Kuitert 2010.

Study characteristics
Methods	RCT. Parallel. Duration: 12 months. Location: CF clinics at Barts and the London, Kings College Hospital and Lewisham University NHS Trusts, UK.
Participants	Participants with a diagnosis of CF (positive sweat test or genotype testing) aged over 16 years (post pubertal‐stage IV Tanner), either sex, pancreatic insufficient (i.e. with a positive faecal elastase test, and requiring pancreatic enzyme supplementation), no overt liver disease and not taking vitamin K. 38 participants recruited. Age: 16 ‐ 43 years.
Interventions	Intervention: 10 mg of menadiol phosphate (water soluble form of vitamin K) once daily orally. Control: placebo.
Outcomes	difference in the ratio of undercarboxylated osteocalcin to total osteocalcin, measured prior to supplementation starting and at the end of the 12 months supplementation total osteocalcin undercarboxylated osteocalcin N Terminal X (marker of bone resorption) bone specific alkaline phosphatase serum vitamin D calcium DEXA scan z and t scores of lumbar spine and femoral neck (scores adjusted for age, height and sex) measured prior to supplementation starting and at the end of the 12 months supplementation
Notes	Trial was undertaken at CF clinics at Barts and the London, Kings College Hospital and Lewisham University NHS Trusts, UK. The trial details could only be obtained as an abstract of poster presentation of conference proceedings or entries on trials registries. An electronic mail communication with the trial author could not obtain any further information.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, but no further details given in the published abstract.
Allocation concealment (selection bias)	Unclear risk	Details not available/published in the abstract.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Details not available/published, although the abstract describes the control as "placebo".
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Details not available/published.
Selective reporting (reporting bias)	Unclear risk	Protocol available on trial registry websites, but limited results only published in abstract form and not a full paper.
Other bias	Unclear risk	Insufficient detail available to make a judgement.

ALT: alanine aminotransferase
AST: aspartate aminotransferase
BMI: body mass index
CF: cystic fibrosis
IU: international units
NCHS: National Center for Health Statistics
PIVKA‐II: proteins induced by vitamin K absence or antagonism factor II
RCT: randomised controlled trial