Health-seeking behaviour among adults with prolonged cough in Vietnam

Objective To assess health‐seeking behaviour among adults with prolonged cough in a population‐based, nationally representative sample in Vietnam. Methods Cross‐sectional survey conducted from September 2006 to July 2007. All inhabitants aged ≥15 years were invited for screening for cough, history of tuberculosis (TB) treatment and chest X‐ray (CXR) examination. TB suspects, defined as any survey participant with CXR abnormalities consistent with TB, or productive cough for more than 2 weeks or TB treatment either currently or in the preceding 2 years submitted sputum specimens for smear examination and culture and provided information on health‐seeking behaviour in an in‐depth interview. Results Of 94 179 persons participating in the survey, 4.6% had prolonged productive cough. Forty‐four percentage of those had sought health care and reported pharmacies (35%), commune health posts (29%), public hospitals (24%) and private physicians (10%) as first point of contact. Only 7% had undergone sputum smear examination. Of TB suspects with prolonged productive cough, 2.9% were diagnosed with TB; 10.2% of these reported smear and 21.9% reported X‐ray examination when visiting a health care facility. The average patient delay was 4.1 weeks (95% CI: 3.9–4.4) among cough suspects and 4.0 weeks (95% CI: 3.1–4.9) among TB cases. Conclusions In this Vietnamese survey, nearly half of persons with cough for more than 2 weeks had visited a health care provider. The commonest first health facility contacted was the pharmacy. Sputum smears were rarely examined, except in the provincial TB hospital. Our findings highlight the need to improve diagnostic practices by retraining health staff on the performance of sputum examination for TB suspects.     

集中推荐发现病人在结核病控制工作中的作用研究

目的评价集中推荐发现病人的方式在结核病控制工作中的可行性和作用，从而制定出完善的、规范的集中推荐发现方式工作流程，使集中推荐发现方式更加科学化、制度化和规范化。方法按照统一设计的7种可疑肺结核线索对象标准，采取“村医生入户调查、乡卫生院胸透初筛、市结防所集中定诊”的集中推荐发现新涂阳肺结核病人。结果采用严格的集中推荐方法，利用3个月时间，在总人口755944人的县级市发现活动性肺结核病人166例，其中新涂阳肺结核病人86例；可疑线索对象中以咳嗽、咯痰≥3周或咯血或痰中带血者的结核病人检出率最高，为13．0％，其中新涂阳肺结核的检出率为7．6％。结论采取村医生入户调查、乡卫生院胸透初筛、市结防所集中定诊的集中推荐方式，不仅是提高新涂阳肺结核病人发现率的一种有效的方法，也是开展结核病健康促进活动的一种有效形式。     

Prevalence of tuberculosis suspects and their healthcare-seeking behavior in urban and rural Jordan

To determine the prevalence and healthcare-seeking behavior of tuberculosis (TB) suspects in Middle and South Jordan. A community-based survey was carried out between June-September 2005, whereby 61,730 adult household members were inquired about the presence of persistent cough for more than three weeks to identify TB suspects. These adults were then interviewed and referred to the nearest health center for clinical and sputum smear examination. Of the 61,730 surveyed household members, 1,544 (2.51%) were identified as TB suspects, of these two were sputum smear positive pulmonary TB. The first action with the onset of symptoms was to visit the health centers. Reasons for timely seeking care were accessibility of the facilities and confidence in obtaining a cure, and obstacles were belief that symptoms would resolve and economic constraints in rural residents. Females, rural residents, expatriates, and using private means of transportation were predictors of delay in seeking care for more than three weeks. This study has set the baseline information about the prevalence of TB suspects in Jordan and their healthcare-seeking behavior that shows community preference to seek care at health centers. These should be upgraded and the health workers trained on suspect management to enhance the TB elimination efforts.     

