cTnI定量检测对不稳定性心绞痛患者冠脉病变程度和预后的判断价值

目的探讨不稳定性心绞痛(UAP)患者cTnI定量检测同冠脉病变数量、程度和预后之间的关系.方法不稳定性心绞痛患者68例,采用美国DPC公司全自动化学发光免疫检测系统及试剂进行血清cTnI定量检测、CK-MB质量试验.并行冠脉造影术.随访观察30天后心脏事件的发生.结果 68例UAP患者中,A组26例(占38.2%),cTnI≥0.4 ng/ml.B组42例(占61.8%),cTnI＜0.4 ng/ml.同步测定CK-MB质量,二组间差异无显著性.A组中C型病变、三支病变、左主干受累和高度狭窄20例(占76.9%),明显高于B组9例(占21.4%,P＜0.05).A组Braunwald分级ⅢA或ⅢB者23例(占88.5%),B组仅3例(占7.1%),明显高于B组(P＜0.001).A组30天内发生心脏事件14例(占53.8%),明显高于B组4例(占9.5%,P＜0.01).结论化学发光免疫分析法cTnI定量检测同冠状动脉病变数量及严重程度、临床Braunwald分级有密切关系.并对判断不稳定性心绞痛患者预后有一定的预测价值.     

肌钙蛋白I和肌红蛋白与不稳定性心绞痛患者的预后

研究旨在观察不稳定性心绞痛 (UA)患者入院后血清肌钙蛋白Ⅰ (cTnI)和肌红蛋白 (Mb)变化 ,探讨其对心脏事件的近期、远期预报价值。1.资料和方法 :60例UA患者分别在入院、入院后 12、2 4、48h、10d各采血 1次。用免疫发光法 (IMMULITE系统 )测定cTnI、Mb和CK MB浓度 ,分析其与心脏事件的关系。分近期 (3 0d)、远期 (6～ 12个月 )随访 ,记录心脏事件发生情况 ,包括入院 2 4h后发生急性心肌梗死、心原性猝死、顽固性心绞痛。2 .结果 :在近期cTnI≥ 0 4ng/ml组与cTnI <0 4ng/ml组心脏事件发生率分别为 48 2 %和 9 1% ,P <0 0 5。…     

血清肌钙蛋白Ⅰ水平与不稳定性心绞痛患者预后的关系

目的探讨肌钙蛋白Ⅰ对不稳定性心绞痛(UA)微小心肌损伤的判断价值以及对其预后的价值.方法对106例UA和44例稳定性心绞痛(SA)患者、68例冠状动脉造影正常者及72例健康者进行血清心肌肌钙蛋白Ⅰ(cTnⅠ)及肌酸激酶同工酶(CK-MB)测定,部分患者测定血清心肌肌钙蛋白T(cTnT),观察住院及出院后90～450 d心脏事件发生率,用Logistic单因素和多因素回归分析23个可能危险因素.结果61例UA患者血清cTnⅠ增高(57.5%),而SA患者只8例增高(18.18%),血清cTnⅠ增高者发生心脏事件者明显高于cTnⅠ正常者(P<0.001),血清cTnⅠ水平越高,心脏事件发生率越高;血清cTnⅠ水平与心绞痛严重程度密切相关(r=0.53,P<0.001);cTnT检出心肌微小损伤及预测预后与cTnⅠ有相似的作用.结论 cTnⅠ是判断心肌细胞微小损伤的敏感和特异性指标,cTnⅠ增高可作为UA患者发生心脏事件的预测指标之一.     

心脏肌钙蛋白T对不稳定性心绞痛患者近期预后的估价

目的：为证实不稳定性心绞痛（ＵＡ）患者心肌微小损伤的发生及其近期预后价值。方法：对３７例ＵＡ患者进行单次采血测定血清心脏肌钙蛋白Ｔ（ｃＴｎＴ）并常规治疗和严密观察２周。结果：１７例血清ｃＴｎＴ阳性ＵＡ患者中６例在２周内发生心脏意外事件，而２０例血清ｃＴｎＴ阴性ＵＡ患者中仅１例在２周内发生心脏意外事件。结论：血清ｃＴｎＴ检测对识别高危ＵＡ患者有一定临床价值，血清ｃＴｎＴ阳性提示存在心肌微小损伤的ＵＡ患者近期预后不良。     

