Osteoporotic fractures can lead to loss of mobility, loss of autonomy, reduced quality of life, medical complications (pneumonia, thromboembolism), and increased mortality!
- Overall 1-year mortality after surgical correction of a hip fracture is about 22%.
- Additionally, there has been found to be a 5-fold increase in women and 8-fold increase in men in relative likelihood of death within the first 3 months after a hip fracture as compared with age- and sex-matched controls.
The goal of osteoporosis screening is to identify individuals at increased risk for fracture who would benefit from intervention to minimize that risk.
Start thinking about increased fracture risk in postmenopausal women, men over 50yo, and any individual who experiences a low-trauma (fragility) fracture.
- Low trauma fracture results from a fall from standing height or less (which should not break normal, healthy bone)
- Advancing age
- Previous fracture
- Long-term glucocorticoid therapy
- Low body weight
- Parental history of hip fracture
- Cigarette smoking
- Excess alcohol intake
- Rheumatoid arthritis
- Disorders strongly associated with osteoporosis (secondary osteoporosis)
FRAX (Fracture Risk Assessment Tool) estimates the 10-year probability of hip fracture and major osteoporotic fractures combined (hip, spine, humerus, or forearm) for an untreated individual.
- FRAX asks us for 12 pieces of information (11 required)
- age, sex, weight, height
- previous fracture
- parent fractured hip
- current smoking
- glucocorticoid use (current or exposed to prednisone 5 mg once daily or more for ≥3 months)
- rheumatoid arthritis
- secondary osteoporosis
- T1DM, OI, untreated hyperthyroidism, hypogonadism, premature menopause (<45yo), chronic malnutrition, malabsorptive disorder, chronic liver disease
- alcohol use (≥3 units/day)
- femoral neck BMD (not required)
Pearls from the 2020 AACE/ACE Guidelines for the Diagnosis and Treatment of Postmenopausal Osteoporosis:
- FRAX underestimates future risk for fractures in general because it only reports risk for hip fracture and major osteoporotic fractures (hip, spine, humerus, and forearm), which comprise half of all fragility fractures
- FRAX underestimates risk in patients with multiple osteoporosis-related fractures, those with lumbar spine BMD significantly lower than femoral neck BMD, and in those with increased risk of falling (fall events are NOT captured in the FRAX score)
- Analysis of 3 recent cohort studies found that people with T2DM had increased fracture risk compared to those without (pathophysiology vs med effect), which FRAX does not account for
- When filling out a FRAX for patient w/ Type 2 DM, enter YES for rheumatoid arthritis in the algorithm for an equivalent surrogate
Traditionally done via DEXA (dual energy x-ray absorptiometry):
- Scores reported as grams of mineral per cm2 of bone area
- T-score represents the number of SDs from the mean values of a young-adult reference population
- Used for diagnostic classification in postmenopausal women and men >50yo
- Z-score represents the number of SDs from a population matched for age, race, ethnicity, and sex
- Used in premenopausal women and men <50yo
Clinical pearl: A regular X-ray can show changes in bone mineral density after bone loss of ~40%, whereas a DEXA scan can detect changes as small as 1%!
Focusing on the 2nd recommendation (postmenopausal women <65yo at increased risk for osteoporosis) leads to 2 approaches:
- Approach #1: Perform BMD testing if 10-year FRAX risk of major osteoporotic fracture exceeds that of a 65yo woman without major risk factors (~8-9% in the US)
- Approach #2 (based on 2020 AACE/ACE Guidelines): Perform BMD testing in presence of specific risk factors, as follows
Screening in Premenopausal Women
Generally, BMD testing is not recommended in premenopausal women in the absence of a known fragility fracture or known cause of secondary osteoporosis:
- osteogenesis imperfecta
- untreated hyperthyroidism
- chronic malnutrition
- malabsorptive disorder
- chronic liver disease
- glucocorticoid use
- rheumatoid arthritis
- significant vitamin D or calcium deficiency
- Cushing’s disease
- *HIV itself and ART therapy increases the risk of osteoporosis. As such, this has its own set of recommendations for when to get DEXA
- Medications: cyclosporine, phenobarbital, phenytoin, GnRH agonists, depot medroxyprogesterone**
- **BMD tends to return to normal with discontinuation of depot medroxyprogesterone. As such, ACOG does not recommend routine DEXA scans for these individuals
Note that the above highlighted topics are not recognized as secondary causes of osteoporosis according to FRAX.
Screening in Men
Recommendations in men are controversial, but it’s suggested that targeted BMD testing be performed in men with clinical manifestations of or risk factors for low bone mass including:
- Radiographic evidence
- History of low-trauma fractures
- Loss of >1.5 inches in height
- Long-term glucocorticoid therapy
- Androgen deprivation therapy (such as for prostate cancer)
- Secondary osteoporosis
There are some groups such as the National Osteoporosis Foundation (NOF), International Society for Clinical Densitometry (ISCD), and the Endocrine Society who do recommend BMD testing based on age alone (for all men ≥70yo) because total hip bone density predicts hip fractures as well or better than in females. However, data from osteoporosis treatment trials are very limited in men, so its not as clear that they will gain as much benefit from treatment.
2020 AACE/ACE Guidelines requires 1 of the following 4:
- Fragility (low-trauma) fracture of the spine or hip
- BMD T-score ≤−2.5 in lumbar spine, femoral neck, or 1/3 radius (WHO criteria)
- T-score between −1.0 and −2.5 (i.e., osteopenia) PLUS fragility fracture of proximal humerus, pelvis, or distal forearm
- T-score between −1.0 and −2.5 (i.e., osteopenia) and high FRAX fracture probability based on country-specific thresholds (in the US: combined osteoporotic fracture risk ≥20% or hip fracture risk ≥3%)
When to repeat screening?
- T-score -2.0 to -2.49 (at any site) or risk factors for ongoing bone loss:
- Every 2 years (as long as risk factors persist)
- T-score -1.5 to -1.99 with no risk factors:
- Every 3-5 years
- T-score -1.01 to -1.49 with no risk factors:
- Every 10-15 years
It’s also acceptable to perform FRAX assessment every five years (or more) and perform a follow-up DEXA earlier if the absolute fracture risk is close to the treatment threshold (≥3% for hip fracture, ≥20% for major osteoporotic fracture).
Of note, the most reliable comparative results are obtained with the same instrument, and ideally the same technologist at a high-quality DEXA facility.
Blog post based on Med-Peds Forum talk by Lindsey Mahoney, PGY3