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Elderly women diagnosed with osteoporosis had higher mortality and hip fracture rates than those without the diagnosis but who had bone mineral density scores indicative of high fracture risk, according to a new study.

The findings suggest that drug therapy could benefit elderly women -- those ages 80 and older -- with definite osteoporosis, the investigators said.

Among more than 1,500 elderly women, those with osteoporosis had a 25% 5-year probability of all-cause mortality (95% CI 21.8%-28.1%) compared with 19.4% (95% CI 16.6%-22.3%) for those without osteoporosis but who had a high fracture risk, reported Kristine Ensrud, MD, MPH, of the University of Minnesota in Minneapolis, and other members of the Study of Osteoporotic Fractures Research Group writing in .

Major findings included that having a higher number of comorbidities was associated with a higher probability of all-cause mortality:

• No comorbidities: 19.7% (osteoporosis) vs 12.6% (high fracture risk)

• One comorbidity: 20.4% vs 16.1%

• Two comorbidities: 29.4% vs 23.7%

• Three comorbidities: 36.1% vs 34.4%

The 5-year probability of having a hip fracture was over three-fold more common among women in the study with osteoporosis versus those without but who were at a high risk for fracture (13% vs 4%). Similarly, the probability for hip fracture also increased along with the number of comorbidities, although it was more pronounced for those with osteoporosis compared with those without but at high risk for fracture:

• No comorbidities: 13% vs 1.9%

• One comorbidity: 12.7% vs 5.1%

• Two comorbidities: 8% vs 6.7%

• Three comorbidities: 18.1% vs 2.5%

"This finding suggests that initiation of drug treatment in late-life women with osteoporosis may still be effective in the prevention of subsequent hip fracture; results of previous fracture-prevention trials have demonstrated that the time horizon to benefit is less than 5 years," Ensrud and co-authors noted.

They continued: "If drug therapy is equally effective in women 80 years and older as in postmenopausal women younger than 80 years, these results suggest that the absolute benefit of treatment in preventing hip fracture in late-life women may be greatest among those women with osteoporosis and substantial comorbidity burden or limited life expectancy, because these characteristics, while predictive of mortality, are also strongly associated with hip fracture risk."

Study Details

The prospective cohort study assessed data on 1,528 community-dwelling women enrolled in the Study of Osteoporotic Fractures. Among this group of women who had never been treated for osteoporosis, 761 met the criteria for having osteoporosis -- defined as a femoral neck or total hip bone BMD (bone marrow density) T-score of -2.5 or lower.

The remaining participants were at high risk for fracture, defined as having osteopenia with a BMD T-score from -2.5 to -2.0 with a 10-year predicted probability for fracture at or above the National Osteoporosis Foundation's intervention threshold or previous forearm, humerus, or pelvic fracture.

The researchers also calculated the 5-year probabilities for mortality and hip fracture risk according to prognostic index score. Similar patterns were seen when the analysis compared women with osteoporosis and those at high fracture risk when their risk was calculated with prognosis.

Among women who scored in the highest prognostic index group -- indicating a poorer prognosis -- those with osteoporosis had a nearly 47% probability of all-cause mortality within 5 years compared with 40% for those at high fracture risk. On the other hand, those with the poorest prognosis and osteoporosis had an over 25% probability for hip fracture compared with only 5% for those at high risk who had the same prognostic index score.

Ensrud and co-authors said that despite the findings suggesting that older women with osteoporosis or osteopenia could benefit from pharmacologic treatment, this group is often excluded from large randomized trials looking at these types of therapies.

"There is a critical need for a better evidence base to inform clinical decision-making regarding whether to initiate drug treatment for fracture prevention in women with osteoporosis in the ninth decade of life, including among those with more comorbid conditions or poorer prognosis," the team underscored. "While ethical concerns may preclude the conduct of randomized placebo-controlled trials, observational studies such as the present investigation that carefully apply methods to minimize inherent biases can provide insight on absolute benefits vs risks of drug treatment in this patient population."

Limitations of the study, the researchers said, include the inclusion of only community-dwelling white women and that only hip BMD, and not spine, was measured.

Writing in an , Sarah Berry, MD, of Hebrew SeniorLife in Boston, and two colleagues called the findings "of great clinical importance, given the ongoing recognition that clinical guidelines should consider multimorbidity."

Berry and colleagues said that if therapies to prevent fractures are just as effective in older women with several comorbidities as in younger women, the benefit of treatment likely outweighs the risk. Patient preference, however, is key in determining whether or not to treat osteoporosis in frail, older women, as well as considering the ever-present competing risk of death.

"We encourage additional research that will guide treatment in this growing patient population, and we hope that future guidelines for osteoporosis treatment will include recommendations for older patients with multimorbidity," the commentators said.

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