肌钙蛋白T检测对心绞痛预后的判断

目的 评价心肌肌钙蛋白T(cTnT)对心绞痛(AP)患者预后的判断价值。方法 采用酶联免疫吸附法(ELISA)动态测定77例心绞痛患者cTnT浓度,同时进行心肌磷酸肌酸激酶(CK)和磷酸肌酸激酶同功酶(CK—MB)测定。结果50例稳定性心绞痛(SAP)患者无1例血清cTnT异常升高,而27例不稳定性心绞痛(UAP)患者,11例血清cTnT异常升高,其中6人发展为急性心肌梗死。结论cTnT预测心绞痛患者预后的阳性预期值为54.5％,阴性预期值为100％。而CK—MB则相应为28.6％和80％,均低于血清cTnT。故在筛选UAP高危病人时,可通过血清cTnT增高加以区分。     

肌钙蛋白Ⅰ对老年不稳定性心绞痛患者危险分层的判断价值

目的　探讨心脏肌钙蛋白I(cTnI)对老年不稳定性心绞痛 (UAP)患者危险分层的判断价值。　方法　对 6 8例老年UAP患者、17例稳定性心绞痛 (SAP)患者及 11例健康对照者分别进行血清cTnI测定 ,并观察住院 1个月内心脏事件发生情况。　结果　UAP组血清cTnI值为 (1 94± 0 6 3)μg/L ,明显高于SAP组的 (0 6 1± 0 11) μg/L及对照组的 (0 47± 0 0 8) μg/L(均为P <0 0 1)。UAP组内 ,随着Braunwald临床分级增高 ,Ⅰ～Ⅲ级血清cTnI值相应增高〔分别为 (1 35± 0 2 8)、(2 0 4± 0 31)及(3 17± 0 74) μg/L〕(P <0 0 5 )。对照组、SAP组及BraunwaldⅠ级UAP患者无 1例发生心脏事件 ;BraunwaldⅡ级 1例患者发生非致命性心肌梗死 ;BraunwaldⅢ级患者中 ,血清cTnI≥ 1 5 μg/L者心脏事件发生率为 42 1% ,高于血清cTnI <1 5 μg/L者的 13 3% (P <0 0 5 ) ,比数比 (OR) 3 15 ,95 %可信限为1 0 1～ 9 81。血清cTnI≥ 1 5 μg/L时判断心脏事件的阳性预测值为 42 1% ,阴性预测值为 86 7%。　结论　血清cTnI检测对老年UAP患者危险分层有较好的判断价值。     

心脏肌钙蛋白T对不稳定性心绞痛危险分层的价值

目的：探讨心脏肌钙蛋白Ｔ（ｃＴｎＴ）对不稳定心绞痛（ＵＡ）危险分层的临床价值。方法：用酶联免疫法测定１１２例ＵＡ患入院即刻、第２、３日血浆ｃＴｎＴ≥０．１ｎｇ／ｍｌ或〈０．１ｎｇ／ｍｌ将患分为ｃＴｎＴ升高组和ｃＴｎＴ正常组;观察住院期间两组急性心肌梗死（ＭＡＩ）、心脏性死亡和难治性心绞痛的发生率。结果：在１１２例ＵＡ患中,ｃＴｎＴ升高４４例（３９％）,ｃＴｎＴ正常６８例（６１％）。住院期间发生ＡＭＩ１２例（１０．７％,死亡５例（４．５％）,非致死性心肌梗死及心脏性死亡１５例（１３．４％）。其中ｃＴｎＴ升高组的死亡率较ｃＴｎＴ正常组有升高趋势,但差异无显性;而ｃＴｎＴ升高组ＡＭＩ、非致死性心肌梗死及心脏性死亡的发生率显高于ｃＴｎＴ正常组（Ｐ〈０．０１）。校正年龄、性别、心绞痛分级、心电图改变等因素后,ｃ     

