Comparative costs of hospitalisation among infants at high risk for respiratory syncytial virus lower respiratory tract infection during the first year of life

Figures & data

Table 1. List of conditions and corresponding ICD-9-CM or DRG codes.

Description of condition	ICD-9-CM or DRG code
Respiratory syncytial virus	079.6
Acute bronchiolitis due to respiratory syncytial virus	466.11
Pneumonia due to respiratory syncytial virus	480.1
Congenital heart disease	425.4, 745.0, 745.4–6, 746.0, 746.3, 747.0, 747.1, 745.1–3, 746.1, 746.2, 746.7, 747.4
Chronic respiratory disease arising in the perinatal period	770.7
Early-preterm	Defined by a DRG code indicating other than term status (389) and an ICD-9-CM diagnosis code specifying < 33 wGA on the birth claim (765.21–765.26)
Late-preterm	Defined by a DRG indicating other than term status (389) and an ICD-9-CM diagnosis code specifying 33–36 wGA on the birth claim (765.27–765.28)
Term	Defined by a DRG for other term (389) or normal newborn (391) on the observed birth admission claim and no diagnosis codes indicating gestational ages < 37 wGA, or DRG for neonate with other significant problems (390) and a diagnosis code indicating gestational age .37 wGA (765.29)

DRG, diagnostic related group; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; wGA, weeks gestational age.

Table 2. Patient characteristics, hospitalisation costs, and resource use among high-risk compared with term infants diagnosed with respiratory syncytial virus during 2003–2007.

Characteristic	Infants at high risk for hospitalisation due to RSV				Reference group
	CHD	CLD	Early-preterm, ≤32 wGA	Late-preterm, 33–36 wGA	Term, ≥37 wGA
Number, n	151	41	40	173	1,983
Mean (SD) age at start of RSV hospitalisation, days	118 (81)*	127 (73)^†	121 (66)^†	99 (77)	95 (73)
Male infants, %	60.3	63.4	70.0	70.5^†	58.6
CLD or other respiratory comorbid conditions^‡, %	9.3*	100.0*	42.5*	2.9*	0.2
CHD or other cardiovascular comorbid conditions, %	100.0*	58.5*	47.5*	17.3*	3.4
All other comorbid conditions, %	23.8*	19.5*	25.0*	9.2*	1.0
Mean (SD) seasonal cost of hospitalisation per infant^§, USD	27,661 (59,642)*	25,119 (49,248)*	15,693 (16,633)*	20,269 (37,449)*	9,635 (28,419)
Median, USD	8,386*	9,623^†	8,018^¶	6,842^†	5,364
Interquartile range, USD	13,254	21,601	16,163	14,066	5,073
Mean (SD) seasonal total length of hospitalisation per infant, days	6.7 (8.6)*	7.0 (9.5)*	4.9 (3.4)*	5.3 (5.3)*	3.4 (3.4)
Average RSV hospitalisations per infant, n	1.13*	1.10	1.03	1.06	1.05
ICU use per hospitalisation
Admissions with any ICU   stay, %	21.8*	13.3	19.5^¶	21.9*	9.6
Mean (SD) time in ICU, days	4.5 (4.8)	7.2 (4.3)^¶	5.4 (3.2)^¶	5.7 (4.8)*	3.4 (4.4)
Mean (SD) total time   hospitalised, days	9.8 (7.7)^†	8.7 (2.9)^¶	7.0 (2.6)	10.4 (5.8)*	6.4 (5.9)
Any cause rehospitalisation ≤30 days after initial RSV hospitalisation, %	15.2*	19.5*	15.0*	5.2	3.2

One admission for $695,227 associated with an early-preterm infant with CLD was identified as an outlier and excluded from all calculations. Pairwise comparisons include estimates from each of the high-risk groups with the term group.

CHD, congenital heart disease; CLD, chronic lung disease of prematurity; ICU, intensive care unit; RSV, respiratory syncytial virus; USD, US dollars; wGA, weeks gestational age.

*p< 0.001; ^†p< 0.01; ^‡Comorbid conditions include diseases of digestive, musculoskeletal, and nervous systems; ^§Cost of hospitalisations reflects allowed costs adjusted to July 2008 by CPI-Medical (CWSR0000SS5702); ^¶p< 0.05.