Muscle loss following a single high-dose intramuscular injection of corticosteroids to treat disease flare in patients with rheumatoid arthritis

Abstract

Objective: Adverse changes in body composition, specifically decreased muscle mass (MM) and in-creased fat mass, characterize rheumatoid arthritis (RA). These changes, termed rheumatoid cachexia(RC), are important contributors to the disability and elevated co-morbidity risk of RA. Recently, weobserved substantial muscle loss (~2 kg) in a patient with RA following a single intramuscular (IM) cor-ticosteroid (CS) injection to treat a disease flare. The aim of the current study is to determine whetherthis apparent iatrogenic effect of IM CS is typical, i.e., does this routine, recommended treatmentcontribute to RC?Methods: Body composition was assessed by dual-energy X-ray absorptiometry (DXA) in eight pa-tients with established RA who received a 120 mg IM methylprednisolone injection to treat a diseaseflare. DXA scans estimated appendicular lean mass (ALM; a surrogate measure of MM), total lean mass(LM), and total and regional adiposity at baseline (injection day) and 4 weeks and 6-9 months post-in-jection. Statistical analysis was performed using one-way ANOVA.Results: There was significant loss of ALM (-0.93 kg, p=0.001, 95% CI [-0.49, -1.36]) and a trend towardreduced LM (-1.10 kg, p=0.165, 95% CI [0.58, -2.79]) at 4 weeks relative to baseline. At 6-9 monthsdespite control of inflammation and disease activity, these losses remained.Conclusion: Substantial muscle loss occurred in patients with RA following IM CS injection to treat adisease flare. Thus, this recommended treatment appears to exacerbate RC, thereby potentially in-creasing disability and co-morbidity risk. If this effect is confirmed by larger studies, the role of one-offhigh-dose CS in the treatment of RA should be reviewed.