SMJ 2003 48(4): 108-110
Win Zaw, Clinical Lecturer/Honorary Specialist Registrar, Department of Child Health, Medical School, Foresterhill, University of Aberdeen, Aberdeen AB25 2ZD
John McDonald, Consultant Paediatrician, Department of Paediatrics, Raigmore Hospital, Old Perth Road, Inverness, IV2 3UJ
Author
for Correspondence
Win Zaw
e-mail: win_zaw@hotmail.com
Short
running heading
An analysis of hospital cost for ex-preterm infants with respiratory syncytial virus bronchiolitis
Abstract
Ex-preterm
infants are vulnerable to respiratory syncytial virus (RSV) bronchiolitis
and their hospital admission is associated with increased morbidity.
Palivizumab is currently available as prophylaxis against RSV infection
but its use in ex-preterm infants is controversial.
A retrospective case review study was, therefore, carried out to
determine the rate of readmission with RSV
bronchiolitis among ex-preterm infants in the
Highland Region of Scotland and to estimate the hospital cost per
admission. Between 1995 and 1999, a
total of 3,046 children under 2
years of age were admitted to Raigmore Hospital, 1,691 of whom (60.4%) lived
outwith Inverness. 507 children had
acute bronchiolitis and ex preterm infants with RSV positive bronchiolitis accounted
for 3.6% of total admissions with acute bronchiolitis. 72% of these children
lived outwith Inverness. The
median length of hospital stay for children born at less than 30 weeks and for
children who had had bronchopulmonary dysplasia (BPD) was 6 and 10.5 days
respectively. The average
hospital costs per admission for children of less than 30 weeks and children of
more than 30 weeks were 3,376 and 2,074 respectively.
It was more expensive for children with
BPD (4,431 per admission) when compared with those without BPD (1,959 per
admission). This study has shown that most of the children admitted to hospital
lived outwith Inverness, many at some considerable distance, and this, as much
as severity of illness, may have contributed
to hospital admission. Further studies are required to determine productivity
losses associated with RSV infection and justification of use of Palivizumab in
ex preterm infants of less than 30 weeks gestation and of BPD living in remote
areas of Scottish Highlands.
Key
words
Preterm, Respiratory syncytial virus, bronchiolitis, cost, palivizumab, prophylaxis, admission
Introduction
Respiratory syncytial virus (RSV) is a major cause of acute bronchiolitis in infants. Although mortality is low, infection is associated with short-term morbidity such as hospital admission, feeding difficulty, respiratory insufficiency requiring oxygen and pneumonia. Preterm infants, especially those with chronic lung disease, are at increased risk of more severe illness and are more likely to be admitted to hospital when compared with term infants. 1 Hospitalization rates for ex-preterm infants with RSV bronchiolitis vary from 2.7% to 37%. 2-5
Currently
two products, RSV intravenous immunoglobulin (RSV-IVIG) and Palivizumab, are
available for prophylaxis against RSV infection. Both have been shown to be
effective in reducing the rate of admission and the duration of stay in
hospital.
6,7
These
preparations could, therefore, have potential benefit for ex-preterm infants
living in remote areas of the Scottish Highlands. It will also possibly reduce the societal cost associated
with admission to Raigmore hospital. However,
there are no published data on the morbidity and mortality from RSV infection in
ex-preterm infants in the Scottish Highlands and the estimated cost for hospital
admission has not yet been calculated.
The
aims of this study are to identify the admission rate and morbidity of ex-preterm
infants with RSV bronchiolitis and to estimate the costs of hospital care during
their stay in hospital.
Methods
Discharges of children under 2 years of age between 01/01/95 and 31/12/99 with ICD codes for acute bronchiolitis [J21.0, J21.9 (ICD10) and 466.1 (ICD9)] were identified and cross-linked with neonatal hospital data for prematurity (<35 weeks of gestation). Residence in the Highlands was determined from the postcodes and children who did not live in the Highlands were excluded. Case notes were then reviewed and neonatal and hospital admission data were recorded. Bronchopulmonary dysplasia (BPD) was diagnosed when the infant required oxygen supplementation beyond 28 days of postnatal age.
Hospital cost data were obtained from the Information and Statistics Division of NHS Scotland (Scottish Health Resource Utilisation Groups (SHRUGs) National Report 2000 published on 30 November 2001). The cost per day was calculated as the total net expenditure of occupied bed days by in-patients in the Childrens Ward at Raigmore Hospital divided by the number of occupied bed days. The cost per admission was calculated by multiplying the cost per day by duration of admission per patient. The cost was at the year 2000 prices. An estimate of the costs of cases of rotavirus infection admitted to hospital in Scotland was done in a similar way by Cowden. 8
Differences between groups were compared with the Mann-Whitney U test for continuous variables and Chi square test for categorical variables. In comparing data, p value <0.05 was considered to be of statistical significance.
