Pfeifer 2009.

Study characteristics
Methods	One‐year double‐blind randomised controlled trial Blinding of outcome assessors unclear Number completed of 242 unclear
Participants	61 men and 181 women aged over 70 years, community‐based study, Austria and Germany, mean age 77 years Inclusion criteria: healthy ambulatory men and women 70 years or older, 25(OH)D < 78 nmol/L Exclusion criteria: hypercalcaemia, primary hyperparathyroidism, fractures of the extremities due to osteoporosis; thiazides, bisphosphonates, calcitonin, vitamin D and vitamin D metabolites, oestrogen, anti‐oestrogen in last 6 months; fluoride in last 2 years; intolerance to study medication; chronic renal failure (serum creatinine above 20% of the upper limit of the reference range); drug or alcohol abuse; more than 20 cigarettes/day; more than 7 cups of coffee/day; holidays along geographic latitude during the study; diabetes mellitus and cardiovascular disease
Interventions	1. 1000 mg calcium as calcium carbonate and 800 IU vitamin D3 as 2 tablets daily (Meda Pharma Inc, Vienna) 2. 1000 mg calcium as calcium carbonate as 2 tablets daily (Meda Pharma Inc, Vienna) Randomised 122;120, numbers enrolled and completed unclear Duration of treatment 1 year with end of follow‐up 8 months later
Outcomes	Measured at 20 months 1. The number of persons sustaining any new fracture 2. The number of persons sustaining a fall (not part of this review)
Notes	Email to author November 2007 requesting details of fractures. Tables and text differ on numbers of participants randomised to groups. 122 and 120 presented in Bischoff‐Ferrari 2012, Comment on 1 June 2021. Based on the finding of inconsistencies in treatment group numbers and primary endpoint data for falls, and therefore for fractures, we are not confident that the data from this trial are reliable. Published correspondence with the first author has failed to assuage these concerns (correspondence dated 2015 added to references for this trial). The concerns raised were: 1. The text and Table 1 reports 121 participants in each treatment group, but Table 3 reports 120 for Ca and 122 for CaD. 2. Table 3 reports that 75 participants fell with Ca and 49 with CaD, but the breakdown of fallers in Table 3 sums to 71 for Ca and 53 for CaD. 3. The text reports the total number of falls as 171 with Ca and 76 with CaD, but Table 3 reports 169 with Ca and 106 with CaD. 4. The breakdown of total falls in Table 3 sums to at least 111 with CaD, which is greater than the total falls for CaD reported in the text (76) and Table 3 (106). 5. The text reports the mean number of falls per group as 1.41 with Ca and 0.63 with CaD which are incompatible with the reported total number of falls in the text and Table 3. 6. The text reports 13 participants with fracture with Ca whereas Table 3 reports 12. The first author replied: 1. Page 319, second paragraph, line 5: 63 % of the individuals in the calcium mono group versus 40 % in the calcium plus vitamin D group experienced at least one fall (p<0.001). The mean number of falls per group was 1.41 in the calcium mono group and 0.63 in the calcium plus vitamin D group (p<0.001). This translated into a total number of falls of 169 in the calcium mono group and to 106 falls in the calcium and vitamin D group (p<0.001). The initially published and wrong numbers in the text were 171 and 76, respectively. 2. Page 319, fourth paragraph, line 6: In total, 12 subjects in the calcium mono group and seven participants in the calcium plus vitamin D group experienced at least one fracture. The initially published and wrong number in the text was 13. After factoring in the author’s response, the remaining outstanding issues are: 1. The text and Table 1 reports 121 participants in each treatment group, but Table 3 reports 120 for Ca and 122 for CaD. 2. Table 3 reports that 75 participants fell with Ca and 49 with CaD, but the breakdown of fallers in Table 3 sums to 71 for Ca and 53 for CaD. 3. The corrected text reports the total number of falls as 169 with Ca and 106 with CaD, which is the same as Table 3. However, the breakdown of total falls in Table 3 sums to at least 111 with CaD, which is greater than the reported number of 106. 4. The text reports the mean number of falls per group as 1.41 with Ca and 0.63 with CaD which are incompatible with the reported total number of falls in the corrected text and Table 3.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	States "randomly assigned"
Allocation concealment (selection bias)	Unclear risk	No details provided