作者：Laurie Barclay MD 齣處：WebMD醫學新聞 　　December 14 體能活力與年長者的腎功能維持有關 - 趣味新聞網

發表日期 2009-12-27T08:10:26+08:00

     作者：Laurie Barclay, MD
齣處：WebMD醫學新聞

December 14, 2009 — 根據發錶於12月14/28日版內科醫學誌(Archives of Internal Medicine)的世代研究結果，體能活力程度高的年長者，其腎功能迅速衰退的風險較低。

西雅圖華盛頓大學的Cassianne Robinson-Cohen醫師等人寫道，習慣性體能活動(physical activity，PA)之生理和代謝功能可以緩解腎功能衰退的風險。我們檢驗的假設是：PA程度高者的腎功能衰退風險較低，研究對象是一個年長世代的縱嚮資料。

該世代包括4,011名參與「Cardiovascular Health Study[CHS]」這項研究、非臥床的65歲以上病患，在7年間完成至少2次腎功能檢測。使用每週消耗的熱量(原始分數為1 – 5分，每週消耗熱量之仟卡數分成五分位)，以及行走步調(原始分類分數為 < 2、2 – 3與 > 3 mph)計算PA分數(範圍從2-8)。使用縱嚮測量血清胱蛋白(Cystatin C)值估計腎絲球過濾速率(Glomerular filtration rate[GFR])，腎功能迅速衰退(rapid decline in kidney function[RDKF])之定義為每年的GFR損失超過3.0 mL/minute/1.73 m2。

有958名病患(23.9%；每100人-年有4.1件)發生RDKF。PA最高組(分數8分)之RDKF估計風險為16%，PA最低組(分數2分)則為30%。多變項校正發現，相較於PA分數最低的兩組(分數2 - 3分)，PA分數最高的兩組(分數7 - 8分)，其RDKF風險降低28% (95%信心區間為降低21% - 41% 風險)。

研究作者寫道，休閑時間體能活動和行走步調消耗熱量較多者，也都與RDKF發生率較低有關。較多體能活動和年長者的RDKF風險較低有關。

研究限製包括屬於觀察型設計、可能有乾擾因素、存活者偏差，以及使用參與者問捲。

研究作者結論錶示，這些發現認為，年長者運動和腎病惡化風險較低之間有因果關係；不過，此一觀察型研究無法提供實際的因果關係。這些發現促使後續研究評估運動是否是預防年紀相關之腎功能衰退的可行方法。

疾病控製與預防中心的Janet E. Fulton博士等人在編輯評論中錶示，這些發現無法一般化到年輕或中年人口。

編輯們寫道，當區隔體能活動處方的組成時，重點在分析時控製其他影響整體運動量的因素(頻率、強度與時間之影響)，因為強度直接與能量消耗有關。

如果時間為定數，密度強之活動消耗的能量約是中度強度活動的2倍。對於許多慢性疾病而言，並未確認適當的體能活動劑量，因此，妥善進行解析體能運動處方之組成與其各自對健康之影響的研究，將有助於提供關於體能活動和健康的證據基礎。

國傢健康研究中心、國傢心髒肺髒與血液研究中心；國傢神經異常與中風研究中心；國傢老化研究中心等支持本研究。研究作者與編輯皆宣告沒有相關財務關係。編輯們的意見並不一定代錶疾病管製與預防中心或國傢心髒肺髒與血液研究中心的官方立場。


Physical Activity Linked to Maintenance of Kidney Function in Older Adults

By Laurie Barclay, MD
Medscape Medical News

December 14, 2009 — Higher levels of physical activity are associated with a lower risk for rapid decline in renal function among older adults, according to the results of a cohort study reported in the December 14/28 issue of the Archives of Internal Medicine.

"Habitual physical activity (PA) has both physiologic and metabolic effects that may moderate the risk of kidney function decline," write Cassianne Robinson-Cohen, MS, from the University of Washington, Seattle, and colleagues. "We tested the hypothesis that higher levels of PA are associated with a lower risk of kidney function decline using longitudinal data from a large cohort of older adults."

The study cohort consisted of 4011 ambulatory participants 65 years or older who were enrolled in the Cardiovascular Health Study (CHS) and who had completed at least 2 measurements of kidney function for 7 years. PA score (ranging from 2 - 8) was calculated by adding kilocalories expended per week (ordinal score of 1 - 5 from quintiles of kilocalories per week) and walking pace (ordinal score for categories of < 2, 2 - 3, and > 3 mph). Glomerular filtration rate (GFR) was estimated using longitudinal measurements of cystatin C levels, with rapid decline in kidney function (RDKF) defined as loss of GFR of more than 3.0 mL/minute/1.73 m2 per year.

RDKF occurred in 958 participants (23.9%; or 4.1 events per 100 person-years). The highest PA group (score of 8) had an estimated risk for RDKF of 16% vs 30% in the lowest PA group (score of 2). Multivariate adjustment revealed that compared with the 2 lowest PA groups (score of 2 - 3), the 2 highest PA groups (scores of 7 - 8) had a 28% lower risk for RDKF (95% confidence interval, 21% - 41% lower risk).

"Greater kilocalories of leisure-time PA and walking pace were also each associated with a lower incidence of RDKF," the study authors write. "Higher levels of PA are associated with a lower risk of RDKF among older adults."

Limitations of this study include observational design, potential for confounding, survivorship bias, and use of participant questionnaires.

"These findings suggest a causal relationship of exercise with a lower risk of kidney disease progression in older people; however, this observational study cannot prove a cause-effect relationship," the study authors conclude. "These findings motivate further studies to evaluate whether exercise represents a viable method for protecting against age-related decline in kidney function."

In an accompanying editorial, Janet E. Fulton, PhD, from the Centers for Disease Control and Prevention in Atlanta, Georgia, and colleagues note that these findings should not be generalized to young or middle-age populations.

"When isolating components of the physical activity prescription, it is important to control for the other components that comprise the total volume of physical activity (the product of frequency, intensity, and time) in the analysis because intensity is directly related to energy expenditure," the editorialists write.

"If time is held constant, an individual expends about twice the energy participating in a vigorous-intensity activity as in a moderate-intensity activity. The optimal physical activity dose for many chronic diseases is not well established, therefore, well-conducted studies that attempt to disentangle components of the physical activity prescription and their independent effects on health will greatly contribute to the evidence base on physical activity and health."

The National Institutes of Health, the National Heart, Lung, and Blood Institute; the National Institute of Neurological Disorders and Stroke; and the National Institutes on Aging supported this study. The study authors and editorialists have disclosed no relevant financial relationships. The opinions of the editorialists do not necessarily represent the official position of the Centers for Disease Control and Prevention or the National Heart, Lung, and Blood Institute.

Arch Intern Med. 2009;169:2116-2123, 2124-2127. 2124-2127.

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