Revised QFracture tool shows enhanced risk-prediction

May 30 2012

By Joanna Lyford

Researchers have developed a new algorithm that may improve upon existing methods for identifying patients at high risk for fracture in primary care.

The updated "QFracture" tool, which was first introduced in 2009, predicts the risk for both osteoporotic and hip fracture and has been modified to account for ethnicity, old age, care home residence, fracture history, and a raft of additional comorbidities.

"Validation statistics suggest that the updated algorithm is probably more effective than previous algorithms at identifying patients at high risk of fracture in primary care in the UK," say Julia Hippisley-Cox (University of Nottingham, UK) and colleagues writing in the British Medical Journal.

The original QFracture algorithm uses 17 variables that are readily available without recourse to laboratory tests or clinical measurements, and has been validated in a large primary-care database. Two versions are available: one to predict hip fracture and one to predict osteoporotic fracture.

Since the algorithm was developed, however, the UK health regulator has recommended various modifications to improve the tool's clinical applicability, which Hippisley-Cox's team implemented using data from a derivation cohort of more than 3 million UK primary-care patients.

The revised algorithms feature four major changes: the inclusion of proximal humerus fracture in the definition of osteoporotic fracture; an extended age range, allowing the tool to be used in the over-85s; 13 additional risk factors, which are easily obtainable from the patient's medical record; and a simplified variable relating to hormone replacement therapy.

Having derived the new algorithms, the researchers validated them in a separate cohort of over 1.5 million UK primary care patients. Both versions outperformed the original tool, with values for the area under the receiver operator characteristics curve of 0.89 and 0.88 for hip fracture in men and women, respectively, and 0.79 and 0.71 for osteoporotic fracture in men and women, respectively.

The authors believe this is the first time a fracture risk tool has been able to account for ethnic differences, which they say will be important given the projected rise in ethnic minority groups in the UK.

"Such tools for fracture risk prediction need to take account of this diversity and current evidence of disparities in screening for and treating osteoporosis between ethnic groups," they write.

The algorithms can be used to predict both 10- and 5-year risk; the latter may be particularly useful in very elderly patients whose mean life expectancy is less than 10 years, the authors add.

An online version of the QFracture tool is available at http://www.qfracture.org/.

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