ALS診断時の栄養状態は生存期間の予測因子

ALS：筋萎縮性側策硬化症診断時の栄養状態は生存期間の予測因子となるという論文を紹介します。

Marin B, et al: Alteration of nutritional status at diagnosis is a prognostic factor for survival of amyotrophic lateral sclerosis patients. J Neurol Neurosurg Psychiatry. 2011 Jun;82(6):628-34.

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http://jnnp.bmj.com/content/82/6/628.full.pdf

ALS診断時に5%以上の体重減少や1以上のBMI低下を認める場合には、生命予後が有意に短いという結果です。それ以上の体重減少やBMI低下では、さらに予後が悪くなります。経過中の低栄養を認める場合も、生命予後が短くなります。

低栄養の場合に予後が悪いことは多くの疾患で明らかになっていますが、ALSでも同様でした。今後は栄養介入で生命予後が改善するかどうかの介入研究が望まれます。ただ、ALS患者でのランダム化比較試験は、倫理面も考慮すると容易ではないと思います。

Abstract
Objectives The aims were to analyse changes in nutritional parameters from diagnosis of amyotrophic lateral sclerosis (ALS) to death and to assess their relationships with survival at the time of diagnosis and during follow-up.

Methods 92 ALS patients were included and clinically assessed every 3months (ALS functional rating scale, manual muscular testing, forced vital capacity, weight, BMI, percentage weight loss). Bioimpedance was performed to evaluate body composition (fat-free mass, fat mass and hydration status) and phase angle. Survival analyses were performed from diagnosis to death or censoring date using a Cox model.

Results The evolution of nutritional parameters in ALS patients was marked by significant decreases in weight, BMI, fat-free mass and phase angle, and increased fat mass. The authors identified an adjusted 30% increased risk of death for a 5% decrease from usual weight at time of diagnosis (RR 1.30; 95% CI 1.08 to 1.56). During follow-up, the authors identified adjusted 34% (95% CI 18% to 51%) and 24% (95% CI 13% to 36%) increased risks of death associated with each 5% decrease in usual weight and each unit decrease in usual BMI, respectively (p<0.0001). Malnutrition during the course was related to a shorter survival (p=0.01), and fat mass level was associated with a better outcome (RR 0.90 for each 2.5kg fat mass increment).

Conclusions Nutritional parameters of ALS patients worsened during evolution of the disease, and worse nutritional status (at time of diagnosis or during the course) was associated with a higher mortality. This study offers some justification for studying the use of therapeutic nutritional intervention to modify the survival of ALS patients.