不稳定性心绞痛患者检测高敏肌钙蛋白T的临床意义

目的评价高敏肌钙蛋白T(hs-cTnT)检测在不稳定性心绞痛(UAP)患者中的临床应用价值。方法选取2017年1月～12月我院收治的老年UAP患者85例为UAP组、稳定性心绞痛(SAP)患者67例为SAP组,以及同期来我院健康体检者50例为对照组。UAP组冠状动脉轻度狭窄49例、中度狭窄20例、重度狭窄11例和完全闭塞5例,随访12周,UAP组hs-cTnT正常46例,hs-cTnT升高(14ng/L)39例,比较3组血清hs-cTnT、血脂和肌酸激酶同工酶(CK-MB)水平,以hs-cTnT14ng/L为升高,评价hs-cTnT与UAP患者的冠状动脉病变严重程度和预后的关系。结果 UAP组hs-cTnT水平与SAP组比较,无统计学差异(P0.05)。与对照组比较,UAP组和SAP组hs-cTnT、血脂和CK-MB水平明显升高,差异有统计学意义(P 0.05,P 0.01)。UAP组入院时hs-cTnT阳性率显著高于SAP组和对照组(55.3%vs 13.3%和2.0%,P0.05)。轻度、中度、重度和完全闭塞患者血清hs-cTnT水平分别为(11.14±3.27)ng/L、(16.87±4.48)ng/L、(20.26±5.42)ng/L和(24.54±5.87)ng/L,重度狭窄和完全闭塞患者血清hs-cTnT水平明显高于轻度狭窄,差异有统计学意义(P0.05);hs-cTnT升高患者心血管事件发生率明显高于hs-cTnT正常者,差异有统计学意义(23.1%vs 2.2%,P=0.000)。结论血清hs-cTnT水平对于UAP患者的早期心肌损伤判断、冠状动脉病变分层、预后具有重要临床指导意义。     

不稳定性心绞痛和急性心肌梗塞肌钙蛋白T变化的比较

目的 :比较不同急性冠状动脉综合征患者肌钙蛋白 T(Tn T)变化。　　方法 :不稳定性心绞痛 (UAP)、Q波型和非 Q波型急性心肌梗塞 (AMI)患者于急诊就诊时、住院后第 2、第 3和第 6日取血测定 Tn T水平。　　结果 :35 %的 UAP患者 Tn T表现为升高 ,其升高的幅度 (均 <3.0 ng/ ml)明显 <非 Q波型 AMI(2 4% >3.0 ng/ml)和 Q波型 AMI(90 % >3.0 ng/ ml) ,且一般 3天后即转为阴性 ,而 AMI患者 6天后多数仍为阳性。非 Q波型 AMI和Q波型 AMI急诊就诊时 Tn T的阳性率分别为 79.1%和 90 .7% ,住院后第 2日均达 10 0 % ,均明显高于同时间谷草转氨酶和肌酸激酶同工酶的阳性率 ,两组 Tn T阳性在持续时间上相似 ,但在升高幅度上有明显的区别。再灌注治疗可能会影响 Q波型 AMI患者 Tn T的自然变化规律。　　结论 :UAP患者 Tn T的变化与非 Q波型 AMI和 Q波型 AMI有显著的不同。     

肌钙蛋白Ⅰ对不稳定型心绞痛患者预后判断的价值

目的探讨血清肌钙蛋白Ⅰ(cTnI)的定量测定对不稳定心绞痛(UA)患者预后的判断价值。方法对96例UA患者及25例健康人分别进行血清cTnI、肌酸磷酸激酶同工酶(CK－MB)的测定,并常规治疗,严密观察住院期间的心脏事件发生率。结果cTnI≥0.3μg/L的28例UA患者中有13例在2周内发生心脏事件,而cTnI＜0.3μg/L的68例UA患者中仅3例在2周内发生心脏事件,差异有显著性(P＜0.05)。结论血清cTnI的定量检测对识别高危UA患者有一定的临床意义,cTnI≥0.3μg/L提示UA患者的预后不良。     

Increased concentrations of inflammatory mediators in unstable angina: correlation with serum troponin T

