Glucocorticoids (GCs) are among the most widely prescribed medications in dermatologic practice. Although GCs are highly effective anti-inflammatory agents, long-term systemic therapy can result in dangerous adverse effects, including GC-induced osteoporosis (GIO), a bone disease associated with a heightened risk for fragility fractures.1,2 In the United States, an estimated 10.2 million adults have osteoporosis—defined as a T-score lower than −2.5 measured via a bone densitometry scan—and 43.4 million adults have low bone mineral density (BMD).3,4 The prevalence of osteoporosis is increasing, and the diagnosis is more common in females and adults 55 years and older.2 More than 2 million individuals have osteoporosis-related fractures annually, and the mortality risk is increased at 5 and 10 years following low-energy osteoporosis-related fractures.3-5
Glucocorticoid therapy is the leading iatrogenic cause of secondary osteoporosis. As many as 30% of all patients treated with systemic GCs for more than 6 months develop GIO.1,6,7 Glucocorticoid-induced BMD loss occurs at a rate of 6% to 12% of total BMD during the first year, slowing to approximately 3% per year during subsequent therapy.1 The risk for insufficiency fractures increases by as much as 75% from baseline in adults with rheumatic, pulmonary, and skin disorders within the first 3 months of therapy and peaks at approximately 12 months.1,2
Despite the risks, many long-term GC users never receive therapy to prevent bone loss; others are only started on therapy once they have sustained an insufficiency fracture. A 5-year international observational study including more than 40,000 postmenopausal women found that only 51% of patients who were on continuous GC therapy were undergoing BMD testing and appropriate medical management.8 This review highlights the existing evidence on the risks of osteoporosis and osteoporotic (OP) fractures in the setting of topical, intralesional, intramuscular, and systemic GC treatment, as well as recommendations for nutritional supplementation to reduce these risks.
Pathophysiology
The pathophysiology of GIO is multifactorial and occurs in both early and late phases.9,10 The early phase is characterized by rapid BMD reduction due to excessive bone resorption. The late phase is characterized by slower and more progressive BMD reduction due to impaired bone formation.9 At the osteocyte level, GCs decrease cell viability and induce apoptosis.11 At the osteoblast level, GCs impair cell replication and differentiation and have proapoptotic effects, resulting in decreased cell numbers and subsequent bone formation.10 At the osteoclast level, GCs increase expression of pro-osteoclastic cytokines and decrease mature osteoclast apoptosis, resulting in an expanded osteoclastic life span and prolonged bone resorption.12,13 Indirectly, GCs alter calcium metabolism by decreasing gastrointestinal calcium absorption and impairing renal absorption.14,15
GCs and Osteoporosis
Oral GCs—Glucocorticoid-induced osteoporosis and fracture risk are dose and duration dependent.6 A study of 244,235 patients taking GCs and 244,235 controls found the relative risk of vertebral fracture was 1.55 (range, 1.20–2.01) for daily prednisone use at less than 2.5 mg, 2.59 (range, 2.16–3.10) for daily prednisone use from 2.5 to 7.4 mg, and 5.18 (range, 4.25–6.31) for daily doses of 7.5 mg or higher; the relative risk for hip fractures was 0.99 (range, 0.82–1.20), 1.77 (range, 1.55–2.02), and 2.27 (range, 1.94–2.66), respectively.16 Another large retrospective cohort study found that continuous treatment with prednisone 10 mg/d for more than 90 days compared to no GC exposure increased the risk for hip fractures 7-fold and 17-fold for vertebral fractures.17 Although the minimum cumulative dose of GCs known to cause osteoporosis is not clearly established, the American College of Rheumatology has proposed an algorithm as a basic approach to anticipate, prevent, and treat GIO (Figure).18,19 Fracture risk should be assessed in all patients who are prescribed prednisone 2.5 mg/d for 3 months or longer or an anticipated cumulative dose of more than 1 g per year. Patients 40 years and older with anticipated GC use of 3 months or longer should have both a bone densitometry scan and a Fracture Risk Assessment (FRAX) score. The FRAX tool estimates the 10-year probability of fracture in patients aged 40 to 80 years, and those patients can be further risk stratified as low (FRAX <10%), moderate (FRAX 10%–19%), or high (FRAX ≥20%) risk. In patients with moderate to high risk of fracture (FRAX >10%), initiation of pharmacologic treatment or referral to a metabolic bone specialist should be considered.18,19 First-line therapy is an oral bisphosphonate, and