Thursday, February 16, 2006

Women's Health Initiative Study may demonstrate that vitamin D and calcium work only if you take it

A recent NEJM article will get wide press coverage as it will allegedly be shocking. The Women's Health Study strikes again, this time seemingly crushing the hopes of those women who take vitamin D and calcium with the expectation that they decrease the risk of osteoporosis.

I think the study demonstrated that vitamin D and calcium in the dose intended only decreased the risk of fractures in those women who actually took the medication.

The authors understate this by saying "It is also plausible that there was benefit only among those women who adhered to the study treatment."

In support of this radical theory,they report a statistically significant 29% decrease in hip fracture risk among adherent participants. Only 59 % of participants took the intended dose by the end of the study.

Another significant issue is that the 400 units of vitamin D may not be enough.The authors quote references that support that claim.

Another issue was the reported increase in kidney stones in the treatment group with a hazard ratio of 1.17 in the treatment group. So few participants actually took the medication as intended, and with such a slight increase in risk measurements it is hard to know what this means and the authors did not discuss this finding in any detail.

It has not been a good month of the WHI results-wise. One study showed that reduction of total dietary fat did not decrease risk of heart attack. Cardiologists,for some time now,have not recommended to decrease total fat but rather saturated and transfat. And now a major, expensive,randomized trial seems to show Vitamin D and calcium only decreases fracture risk if you actually take the pills.

It is currently trendy for folks in the medical policy arena to talk about value as defined by the ratio to quality to cost. Ignoring for the moment the monumental problems of measuring quality, if you consider this study enrolled 36,282 participants and the NEJM needed 9 printed lines to list the authors and only arguably demonstrated that medicine only works if you actually take it, you have to wonder about the value of that effort.

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