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Optimal cost-effective timing of cranial ultrasound screening in low-birth-weight infants |
Boal D K, Watterberg K L, Miles S, Gifford K L |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Cranial ultrasound screening at 2 weeks of age (on day of life 10-14) in low-birth-weight infants (intervention) versuscranial ultrasound screening beginning in the first week of life and carried out in two stages involving ultrasound examinations on day of life (DOL) 4 or 5 and DOL 14 (comparator) for the detection of specific intracranial pathology in low-birth-weight infants.
Economic study type Cost-effectiveness analysis.
Study population Premature infants of less than 33 weeks gestation or less than 1500g birth weight.
Setting Hospital. The economic study was carried out in Pennsylvania, USA.
Dates to which data relate The resource and effectiveness data were from the period January 1989-August 1992 (the control group was examined before August 1991). The prices used were not dated.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was retrospectively undertaken on a different patient sample from that used for the effectiveness study.
Study sample The study comprised 338 subjects, with 253 in the comparator group (74 in the DOL 1-3 category and 179 in the 4-7 category) and 85 in the intervention group (DOL 8-14).
Study design The study was a retrospective cohort study, carried out in a single centre. The comparator group was followed up for 1 week in order to assess changes in diagnosis. No loss to follow up was reported.
Analysis of effectiveness The analysis was based on babies scanned (not missed from eligible subjects). The primary health outcomes used were change in diagnosis, defined as a change in the diagnostic category, incidence of major abnormalities (including ventricular haemorrhage (IVH) grades III and IV, persistent ventricular dilatation, and periventricular leukomalacia (PVL)), and minor abnormalities (including IVH, grades I and II, and resolvedventricular dilatation), and incidence of questionable PVL. All cranial ultrasounds have been performed with Ultramark 4 or an Acuson unit with a 5.0, 7.5 or 10.0 MHz transducer. Infants with central nervous system anomalies were excluded while birth weight, gestational age and final diagnosis characteristics were shown not to be significantly different (p<0.02). Subjects screened on DOL 4-7 and DOL 8-14 were similar with regard to diagnosis except for periventricular leukomalacia (PVL), with DOLs 4-7 having more subjects diagnosed with questionable PVL compared with subjects scanned on DOL 8-14 (p<0.04). The screenings of DOL 1-3 were considered as being clinically ordered studies, rather thanscreening examinations.
Effectiveness results 144 subjects had an ultrasound examination during the first week of life with a follow-up study during the second week. Fifteen infants (10%) had significant changes in ultrasound diagnosis from first to second weeks. A total of 13 patients changed category from either normal or minor abnormality to major abnormality and 2 changed from major abnormality to normal or minor abnormality. The seven subjects screened on DOL 4-7 (for this follow up subgroup) changed to a more severe diagnostic category in the second week. The percentages of incidence of major abnormalities for DOL 1-3, DOL 4-7, and DOL 8-14 were 36%, 20%, and 14%, respectively. The percentages of incidence of minor abnormalities for DOL 1-3, DOL 4-7, and DOL 8-14 were 16%, 23%, and 21%, respectively. The percentages of incidence of questionable PVL for DOL 1-3, DOL 4-7, and DOL 8-14 were 46%, 25%, and 15%, respectively.
Clinical conclusions The only significant diagnostic difference that the study revealed between the two strategies was that patients initially scanned during the second week of life were diagnosed with questionable PVL. It is more difficult to reliably diagnose PVL with ultrasound.
Measure of benefits used in the economic analysis No summary benefit measure was identified in the economic study, and only separate clinical outcomes were reported.
Direct costs Quantities were calculated and assuming a specific price, costs were estimated. The cost items measured were operating costs represented by screening costs. The boundary adopted was the hospital. The estimation of quantities was based on actual data using two groups divided by the critical date in which a new protocol became effective. The estimation of costs was based on a reported "average" charge. The source of quantities was the neonatal database. The quantity of resources was measured from January 1989 to just before 1 August 1991 (when the new second week screening protocol was introduced) for the comparator, and from 1 August 1991 to August 1992 for the intervention group. No dates were reported for the price data.
Sensitivity analysis No sensitivity analysis was performed.
Estimated benefits used in the economic analysis Cost results With an average charge of $275 for a cranial ultrasound examination, it was estimated that the adoption of the intervention would result in a saving of up to $3 million annually, for approximately 53,000 babies weighing less than 1501g in the USA in 1992.
Synthesis of costs and benefits Costs and benefits were not combined.
Authors' conclusions Delaying the screening cranial ultrasound until the second week of life did result in significantly fewer scans per patient being performed. While the prognostic significance of transient PVL might be an appropriate research issue, the diagnosis of subtle PVL would not be expected to alter patient management. Routine initial screening with cranial ultrasound could be delayed until the second week of life, thereby decreasing the number and cost of imaging studies without compromising patient care.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator is clear. Validity of estimate of measure of effectiveness The internal validity of the results may not be assured due to the lack of a randomised design and the small sample size. Validity of estimate of costs The resource utilisation and cost items were not reported separately, and insufficient details of the methods of cost estimation were provided. Other issues Givenn the lack of randomisation, sensitivity analysis, and statistical analysis of the costs,the results need to be treated with some caution. The issue of generalisability to other settings or countries was not addressed. Bibliographic details Boal D K, Watterberg K L, Miles S, Gifford K L. Optimal cost-effective timing of cranial ultrasound screening in low-birth-weight infants. Pediatric Radiology 1995; 25(6): 425-428 Indexing Status Subject indexing assigned by NLM MeSH Cerebral Hemorrhage /ultrasonography; Clinical Protocols; Cost-Benefit Analysis; Follow-Up Studies; Humans; Hydrocephalus /ultrasonography; Infant, Low Birth Weight; Infant, Newborn; Infant, Premature, Diseases /ultrasonography; Leukomalacia, Periventricular /ultrasonography; Ultrasonography /economics AccessionNumber 21995000975 Date bibliographic record published 31/07/1999 Date abstract record published 31/07/1999 |
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