Note: The WHO calculator uses T-scores from young WOMEN. Most of the DEXA printouts from men or other races use T-scores based on MEN or other races.
Use this converter to figure out the female-based T-score from a male-based T-score.
The equation, based on the NHANES data, is: [((T x .137) + .934)) - .858]/.120. You can read more details about T and Z scores.
The WHO calculator became available in February 2008. The results are a little different from my calculator. Notice that the Swedish risks are higher than those in the US. The risks for people without any clinical risk factors are now lower than previously; this is because some of the risk factors are so common that they increased the average risk. There is a definite relationship between age and risk due to hip fracture in a parent; this has not been previously published. Combinations of more than 3 factors don't increase the risk as much is the WHO computer model as they do in the less complex calculator below.
I'll leave this calculator here for a little while during the transition.
The latest version corrects a small error when there were multiple risk factors.
The calculator has included the risk factors from several meta-analyses by the WHO (Kanis, 2005) which apply to both men and women. A recent paper from these investigators (Kanis, 2007) has validated these clinical fractures with several very large cohorts. When there are several risk factors, they may interact with each other, so simply multiplying the base rate time the relative risks will only be an estimation. Furthermore, the base rates are taken from the paper by Johnell, which are from Sweden. This is not exactly the same as a population without any risks. In order to take all these complications into account, a computer program with values from almost 50,000 people around the world is being developed by the WHO. When this is finished, my fracture risk calculator will become obsolete!
Alcohol: A "standard drink" in the USA is 14 grams of ethanol. The following drinks contain this amount: one can (12oz) beer, one small glass (5oz) wine, 1 jigger (1.5oz) spirits. The alcohol content varies among brands so these are approximate. In the UK, alcohol is expressed by "units" and each unit is 8 grams, so that a "drink" is about 2 units.
Weight: The Black index used weight less than 125 pounds, which applies to women. The WHO used Body Mass Index, which also depends on height, and this risk should be clicked if BMI is less than 21. Details about clinical risk factors are in the page about clinical risk factors.
The calculator now includes the absolute fracture risk as recommended by the Canadian Association of Radiologists guidelines (Siminoski K).
These have been modified slightly because I did not include bone density of the radius nor of the spine in men.
For women whose spine bone density is lower than the hip, the vertebral fracture risk is more closely predicted by the spine measurement (Fink, ASBMR 2005 abstract), so it is now possible to enter both hip and spine measurement for women. There are more details in the new page about discordance.
With all these new changes, I hope I have not made any errors. I can't guarantee that this is bug-free, so let me know if you find a problem. I would like to acknowledge Dr. Dean Kramer who has essentially been a beta tester and discovered several errors in the calculations. Send me an email message.
The T and Z scores and standardized bone density values are based on the NHANES data published by Looker. The SOF (Study of Osteoporotic Fractures) data was from several papers including Cummings, 2002 and
Black.
The intervention thresholds for cost-effectiveness were taken from
Kanis. The meta-analysis by
Johnell was used to predict the 10-year hip fracture risks. There are many details in the page about fracture risks.
These sources all used slightly different age ranges or bone density ranges, so the values have been extrapolated. For persons of African ancestry, the fracture risk calculations assumed that the relative risks for the bone density and fractures were the same as for Caucasian persons, more data about this are needed.
The risk factors may interact with each other and they may be more important at different ages. As more work is done, this calculator will need to be updated to take these interactions into account. Also, the cost-effectiveness will be changing as new drugs are available, as costs change, and as complications are defined.
The latest version corrects a small error when there were multiple risk factors.
The calculator has included the risk factors from several meta-analyses by the WHO (Kanis, 2005) which apply to both men and women. A recent paper from these investigators (Kanis, 2007) has validated these clinical fractures with several very large cohorts. When there are several risk factors, they may interact with each other, so simply multiplying the base rate time the relative risks will only be an estimation. Furthermore, the base rates are taken from the paper by Johnell, which are from Sweden. This is not exactly the same as a population without any risks. In order to take all these complications into account, a computer program with values from almost 50,000 people around the world is being developed by the WHO. When this is finished, my fracture risk calculator will become obsolete!
