Rationale and evidence
Rationale
There's still uncertainty over the most appropriate intervals for repeating Dual-energy X-ray Absorptiometry (DEXA) scans for monitoring bone density. Because changes in bone density over short intervals are often smaller than the measurement error of most DEXA scanners, frequent testing of less than 2 years is unnecessary in most patients.
The baseline T score (which indicates osteoporosis development) is the most important determinant of a BMD testing interval. For instance, one study estimated that among older postmenopausal women with T scores above -1.50, less than 10% will develop osteoporosis over a 15-year period, while among those with T scores between -1.50 and -1.99, less than 10% will develop osteoporosis over a 5-year period. The equivalent periods are slightly longer for older men.
Based on this and other recent evidence on cumulative incidence of osteoporosis over time, we recommend against DEXA scan monitoring more frequently than every 5 years in patients with T scores above -2.00, who are in good health and have no additional risk factors for accelerated bone loss. Risk factors for accelerated bone loss include (but are not limited to) hyperparathyroidism, aromatase inhibitor therapy, androgen deprivation therapy, steroid therapy and Vitamin D deficiency.
Evidence
Gourlay ML, Fine JP, Preisser JS, et al. Study of Osteoporotic Fractures Research Group. Bone-density testing interval and transition to osteoporosis in older women. N Engl J Med. 2012; 366:225–33.
Gourlay ML, Overman RA, Fine JP, et al. Time to osteoporosis and major fracture in older men: The MrOS study. Am J Prev Med. 2016 Jun;50 (6): 727-736.
US Preventive Services Task Force. 'Screening for osteoporosis: U.S. preventive services task force recommendation statement'. Ann Intern Med 2011; 154:356–364.
White VG, Franks P, Robbins JA, Fenton JJ. Incidence and predictors of repeat bone mineral densitometry: A longitudinal cohort study. J Gen Intern Med. 2017 Oct;32 (10): 1090-1096.