We pre-specified the following study level variables for entry into this interaction analysis: vitamin D daily dose equivalent, route (oral or intramuscular), and co-administration of calcium. We then used variables that interacted significantly to stratify the subsequent fixed effects Cox fracture-free survival analysis, which contained a series of dummy variables to capture residual differences in risk of fracture between trials. A subgroup analysis by dose (10 µg/day v 20 µg/day) was pre-specified. We thus classified the Meyer, Larsen, and Women’s Health Initiative (WHI) studies as 10 µg studies and classified the Smith study (equivalent to 20.5 µg/day), the Lyons study, the RECORD study, and the Porthouse study (all equivalent to 20 µg/day) as 20 µg studies. Observations were truncated after 36 months; only the WHI study provided sufficient patients to populate the analysis beyond this.
BRAVO!!! Thank you for finding the original article.
That's a puny amount of vitamin D. Or is it? Converting micrograms, µg, of vitamin D to international units(IU) says 10 µg equals 400 IU. That's the smallest vitamin D supplement that I've seen.
Look up opening a link in a new window.
It helps me posting and following an argument.
You can’t tell if a link opens in a new window so I right-click them and open them, usually, in a new tab.