)	.002
Other specified status	19.8%	179 (19.1%)	69 (22.2%)	.23
Viral infection	19.8%	157 (16.7%)	90 (28.9%)	<.001
Hemorrhagic and hematologic disorders of newborn	19.4%	221 (23.5%)	22 (7.1%)	<.001
Abdominal pain and other digestive/abdomen signs and symptoms	17.9%	162 (17.2%)	62 (19.9%)	.28
Respiratory signs and symptoms	17.7%	155 (16.5%)	66 (21.2%)	.059
Circulatory signs and symptoms	17.4%	165 (17.6%)	52 (16.7%)	.73
Respiratory failure; insufficiency; arrest	16.0%	135 (14.4%)	65 (20.9%)	.007
Other aftercare encounter	14.7%	134 (14.3%)	50 (16.1%)	.44
Contact dermatitis	14.0%	154 (16.4%)	21 (6.8%)	<.001
Neonatal cerebral disorders	13.4%	149 (15.9%)	18 (5.8%)	<.001
Medical examination/evaluation	13.3%	151 (16.1%)	15 (4.8%)	<.001
Pleurisy, pleural effusion and pulmonary collapse	13.1%	123 (13.1%)	41 (13.2%)	.97
Bacterial infections	13.0%	123 (13.1%)	40 (12.9%)	.91
Other and ill-defined heart disease	11.8%	126 (13.4%)	22 (7.1%)	.003
Other specified and unspecified lower respiratory disease	10.3%	103 (11.0%)	26 (8.4%)	.19

CCSR categories presented in this table were present for at least 10% of the 1250 of readmitted neonates.

Figure 1. Cases, controls, and readmission per cohort yearly (year 2015 and 2021 were excluded due to incomplete yearly data. Given the average monthly estimates based on the 5 months of available data the projected 2021 total cases would be 276. The projected number of rehospitalizations for this same time period would be 151 for cases and 88 for controls).

Data availability statement

Data is available upon request.