慢性疼痛與老年病患跌倒風險有關
作者：Laurie Barclay, MD
出處：WebMD醫學新聞
November 24, 2009 — 根據一項發表在11月25日美國醫學會期刊、以群眾為基礎的綜向研究結果，多處區域嚴重的慢性疼痛可能預測老年病患的跌倒風險。
麻州波士頓貝斯以色列女執事醫療中心與波士頓麻州大學的Suzanne G. Leveille博士及其同事們寫到，慢性疼痛是造成老年病患失能的主要原因，然而，慢性疼痛的潛在角色是否為跌倒的危險因子，目前仍然不清楚。跌倒是美國老年病患的十大死因之一，每年的健康照護支出超過190億。即使有越來越多的研究證據支持許多危險因子與跌倒之間的關係，但將這些發現轉換化為有效預防跌倒的措施仍然非常有限。
這項研究的目標在於檢驗慢性肌肉骨骼疼痛是否與跌倒盛行率較高有關，749位居住在社區的70歲以上老年病患，他們都收納到「the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly（MOBILIZE）」波士頓研究中。
受試者在2005年9月到2008年1月之間收納到研究中，他們在18個月的研究期間，在月曆上記錄跌倒次數，並且以明信片寄到研究中心；此外，透過問卷方式評估疼痛情況。
在後續追蹤中，總共報告1,029件跌倒事件，405位受試者（55%）在後續追蹤中至少跌倒一次。在試驗前報告至少兩個部位有肌肉骨骼疼痛，可預測較高的跌倒發生率，300位（40%）有兩個部位以上關節疼痛的受試者，以年齡校正每位病患每年跌倒率為1.18（95%信賴區間[CI]為1.13-1.23），181位（24%）有單一部位疼痛的受試者為0.90（95% CI為0.87-0.92），而267位沒有關節疼痛的受試者則為0.78（95%CI為0.74-0.81）。
試驗前更嚴重或令人失能的疼痛，也與跌倒率較高有關（P<0.05），即使在校正多重影響因子與其他跌倒危險因子，結果仍然不變。至少有兩個疼痛部位跌倒的風險最高（校正危險比值[RR]為1.53；95% CI為1.17-1.99），相較於沒有疼痛或疼痛分數處於最低三分位數的受試者，以及干擾日常生活的疼痛（校正RR為1.53；95% CI為1.15-2.05），疼痛嚴重度三分位數最高，同樣也是高風險（校正RR為1.53；95% CI為1.12-2.08）。
研究作者們寫到，根據部位數目、嚴重度或干擾日常生活之疼痛，慢性疼痛評量與老年病患的跌倒風險增加有關。慢性疼痛可能是一種導因，在某些情況下，干擾需要避免跌倒的認知功能；成功地避免或是中斷跌倒，需要認知調控的生理行為。
這項研究的方法包括觀察性設計，且無法排除試驗前疼痛是過去跌倒後果的可能性，以及疼痛相關的病理狀況是跌倒的潛在原因。
研究作者們的結論是，這些研究發現提供代表老年病患隱痛及疼痛等常見抱怨與過去所想更大的風險有關。這項研究工作的顯著性，在於找出慢性疼痛是老年病患跌倒一個被輕忽且潛在的重要危險因子。仍需要一項隨機分派研究，來確定改善疼痛控制是否可以降低慢性疼痛老年病患的跌倒風險。
國家老化機構（NIA）研究護理照護機構計畫贊助這項研究，NIA機構內研究計畫贊助其中一位試驗作者。MOBILIZE波士頓研究的藥物編碼資料由Pfizer藥廠未受限的經費贊助。其中一位試驗作者（Kiel博士）表示與Pfizer、Amgen、Merck、Novartis、Hologic、GlaxoSmithKline、Lilly、Procter與Gamble、Philips Lifeline與Wyeth藥廠有不同程度的資金往來。
Chronic Pain Linked to Risk for Falls in Older Adults
By Laurie Barclay, MD
Medscape Medical News
November 24, 2009 — Severe, chronic pain in multiple areas may predict risk for falls in older adults, according to the results of a population-based longitudinal study reported in the November 25 issue of the Journal of the American Medical Association.
"Chronic pain is a major contributor to disability in older adults; however, the potential role of chronic pain as a risk factor for falls is poorly understood," write Suzanne G. Leveille, PhD, RN, from Beth Israel Deaconess Medical Center in Boston, Massachusetts, and the University of Massachusetts-Boston, and colleagues. "Falls rank among the 10 leading causes of death in older adults in the United States, resulting in more than $19 billion in health care costs annually. Despite a growing body of scientific evidence supporting associations between a number of risk factors and falls, efforts to translate these findings into effective fall prevention strategies have been limited."
The goal of this study was to examine whether chronic musculoskeletal pain is associated with greater prevalence of falls in a cohort of 749 community-dwelling adults 70 years and older enrolled in the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly (MOBILIZE) Boston Study.
From September 2005 through January 2008, participants were enrolled, and they subsequently recorded falls on monthly calendar postcards mailed to the study center during an 18-month period. Pain was evaluated via questionnaires.
During follow-up, 1029 falls were reported, and 405 participants (55%) fell at least once during the follow-up. Reporting at least 2 locations of musculoskeletal pain at baseline predicted higher incidence of falls, with age-adjusted rates of falls per person-year being 1.18 (95% confidence interval [CI], 1.13 - 1.23) for the 300 participants (40%) with 2 or more sites of joint pain, 0.90 (95% CI, 0.87 - 0.92) for the 181 participants (24%) with single-site pain, and 0.78 (95% CI, 0.74 - 0.81) for the 267 participants with no joint pain.
More severe or disabling pain at baseline was also associated with higher fall rates (P < .05), even after adjustment for multiple confounders and fall risk factors. Persons with at least 2 pain sites had the greatest risk for falls (adjusted rate ratio [RR], 1.53; 95% CI, 1.17 - 1.99), as did those in the highest tertiles of pain severity (adjusted RR, 1.53; 95% CI, 1.12 - 2.08) and pain interference with activities (adjusted RR, 1.53; 95%CI, 1.15 - 2.05), vs participants who had no pain or who were in the lowest tertiles of pain scores.
"Chronic pain measured according to number of locations, severity, or pain interference with daily activities was associated with greater risk of falls in older adults," the study authors write. "Chronic pain may serve as a distractor or, in some way, interfere with cognitive activity needed to prevent a fall. Successful avoidance or interruptions of a fall typically requires a cognitively mediated physical maneuver."
Limitations of this study include observational design and inability to exclude the possibilities that baseline pain was a consequence of previous falls or that a pain-related pathologic condition was the underlying cause of the falls.
"The findings provide evidence suggesting that the common complaint of the aches and pains of old age is related to a greater hazard than previously thought," the study authors conclude. "The significance of this work is in the identification of chronic pain as an overlooked and potentially important risk factor for falls in older adults. A randomized controlled trial is needed to determine whether improved pain control could reduce risk for falls among older patients with chronic pain."
The National Institute on Aging (NIA) Research Nursing Home Program Project supported this study, and the NIA Intramural Research Program funded the time for one of the study authors. The coding of the medication data for the MOBILIZE Boston Study was supported by an unrestricted grant from Pfizer Inc. One of the study authors (Dr. Kiel) has disclosed various financial relationships with Pfizer, Amgen, Merck, Novartis, Hologic, GlaxoSmithKline, Lilly, Procter Gamble, Philips Lifeline, and Wyeth.
JAMA. 2009;302:2214-2221.