OBJECTIVE—To measure plasma interferon γ, monocyte chemotactic protein-1 (MCP-1), and interleukin 6 and to assess their correlation with cardiac troponin T in unstable angina.
DESIGN—Blood sampling in patients undergoing coronary arteriography for known or suspected ischaemic heart disease.
PATIENTS—76 patients divided in three groups: 29 with unstable angina (group 1), 28 with stable angina (group 2), and 19 without ischaemic heart disease and with angiographically normal coronary arteries (group 3).
MAIN OUTCOME MEASURES—Plasma interleukin 6, interferon γ, MCP-1, and troponin T in the three groups of patients.
RESULTS—Interleukin 6 was increased in group 1 (median 2.19 (range 0.53-50.84) pg/ml) compared with the control group (1.62 (0.79-3.98) pg/ml) (p < 0.005), whereas interferon γ was higher in group 1 (range 0-5.51 pg/ml) than in the other two groups (range 0-0.74 pg/ml and 0-0.37 pg/ml; p < 0.005 and p < 0.001, respectively). Patients with unstable angina (group 1) and positive troponin T had higher concentrations of interferon γ than those with negative troponin T (0-5.51 pg/ml v 0-0.60 pg/ml, p < 0.001). Plasma MCP-1 was also higher in group 1 (median 267 (range 6-8670) pg/ml) than in the other two groups (134 (19-890) pg/ml and 84.5 (5-325) pg/ml; p < 0.005 and p < 0.001, respectively), and among group 1 patients with a positive troponin T assay than in those with normal troponin T (531 (14.5-8670) pg/ml v 69 (6-3333) pg/ml; p < 0.01). There was no difference in plasma interleukin 6 in group 1 patients between those with and without raised troponin T.
CONCLUSIONS—The inflammatory cytokines interferon γ and MCP-1 are increased in patients with unstable angina, particularly in those with raised concentrations of troponin T, suggesting that they are probably related to myocardial cell damage or to plaque rupture and thrombus formation.


Keywords: inflammatory cytokines; troponin T; unstable angina     

cTnT在判断急性心肌梗死及不稳定型心绞痛预后中的价值

目的 :探讨心肌肌钙蛋白 T（c Tn T）对急性心肌梗死 （AMI）诊断及评估不稳定型心绞痛 （U AP）预后的临床价值。方法 :对 76例胸痛患者进行入院即刻血浆 c Tn T半定量、同步心肌酶学定量测定 ,观察对比 c Tn T与心肌酶学在诊断 AMI及评估 U AP患者预后中的特异性和敏感性。结果 :76例胸痛患者中 AMI 34例、U AP 2 7例、稳定劳力性心绞痛 8例、其它胸痛疾患 7例。AMI34例 c Tn T全部阳性 ,而 U AP2 3例和其余病例 c Tn T均为阴性。AMI患者同步 CK,AST升高者 2 8例 ,L DH升高者 30例。c Tn T与心肌酶学差异未达显著水平 （P>0 .0 5 ） ,但发病 2～ 5 h者 10例 ,心肌酶各项均正常 ,与 c Tn T对比有高度显著性差异 （P<0 .0 1） ;发病 5～ 11d者 6例 ,仅 2例 L DH还表现出升高外 ,其余心肌酶均正常 ,与 c Tn T对比有显著性差异 （P<0 .0 5 ） ;发病 5～ 12 0 h者相差均不显著 （P>0 .0 5 ）。在 2 7例 U AP患者中 ,c Tn T阳性组 AMI和难治性心绞痛发生率显著高于 c Tn T阴性组 （P<0 .0 1） ;c Tn T阴性组药物疗效好 ,近期心脏事件发生率低 ,与 c Tn T阳性组对比亦有高度显著性差异 （P<0 .0 1）。结论 :c Tn T是反映心肌细胞损伤灵敏性、特异性均较好的生化指标 ;c Tn T对诊断早期和晚期 AMI的价值高于心肌酶学 ;c Tn T阳性     

不稳定性心绞痛患者血清心肌钙蛋白T含量变化及临床意义

为探讨心脏特异性肌钙蛋白T（cTnT）在不稳定性心绞痛（UA）患者血清中检测的临床意义。应用酶联免疫法测定42例稳定性心绞痛（SA）患者和86例UA患者血清cTnT、肌酸磷酸激酶同功酶-MB（CK-MB）．并作对照分析。结果显示：SA患者血清cTnT无例升高（以cTnT＞0．2μg／L为界限值）；28例UA患者血消cTnT至少有1次升高．占32．6％，先均值为0．98±0．47μg／L，范围为0．20～1．86μg／L，这28例在入院后1周内有7例发生急性心肌梗塞（AMI），1例发生猝死；其余58例。cTnT不升高者中，在相同时间内，仅1例发生AMI，无猝死者。UA患者中cTnT阳性与阴性者的预后差别有统计意义（χ2=14．26，P＜0.001）。UA中CK－MB只有2例轻度升高，其中cTnT阳性与阴性各占1例。结果提示：①cTnT为较CK-MB更敏感、更特异的反应心肌损伤的指标；②UA中约有32．6％的患者血清cTnT异常升高，说明这部分患者已经发生心肌细胞损伤、心内膜下心肌梗塞或小灶性心肌梗塞，该类患者处于高危状态，极易发展成典型的AMI或猝死；③UA中cTnT不升高者，在很大程度上将有一个良好的预后。     

