Leviton 1999.

Study characteristics
Methods	Cluster‐randomised controlled trial Hospitals from the Albert Einstin College of Medicine (AECOM) affiliated hospitals and hospitals from the National Perinatal Information Centre (NPIC) randomised to intervention and control groups Data were abstracted from medical records at baseline (12 months before consensus conference, March 1993 to February 1994) and after (12 months after consensus conference, April 1995 to July 1996)
Participants	27 hospitals (8 AECOM and 22 NPIC); All hospitals were tertiary care facilities with neonatal intensive care unit facilities Criteria for inclusion of hospitals: at least 100 eligible cases in baseline care; no standing protocol on ACS; not participating in other ACS related research Eligible participants: all women giving birth at 34/52 or less, including cases of spontaneous labour, PROM, and preterm delivery indicated by medical conditions No data on women who received ACS but did not deliver prematurely
Interventions	Control: usual dissemination (n = 14) ‐ NIH Consensus Conference in February 1994, final statement released May 1994 ‐ American College of Obstetricians and Gynaecologicsts' opinion statement on ACS mailed to members in December 1994 ‐ End January 1995, NIH brochures on consensus statement mailed to medical care institutions, universities, medical societies and obstetricians. ‐ JAMA published the NIH recommendations in February 1995 ‐ 2nd publication in American Journal of Obstetrics and Gynaecology July 1995 ‐ Lectures, word‐of‐mouth discussions, available literature Intervention: active dissemination (n = 13) comprised 5 components Influential physician and nurse co‐ordinator at each hospital. Liaised with colleagues who managed high risk cases. Facilitated the active dissemination strategies at treatment hospitals, in partnership with nurse co‐ordinators Grand rounds lecture on ACS by a nationally respected expert. Emphasising that the majority of women at risk for preterm delivery should receive ACS. Those attending received consensus conference statement, key research articles and citations, samples of a sticker prompt and chart reminder Chart reminder system to prompt physicians to consider prescribing therapy on a timely basis. Reminders were inserted in eligible charts as soon as possible after admission. These were brightly coloured and large. Outside of flagged charts also had brightly coloured sticker Group discussions by influential physician. 1‐hour long, informal group discussions with hospital's obstetricians and residents, discussing 4 case scenarios in which ACS might be administered (spontaneous preterm labour, PROM, early gestational age and no prenatal care, complicated pregnancy). Goals were to gain consensus on basic management, elicit reasons why corticosteroids would/would not be used, draw out differences in management strategies in accordance with the scenarios) Monitoring of care provided feedback to physicians. Nurse co‐ordinators kept logs of preterm admissions and deliveries to determine whether charts had reminder systems whether ACS was administered and when. Influential physicians received reports.
Outcomes	Primary outcome: use of antenatal corticosteroids
Notes	Time period: March 1993 to July 1996 Trial registration number: not reported Funding source: the Patient Outcomes Research Team on Low Birthweight contract 290‐92‐0055 from the Agency for Health Care Policy and Research, Rockville, Md Conflict of interests: not reported Author contacted to request missing information related to methods and results, but email address no longer valid and not able to find alternative address.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random table of numbers was used to allocate hospitals
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding not possible. Physicians in the active dissemination hospitals were aware of the study, whereas in the control hospitals only the hospital leadership were aware.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	All hospitals that were randomised were included in the analysis
Selective reporting (reporting bias)	Unclear risk	Protocol not available.
Other bias	Low risk	No other source of bias identified
Recruitment bias	Low risk	Hospitals recruited before randomisation
Baseline imbalance	Unclear risk	Quote: "A difference between intervention and control cases in frequency of abnormal fetal conditions or fetal distress was significant at patient level". "During the after conference year, 2 differences in hospital case mix emerged between intervention and control institutions. Based on hospital census (not sampling), treatment hospitals had a larger proportion of the lowest GA cases in the after‐conference year because 3 control hospitals reduced their proportions of such cases, while 1 treatment hospital increased its proportion of these cases. In addition, in the after‐conference year the average proportion of reported PROM cases increased in all hospitals but increased significantly more in treatment than in control hospitals". "The change in case mix did not cause increased use of the therapy in the active dissemination group"
Loss of clusters	Unclear risk	One hospital refused participation after randomisation
Incorrect analysis	Unclear risk	Unclear whether results at patient level were adjusted for clustering
Compatibility with individually randomised RCTs	Unclear risk	No individually‐randomised RCTs for comparison.

ACS: antenatal corticosteroids;GA: gestational age; LBW: low birth weight; LMP: last menstrual period; MgSO4: magnesium sulphate; NIH: National Institutes of Health; PROM: premature rupture of membranes; RCT: randomised controlled trial