早期RAの体重増加：ステロイド副作用か疾患改善か

早期関節リウマチでの体重増加の原因はステロイド副作用か疾患活動性の改善かという論文を紹介します。

Maud S. Jurgens, et al: Increase of body mass index in a tight controlled methotrexate-based strategy with prednisone in early rheumatoid arthritis (CAMERA-II): Side–effect of the prednisone or better control of disease activity? Arthritis Care & Research, DOI: 10.1002/acr.21797

メトトレキセート＋ステロイド群とメトトレキセート＋プラセボ群で比較すると、前者のほうが有意に体重増加が多いという研究結果が出ています（2.9kg対1.3kg）。その体重増加の原因を調査した二次的研究です。関節リウマチの疾患活動性としてDAS28で評価しています。

結果ですが、ステロイド使用とBMI変化には独立した関連を認めませんでしたが、低い疾患活動性は6か月後のBMI増加と関連していました。特に閉経後女性でDAS28とBMIに強い関連を認めました。これより、早期関節リウマチでの体重増加の原因は、疾患活動性の改善だろうという結論です。

関節リウマチのコントロールがよくなると、食欲が増加して体重が増加傾向になります。特に生物学的製剤でこのことは報告されていましたが、他の薬物治療でも同様のようです。体重増加が脂肪でなく筋肉量の増加でもたらされていればよいのですが、それは今後の研究課題ですね。

Abstract

Objective.

To clarify whether increase of body weight in patients with early rheumatoid arthritis upon administration of prednisone is a side-effect of prednisone or a result of better control of disease activity, we examined the association of prednisone and disease activity with a subsequent change in body mass index (BMI).

Methods.

In the Computer Assisted Management in Early Rheumatoid Arthritis trial-II (CAMERA-II), patients aged ≥ 18 years with early rheumatoid arthritis (RA, disease duration < 1 year, no prior use of DMARDs) had been randomized to a methotrexate (MTX)-based tight control strategy with either 10 mg Prednisone (MTX+pred) or placebo (MTX+plac). The MTX+pred group had lower disease activity, but gained more weight than the MTX+plac group: 2.9±4.2 kg versus 1.3±5.3 kg (P=0.03). Data from patients with monthly measurements of disease activity (DAS28) and BMI were analyzed with longitudinal regression (mixed model) analysis with BMI as dependent variable and treatment strategy and DAS28 as independent variables, correcting for baseline BMI and possible confounders (gender, age, rheumatoid factor status).

Results.

There was no independent association of glucocorticoid therapy with a change in BMI, but a lower DAS28 was associated with an increased BMI 6 months later. The association of the DAS28 with BMI was most strongly present in postmenopausal women. Clinical cut-off points showed a clear association between DAS28 level and the change in BMI 6 months later.

Conclusion.

Weight gain during treatment with prednisone seems attributable to a reduction of disease activity and is probably, at least partly, regained weight.