Grady 1991.

Methods	Randomised, double‐blind, placebo‐controlled trial using parallel group design (2 intervention groups)
Participants	Number of participants randomised: 98 elderly ambulatory men and women (54% women), aged 70 to 97 (mean 79.1) years of age Inclusion criteria: elderly ambulatory men and women. Exclusion criteria: serum calcium levels of 2.57 mmol/L or more, urinary calcium levels of 7.28 mmol/day or more, creatinine clearance less than 0.42 mmol/s, history of hypercalcaemia, nephrolithiasis, seizure disorder, hyperparathyroidism, treatment with calcium, vitamin D or thiazide diuretics, and average calcium intake greater than 1000 mg/day.
Interventions	Participants were randomly assigned to receive: Intervention group: calcitriol (0.5 μg) daily (n = 50) Comparator group: placebo vitamin D (n = 48), for a 6‐months period.
Outcomes	Outcomes reported in abstract of publication Primary outcomes: muscle strength. Secondary outcomes: none defined.
Stated aim of study	Quote from the publication: "To test the hypothesis that the weakness associated with aging is in part due to inadequate serum concentrations of 1,25‐(OH₂) D₃."
Notes	"Participants were evaluated at 1, 2, 4, 8, 12, 18, and 24 weeks of intervention regimen to maintain compliance. Participants in both groups took more than 95% of the assigned medication."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: the trial is described as randomised but the method of sequence generation was not specified.
Allocation concealment (selection bias)	Unclear risk	Comment: the trial was described as randomised but the method used to conceal the allocation was not described, so that intervention allocations may have been foreseen in advance of, or during, enrolment.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote from the publication: "We conducted a randomized controlled, double‐blinded trial in 98 men and women volunteers over 69 yr old." Comment: the trial was described as double‐blind, but the method of blinding was not described, so that knowledge of allocation was possible during the trial.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote from the publication: "We conducted a randomized controlled, double‐blinded trial in 98 men and women volunteers over 69 yr old." Comment: the trial was described as double‐blind, but the method of blinding was not described, so that knowledge of allocation was possible during the trial.
Incomplete outcome data (attrition bias)	Low risk	Quote from the publication: "One subject (assigned to treatment with 1,25‐(OH)₂ 2D₃) died following surgery for gastric cancer during the second month of the study. A second subject (assigned to placebo) suffered a stroke during the third month of the study and was unable to complete the protocol." Comment: the numbers and reasons for dropouts and withdrawals in all intervention groups were described.
Selective reporting (reporting bias)	Low risk	Comment: predefined, or clinically relevant and reasonably expected outcomes are reported on.
For‐profit bias	High risk	Quote from the publication: "Calcitriol and placebo capsules were provided by Hoffman‐LaRoche (Nutley, NJ)." Comment: the trial was sponsored by the industry.
Other bias	Low risk	Comment: the trial appears to be free of other components that could put it at risk of bias.