medwireNews: Cumulative prednisone dose and effective disease control are both associated with increased BMI among patients with giant cell arteritis (GCA), post-hoc analysis of the GiACTA trial suggests.
“Weight gain is associated with morbidity and mortality and is a major concern for patients receiving glucocorticoids for treatment of rheumatic disease,” write the study authors in Rheumatology and Therapy.
But they also report that “a modest increase in BMI may actually be an indicator of effective disease control regardless of treatment regimen.”
The analysis included 250 individuals with newly diagnosed (48%) or relapsing (52%) GCA who were at least 50 years old (mean 69 years; 75% women). They were randomly assigned to receive weekly or fortnightly tocilizumab 162 mg in conjunction with a 26-week prednisone taper, or placebo alongside a 26- or 52-week prednisone taper, as part of the GiACTA trial.
In the overall population, mean BMI increased from 25.9 kg/m2 at baseline to 27.1 kg/m2 at 24 weeks and persisted at this level until the end of follow-up at 52 weeks. This translated into a BMI increase of 0–2.0 kg/m2 for almost half (49%) of the patients, a 2.1–5.0 kg/m2 increase for 27%, and a more than 5.0 kg/m2 increase for 3%. The remaining 21% had an overall decrease in BMI.
The study authors note that there was no significant difference in BMI change between patients who received tocilizumab versus placebo in multivariable analyses, whereas the cumulative prednisone dose at 52 weeks was identified as an independent predictor for increased BMI.
Over the 52-week study, patients were exposed to a mean cumulative prednisone dose of 3077 mg, with the greatest exposure (mean 1999 mg) occurring in the first 24 weeks. For patients exposed to a cumulative dose of up to 1000 mg of prednisone, BMI increased by a significant 0.92 kg/m2, and by 1.45 kg/m2 among those exposed to 4000 mg or more.
The researchers highlight, however, that there were factors other than glucocorticoid exposure that contributed to a change in BMI, namely relapsing disease at baseline and disease flares in newly diagnosed patients, both of which were independently associated with a reduced increase in BMI.
“Therefore, effective disease control also contributes to an increase in BMI among GCA patients,” explain John Stone (Massachusetts General Hospital, Boston, USA) and team.
They found that a significantly greater proportion of patients with relapsing versus newly diagnosed disease experienced a 2.1 to 5.0 kg/m2 decrease in BMI, at corresponding rates of 10% versus 2%, and a significantly smaller proportion experienced an increase of 2.1 to 5.0 kg/m2, at 22% versus 32%. Patients with relapsing disease also had a significant 0.42 kg/m2 lower BMI than those with newly diagnosed GCA at baseline.
“The reasons why patients with relapsing disease experienced less weight gain are not entirely clear,” say the study authors, noting that “possible explanations for this include prior [glucocorticoid] exposure or that patients with relapsing disease may have experienced weight gain following their initial disease diagnosis prior to enrollment in the GiACTA trial.”
The occurrence of disease flares over 52 weeks in newly diagnosed patients also significantly predicted a lower BMI increase, whereby each flare was associated with a BMI reduction of 0.18 kg/m2.
“Regardless of the treatment group to which patients were assigned in the trial, systemic inflammation associated with poor disease control (i.e., flares of GCA) seems to counterbalance the weight gain one might expect from [glucocorticoid] exposure,” the researchers comment.
They conclude that “although [glucocorticoid] use and weight gain are linked tightly in the minds of both providers and patients, our study demonstrates that these relationships are complex.”
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