Results
During the study period, a total of 3,046 children (excluding those living outwith Highlands) were admitted to the Childrens Ward, Raigmore Hospital. 1,355 (39.6%) lived in Inverness and 1,691 (60.4%) outwith Inverness. Among those children, 507 were admitted with a clinical diagnosis of acute bronchiolitis. Eighteen children (9 males and 9 females) were identified as ex-preterm infants (<35 weeks gestational age) with RSV infection confirmed by immunofluorescent staining of virus in nasopharyngeal aspirate. This accounted for 3.6% of total admissions with acute bronchiolitis.
Their median gestational age was 32 weeks (interquartile range 28-33) and the median birth weight was 1,535 gms (interquartile range 1,250-2,290 gms). The median stay in hospital for bronchiolitis was 5 days (interquartile range 2-8.8). Eight (44%) infants required supplemental oxygen but only 2 (11%) infants were admitted to SCBU (Special Care Baby Unit) for nasal CPAP (Continuous Positive Airways Pressure) ventilation and the remaining sixteen infants (89%) were managed on the ward. There were no deaths or admissions to intensive care for mechanical ventilation.
Gestational age and RSV positive bronchiolitis
Two groups, infants born at 30 weeks gestation or less and those born at over 30 weeks gestation were compared (Table). Respiratory score 7 was similar in both groups on admission. The median length of hospital stay for the lower gestational age group was longer than those with older gestational age group but it did not reach statistical significance (p=0.2).
BPD
and RSV positive bronchiolitis
There were 4 preterm infants who developed BPD during their stay in SCBU. Their respiratory score at the time of admission for bronchiolitis was similar to patients who did not have BPD but the median duration of stay in hospital was longer (10.5 vs 2.5 days) (p=0.04). All required supplemental oxygen whereas only 28.6% (4/14) of non-BPD patients needed oxygen (p=0.02). The median (interquartile range) duration of oxygen requirement for BPD infants was 7 (2.25-9.50) days as compared with 2 (1-3.5) days for non-BPD infants (p=0.014).
Post
code and RSV positive bronchiolitis
Among RSV positive patients, 13 (72%) infants lived outwith Inverness and 5 (28%) lived in Inverness. 46% of infants who lived outwith Inverness, were born at less than 30 weeks gestation. Seven (54%) of these infants living outwith Inverness required supplemental oxygen when they were admitted with bronchiolitis and two infants required admission to the special care baby unit for nasal CPAP ventilation. Median length of hospital stay was longer in infants who lived outwith Inverness (6 vs 2 days) (p=0.04).
Estimated
hospital costs
The average cost per occupied bed day was calculated as 422 per day. The cost per admission was then calculated by multiplying the cost per day (422) by average length of hospital stay for individual gestational age group. The calculated cost for infants varied from 633 per admission for infants of 34 weeks gestation to 6,330 per admission for infants of 28 weeks gestation. The lower gestational age group (less than 30 weeks) was more expensive (3,376 per admission) than more mature group (2,074 per admission). The average cost of infants with BPD was 4,431 per admission as compared with 1,959 per admission for infants without BPD. The average costs per admission for those infants living outwith and within Inverness were 2,954 and 1,350 respectively.
Discussion
As in previous studies, 1,2 we found that ex-preterm infants with BPD who developed RSV bronchiolitis spent more time in hospital and needed a longer period of supplemental oxygen. Infants born at less than 30 weeks gestation had a longer stay in hospital compared with the more mature group.
In the Scottish Highlands, an estimated population in 1998 was 208,300 with childhood population of 42,899 (0-15 years). The population has remained almost constant over the last decade. The majority of the population lives outwith Inverness accounting for 60.4% of total hospital admissions to the Childrens ward. We observed a higher proportion of more premature infants and infants with BPD living in rural areas. When they were admitted to hospital with bronchiolitis their length of stay was longer, increasing the emotional and financial burden on their families.
Therefore, these children, and their families, may possibly benefit from RSV prophylaxis. RSV-IGIV and Palivizumab have been shown to reduce hospital admission rates by 41% and 55% respectively 6,7 and Palivizumab has an advantage of the route and ease of administration over RSV-IGIV, which is not licensed in the UK. However, the substantial cost of these interventions constrains wider use among pre-term infants and we, therefore, attempted to determine the cost of hospital admission and the comparative cost of Palivizumab treatment.
It is not possible to quantify the actual cost for an individual admission to hospital and our estimate of cost per day was based on the total net expenditure at the Childrens Ward and occupied bed days per year. This cost covered the staffing, infrastructure and other general expenses. We have made no attempt to include a detailed cost estimate covering radiological examinations, requirement for oxygen and CPAP, intravenous fluids, nasogastric feeds and one to one nursing. Our cost estimate is, therefore, minimal cost that incurred during hospital admission. Similar estimates of cost of hospital admission had been published in several UK papers. 8-10
We
found that the cost of hospital admission for infants with BPD and in the lower
gestational age group was higher. Greenough
et al also has reported that RSV hospitalisation in patients with BPD is
associated with increased costs.
10
However the cost of treatment with Palivizumab would be higher than the cost of
hospital admission. The
current price for Palivizumab is approximately 706 for a 100mg vial and the
dose is 15 mg/kg. If we assume that
one vial is given at monthly intervals for five months throughout the RSV
season, the total cost will be 3,530 per infant.