Unstable angina pectoris

The pathophysiology of unstable angina has been better elucidated in the past five years and has led to more rational therapy. Coronary arteries in patients with unstable angina have atherosclerotic plaques which are often complex and are the site of platelet activation and fibrin deposition. Nitrates, one of the oldest therapies, are efficacious and act not only by dilating coronary vessels but by reducing preload and afterload. Beta blockers have a salutary effect by decreasing myocardial oxygen demand. Calcium channel blockers attenuate smooth muscle contraction and thereby act to decrease coronary artery spasm. Beta blockers and calcium channel blockers are equally efficacious in unstable angina. The antiplatelet agent, aspirin, has been shown to reduce fatal or non-fatal myocardial infarction and probably overall mortality. The use of heparin acutely for unstable angina has been demonstrated to decrease refractory angina and myocardial infarction, and acutely is probably better than aspirin. For patients with reduced ejection fractions (0.30-0.49), a prospective randomized trial has shown that coronary artery bypass graft surgery offers an improved three-year survival compared with medical therapy; however, surgery does not prevent myocardial infarction. Percutaneous transluminal coronary angioplasty may be a reasonable therapeutic alternative for some patients with single-vessel disease who are refractory to medical therapy but there are as yet no controlled trials of this question. To date a clinical benefit from thrombolytic therapy has not been demonstrated.     

Cardiovascular risk and therapeutic benefit of coronary interventions for patients with unstable angina according to the troponin T status.

AIMS: Elevation of troponin T in patients with unstable angina is predictive of adverse outcomes. Since no advanced therapeutic concept for such high-risk patients has been established, we investigated cardiac risk prior to, during, and after coronary revascularization in patients with unstable angina stratified according to the troponin T status. METHODS AND RESULTS: Out of 351 patients with unstable angina, troponin was elevated for 36% of the patients as determined by qualitative bedside tests. The patients were followed during hospitalization and 30 days after discharge for incidence of death and myocardial infarction. In troponin-positive patients, clinical symptoms were more refractory to medical treatment than in troponin-negative patients (78% vs 44%;P=0.002). Although these patients were catheterized earlier (1.6 vs 3.4 days;P=0.005) and more frequently (95% vs 69%;P<0.001), troponin-positive patients suffered a higher incidence of cardiac events prior to scheduled revascularization (death, myocardial infarction; 6.4% vs 0.4%;P<0.001). The angiogram for troponin-positive patients confirmed a more severe coronary artery disease requiring revascularization (69% vs 50%;P=0.001). Also the following coronary intervention was more complicated (death, myocardial infarction; 15.3% vs 4.8%;P=0.02). During the 30-day follow-up period, cardiac risk remained elevated for troponin-positive patients. CONCLUSIONS: Troponin T rapid testing reliably identified high-risk patients with unstable angina. A higher event rate was observed prior to and particularly in association with the coronary intervention. Coronary revascularization did not abrogate the increased risk of troponin-positive patients during the 30-day follow-up.     

Lactate metabolism as a prognostic index in unstable angina

Fifty patients evaluated because of unstable angina were followed up for a mean period of 63.7 months. Analysis of transmyocardial lactate metabolism was performed in all patients in addition to coronary angiography and ventriculography. All patients had at least one coronary lesion of great than 75%. Although technically feasible, aortocoronary bypass surgery was not performed on initial hospitalization and all patients were treated medically. Patients were divided into two groups on the basis of lactate metabolism; group A lactate production great than 15%, group B lactate production less than 15% or lactate extraction. There was no difference in left ventricular end-diastolic pressure or ejection fraction between the two groups. A coronary score index was higher in group A than group B (5.45 +/- 2.2 vs 3.13 +/- 1.2) (p less than 0.05). The incidence of myocardial infarction was higher in group A than group B in hospital (44.4% vs. 4.3%, p less than 0.05), and long term (70.3% vs. 17.3%, p less than 0.05). Mortality was higher in group A than group B in hospital (25.9% vs. 0%, p less than 0.05) and long term (66.7% vs. 13%, p less than 0.05). Analysis of lactate metabolism thus provides a prognostic index in unstable angina which complements information obtained by coronary angiography and ventriculography.     

