Large meta-analysis validates utility of BMD in predicting fracture

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Large meta-analysis validates utility of BMD in predicting fracture

Aug 5, 2005 Gandey

Malmo, Sweden - International investigators have confirmed that hip

bone-mineral density (BMD) is an important predictor of fracture risk.

In their meta-analysis of 12 cohort studies of roughly 39 000

participants, the team reports that the scope of their study and the

homogeneity of the data suggest that the findings can be applied

generally, at least in the developed world [1]. " An advantage of this

study is that the meta-analysis is based on individual data from each

cohort and not on published values with summary statistics, " comment

the researchers, led by Dr Olof ell (Malmo University Hospital,

Sweden). " This eliminates publication bias and has the advantage that

important potential interactions between BMD and fracture risk could be

examined. " Their work appears in the July 2005 issue of the Journal of

Bone and Mineral Research.

Dr Olof ell (Source: International Osteoporosis Foundation)

Screening for osteoporosis by measuring BMD, although recommended by

several groups, is still controversial because evidence is so limited.

Both the US National Osteoporosis Foundation and the US Preventive

Services Task Force recommend it, but the US National Institutes of

Health argues that current evidence is insufficient to recommend

population-based screening.

In the present analysis, ell and colleagues wanted to quantify the

relationship between BMD and fracture risk and examine the effect of

age, sex, time since measurement, and initial BMD value. Fourteen of

the study's authors report no conflicts of interest, but three work as

consultants for a variety of companies, including Aventis, Eli Lilly,

Merck, and Amgen, among others.

The research team looked at 9891 men and 29 082 women from 12 cohort

studies. They report that cohorts were followed for up to 16.3 years

and a total of over 168 000 person-years. They examined the effect of

BMD on fracture risk using a Poisson model in each cohort and each sex

separately. They then merged the results of the different studies using

weighted coefficients.

Characteristics of cohort studies included in the meta-analysis

ell and colleagues found that BMD measurement at the femoral neck

with dual-energy X-ray absorptiometry was a strong predictor of hip

fractures in both men and women, with a similar predictive ability.

They observed that at 65 years of age, risk ratio increased by 2.94

(95% CI 2.02-4.27) in men and by 2.88 (95% CI 2.31-3.59) in women for

each standard-deviation decrease in BMD. However, they found that the

effect depended on age, with a significantly higher gradient of risk at

age 50 than at age 80. Although the gradient of hip-fracture risk

decreased with age, the absolute risk still rose markedly. For any

fracture and for any osteoporotic fracture, they found that the

gradient of risk was lower than for hip fractures.

At the age of 65 years, the group found that the risk of osteoporotic

fractures increased in men by 1.41 per standard-deviation decrease in

BMD (95% CI 1.33-1.51) and in women by 1.38 (95% CI 1.28-1.48). In

contrast with hip-fracture risk, the gradient of risk increased with

age. For the prediction of any osteoporotic fracture, there was a

higher gradient of risk the lower the BMD. At a z score of -4 standard

deviation, the risk gradient was 2.10 per standard deviation (95% CI

1.63-2.71), and at a z score of -1 standard deviation, the risk was

1.73 per standard deviation (95% CI 1.59-1.89), in men and women

combined.

" We conclude that BMD is a risk factor for fracture of substantial

importance and is similar in both sexes, " write the researchers. " Its

validation on an international basis permits its use in case-finding

strategies. Its use should, however, take account of the variations in

predictive value with age and BMD. "

Source

1. ell O, Kanis JA, Oden A, et al. Predictive value of BMD for

hip and other fractures. J Bone Miner Res 2005; 20:1185-1194.