老人ホームでの骨格筋異常と生存率

老人ホームでの骨格筋異常と生存率の関連に関する論文を紹介します。

S. Kimyagarov, R. Klid, Y. Fleissig, B. Kopel, M. Arad and A. Adunsky: Skeletal muscle mass abnormalities are associated with survival rates of institutionalized elderly nursing home residents. The Journal of Nutrition, Health & Aging DOI: 10.1007/s12603-012-0005-4

抄録しか読んでいないので分類方法は不明ですが、骨格筋異常をsarcopenia、 muscle wasting/atrophy、cachexiaの3種類に分類しています。

結果ですが、骨格筋異常は入所者109人中73人（67％）に認めました。男性97.8％、女性43.8％と男女差がありました。骨格筋異常の内訳はmuscle wasting/atrophyが51.4％、サルコペニアが40.3％、悪液質が9.7％でした。

骨格筋異常のうち、中等度の筋肉量低下を認めたのは34.7％で、重度の筋肉量低下を認めたのが65.3％でした。

1年後の生存率は骨格筋異常がない群で73％、サルコペニア群で60％、muscle wastingと悪液質群で53％と、骨格筋異常の有無で有意差を認めました。骨格筋異常の種類の違いによる生存率の有意差は認めませんでした。

老人ホーム入所者の3分の2に骨格筋異常を認めるという結果はうなずけます。日本で同じ研究をやったらもっと多いと思います。分類方法がわかりませんが、筋肉量低下を原因で分類することはとても重要だと考えます。誰か日本でやりませんか（笑）。

Abstract
Background
Knowledge about the changes in skeletal muscle mass in nursing home residents is very limited. We hypothesized that such patients have different types of skeletal muscle mass abnormalities that may affect mortality rates. Therefore, the objective of this study was to evaluate the prevalence and extent of skeletal muscle mass decline, its different clinical phenotypes (sarcopenia, wasting/atrophy and cachexia) and the mortality rates associated with these abnormalities.

Methods
A retrospective chart-review study comprising 109 institutionalized nursing home residents. Body mass index, body fat mass, fat free mass, skeletal muscle mass and survival rates were assessed.

Results
Skeletal muscle mass abnormalities were found among 73 out of 109 (67.0%) patients and were more prevalent in males compared with females (97.8% and 43.8%, respectively, p<0.001). Most of these patients had muscle wasting/atrophy (51.4%) or sarcopenia (40.3%), and 9.7% suffered from cachexia. One third of the patients with abnormal skeletal muscle mass showed a moderate decline of skeletal muscle mass (34.7%) while the remainder (65.3%) had very low levels of skeletal muscle mass. Each group was characterized by typical medical conditions associated with skeletal muscle mass abnormality. A Kaplan-Meier survival plot of mortality showed only lower one-year survival rates in the group with sarcopenia (60%) and muscle atrophy or cachexia (53%), compared with elderly participants with a normal skeletal muscle mass (73%), (p<0.0001). There were no significant differences in 1-year mortality rates between patients with abnormal skeletal muscle mass (whether sarcopenia, cachexia or wasting).

Conclusion
About two thirds of nursing home patients show skeletal muscle mass abnormalities, most within the range of very low skeletal muscle mass rather than moderately low skeletal muscle mass, that are associated with shorter survival rates, compared with normal skeletal muscle mass patients.