集中推荐发现病人在结核病控制工作中的作用研究

目的评价集中推荐发现病人的方式在结核病控制工作中的可行性和作用,从而制定出完善的、规范的集中推荐发现方式工作流程,使集中推荐发现方式更加科学化、制度化和规范化。方法按照统一设计的7种可疑肺结核线索对象标准,采取“村医生入户调查、乡卫生院胸透初筛、市结防所集中定诊”的集中推荐发现新涂阳肺结核病人。结果采用严格的集中推荐方法,利用3个月时间,在总人口755944人的县级市发现活动性肺结核病人166例,其中新涂阳肺结核病人86例;可疑线索对象中以咳嗽、咯痰≥3周或咯血或痰中带血者的结核病人检出率最高,为13.0%,其中新涂阳肺结核的检出率为7.6%。结论采取村医生入户调查、乡卫生院胸透初筛、市结防所集中定诊的集中推荐方式,不仅是提高新涂阳肺结核病人发现率的一种有效的方法,也是开展结核病健康促进活动的一种有效形式。     

对肺结核可疑者采用症状查痰法提高患者发现率

目的探讨更全面的发现肺结核病例的检查诊断程序。方法在采用通用的胸透筛查法发现肺结核患者的基础上，采用症状查痰法，对有症状且≥3周者，直接做痰结核分枝杆菌检查，并拍摄X线胸片，对按胸透筛查法和症状查痰法发现的患者进行比较；对肺结核诊断程序改进后的结核病患者的发现情况进行分析。结果采用症状查痰法发现活动性肺结核新病例900例，比胸透筛查法多发现活动性肺结核患者73例，患者发现率提高8．8％(73／827)；发现涂阳肺结核病例262例，比胸透筛查法多发现活动性肺结核患者30例，患者发现率提高12．9％(30／232)；培养阳性肺结核病例360例，比胸透筛查法多发现患者63例，患者发现率提高21．2％(63／297)。症状查痰法发现新病例的细菌学检查阳性者的比例高于胸透筛查法，胸透筛查法发现新病例中，涂片阳性者占28．1％(232／827)，痰菌培养阳性者占35．9％(297／827)；而症状查痰法发现新病例中，涂片阳性者占29．1％(262／900)，痰菌培养阳性者占40．0％(360／900)。症状查痰法多检出的活动性肺结核患者73例中，涂阳和菌阳患者的比例均很高，分别为41．1％(30／73)和86．3％(63／73)，较胸透筛查法的检出涂阳比例(28．1％)和菌阳比例(35．9％)高。结论采用症状查痰法比胸透筛查法发现的活动性肺结核患者增加，特别是菌阳肺结核患者的发现率增加21．2％，使这些患者得到及时诊断，有利于结核病传染源的控制。     

Gender disparity amongst TB suspects and new TB patients according to data recorded at the South African Institute of Medical Research laboratory for the Western Cape Region of South Africa.

OBJECTIVE: To describe the sex and age distribution of sputum submission and smear positivity in the Western Cape Province of South Africa. METHOD: Laboratory registers of the South African Institute of Medical Research were examined retrospectively for the year 1999. RESULTS: Male tuberculosis (TB) suspects outnumbered females by 1.45:1, whereas amongst confirmed TB cases the ratio was 2.08:1. The odds ratio (OR) for smear positivity amongst males and females was 1.544. The proportion of male sputum positives significantly exceeded the proportion of males in the general population, as measured by the 1996 census. Not only did the number of male TB suspects and confirmed cases exceed that of females in absolute terms, but the proportion of male suspects proving smear-positive exceeded that of females. The age by sex distribution of new smear-positive patients followed the trend reported in recent literature. CONCLUSION: The gendered incidence of tuberculosis identified from this census is consistent with that of other developing countries. However, the smaller proportion of female TB suspects proving smear-positive suggests a higher index of suspicion in females and/or longer delays prior to care seeking amongst males.     

How many sputum smears are necessary for case finding in pulmonary tuberculosis?

We reviewed the laboratory registers of 42 tuberculosis (TB) diagnostic centres in the southern region of Ethiopia to determine the value of submitting serial sputum samples for the diagnosis of pulmonary TB (PTB) and estimate the proportion of suspects that are smear positive. A total of 15,821 TB suspects submitted three smears each (47,463 smears) in 2000 with a median of 228 per centre. The smear positivity rate (two or more positive smears) was 25%, with a range of 16.8-36.4% per zone. This exceeds the international recommendations of examining 10 suspects to identify one case. A total of 4099 (26%) of the suspects had at least one positive smear with 3753 (91.6%) of the first specimens being positive. A further 303 (7.4%) were negative in the first specimen but had a positive second specimen and 42 (1%) suspects had two negative specimens followed by a positive third smear. The value of the third sputum is negligible as 99% of the cases were identified from the first and second specimens. Reducing the number of specimens to two or even one would have multiple advantages in countries where laboratories are usually over-burdened and are not easily accessible to the population. Submission of two specimens on the same day could improve compliance in submitting samples and collecting results as the number of diagnostic visits would be reduced without significant loss of sensitivity.     