From the IMpact Study, NNT (numbers needed to treat) was 17 for the
overall study group and 20 for BPD group. If
we assume that our rate of hospital admission was similar to that of the IMpact
Trial, we would have to spend 60,010 on Palivizumab to prevent one admission,
which would cost 2,110. Similarly
we would have to spend 70,600 in patients with BPD to prevent one admission
from this group, which would cost 4,431.
Although the IMpact study included all preterm infants born at less than
35 weeks gestation, the use of Palivizumab in all of these children cannot be
justified on the grounds of cost benefit alone. We found that the hospital cost
of infants born at 34 weeks gestation was just 633 per admission.
Costs for infants under 30 weeks gestation were higher than for infants over 30
weeks gestation. Stevens et al
estimated that to prevent one admission to hospital, treatment of infants of 26
weeks gestation with palivizumab would cost $24,476 but for infants born at 30
to 32 weeks gestation the cost increased to $78,785.
5
Our study did not include a societal cost analysis. As
72% of our patients lived
in remote highland areas and these children stayed longer in hospital, we do not
know the cost attributable to days lost from work by parents and caregivers and
additional cost to these families. These
factors also need to be taken into consideration.
Research into potentially less expensive educational methods to prevent RSV infection should be encouraged. 11 The risk of acquisition of RSV by children without BPD has been correlated with crowding, smoking and young age. 12 Passive smoking is a significant risk factor for children with BPD developing RSV infection. 3 We found that there were more smokers in households of infants born less than 30 weeks gestation. Advice on avoidance of passive smoking should, therefore, be reinforced at the time of discharge from the neonatal unit.
Conclusion
The
majority of ex-preterm infants who were admitted with RSV bronchiolitis, lived
in rural areas of the Highlands. The costs
of hospital admission of preterm infants (especially less than 30 weeks
gestational age) and infants with BPD were high.
Further studies are required to determine productivity losses associated
with RSV infection and justification of use of RSV vaccine in infants of less
than 30 weeks gestation and of BPD living in remote areas of Scottish Highlands.
Acknowledgements
We would like to thank Dr. S M Vaughan, Mrs. H Brough (Highland Clinical Audit Services) and Ms. R Finlayson (Clinical Nurse Practitioner). We would also like to acknowledge the help of medical records staff of Raigmore Hospital in retrieving case records.
References
1. Cunningham CK,
McMillan JA, Gross SJ. Rehospitalization for respiratory
illness in infants of less than 32 weeks' gestation.
Pediatrics 1991;88:527-532.
2. Groothuis JR,
Gutierrez KM, Lauer BA. Respiratory syncytial virus infection in
children with bronchopulmonary dysplasia.
Pediatrics 1988;82:199-203.
3. Groothuis JR, Simoes
EA, Hemming VG. Respiratory syncytial virus (RSV)
infection in preterm infants and the protective effects of RSV immune
globulin
(RSVIG). Respiratory Syncytial Virus Immune Globulin Study Group.
Pediatrics 1995;95:463-467.
4. Nachman,
Navaie-Waliser M, Qureshi MZ. Rehospitalization with respiratory
syncytial virus after neonatal intensive care unit discharge: a 3-year
follow-up.
Pediatrics 1997;100:e8
5. Stevens TP, Sinkin
RA, Hall CB, Maniscalco WM, McConnochie KM.
Respiratory syncytial virus and premature infants born at 32 weeks'
gestation or
earlier: hospitalization and economic implications of prophylaxis.
Arch Pediatr
Adolesc Med 2000;154:55-61.
6. The IMpact-RSV Study
Group. Palivizumab, a humanized respiratory syncytial
virus monoclonal antibody, reduces hospitalization from respiratory
syncytial
virus infection in high-risk infants.
Pediatrics 1998;102:531-537.
7. The PREVENT Study
Group. Reduction of respiratory syncytial virus
hospitalization among premature infants and infants with bronchopulmonary
dysplasia using respiratory syncytial virus immune globulin prophylaxis.
Pediatrics 1997;99:93-99.
8. Cowden JM. An
estimate of the costs of cases of rotavirus infection admitted to
hospital in Scotland, 1997. Health
Bulletin 2001;59:188-192.
9. Clark SJ, Beresford
MW, Subhedar NV, Shaw NJ. Respiratory syncytial virus
infection in high risk infants and the potential impact of prophylaxis in
a United
Kingdom cohort. Arch Dis
Child 2000;83:313-316.
10.
Greenough A, Cox S, Alexander J, et al. Health care utilisation of
infants with
chronic lung disease, related to hospitalisation for RSV infection.
Arch.Dis.Child 2001;85:463-468.
11.
Moler FW. RSV immune globulin prophylaxis: is an ounce of prevention
worth
a pound of cure? Pediatrics
1999;104:559-560.
12.
McConnochie KM, Roghmann KJ. Parental smoking, presence of older
siblings,
and family history of asthma increase risk of bronchiolitis.
American Journal of