second-line therapies include intravenous bisphosphonates, teriparatide, denosumab, or raloxifene for patients at high risk for GIO.19 Adults younger than 40 years with a history of OP fracture or considerable risk factors for OP fractures should have a bone densitometry scan, and, if results are abnormal, the patient should be referred to a metabolic bone specialist. Those with low fracture risk based on bone densitometry and FRAX and those with no risk factors should be assessed annually for bone health (additional risk factors, GC dose and duration, bone densitometry/FRAX if indicated).18 In addition to GC dose and duration, additional risk factors for GIO, which are factored into the FRAX tool, include advanced age, low body mass index, history of bone fracture, smoking, excessive alcohol use (≥3 drinks/d), history of falls, low BMD, family history of bone fracture, and hypovitaminosis D.6
Therapeutic algorithm for adults treated with glucocorticoids (GCs). BMD indicates bone mineral density; FRAX, Fracture Risk Assessment score; IV, intravenous; OP, osteoporotic; PMP, postmenopausal. Reproduced with permission from Buckley et al.19
Topical GCs—Although there is strong evidence and clear guidelines regarding oral GIO, there is a dearth of data surrounding OP risk due to treatment with topical GCs. A recent retrospective nationwide Danish study evaluating the risk of osteoporosis and major OP fracture in 723,251 adults treated with potent or very potent topical steroids sought to evaluate these risks.20 Patients were included if they had filled prescriptions of at least 500 g of topical mometasone or an equivalent alternative. The investigators reported a 3% increase in relative risk of osteoporosis and major OP fracture with doubling of the cumulative topical GC dose (hazard ratio [HR], 1.03 [95% CI, 1.02-1.04] for both). The overall population-attributable risk was 4.3% (95% CI, 2.7%-5.8%) for osteoporosis and 2.7% (95% CI, 1.7%-3.8%) for major OP fracture. Notably, at least 10,000 g of mometasone was required for 1 additional patient to have a major OP fracture.20 In a commentary based on this study, Jackson21 noted that the number of patient-years of topical GC use needed for 1 fracture was 4-fold higher than that for high-dose oral GCs (40 mg/d prednisolone for ≥30 days). Another study assessed the effects of topical GCs on BMD in adults with moderate to severe atopic dermatitis over a 2-year period.22 No significant difference in BMD assessed via bone densitometry of either the lumbar spine or total hip at baseline or at 2-year follow-up was reported for either group treated with corticosteroids (<75 g per month or ≥75 g per month). Of note, the authors did not account for steroid potency, which ranged from class 1 through class 4.22 Although limited data exist, these studies suggest topical GCs used at conventional doses with appropriate breaks in therapy will not substantially increase risk for GIO or OP fracture; however, in the small subset of patients requiring chronic use of superpotent topical corticosteroids with other OP risk factors, transitioning to non–GC-based therapy or initiating bone health therapy may be advised to improve patient outcomes. Risk assessment, as in cases of chronic topical GC use, may be beneficial.
Intralesional GCs—Intralesional GCs are indicated for numerous inflammatory conditions including alopecia areata, discoid lupus erythematosus, keloids, and granuloma annulare. It generally is accepted that doses of triamcinolone acetonide should not exceed 20 mg per session spaced at least 3 weeks apart or up to 40 mg per month.18 One study demonstrated that doses of triamcinolone diacetate of 25 mg or less were unlikely to produce systemic effects and were determined to be a safe dose for intralesional injections.23 A retrospective cross-sectional case series including 18 patients with alopecia areata reported decreased BMD in 9 patients receiving intralesional triamcinolone acetonide 10 mg/mL at 4- to 8-week intervals for at least 20 months, with cumulative doses greater than 500 mg. This was particularly notable in postmenopausal women and men older than 50 years; participants with a body mass index less than 18.5 kg/m2, history of a stress fracture, family history of osteopenia or osteoporosis, and history of smoking; and those who did not regularly engage in weight-bearing exercises.24 Patients receiving long-term (ie, >1 year) intralesional steroids should be evaluated for osteoporosis risk and preventative strategies should be considered (ie, regular weight-bearing exercises, calcium and vitamin D supplementation, bisphosphate therapy). As with topical GCs, there are no clear guidelines for risk assessment or treatment recommendations for GIO.