武汉市社区肺结核可疑症状者求医行为及其影响因素分析

目的 了解武汉市社区肺结核可疑症状者的求医行为及其影响因素,为提高肺结核患者发现率提供依据。 方法 采用整群等比例随机抽样方法,抽取4个调查点,每个调查点15岁以上常住人口共5878名。2010年5-7月,筛选出调查前6个月内连续咳嗽、咯痰2周以上或咯血、痰中带血者作为调查对象（共270名）,进行面访式问卷调查。270份调查问卷中,259份合格,合格率95.9%。对270名调查对象进行X线胸片检查、3次痰涂片和2次痰培养检查。用卡方检验及logistic回归对肺结核可疑症状者求医行为的影响因素进行分析。 结果 259例中,79例（30.5%）没有任何求医行为,86例（33.2%）曾去社区及以上医疗机构正式就诊,89例（34.4%）曾自我药疗,5例（1.9%）曾去私人诊所就诊。多因素logistic回归分析显示,有无医疗保障与可疑症状者是否正式就诊相关,差异有统计学意义（β=1.225,Wald χ²=3.955,OR=3.405, 95%CI＝1.018~11.392,P<0.05）;有无严重或慢性呼吸道症状与可疑症状者是否正式就诊高度相关,差异有统计学意义（β=1.601,Wald χ²=22.210,OR=4.959, 95%CI＝2.548~9.652,P<0.01）;是否感到羞耻与可疑症状者是否正式就诊高度相关,差异有统计学意义（β=0.927,Wald χ²=7.767,OR=2.528, 95%CI＝1.317~4.853,P<0.01）。 结论 武汉市社区肺结核可疑症状者主动就诊率不高,有无医疗保障、有无严重或慢性呼吸道症状及是否感到羞耻是影响肺结核可疑症状者求医行为的主要因素。     

Prevalence of pulmonary tuberculosis and comparative evaluation of screening strategies in a Brazilian prison.

SETTING: A prison (1171 male inmates) in Rio de Janeiro, Brazil. OBJECTIVES: To determine the prevalence of active pulmonary tuberculosis (TB) and to assess the performance of several screening strategies. DESIGN: In a cross-sectional study, all inmates underwent chest radiographic screening. Subjects with abnormal findings underwent sputum smear examination and sputum culture. Taking this strategy as the reference, we assessed three targeted screening strategies to identify TB suspects: Strategy 1: cough >3 weeks; Strategy 2: WHO score > or = 5; Strategy 3: presence of at least one potentially TB-related symptom. RESULTS: The prevalence of TB cases was 4.6% (48/1052) and 2.7% for definite TB cases. If TB suspects identified by targeted screening had sputum smear examination alone, 37 (86.0%) of the 43 cases would have been missed by Strategy 1, 34/43 (79.1%) by Strategy 2 and 34/43 (79.1%) by Strategy 3. If TB suspects had both sputum smear examination and, for smear-negative subjects, chest radiography, respectively 28/43 (65.1%), 18/43 (41.9%) and 13/43 (30.2%) of cases would have been missed. CONCLUSION: All three targeted screening strategies were unreliable. Given the importance of early TB diagnosis in overcrowded and highly endemic settings, routine radiography-based screening may be warranted.     

Efficiency of serial smear examinations in excluding sputum smear-positive tuberculosis.

SETTING: This study determined the number of slides required to identify one additional case of sputum smear-positive tuberculosis (TB) from the third smear. The study hypothesis was that not more than 100 and 75 slides, respectively, in Mongolia and Zimbabwe, need to be examined to find one additional case of TB with a third serial diagnostic sputum smear examination. METHODS: In a retrospective, record-based study, data were abstracted from TB laboratory registers from all 31 laboratories in Mongolia and 23 randomly selected laboratories in Zimbabwe using a uniform EpiData collection instrument. RESULTS: A total of 52,909 records of examinees were available. In Mongolia, of 15 103 suspects, 1717 (11.4%) were positive. Of these, 0.7% were positive for the first time on the third smear examination. In Zimbabwe, of 25 693 suspects, 3452 (13.4%) were positive and 4.5% were positive only on the third smear examination. The expected number of slides required to detect one additional case on the third examination was 1153.3 for Mongolia and 132.6 for Zimbabwe. CONCLUSIONS: The requirement of routine examination of three serial smears before declaring a suspect as a 'non-case' (of sputum smear-positive TB) will need to be reviewed in both Mongolia and Zimbabwe.     

