The Effects of Treatment on Body Mass Index in Giant Cell Arteritis: A Post Hoc Analysis of the GiACTA Trial

INTRODUCTION: Giant cell arteritis (GCA) requires treatment with high-dose, long-term glucocorticoids (GCs), and tocilizumab is often used early in the treatment paradigm. Weight gain, which is associated with morbidity and mortality, is a major concern for patients, though the factors that contribute to changes in body mass index (BMI) throughout the treatment of GCA are poorly understood. METHODS: We analyzed GCA patients enrolled in the GiACTA (Tocilizumab in Giant Cell Arteritis) trial. We used univariable and multivariable mixed-effects modeling to examine the association between changes in BMI and cumulative GC dose, disease status at baseline (newly diagnosed versus relapsing), randomization to tocilizumab, and disease flares. RESULTS: A total of 250 patients were included (75% females, mean age 69 years). The mean ± SD BMI change over 52 weeks was 1.18 ± 1.98 kg/m(2). On multivariable analysis, cumulative prednisone dose at 52 weeks was independently associated with BMI increase (β = 0.94 kg/m(2) for 0–1 g exposure; β = 1.40 kg/m(2) for ≥ 4 g exposure; p for trend < 0.001). Relapsing disease at baseline (β = − 0.42 kg/m(2) compared to those with newly diagnosed disease; p = 0.002) and flares over 52 weeks in newly diagnosed patients (β = − 0.18 kg/m(2) per flare; p = 0.03) were independently associated with lower BMI increase. CONCLUSIONS: Cumulative prednisone exposure is associated with increased BMI in GCA patients. In those with newly diagnosed disease, effective disease control regardless of the treatment used also contributes to BMI increase. Modest weight gain may be an indicator of adequate treatment response.