Abstract
Objective: To examine the variation between hospitals in rates of severe intraventricular haemorrhage (IVH) in preterm babies adjusting for case mix and sampling variability.
Design: Cross sectional study of pooled data from 1995 to 1997.
Setting: 24 neonatal intensive care units (NICUs) in the Australian and New Zealand Neonatal Network.
Participants: 5413 infants of gestational age 24–30 weeks.
Main outcome measures: Crude rates of severe (grades 3 and 4) IVH and rates adjusted for case mix using logistic regression, and for sampling variability using shrinkage estimators.
Results: The overall rate of severe IVH was 6.8%, but crude rates for individual units ranged from 2.9 to 21.4%, with interquartile range (IQR) 5.7–8.1%. Adjusting for the five significant predictor variables—gestational age at birth, 1 minute Apgar score, antenatal corticosteroids, transfer after birth, and sex—actually increased the variability in rates (IQR 5.9–9.7%). Shrinkage estimators, which adjust for differences in unit sizes and outcome rates, reduced the variation in rates (IQR 6.3–7.5%). Adjusting for case mix and using shrinkage estimators showed that one unit had a significantly higher adjusted rate than expected, while another was significantly lower. If all units could achieve an average rate equal to the 20th centile (5.74%), then 60 cases of severe IVH could be prevented in a 3 year period.
Conclusions: The use of shrinkage estimators may have a greater impact on the variation in outcomes between hospitals than adjusting for case mix. Greater reductions in morbidity may be achieved by concentrating on the best rather than the worst performing hospitals.
Full Text
The Full Text of this article is available as a PDF (179.0 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Burstein J., Papile L. A., Burstein R. Intraventricular hemorrhage and hydrocephalus in premature newborns: a prospective study with CT. AJR Am J Roentgenol. 1979 Apr;132(4):631–635. doi: 10.2214/ajr.132.4.631. [DOI] [PubMed] [Google Scholar]
- Catto-Smith A. G., Yu V. Y., Bajuk B., Orgill A. A., Astbury J. Effect of neonatal periventricular haemorrhage on neurodevelopmental outcome. Arch Dis Child. 1985 Jan;60(1):8–11. doi: 10.1136/adc.60.1.8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Christiansen C. L., Morris C. N. Improving the statistical approach to health care provider profiling. Ann Intern Med. 1997 Oct 15;127(8 Pt 2):764–768. doi: 10.7326/0003-4819-127-8_part_2-199710151-00065. [DOI] [PubMed] [Google Scholar]
- Coory M., Gibberd R. New measures for reporting the magnitude of small-area variation in rates. Stat Med. 1998 Nov 30;17(22):2625–2634. doi: 10.1002/(sici)1097-0258(19981130)17:22<2625::aid-sim957>3.0.co;2-4. [DOI] [PubMed] [Google Scholar]
- Gibberd R., Pathmeswaran A., Burtenshaw K. Using clinical indicators to identify areas for quality improvement. J Qual Clin Pract. 2000 Dec;20(4):136–144. doi: 10.1046/j.1440-1762.2000.00378.x. [DOI] [PubMed] [Google Scholar]
- Heuchan A. M., Evans N., Henderson Smart D. J., Simpson J. M. Perinatal risk factors for major intraventricular haemorrhage in the Australian and New Zealand Neonatal Network, 1995-97. Arch Dis Child Fetal Neonatal Ed. 2002 Mar;86(2):F86–F90. doi: 10.1136/fn.86.2.F86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Horbar J. D., Rogowski J., Plsek P. E., Delmore P., Edwards W. H., Hocker J., Kantak A. D., Lewallen P., Lewis W., Lewit E. Collaborative quality improvement for neonatal intensive care. NIC/Q Project Investigators of the Vermont Oxford Network. Pediatrics. 2001 Jan;107(1):14–22. doi: 10.1542/peds.107.1.14. [DOI] [PubMed] [Google Scholar]
- Martuzzi M., Hills M. Estimating the degree of heterogeneity between event rates using likelihood. Am J Epidemiol. 1995 Feb 15;141(4):369–374. doi: 10.1093/aje/141.4.369. [DOI] [PubMed] [Google Scholar]
- Parry G. J., Gould C. R., McCabe C. J., Tarnow-Mordi W. O. Annual league tables of mortality in neonatal intensive care units: longitudinal study. International Neonatal Network and the Scottish Neonatal Consultants and Nurses Collaborative Study Group. BMJ. 1998 Jun 27;316(7149):1931–1935. doi: 10.1136/bmj.316.7149.1931. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Richardson D., Tarnow-Mordi W. O., Lee S. K. Risk adjustment for quality improvement. Pediatrics. 1999 Jan;103(1 Suppl E):255–265. [PubMed] [Google Scholar]
- Shepherd David. Effect of patient centredness and positive approach. Airing uncertainty can be positive. BMJ. 2002 Mar 2;324(7336):543–543. [PMC free article] [PubMed] [Google Scholar]
- Spiegelhalter D. J., Myles J. P., Jones D. R., Abrams K. R. Methods in health service research. An introduction to bayesian methods in health technology assessment. BMJ. 1999 Aug 21;319(7208):508–512. doi: 10.1136/bmj.319.7208.508. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Synnes A. R., Chien L. Y., Peliowski A., Baboolal R., Lee S. K., Canadian NICU Network Variations in intraventricular hemorrhage incidence rates among Canadian neonatal intensive care units. J Pediatr. 2001 Apr;138(4):525–531. doi: 10.1067/mpd.2001.111822. [DOI] [PubMed] [Google Scholar]
- Vass A. Doctors urge caution in interpretation of league tables. BMJ. 2001 Nov 24;323(7323):1205–1205. doi: 10.1136/bmj.323.7323.1205. [DOI] [PMC free article] [PubMed] [Google Scholar]