福清市设立乡镇初筛点提高结核病人发现探讨

目的　探讨在乡镇卫生院设立初筛点提高结核病发现率。方法 将全市22个乡镇(农场)分成6个初筛点,由其中1个中心卫生院负责痰涂片、X线检查,经市(县)结防科定诊。结果 2003年6个初筛点可疑症状者就诊率1.93%,查痰率85.8%,涂阳病人占67.2%,涂阳新登记率40.6/10万,分别比2002年提高了91.1%,14.4%,60.4%,20.1%。结论 通过乡镇初筛既可提高结核病服务的可行性,又能提高涂阳病例发现。     

综合医院结核病查痰点痰检工作分析

目的分析综合医院门诊可疑肺结核症状者查痰工作情况,探讨综合医院提高涂阳病人发现的措施。方法根据综合医院和结防机构门诊病人登记本、查痰登记本、转诊登记本及结防机构对综合医院的督导和痰检质量控制情况进行综合分析和评价。结果40所综合医院1年间,共登记可疑肺结核症状者11 303例,发现涂阳肺结核859例,涂阳检出率15.6%,转到结防机构的涂阴及未查痰病人2 094例,在结防机构查痰1 685例,发现涂阳肺结核804例,涂阳检出率47.7%,其中未查痰直接转到结防机构查痰1 026例,发现涂阳肺结核551例,涂阳检出率53.7%,痰阴病人转到结防机构再查痰659例,发现涂阳肺结核253例,涂阳检出率38.4%,结防机构门诊查痰25 238例,涂阳检出率55.7%,与综合医院涂阳检出率比较差异有显著性(P<0.05)。结论在综合医院建立查痰点,加大行政干预力度,加强综合医院与结防机构的合作,医院内相关科室建立协调机制,将痰检工作纳入综合医院临床检查常规项目,加强痰检质量控制和结防专业机构对综合医院相关专业人员的培训和复训,是提高传染源发现水平的有效途径。     

Prevalence of smear-positive pulmonary tuberculosis in a rural district of Ethiopia.

SETTING: A rural district in Southern Ethiopia. OBJECTIVE: To estimate the prevalence of smear-positive pulmonary tuberculosis (TB). DESIGN: In this cross-sectional study, adults aged >14 years were surveyed by home-to-home visit, and asked about cough of > or = 2 weeks with or without sputum, chest pain or difficulty in breathing. Symptomatic suspects submitted three sputum samples for standard smear microscopy. RESULTS: Of 16697 adults surveyed, 436 (2.6%) were symptomatic and submitted sputum samples. Thirteen (3%) were positive for acid-fast bacilli, and the prevalence of smear-positive TB was 78 per 100 000 population (95%CI 36-120). Twenty-four smear-positive cases identified through the existing health care delivery were on anti-tuberculosis medication at the time of the survey. The ratio of smear-positive cases on treatment to those newly detected by the survey was 2:1. CONCLUSION: The prevalence of TB in this rural setting was unexpectedly low. For every two cases of smear-positive TB on treatment, there was one undetected infectious case in the community. However, as our screening technique did not allow detection of cases who did not report symptoms, the true prevalence may have been underestimated.     

Reducing the number of sputum samples examined and thresholds for positivity: an opportunity to optimise smear microscopy.

