What this calculator does
Osteoporosis risk score (OST index) works out a quick screening score from age and weight, flagging who might need bone density testing. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaOST = (weight(kg) − age) / 5
The inputs explained
| Field | What to enter |
|---|---|
| Weight (kg) | A number, measured in kg. Starts at 65. |
| Age (years) | A number, measured in years. Starts at 60. |
| Sex | Choose from Female, Male. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with weight
Every other input is held at the calculator’s starting values while weight varies. Select any row to load that scenario into the calculator.
How the answer changes with weight
| Weight (kg) | OST index | Risk band | Source |
|---|---|---|---|
| 32.5 | -5.5 | High risk | Osteoporosis Self-Assessment Tool (OST), Skedros et al., J Bone Joint Surg 2007. |
| 48.75 | -2.3 | Moderate risk | Osteoporosis Self-Assessment Tool (OST), Skedros et al., J Bone Joint Surg 2007. |
| 65 | 1.0 | Moderate risk | Osteoporosis Self-Assessment Tool (OST), Skedros et al., J Bone Joint Surg 2007. |
| 97.5 | 7.5 | Low risk | Osteoporosis Self-Assessment Tool (OST), Skedros et al., J Bone Joint Surg 2007. |
| 130 | 14.0 | Low risk | Osteoporosis Self-Assessment Tool (OST), Skedros et al., J Bone Joint Surg 2007. |
| 195 | 27.0 | Low risk | Osteoporosis Self-Assessment Tool (OST), Skedros et al., J Bone Joint Surg 2007. |