March 14, 2006

Break a Leg?

Sometimes I wonder what disease will get me in the end: statistically speaking, it’s a toss up between cancer and heart disease. But I worry even more about breaking a hip. For many older people, a hip fracture is the beginning of the end. After sustaining a hip fracture, only 50-60% of people walk as well as they did previously. About 20% never walk again and 40% end up in a nursing home. Within a year, 37% of elderly Americans who break a hip are dead.

Not only are your odds of returning to your baseline level of functioning poor, but the chance of breaking a hip is substantial: 350,000 Americans break a hip each year. Older people are at risk of fractures because they fall and because they have thin (osteoporotic) bones. So articles in two major medical journals in the last month that call into question the efficacy of two leading preventive strategies—calcium and vitamin D on the one hand and hip protector pads on the other—are worrisome. Should all older people give up their calcium supplements and forget about wearing hip pads?

The study of calcium and vitamin D appeared in the New England Journal of Medicine (R. Jackson, A. Lacroix, M. Gass et al, “Calcium Plus Vitamin D Supplements and the Risk of Fractures,” NEJM 2006; 354:669-83). The authors had the opportunity to randomize over 36,000 women who had previously enrolled in a Women’s Health Initiative trial to receive either 1000 mg of calcium carbonate and 400 units of vitamin D or placebo. They were monitored for fractures for the next 7 years and their bone density was measured. The results? There was a small but not statistically significant decrease in the risk of hip fracture, a small improvement in bone density, and a small increased risk of kidney stones.

Before throwing away those calcium and vitamin D pills, it’s important to realize that only 59% of the women were actually taking the recommended dose at the end of the study. When the authors evaluated the outcomes in women who really took the medicine, there was a 29% statistically significant decrease in the likelihood of hip fracture. For scientific reasons, the analysis should be done the way the authors did it—using an “intent to treat” approach. This allows them to conclude that from a public health or policy perspective, they cannot recommend the use of calcium and vitamin D because prescribing those supplements is not likely to produce the desired outcome. But that’s different from concluding that taking the medication will not result in lowering your chance of hip fracture. It’s also important to realize that the 36,000 women in the study were healthy, community-dwelling post-menopausal women with an average age of 62. Inferring from this study that calcium and vitamin D do not prevent hip fractures in older women with other medical problems is not warranted. And in fact there was some suggestion that women over 60 did in fact benefit.

The second study on a related subject was a meta-analysis or pooled analysis of previous studies that was published in the British Medical Journal. (M. Parker, W. Gillespie and R. Gillespie, “Effectiveness of Hip Protection for Preventing Hip Fractures in Elderly People: Systematic Review,” BMJ 2006; 332: 571-4). It asked whether hip pads achieved their initial promise: earlier studies of nursing home patients had found that hip protectors could halve the rate of hip fractures. After combining the information from 14 studies, 11 of which involved nursing home patients and 3 of which were conducted in community-dwellers, the authors were unimpressed. They concluded that the pads were ineffective in the home setting and conferred only a small (but statistically significant) benefit in institutionalized individuals. But very much like the work on calcium, it turns out that many of the people who were supposed to wear the hip pads didn’t do so for much of the time. They found them inconvenient or awkward or uncomfortable, despite efforts to streamline the pads. Once again, it’s reasonable to conclude that hip pads should not at this point be the “standard of care.” We shouldn’t routinely expect insurance companies to pay for them or nursing homes to provide them. But there may well be a benefit for the person who is at high risk of falls and fractures and who is motivated to use them.

The data aren’t all in yet—we may find that calcium and vitamin D are effective, but higher doses are required, or it may turn out they are principally useful in an as yet undefined subgroup of the population. We may discover that certain types of hip protectors work and others, made of different materials, do not. In the meantime, these two interventions may make a lot of sense for people who want to do everything they can to avoid a hip fracture. And that’s not such a bad idea.

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