BMIとCOPD急性増悪による入院の予後との関連

BMIとCOPD急性増悪による入院の予後との関連を見た論文を紹介します。

Mitja Lainscak, Stephan von Haehling, Wolfram Doehner, Irena Sarc and Tina Jeric, et al: Body mass index and prognosis in patients hospitalized with acute exacerbation of chronic obstructive pulmonary disease. J Cachexia Sarcopenia Muscle DOI 10.1007/s13539-011-0023-9

下記のHPで全文PDFファイルで見ることができます。

http://www.springerlink.com/content/382j81j72m7416g7/fulltext.pdf

後ろ向き研究ですが、COPD急性増悪による入院の死亡率がもっとも低かった群は、BMI25.09–29.05kg/m2の群でした。図に示すように、やせている患者の予後が最も悪く、BMIが正常範囲（18.5～25）の患者も予後がかなり悪いですが、中等度以上の肥満患者の予後も、BMI25.09–29.05kg/m2の群よりは悪いという結果でした。

COPDではObesity Paradox（肥満の患者ほど生命予後がよい）が指摘されていましたが、今回の研究結果では、中等度以上の肥満より軽度肥満（日本ですとBMI25以上で肥満ですので）のほうがよかったです。

るいそう患者に栄養改善が必要なことは間違いありませんが、BMI25以上であれば栄養改善（体重増加）を勧める必要はないのかもしれません。また、BMIが18.5以上の正常範囲であっても、BMI22～25を目指すべきかもしれません。

Abstract

Background
Nutritional status, weight loss and cachexia have important prognostic implications in patients with chronic obstructive pulmonary disease (COPD). Body mass index (BMI) has been implicated in COPD risk assessment, but information is mostly limited to composite scores or to patients with stable disease. We aimed to analyse the association between BMI and mortality in acute exacerbation of COPD.

Methods
This retrospective survey included 968 patients hospitalized due to acute exacerbation of COPD at the University Clinic Golnik from February 2002 to June 2007. Vital status was ascertained with Central Population Registry, and database was censored on November 1, 2008.

Results
Median BMI was 25.08 kg/m2 (interquartile range, 21.55–29.05 kg/m2) and 210 patients (22%) had BMI < 21 kg/m2. During median follow-up of 3.26 years (1.79–4.76 years), 430 patients (44%) died. Lowest mortality was found for BMI 25.09–29.05 kg/m2. When divided per BMI decile, mortality was lowest for BMI 25.09–26.56 kg/m2 (33%). In univariate analysis, BMI per quartile and BMI per unit increase were predictive for all-cause mortality. In an adjusted model, BMI per 1 kg/m2 unit increase was associated with 5% less chance of death (hazard ratio 0.95, 95% confidence interval 0.93–0.97).

Conclusions
Low BMI < 21 kg/m2 is frequent in patients hospitalized due to acute exacerbation of COPD. Higher BMI was independently predictive of better long-term survival. A better outcome in obese patients compared to normal weight is in contrast to primary prevention data but concurs with observations of an obesity paradox in other cardiovascular diseases.