用於睡眠呼吸中止症的CPAP或許可預防高血壓


  【24drs.com】兩篇研究確認了阻塞性睡眠呼吸中止症(OSA)和高血壓的關聯,並指出運用連續陽壓呼吸道療法(CPAP)或許可降低高血壓風險。
  
  這些研究刊載於5月23/30日版的JAMA,編輯評論作者指出,這些資料大致支持OSA和高血壓之間的關聯。
  
  華盛頓大學的Vishesh K. Kapur醫師和Edward M. Weaver醫師指出,OSA的治療可能不只可以降低高血壓(平均效果為中等),如果有後續研究確認,或許還可以預防有風險患者的高血壓;因此,對於已經發生或者有發生高血壓風險的病患,OSA可作為潛在的治療原因且有臨床重要結果。
  
  西班牙Miguel Servet大學醫院的Jose M. Marin醫師等人在他們的報告中發表一篇觀察世代的結果,研究對象是在1994年1月1日至2000年12月31日之間、轉診進行多層次睡眠檢查的1,889名無高血壓病患。
  
  在1,579名OSA病患中,依據國家治療指引,462人不適合CPAP治療,195人適合但是拒絕CPAP,98人適合且開始CPAP但是未確實執行,824人適合且遵循CPAP。
  
  追蹤期間中位數為12.2年,705名病患(37.3%)發生高血壓;Marin醫師表示,與沒有OSA者相比,未治療之OSA和新發生的高血壓風險增加有關,而使用CPAP治療和新發生之高血壓風險降低有關。
  
  表、OSA之高血壓風險
組別 校正風險比(95%信心區間)
不適用CPAP 1.33 (1.01 - 1.75)
拒絕CPAP 1.96 (1.44 - 2.66)
未落實CPAP 1.78 (1.23 - 2.58)
CPAP治療 0.71 (0.53 - 0.94)

  Marin醫師表示,對於新發生的高血壓,OSA看來是個可修飾的風險因素,這類結果的臨床關聯是,OSA雖然在西方人有高盛行率,絕大多數仍然無法識別和未經治療的。
  
  另一篇報告中,西班牙Recerca Biomedica研究中心的Ferran Barbe醫師等人報告了一篇隨機控制試驗(RCT)結果,檢視了CPAP對723名有OSA但是沒有日間嗜睡之成人的偶發高血壓或心血管事件的影響;CPAP組有357名成人,對照組(一般照護)有366人。
  
  在追蹤中位數4年之間,CPAP組有68例新發生高血壓和28例心血管事件,對照組則是79例新發生高血壓和31例心血管事件。
  
  CPAP組中,高血壓和心血管事件發生率傾向較低,但是未達統計上的顯著意義。每100人-年之新發生高血壓或心血管事件的發生率,CPAP組為9.20 (95%信心區間[CI],7.36 - 11.04),對照組為11.02 (95% CI,8.96 - 13.08)(發生率密度比為0.83;95% CI,0.63 - 1.1;P = .20)。
  
  不過,研究者指出,他們的研究未能顯出顯著差異,若有更大型或追蹤更久的研究,或許可以確認治療和結果之間的顯著關聯。
  
  他們指出,事後分析認為,CPAP治療可降低每晚使用CPAP 4小時以上者的高血壓或心血管事件的發生率。
  
  Barbe醫師表示,這是第一篇聚焦在CPAP治療對預防睡眠呼吸中止患者之高血壓和心血管事件的RCT,我們的結果顯示,當病患夜間使用CPAP達4小時以上,則高血壓和心血管事件發生率降低。
  
  Barbe醫師建議,如果你要預防心血管事件或發生高血壓,督促你的病患每晚使用CPAP治療超過4小時。
  
  Kapur 醫師和Weaver醫師在編輯評論中寫道,整體看來,這些研究增加了「OSA患者有偶發高血壓風險」的證據,且提出強烈但未定論的證據認為,CPAP治療或許可降低風險;在睡眠困難的OSA病患中,CPAP治療處方的效果依舊不清楚。
  
  他們也指出,有關OSA、高血壓和治療還有許多問題:
  * 哪些屬於適合與有反應者(例如OSA嚴重度分組、入睡和未入睡病患、地緣區分)?
  * 多常使用CPAP才會有重要的治療效果?
  * 其他OSA治療的影響?
  
  Kapur醫師和Weaver醫師表示,這些問題將需要一些可行的RCT且進行次組分析、以及對照適當的觀察研究,也需要一些新方法,如治療戒斷規範。
  
  儘管有這些問題,他們結論表示,相當多證據支持確認並治療OSA對改善症狀、生活品質、和心血管事件的重要性。
  
  資料來源:http://www.24drs.com/professional/list/content.asp?x_idno=6831&x_classno=0&x_chkdelpoint=Y
  

CPAP for Sleep Apnea May Prevent New Hypertension

By Megan Brooks
Medscape Medical News

May 23, 2012 — A pair of studies released this week confirm an association between obstructive sleep apnea (OSA) and hypertension, and hint that adherent continuous positive airway pressure (CPAP) therapy may reduce the risk for new-onset hypertension.

The studies appear in the May 23/30 issue of JAMA. The authors of an accompanying editorial point out that the data "generally support" a causal link between OSA and hypertension.