SETTING: Urban health clinic, Nairobi. OBJECTIVE: To evaluate the impact on tuberculosis (TB) case detection and laboratory workload of reducing the number of sputum smears examined and thresholds for diagnosing positive smears and positive cases. DESIGN: In this prospective study, three Ziehl-Neelsen stained sputum smears from consecutive pulmonary TB suspects were examined blind. The standard approach (A), > or = 2 positive smears out of 3, using a cut-off of 10 acid-fast bacilli (AFB)/100 high-power fields (HPF), was compared with approaches B, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3, one of which is > or = 10 AFB/100 HPF; C, > or = 2 positive smears (> or = 4 AFB/100 HPF) out of 3; D, > or = 1 positive smear (> or = 10 AFB/100 HPF) out of 2; and E, > or = 1 positive smear (> or = 4 AFB/100 HPF) out of 2. The microscopy gold standard was detection of at least one positive smear (> or = 4 AFB/100 HPF) out of 3. RESULTS: Among 644 TB suspects, the alternative approaches detected from 114 (17.7%) (approach B) to 123 cases (19.1%) (approach E) compared to 105 cases (16.3%) for approach A (P < 0.005). Sensitivity ranged between 82.0% (105/128) for A and 96.1% (123/128) for E. The single positive smear approaches reduced the number of smears by 36% compared to approach A. CONCLUSION: Reducing the number of specimens and the positivity threshold to define a positive case increased the sensitivity of microscopy and reduced laboratory workload.     

Efficiency of a third serial sputum smear examination in the diagnosis of tuberculosis in Moldova and Uganda.

SETTING: Twenty-four and 30 tuberculosis (TB) microscopy laboratories in Moldova and Uganda, respectively. OBJECTIVE: To estimate the workload required to identify one additional case of TB with a third serial sputum smear examination. METHODS: Retrospective laboratory register study to determine the prevalence and the incremental yield of TB cases from a third serial sputum smear examination among suspects in Moldova and Uganda, with the reciprocal of the product of these two fractions providing the number of examinations required to identify one additional TB case. RESULTS: In Moldova, 9% (1141/12525) and in Uganda 20% (7280/36054) of suspects met the TB case definition with at least one positive sputum smear. The incremental yield from the third examination was 4% in Moldova and 3% in Uganda. To detect one additional TB case on a third smear, 273 examinations (95%CI 200-389) in Moldova and 175 (95%CI 153-222) in Uganda were thus required. This corresponded to an average of 11 days (8-16) and 7 days (6-9), respectively, to diagnose one additional case of TB. CONCLUSION: In both countries, the third serial sputum smear examination was inefficient in diagnosing sputum smear-positive TB.     

Validation of the surveillance system for tuberculosis in Botswana.

SETTING: Gaborone and Francistown, Botswana, where surveillance data in the 1997 Electronic Tuberculosis (TB) Register suggest that 39% of pulmonary TB patients did not have pre-treatment sputum smear microscopy performed. OBJECTIVE: To determine the proportion of patients with reportedly missing pre-treatment sputum smear results in 1997 who had smears examined, and to identify stages in the system where results were lost. METHODS: Patients with pulmonary TB in 1997 who were missing pre-treatment sputum smear results in the Electronic TB Register were cross-matched with laboratory records; medical records were reviewed. RESULTS: Of 374 patients with pre-treatment sputum smear results missing, 224 (60%) actually had had a sputum smear examined in the laboratory. The proportion of pulmonary TB patients in Gaborone and Francistown who did not have sputum examined was therefore 16% instead of 39%. Most missing results (69%) had not been transcribed from the laboratory results onto the TB Treatment Card. Patients who had a negative smear result or who sought care at a clinic that was different from where their diagnostic evaluation had been initiated were more likely to have missing results. CONCLUSIONS: The actual performance of the Botswana National TB Programme with respect to sputum microscopy examination is much better than surveillance indicators suggest. In addition to sputum collection, proper recording of results needs reinforcement among health care workers to improve routine performance indicators.     

四川省成都市入户调查集中推荐可疑症状者检查发现肺结核患者分析

目的 探讨入户调查、集中推荐发现病人方式对提高肺结核病人发现的作用。 方法 采取政府组织、部门参与、开展健康教育,发动群众自报互报;镇村干部配合、乡村医生入户调查、登记常住人口,以当面询问与观察的方式发现线索患者,并集中推荐到指定医院初筛,疑似患者由结防机构定诊。 结果 成都市于2009年先后在9个区县入户登记应调查人数3 910 504人,实际调查3 817 928人,调查率97.6%,新发现活动性肺结核411例,其中新发涂阳172例,占41.8%;新发现活动性病例数与涂阳新病例数分别占同期CDC登记总病例数的23.8%和21.9%。 结论 适时开展入户调查集中推荐可疑者就诊是提高病人发现率的有效方法 。通过入户调查、集中推荐工作的实施,有利于现代结核病控制策略落实到基层;有利于提高群众推荐可疑者、可疑者主动就诊的积极性,提高肺结核患者的发现。     

