[table A posted as supplied by authors]

Online supplement 1: Quality Assessment of diagnostic accuracy study using the QUADAS checklist¹⁸

Table A

Roovers, E.A., et al., Effectiveness of ultrasound screening for developmental dysplasia of the hip, in Doctoral Thesis 'Post-neonatal ultrasound screening for developmental dysplasia of the hip. A study of cost-effectiveness in the Netherlands'. 2004: University of Twente, Enschede, Netherlands. p. 41-53.
Item	Description	Yes/No	Comments/Further information
1.	Was the spectrum of patients representative of the patients who will receive the test in practice?	Yes	The population was an unselected population as is appropriate for screening.
2.	Were selection criteria clearly described?	Yes	Inclusion criteria were very general, with no detailed criteria for exclusion.
3.	Is the reference standard likely to correctly classify the target condition?	No	Reference test is end of follow-up but as this encompasses decision to treat at any age, it is very possible that some treated infants would have resolved spontaneously and therefore such cases represent over-treatment. Thus the sensitivity of the test will be over estimated.
4.	Is the time period between reference standard and index test short enough to be reasonably sure that the target condition did not change between the two tests?	NA	There is a real possibility that the hip dysplasia will spontaneously resolve between the index text and the reference test if the reference test is conducted at 8 months. This is an important aspect of the reference test and is not a flaw. Unfortunately, because some infants were treated early rather than receiving the reference test at 8 months some information was lost.
5.	Did the whole sample or a random selection of the sample, receive verification using a reference standard of diagnosis?	Yes	It should be noted that as the reference standard was treatment or reference test at 8 months not all children were exposed to the same reference standard.
6.	Did patients receive the same reference standard regardless of the index test result?	No	As above.
7.	Was the reference standard independent of the index test (i.e. the index test did not form part of the reference standard)?	No
8.	Was the execution of the index test described in sufficient detail to permit replication of the test?	Yes
9.	Was the execution of the reference standard described in sufficient detail to permit its replication?	Yes	Clinical judgement and various assessments involved, so not exactly the same for each infant.
10.	Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
11.	Were the reference standard results interpreted without knowledge of the results of the index test?	No
12.	Were the same clinical data available when test results were interpreted as would be available when the test is used in practice?	Yes
13.	Were uninterpretable/ intermediate test results reported?	Partially Yes	All infants followed up until a definite decision made, however, there may have been some uninterpretable results.
14.	Were withdrawals from the study explained?	Yes

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[tableB posted as supplied by authors]

Online Supplement 2. Quality of the included studies

Table B

Study	Study design	Sufficient description of groups and distribution of prognostic factors?	Is there an adequate description of the screening process?	Were the groups comparable on all confounding factors?	If the groups were not comparable was adequate adjustment for the effects of the confounding factors made?	Was follow-up long enough for the reported outcomes to occur?	Is it reported what proportion of unselected newborn population was screened?	Is it reported what proportion of the screened population was followed-up?
Clegg 1999¹⁶	Retrospective comparator study	No	Yes	No	No	Yes	No	No
Eggl 1993²³	Retrospective comparator study	No	No	No	No	Yes	No	No
Grill 1997¹⁷	Retrospective comparator study	No	No	No	No	Yes	No	No
Holen 2002²²	Randomised controlled trial	Yes	Yes	Yes	Not applicable	Yes	Yes (98%)	Yes (100%)
Krolo 2003²⁶	Retrospective comparator study with historical control group	No	Yes	No	No	No	No	No
Maj 1989²⁴	Retrospective comparator study	No	No	No	No	Yes	??	Yes (66.2%)
Malkawi 1997²⁵	Retrospective comparator study	No	Yes	No	No	Yes	Yes (100%)	No
Roovers 2004²⁴	Prospective cohort study with historical control group	No	Yes	No	Yes	Yes	Yes (82.6%)	Yes (94.5%)
Rosendahl 1994²¹	Randomised controlled trial	Yes	Yes	No	No	Yes	Yes (97.5%)	Yes (100%)
Tegnander 1994²⁸	Retrospective comparator study	No	Yes	No	No	No	No (implies 100%)	No