The so-called ‘timed up and go’ (TUG) test is a “feasible inexpensive physical performance assessment” clinicians can use to screen patients at increased risk of fracture, the study team concludes in the October 10 issue of Archives of Internal Medicine.
The TUG test is a validated predictor of falls and low hip BMD as detected by dual x-ray absorptiometry is a predictor of fracture. Dr. Kun Zhu from University of Western Australia, Nedlands, and colleagues examined slow TUG test performance relative to hip BMD in predicting fractures in a population-based 10-year longitudinal study.
A total of 1,126 women with a mean age of 75 years at the outset took the TUG test at baseline and had total hip BMD measured at 1 year using dual x-ray absorptiometry (DXA).
During follow up, 17.5% of the women suffered nonvertebral fracture and 6.0% suffered vertebral fracture, with 1.6% of participants having at least one incident fracture of each type.
Roughly one third of the women (32.7%) had slow TUG performance, defined as more than 10.2 seconds, and more than half (54.2%) had low hip BMD (T-score of less than minus 1).
Women with slow TUG tests (relative to those with normal TUG tests) had significantly higher rates of nonvertebral fracture (21.2% vs 15.7%) and hip fracture (9.2% vs 5.3%).
Women with low hip BMD (relative to those with normal hip BMD) had significantly higher rates of nonvertebral fracture (21.0% vs 13.4%), hip fracture (8.9% vs 3.9%), and clinical vertebral fracture (7.7% vs 3.9%).
Compared with women with normal TUG test performance and normal BMD, those with slow TUG and normal hip BMD had significantly increased risks of nonvertebral fracture and hip fracture (hazard ratio [HR], 1.84 and 2.48, respectively).
Women with slow TUG tests and low hip BMD had a significantly increased risk of nonvertebral fractures and hip fractures (HR, 2.51 and 4.68, respectively).
For nonvertebral fracture and hip fracture, population-attributable risks were 19.3% and 32.3%, respectively, for slow TUG test performance and normal hip BMD, and 30.1% and 55.9%, respectively, for both slow TUG test performance and low hip BMD.
After adjusting for BMD, a slow TUG test was associated with a 54% increased risk of nonvertebral fracture, the investigators report.
Dr. Zhu and colleagues say, if these findings are replicated in other cohort studies, “it may be concluded that fracture prediction should include assessment of both physical performance and skeletal structural risk as assessed by the TUG test performance and DXA hip BMD.”
In a commentary published with the study, Dr. Douglas Bauer of the University of California, San Francisco, says the authors “convincingly demonstrate” the value of a single baseline TUG test in determining fracture risk over 10 years.
“Unfortunately, because TUG was the only physical performance measurement assessed…it cannot answer the important question of which performance test is optimal or if several different tests are better than one. Evidence from other studies suggest that gait speed, which is somewhat easier to measure than TUG, is as good as TUG for prediction of falls,” Dr. Bauer notes.
Next steps, he said, should include confirming these results in other prospective cohortsand then assembling and pooling the studies relating TUG (and perhaps other simple measurements of physical performance) to fracture risk in older individuals. “Pooling studies will improve our confidence in the clinical utility of the TUG test across different populations and subgroups,” Dr. Bauer writes.
Arch Intern Med 2011;171:1655-1662.