血清超敏肌钙蛋白T在不稳定型心绞痛患者危险分层和预后中的价值研究

目的 本研究旨在探讨血清超敏肌钙蛋白T（hs-nT）对不稳定型心绞痛（UAP）患者的临床诊断、冠脉病变严重程度和短期预后价值的关系.方法 人选161例常规血清TnT阴性的UAP患者,冠状动脉造影前所有患者均测定血清hs-TnT水平,随访30 d,记录主要心血管不良事件（MACE）.结果 血清hs-TnT随着冠脉病变的严重程度而升高,血清hs-TnT水平越高,冠脉狭窄程度及病变累及的血管越严重,重度狭窄、完全闭塞组hs-TnT水平分别为（0.0190±0.02419）ng/ml、（0.0652±0.0099）ng/ml,其组间差异均有统计学意义（P＜0.05）,三支病变组[hs-TnT（0.0261±0.0498）ng/ml]与正常组[hs-TnT（0.0069±0.0041）ng/ml]比较差异有统计学意义（P＜0.01）.对于UAP患者短期预后的预测,血清hs-TnT升高,其短期心血管事件（心源性猝死、急性心梗、心绞痛再入院）的风险较正常组高,差异有统计学意义（P＜0.01）.结论 在常规TnT阴性的UAP患者中,血清hs-TnT可检测出更多的心肌坏死,同时其血清学水平的高低可预测冠脉病变的狭窄严重程度与病变范围;其升高亦可提示短期预后不佳、主要心血管事件的增加,可作为对UAP的早期危险分层的一个指标并指导临床治疗.     

One-year prognosis in patients hospitalized with a history of unstable angina pectoris

The prognosis during 1 year of follow-up in 715 patients admitted to one single hospital due to suspected acute myocardial infarction (AMI) with a history of unstable angina pectoris immediately preceding hospitalization is described. AMI developed in 192 patients (27%) during the first three days and in 255 patients (38%) during the first year. The mortality during hospitalization was 7% (50 patients) and during 1 year 19% (130 patients). Of the nonsurvivors, 54% died of AMI, 28% of congestive heart failure, and 20% of cardiogenic shock. Based on simple clinical parameters on admission to the emergency room, risk indicators for death during the following year could be identified as follows, in the order of significance: high age (p < 0.001), ST-segment depression on admission (p < 0.001), and a history of diabetes mellitus (p < 0.05). At admission to the emergency room, risk indicators for development of AMI during the following year were as follows: initial degree of suspicion of AMI (p < 0.001), electrocardiographic signs of acute ischemia on admission (p < 0.001), ST-segment elevation on admission (p < 0.01), age (p < 0.05), and lack of a previous history of chronic stable angina pectoris (p < 0.05). We conclude that, among patients admitted to hospital due to suspected AMI with a history of unstable angina pectoris immediately preceding hospitalization, 38% developed a confirmed infarction and 19% died during the following year.     

不稳定心绞痛心肌钙蛋白T测定的意义

目的：探讨心肌钙蛋白T（cTnT)对不稳定心绞痛（UAP）危险分层的临床价值。方法：用酶联免疫法测定80例UAP患入院当天、第2天、第3天血浆cTn水平，据cTn≥0.1ng/ml或＜0．1ng/ml将患分为cTn升高组和正常组，观察住院期间UAP胸痛发作时ST－T变化以及急性心肌梗死（AMI）的发生率。结果：在80例UAP中cTn升高24例（30％）；正常56例（70％）；cTnT升高24例中发生AMI3例（12．5％），其中死亡1例，cTnT正常无1例发生AMI或死亡：cTnT升高组胸痛发作时的心电图ST－T改变发生率100％（24／24）高于正常组的0％（0／56）（P＜0．01）。结论：cTnT测定对判断UAP在短期内发生AMI和心性死亡预测价值，可作为UAP危险度分层指标。