Roux et al developed a probability equation and risk index for predicting nonvertebral fractures in postmenopausal women with osteoporosis. These can help identify a woman at risk for fracture who may benefit from more aggressive management. The authors are from Universite Paris-Descartes, the University of Cincinnati, Center for Metabolic Bone Diseases (Leuven, Belgium) and Procter & Gamble.
Patient selection: postmenopausal woman with inclusion criteria on pages 931-932.
Parameters:
(1) age in years
(2) height in cm
(3) femoral neck T-score
(4) serum vitamin D in ng/mL (25OH D3; reference range and method not given)
(5) number of previous or current vertebral fractures at time of enrollment ("prevalent")
(6) points for previous or current nonvertebral fracture(s) at enrollment ("prevalent")
There are 2 means of determining risk:
(1) probability equation
(2) risk index
X =
= (0.0371 * (age in years)) + (0.0236 * (height in cm)) - (0.2549 * (femoral neck T score)) - (0.0106 * (serum vitamin 25OH D3)) + (0.1073 * (vertebral fractures)) - (0.2207 * (nonvertebral fracture points)) - 9.1119
where:
• Nonvertebral fracture points is (-1) for previous fracture and (+1) for no previous fracture.
• Nonvertebral fractures evaluated included hip, leg, pelvis, wrist, humerus and clavicle. Fractures were excluded if pathological or due to high-energy trauma.
• Vitamin D therapy was given if the serum level was < 16 ng/mL so the lower limit of the reference range is probably 16 ng/mL (range in Tietz's Clinical Guide to Laboratory Tests is 14 to 60).
probability of a nonvertebral fracture =
= 1 / (1 + EXP((-1) * X))
Risk Index
|
Parameter |
Finding |
Points |
|
age in years |
< 65 years |
0 |
|
|
65 to 69.9 years |
0.2 |
|
|
70 to 74.9 years |
0.4 |
|
|
75 to 79.9 years |
0.6 |
|
|
>= 80 years |
0.8 |
|
height in cm |
>= 167 cm |
0.7 |
|
|
161 to 166.9 cm |
0.5 |
|
|
153 to 160.9 cm |
0.4 |
|
|
147 to 152.9 |
0.2 |
|
|
< 147 |
0 |
|
femoral neck T score |
>= -1.4 |
0 |
|
|
-1.4 to -2.2 |
0.2 |
|
|
-2.19 to -3.0 |
0.4 |
|
|
-3.01 to -3.8 |
0.6 |
|
|
< - 3.8 |
0.8 |
|
serum vitamin D |
< 30 ng/mL |
0.8 |
|
|
30 to 49.9 ng/mL |
0.6 |
|
|
50 to 69.9 ng/mL |
0.4 |
|
|
70 to 89.9 ng/mL |
0.2 |
|
|
>= 90 ng/mL |
0 |
|
vertebral fracture |
0 |
0 |
|
|
1 |
0.1 |
|
|
2 to 6 |
0.4 |
|
|
7 or more |
1.1 |
|
nonvertebral fractures |
no |
0 |
|
|
yes |
0.4 |
where:
• Table 2 shows overlap in the first 4 parameters at the endpoints for interval ranges.
total risk index =
= SUM(points for all 6 parameters)
Interpretation:
• minimum risk index: 0
• maximum risk index: 4.6
• The higher the index the greater the risk for nonvertebral fracture.
|
Index |
Probability of Fracture within 3 years |
|
0 to 1.0 |
2.5% |
|
1.1 to 2.0 |
6% |
|
2.1 to 3.0 |
12% |
|
3.1 to 4.6 |
24.5% |
Specialty: Surgery, orthopedic, Endocrinology, Nutrition
ICD-10: ,