Vishesh K. Kapur, MD, MPH, and Edward M. Weaver, MD, MPH, both from the University of Washington in Seattle, add that treatment of OSA "may not only reduce blood pressure (although modestly on average), but if confirmed by future studies also may prevent hypertension in at-risk patients. Thus, OSA deserves attention in patients with or at risk of developing hypertension as a potentially treatable cause of hypertension as well as other clinically important outcomes."

A Modifiable Risk Factor

In their paper, Jose M. Marin, MD, from the Hospital Universitario Miguel Servet in Zaragoza, Spain, and colleagues report results of an observational cohort study of 1889 adults without hypertension referred for polysomnography between January 1, 1994, and December 31, 2000.

Among the 1579 patients with OSA, 462 were ineligible for CPAP therapy according to national treatment guidelines, 195 were eligible but declined CPAP, 98 were eligible and started CPAP but were nonadherent, and 824 were eligible and adhered to CPAP.

During a median follow-up of 12.2 years, 705 patients (37.3%) developed hypertension. "Compared with participants without OSA, untreated OSA was associated with an increased risk of new-onset hypertension, whereas treatment with CPAP therapy was associated with a lower risk of new-onset hypertension," Dr. Marin told Medscape Medical News.

Table. Risk for Hypertension With OSA

Group Adjusted Hazard Ratio (95% Confidence Interval)
Ineligible for CPAP 1.33 (1.01 - 1.75)
Declined CPAP 1.96 (1.44 - 2.66)
Nonadherent to CPAP 1.78 (1.23 - 2.58)
CPAP therapy 0.71 (0.53 - 0.94)

"OSA appears to be a modifiable risk factor for new-onset hypertension. Such findings are clinically relevant considering that OSA, despite a high prevalence in Western populations, remains overwhelmingly unrecognized and untreated," Dr. Marin said.

In a separate paper, Ferran Barbe, MD, from the Institut de Recerca Biomedica, Lleida, Spain, and colleagues report results of a randomized, controlled trial (RCT) testing the effects of CPAP on incident hypertension or cardiovascular events in 723 adults with OSA but without daytime sleepiness. There were 357 adults in the CPAP group and 366 in the control group (usual care).

During follow-up lasting a median of 4 years, there were 68 cases of new hypertension and 28 cardiovascular events in the CPAP group, compared with 79 cases of new hypertension and 31 cardiovascular events in the control group.

In the CPAP group, there was a trend toward a reduction in the incidence of hypertension and cardiovascular events that did not reach statistical significance. The incidence of new hypertension or cardiovascular event per 100 person-years was 9.20 (95% confidence interval [CI], 7.36 - 11.04) in the CPAP group vs 11.02 (95% CI, 8.96 - 13.08) in the control group (incidence density ratio, 0.83; 95% CI, 0.63 - 1.1; P = .20).

However, the investigators note that their study may have limited power to detect a significant difference, and that a larger study or longer follow-up might have been able to identify a significant association between treatment and outcome.

They point out that a post hoc analysis "suggested that CPAP treatment may reduce the incidence of hypertension or cardiovascular events in patients with CPAP adherence of 4 h/night or longer."

"This is the first RCT to focus on the effects of CPAP treatment in the prevention of hypertension and cardiovascular events in patients with sleep apnea," Dr. Barbe added in comments to Medscape Medical News. "Our results show that when the patients use CPAP for more than 4 hours per night there is a reduction in the incidence of hypertension and cardiovascular events."

Dr. Barbe's advice: "If you want to prevent cardiovascular events or the development of hypertension, push your patients to use CPAP treatment for more than 4 hours per night."

Questions Remain

In their editorial, Dr. Kapur and Dr. Weaver write that, "Taken together, these studies augment the evidence that the presence of OSA poses a risk for incident hypertension and provide strong but not definitive evidence that CPAP therapy may reduce the risk. In nonsleepy patients with OSA, the effect of CPAP therapy prescription remains unclear."

They also note that many questions remain regarding OSA, hypertension, and treatment, including:

  • What are the susceptible and responsive subgroups (eg, OSA severity subgroups, sleepy vs nonsleepy patients, and demographic subgroups)?
  • How much CPAP use is necessary for an important treatment effect?
  • What are the effects of other OSA treatments?

These questions, Dr. Kapur and Dr. Weaver say, "will require RCTs when feasible, subgroup analyses within these trials, and well-controlled observational studies. Novel approaches are needed, such as treatment withdrawal protocols."

Despite lingering questions, they conclude, "considerable evidence supports the role of identification and treatment of OSA to improve symptoms, quality of life, and cardiovascular end points."

Both studies were supported by grants from the Instituto Carlos III, Ministry of Health, Madrid, and the Spanish Society of Respiratory Medicine. The study by Dr. Barbe was also supported by Resmed (Bella Vista, Australia), Air Products-Carburos Metalicos (Barcelona), Respironics (Murrysville, Pennsylvania) and Breas Medical (Madrid). The study authors have disclosed no relevant disclosures. Dr. Kapur reported having owned stock within the last 3 years in Merck, Johnson & Johnson, and Bristol-Myers Squibb. Dr. Weaver had disclosed no relevant financial relationships.

JAMA. 2012;307:2161-2168, 2169-2176, 2197-2198.

    
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