Witham 2010.

Study characteristics
Methods	Double‐blind, placebo‐controlled trial Blinding of outcome assessors stated 96 of 105 completed
Participants	Participants recruited from primary and secondary care, Tayside and Fife, Scotland, UK 105 participants, (69 men, 36 women), mean age 80 years Inclusion criteria: aged ≥ 70 years with recorded clinical diagnosis of chronic heart failure; previously documented left ventricular systolic dysfunction by echocardiography, radionuclide ventriculography, or angiography as part of their usual clinical care; New York Heart Association class II or III symptoms; 25(OH)D level of < 50 nmol/L Exclusion criteria: a clinical diagnosis of osteomalacia, under investigation for recurrent falls, taking vitamin D supplements, moderate to severe cognitive impairment (defined as a Folstein mini‐mental state examination < 15/30), serum creatinine > 200 μmol/L, liver function tests (bilirubin, alanine aminotransferase, and alkaline phosphatase) > 3 times the upper limit of the local reference range, systolic blood pressure < 90 mmHg, albumin‐adjusted calcium (> 2.55 mmol/L or < 2.20 mmol/L), and metastatic malignancy, wheelchair‐bound
Interventions	1. 100,000 IU D2 orally at start and 10 weeks 2. Placebo orally at start and 10 weeks Randomised 53; 52, 48; 48 completed 20 weeks Duration of treatment 10 weeks
Outcomes	Measured over a follow‐up of 20 weeks 1. Number of persons with all new fractures 2. Number of persons with gastrointestinal adverse events, hypercalcaemia 3. Number of persons dying
Notes	Further information on fractures obtained from Miles Witham on 15 January 2013
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	States "computer‐generated random number tables"
Allocation concealment (selection bias)	Low risk	States "Randomization was performed . . . by DHP Pharmaceuticals. . . Code allocation was concealed from the research nurse and investigators until after data analysis was complete"