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作者：Laurie Barclay, MD  
出處：WebMD醫學新聞

　　October 8, 2009 — 根據線上發表於10月6日英國醫學期刊(British Medical Journal)的一篇創始世代研究結果，無併發症的慢性下背痛病患，約有40%在一年內恢復。
　　
　　澳洲雪梨大學、喬治國際健康研究中心博士候選人Luciola da Cunha Menezes Costa與其研究夥伴寫道，慢性下背痛的預後不確定。雖然臨床指引一般將此狀況描寫為預後不佳，但可能依據的是不具代表性的存活世代研究、或者大部份未加以追蹤的研究。有關慢性下背痛的預後研究，獲得有代表性的世代是研究設計時最主要的問題。
　　
　　本研究的目標是，評估一個創始世代的慢性下背痛療程，辨識發生慢性時的預後標記，研究使用在澳洲雪梨的一級照護診所、在近兩週出現急性下背痛之973名病患這個創始世代中的亞群體資料，有慢性下背痛的創始世代病患包括406名背痛持續3個月的研究對象。
　　
　　在初見病患時、進入研究時、9個月和12個月追蹤時，測量結果與評估造成慢性的可能預測因子；評估項目包括疼痛度、失能、工作狀態，以確認恢復情況。使用Cox回歸模式幫助評估可能預後因子和達到復原時間之間的關聯。
　　
　　對於各項結果，所有病患與時間的追蹤完成率為97%。在9個月時，無痛的累積可能性為35%，12個月時增加到42%。在9個月和12個月時的完全恢復比率分別為35%和41%。進入慢性研究時，259名參與者尚未從疼痛相關失能恢復，但是其中的47%在12個月時恢復。
　　
　　與延遲恢復有關的因素，包括之前的下背疼痛程度、發生慢性狀況時的失能程度或疼痛密集度較高、教育程度低、發現持續疼痛的風險較高、非出生於澳洲者。
　　
　　研究限制包括，無法測量隱蔽的預後結果，自我報告預後標記。
　　
　　英國Keele大學國家初級照護中心、關節炎研究活動的Elaine M. Hay醫師和Kate M. Dunn博士在編輯評論中指出，需要更長期的追蹤來確認慢性下背痛的真正預後。
　　
　　Hay醫師和Dunn博士寫道，作者們認為，即使是他們的創始世代內經高度篩選的慢性背痛病患，非特定背痛還是一個異質性的狀況。有些病患在一年的療程後恢復，有些則否，持續的可能性受到某些可在諮商時確認的預後因素影響。研究者的挑戰在於將這些發現轉為新的介入方式研究，處理病患想知道的議題：根據我的症狀，哪種治療對我的現在和未來最好？
　　
　　澳洲國家健康與醫學研究委員會贊助本研究與其中幾位作者。研究作者與編輯皆宣告沒有相關財務關係。
　　
　　BMJ. 線上發表於2009年10月6日。

More Than One Third of Patients With Chronic Low Back Pain Recover Within 1 Year

By Laurie Barclay, MD
Medscape Medical News

October 8, 2009 — About 40% of patients with uncomplicated chronic low back pain recover within 1 year, according to the results of an inception cohort study published online October 6 in the British Medical Journal.

"The prognosis of chronic low back pain is uncertain," write Luciola da Cunha Menezes Costa, PhD candidate from George Institute for International Health, University of Sydney in Australia, and colleagues. "Although clinical guidelines generally portray the condition as having a poor prognosis this is based either on studies of potentially unrepresentative survival cohorts or on studies with large losses to follow-up. Obtaining a representative cohort is the major problem in designing valid studies on the prognosis of chronic low back pain."

The goal of this study was to assess the course of chronic low back pain in an inception cohort and to identify prognostic markers at the onset of chronicity, using a subcohort of an inception cohort of 973 consecutive patients seen at primary care clinics in Sydney, Australia, with acute low back pain starting less than 2 weeks previously. The inception cohort of patients with chronic low back pain consisted of 406 participants with back pain persisting for 3 months.

Outcome measures and potential predictors of chronicity were evaluated when the patients were first seen, at study entry, and at 9- and 12-month follow-up. Assessment of pain intensity, disability, and work status allowed determination of recovery. Cox regression modeling helped evaluate the association between potential prognostic markers and time to recovery.

For all outcomes, completeness of follow-up was 97% of total person time. At 9 months, the cumulative probability of being pain-free was 35% and increased to 42% at 12 months. For complete recovery, the percentages were 35% and 41%, respectively. At entry to the chronic study, 259 participants had not recovered from pain-related disability, but 47% of these had recovered by 12 months.

Factors associated with delayed recovery were previous sick leave for low back pain, high levels of disability or pain intensity at onset of chronicity, low educational levels, higher perceived risk for persistent pain, and birthplace outside Australia.

Limitations of this study include inability to measure prognostic outcomes blinded and self- reporting of prognostic markers.

In an accompanying editorial, Elaine M. Hay, MD, and Kate M. Dunn, PhD, from the Arthritis Research Campaign National Primary Care Centre of Keele University in Staffordshire, United Kingdom, note that much longer follow-up is needed to determine the true prognosis of chronic low back pain.

"The authors have shown that even within the highly selected group of patients with chronic back pain included in their inception cohort, non-specific back pain is a heterogeneous condition," Dr. Hay and Dr. Dunn write. "Some patients recover over the course of a year, but most do not, and the likelihood of persistence is influenced by certain (prognostic) factors identified at the point of consultation. The challenge remains for researchers to translate these findings into novel intervention studies that tackle what patients want to know — given my symptoms, which treatment will work best for me now, and in the future?"

The National Health and Medical Research Council of Australia supported this study and some of its authors. The study authors and editorialists have disclosed no relevant financial relationships.

BMJ. Published online October 6, 2009.