UK Trial 1991.

Methods	Screening from January 1985 to December 1989 in Wales and from January 1985 to October 1989 in the West Midlands. Randomisation method: screening on alternate weeks. Control participants were identified by clinical manifestations of the disease. Validity: ascertainment bias and lead time bias.
Participants	230,076 screened and 234,510 not screened neonates (Doull 2001). 176 CF participants: 86 were in the screened group and 90 in the control group. Number of males and females was not reported. Infants born in the central Birmingham area, those with MI and those with an elder sibling with CF were excluded from analysis. In earlier reports 13 participants with a false‐negative screening result were incorrectly analysed as part of the control group. Age range 0 ‐ 4 years (data up to years are described in the study by Sebire (Sebire 1995)) and, in abstract only, to 10 years by Ryley (Ryley 2001).
Interventions	Type of screening: IRT test followed by a second IRT test when the first IRT test was positive (IRT levels > 900 ng/ml).
Outcomes	Outcomes included in this review: weight and height SD scores, carriage rates for P. aeruginosa and S. aureus, chest radiograph scores, lung function tests, number of hospital admissions, number of hospital days, survival and Shwachman score.
Notes	Lung function tests are only reported in the study by Sebire (Sebire 1995) and, as an abstract only by Ryley (Ryley 2001). In both these reports there is only a description of the results given, no data are published.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Randomisation method: screening on alternate weeks, but doesn't state how it was decided which group (screened or non‐screened) would be first. A change in attitude to the protocol in one district in the West Midlands led to the screening being stopped in October 1989, but it continued in Wales until December 1989. Babies born in the West Midlands between October and December 1989 are included in the unscreened group, but the investigators state that this 3‐month period was unlikely to have a significant effect to allocation over the whole 5‐year period.
Allocation concealment?	High risk	Alternation method ‐ screening on alternate weeks, investigators would be able to foresee which group babies would be allocated to.
Blinding? All outcomes	Unclear risk	Not reported in paper.
Incomplete outcome data addressed? All outcomes	High risk	ITT not possible. Infants born in the central Birmingham area, those with MI and those with an elder sibling with CF were excluded from analysis.
Free of selective reporting?	High risk	Lung function tests are only reported in the study by Sebire (Sebire 1995) and, as an abstract only by Ryley (Ryley 2001). In both these reports there is only a description of the results given, no data are published.
Free of other bias?	High risk	Ascertainment bias; lead time bias