Beker 1997.

Methods	Randomised cross‐over trial (2 periods of 4 weeks). CF Clinic Children's National Medical Center (CNMC), Washington DC. No date specified.
Participants	Randomised: N = 18 (8 male, 10 female); mean age 20 years (range 13 ‐ 35 years). Inclusion criteria confirmed diagnosis of CF by duplicate sweat test clinically stable as determined by physical exam; afebrile moderate lung disease based on an average radiograph score of 15 using the Brasfield scoring method within or above the fifth NCHS height percentile for age and body mass index (BMI) ≥20 AST/ALT levels within the normal range, and normal plasma albumin levels Exclusion criteria without cholestasis or overt liver disease elevated AST/ALT Withdrawal or loss to follow‐up: none reported.
Interventions	Intervention: 5 mg oral vitamin K1 supplementation per week. Control: no supplementation. 4 weeks of first treatment then crossed over to the other treatment for a second 4‐week period. Concomitant medications permitted: cephalosporin (13); sulfamethoxazole (3); erythromycin (1); bronchodilators; standard multivitamins and 200 ‐ 400 IU vitamin E.
Outcomes	Primary outcomes: none reported Secondary outcomes (assessments at entry and end of each trial period) plasma vitamin K1 and vitamin K1‐2,3 epoxide plasma PIVKA‐II serum osteocalcin 3‐day dietary intake records were completed during each treatment period, but these did not correspond with the nutritional parameters sought as secondary outcomes for this review. Patient compliance was verified by the trial coordinator at each visit.
Notes	Randomised cross‐over trial, vitamin K supplementation compared with no treatment. No wash‐out period with a potential carry‐over of treatment effect. No first‐period data available. "Supported in part by grants from the Board of Lady Visitors, Children's National Medical Center, Washington, DC, and the University of Maryland, College Park, Maryland."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomly assigned" Page 512 Comment: insufficient information to make a clear judgement of 'Yes' or 'No'.
Allocation concealment (selection bias)	Unclear risk	Not reported. Probably not done.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Participants: not possible; control was 'no treatment'. Healthcare providers: not possible; control was 'no treatment'. Outcomes assessors and data analysts: unclear. Comment: overall judgement unclear.
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were no withdrawals and no missing or incomplete data.
Selective reporting (reporting bias)	Low risk	Although the protocol was not available all relevant outcomes appear to have been addressed.
Other bias	Unclear risk	Quote: "Supported in part by grants from the Board of Lady Visitors, Children's National Medical Center, Washington, DC, and the University of Maryland, College Park, Maryland." Comment: it is unclear to what extent the support provided may have had on the results of this study. Insufficient information to assess whether an important risk of bias exists.