利用症状者检查作为肺结核患病率调查方法的研究

目的　建立一个新的肺结核病涂阳患病率调查方法及其推算公式。方法 利用肺结核可疑症状者与无肺结核可疑症状者涂阳病人数构成比的参数作常数,建立直接症状检查法及其推数公式,并作费用分析。结果 (1)有肺结核可疑症状者与无结核症状者的涂阳病人比例,分别为 75%和25%。以此参数建立的(直接症状检查法 )肺结核涂阳患病率计算公式为:R=Sn×(1+1/3)N。R为肺结核涂阳患病率;Sn为有症状者患病人数;N为调查人数。(2)直接症状检查法调费用低,仅为普查法的24 .3%。结论 新建立的直接症状检查法样本大、参数(常数)稳定、科学性好、调查方法简便、实施工作费用低,可作为今后的肺结核患病率调查方法。     

黔南州结核病传染源调查研究

目的　探索结核病传染源的发现方法,了解其分布,为制定结核病控制措施提供科学依据。方法 选择 12个县市中的 8个县为调查点,余 4个县为对照点。调查点与对照点县疾控中心设结核防治组,负责可疑结核病例的痰检,对胸片或胸透异常及有可疑结核病症状者,进行痰涂片检查。调查点工作内容除病例痰检免费、涂阳病例免费治疗外与对照相同。结果 调查点肺结核报告病例痰检率 51.1%,涂阳年登记率 25.99/10万,对照点肺结核痰检率 18.3%,涂阳病例年登记率 0.26/10万 ;临床首诊为支气管炎、肺部感染和其他痰病病例中结核菌检出率分别为 12.4%、11.8%、8.2%。结论 农村结核感染形势严峻,政府应加大投入,对农村现阶段应免费痰检,涂阳病例免费治疗,医疗单位应将结核菌痰检作为呼吸系统疾病的常规检验项目,以及早发现传染源。     

Application value of GeneXpert MTB/RIF system in diagnosis of pulmonary tuberculosis

为了解利福平耐药实时荧光定量核酸扩增检测技术(GeneXpert MTB/RIF)在初诊肺结核患者诊断中的应用价值,作者收集了2015年1月至2016年12月浙江省嘉兴市第一医院就诊的初诊疑似肺结核患者361例,留取痰液标本分别进行涂片荧光金胺O染色镜检(简称“涂片镜检”)、结核分枝杆菌MGIT 320液体培养(简称“液体培养”)、GeneXpert MTB/RIF检测(简称“Xpert检测”)和固体比例法药物敏感性试验。最终临床诊断为:肺结核184例(50.97%),肺部感染162例(44.88%),非典型分枝杆菌肺部感染15例(4.15%)。361例疑似肺结核患者中,Xpert 检测的阳性率[32.41%(117/361)]明显高于涂片镜检[22.71%(82/361)](χ ²=8.49,P<0.05),与液体培养[26.32%(95/361)]比较不存在明显差异(χ ²=3.23,P=0.072),涂片镜检法与液体培养法比较差异无统计学意义(χ ²=1.26,P=0.261)。184例肺结核患者中,Xpert 检测的阳性率[63.59%(117/184)]高于涂片镜检[36.41%(67/184)]和液体培养[48.91%(90/184)](χ ²=27.17,P<0.01;χ ²=8.05,P<0.05);117例涂阴肺结核患者的Xpert检测阳性率[42.74%(50/117)]高于液体培养[24.79%(29/117)](χ ²=8.43,P=0.004)。以临床诊断为标准,Xpert检测初诊疑似肺结核患者的敏感度为63.59%(117/184),特异度为100.00%(177/177),正确指数为0.64。以固体比例法药物敏感性试验结果为金标准,Xpert 检测利福平耐药的敏感度为4/5,特异度为97.70%(85/87),正确指数为0.97。说明GeneXpert MTB/RIF在初诊疑似肺结核患者,尤其是涂阴肺结核患者中,检测结核分枝杆菌感染及对利福平耐药具有较高的效能。