Diagnostic Tools

The mainstay of primary prevention in osteoporosis is to detect and treat the disease before fractures occur.


Fracture prevention lies in predicting those at high risk for fracture based on assessments of BMD together with consideration of risk factors for fracture. These risk factors include BMI, smoking status, alcohol consumption, corticosteroid exposure, concurrent rheumatological condition, family history of hip fracture, and secondary causes of osteoporosis.1



Table 1. Secondary causes of osteoporosis

Secondary contributing factors
Adverse events of drug therapy
Endocrine disorders
Eating disorders
Immobilization
Marrow-related disorders
Gastrointestinal/biliary-tract disorders
Renal disease
Cancer
Organ transplantation

Dual energy x-ray absorptiometry

Osteoporosis has been defined on the basis of BMD assessment at the lumbar spine and femoral neck by dual energy x-ray absorptiometry (DXA), which is the most widely validated technique for measuring BMD.3,4 The World Health Organization (WHO) criteria classifies BMD as normal, osteopenia (low BMD), or osteoporosis based on T-scores, which refer to the number of standard deviations (SDs) a patient’s BMD lies below either the reference BMD for a young, healthy, gender-matched reference population (T-score) or an age- and gender-matched reference population (Z-score); the latter being a preferable measure for individuals <50 years old.5



Table 2. Definition of normal, osteopenia, osteoporosis and abnormal BMD.3,4,6 

  Population Score at the hip or spine
Normal Postmenopausal women and men aged ≥50 years T score ≥–1.0
Osteopenia Postmenopausal women and men aged ≥50 years T-score –1 to –2.49
Osteoporosis Postmenopausal women and men aged ≥50 years T-score ≤–2.5
Abnormal <50 years old* Z-score ≤–2.0

*Diagnosis should not be made on the basis of BMD testing alone



European AIDS Clinical Society Guidelines recommend that HIV-infected patients with >1 major risk factor for low BMD should undergo DXA scanning. These risk factors include post-menopausal women, men over the age of 50, patients with symptomatic hypogonadism, patients with a history of fragility fracture and those with significant steroid exposure.



Figure 1.* Algorithm for the screening, assessment, management, and monitoring of bone disease in PLWHIV.1

*Abbreviations: FN - femoral neck; LS - lumbar spine; TH - total hip

However, although low BMD based on DXA criteria is prevalent in younger PLWHIV, it is uncertain if these DXA values correspond to an increased risk of fractures, particularly in those under the age of 50. Caution should therefore be used when interpreting results from DXA in the HIV-infected population, particularly in young men.



As well as establishing a diagnosis of low BMD, DXA can also be used to monitor the effect of interventions over time.
 


FRAX®

The FRAX® tool has been developed by the WHO to combine BMD readings with classical risk factors for osteoporosis and fracture in order to provide a more accurate fracture risk. The FRAX algorithms provide a 10-year probability of hip fracture and the 10-year probability of a major osteoporotic fracture (spine, forearm, hip or shoulder). It is country specific and should only be used in patients >40 years old, as the tool utilizes real-life data from population-based cohorts around the world that have a limited age range (>40 years). The European AIDS Clinical Society (EACS) Guidelines state that the risk of fracture should be assessed biannually. FRAX may underestimate the fracture risk in people living with HIV (PLWHIV);7 using HIV as a secondary risk factor may help identify those patients at high risk of osteoporosis even if DXA results are not available.
 


Fall Risk Assessment Tool (FRAT)

As most fractures result from falls, the risk factors for falling can be evaluated using the FRAT, which was developed and validated in the non-HIV infected population. It comprises three sections – falls risk status, risk factor checklist and action plan. 




 

References

  1. Brown TT, Hoy J, Borderi M, et al. Recommendations for evaluation and management of bone disease in HIV. Mayer KH, ed. Clin Infect Dis. 2015 Apr 15; 60(8): 1242–1251.  
  2. Fitzpatrick PA. Secondary causes of osteoporosis. Mayo Clin Proc. 2002 May;77(5):453-468.
  3. McComsey GA, Tebas P, Shane E, et al. Bone disease in HIV infection: a practical review and recommendations for HIV care providers. Clin Infect Dis. 2010;51:937–946. 
  4. The World Health Organization. Assessment of fracture risk and its application to screening for postmenopausal osteoporosis. Report of a WHO Study Group. Geneva, World Health Organization, 1994 (WHO Technical Report Series, No. 843). Accessed 10 April 2011.
  5. Kanis JA, Melton LJ 3rd, Christiansen C, Johnston CC, Khaltaev N. The diagnosis of osteoporosis. J Bone Miner Res. 1994;9:1137–1141.
  6. International Society of Clinical Densitometry. 2013 ISCD Official Positions – Pediatric. Accessed 19 April 2017.
  7. National Osteoporosis Foundation. Clinician’s Guide to Prevention and Treatment of Osteoporosis. Accessed 14 April 2017.