Efficacy and safety of single-dose zoledronic acid for osteoporosis in frail elderly women: a randomized clinical trial

Abstract

Importance: Eighty-five percent of institutionalized elderly people have osteoporosis and bone fracture rates 8 to 9 times higher than rates observed among community-dwelling elderly people. Nevertheless, most of these persons are left untreated and are excluded from pivotal osteoporosis trials.

Objective: To determine the efficacy and safety of zoledronic acid to treat osteoporosis in frail elderly women in long-term care facilities.

Design, setting, and participants: We conducted a 2-year, randomized, placebo-controlled, double-blinded study from December 2007 through March 2012. Included were 181 women 65 or older with osteoporosis, including those with cognitive impairment, immobility, and multimorbidity, who were living in nursing homes and assisted-living facilities.

Interventions: One 5-mg dose of zoledronic acid or placebo intravenously and daily calcium and vitamin D supplementation.

Main outcomes and measures: Hip and spine bone mineral density (BMD) at 12 and 24 months and adverse events.

Results: There were no baseline differences in mean (SE) age (85.4 [0.6] years), BMD, or functional or cognitive status, but the treatment group included more participants with frailty, falls history, diabetes, and anticonvulsant medication use. Values for BMD were available for 87% of participants at 12 months and 73% at 24 months. Mean (SE) BMD changes were greater in the treatment group: 3.2 (0.7) and 3.9 (0.7) percentage-point differences in the total hip at 12 and 24 months, respectively (P < .01 for both comparisons), and 1.8 (0.7) and 3.6 (0.7) percentage-point differences at the spine (P < .01); adjusted analyses were similar. The treatment and placebo groups' fracture rates were 20% and 16%, respectively (OR, 1.30; 95% CI, 0.61-2.78); mortality rates were 16% and 13% (OR, 1.24; 95% CI, 0.54-2.86). Groups did not differ in the proportion of single fallers (28% vs 24%; OR, 1.24; 95% CI, 0.64-2.42; P = .52), but more participants in the treatment group had multiple falls (49% vs 35%; OR, 1.83; 95% CI, 1.01-3.33; P = .047); however, this difference was no longer significant when adjusted for baseline frailty.

Conclusions and relevance: In this group of frail elderly women with osteoporosis, 1 dose of zoledronic acid improved BMD over 2 years. The clinical importance of nonsignificant increases in fracture and mortality rates in the treatment group needs further study. Since it is not known whether such therapy reduces the risk of fracture in this cohort, any change in nursing home practice must await results of larger trials powered to assess fracture rates.

Trial registration: clinicaltrials.gov Identifier: NCT00558012.

Figure 1

Enrollment and Study Design Flow Chart

Figure 2

Mean ± SE percent change in bone mineral density (BMD) from baseline to 24 months (unadjusted). * p<0.05, ** p<0.01 change from baseline using paired t-test. # p<0.05, ## p<0.01 for comparison between zoledronic acid (solid line) and placebo (dashed line) groups using linear mixed models.

Figure 3

Mean ± SE change in biochemical markers of bone turnover including CTX (nmol/L BCE) and P1NP (µg/L) from baseline to 24 months (unadjusted). * p<0.05, ** p<0.01 change from baseline using paired t-test. #p<0.05, ##p<0.01 for comparison between zoledronic acid (solid line) and placebo (dashed line) groups using linear mixed models.