Latent class analysis

潜在类别分析
  • 文章类型: Journal Article
    背景:这项研究的目的是确定50μl(TBS-50)的厚血涂片的性能指标,遵循诊断准确性研究报告标准-贝叶斯潜在类别模型(STARD-BLCM)指南。将TBS-50与两种常见的寄生虫学技术-直接检查10μl血液和5ml的白细胞浓度-进行了比较,以诊断微丝病。
    方法:研究人群是在寄生虫-真菌学-热带医学系1年的患者中招募的。年龄,性别,症状,和嗜酸性粒细胞增多症变量从实验室登记簿和医疗档案中记录.直接检查10μl血液,对每位患者进行TBS-50和5ml血液的白细胞浓缩技术。经典公式和BLCM用于确定这三种技术的诊断准确性以及微丝病的患病率。在BLCM的框架内建立了三个模型-BLCM模型I和替代模型II和III-用于敏感性分析。
    结果:总计,191名患者同意纳入。直接血液检查和TBS-50产生了可比的定性和定量结果。因此,他们一起报告。Loaloa微丝血症的患病率为9.4%(95%CI5.7-14.5;n=18/191),采用直接血液检查/TBS-50,白细胞浓度为12.6%[8.2-18.1](n=24/191)。将TBS-50与使用经典公式的白细胞浓缩方法进行比较,灵敏度为75.0%[53.3-90.2],特异性为100.0%[97.8-100.0],阳性预测值为100.0%[81.5-100.0],阴性预测值为96.5%[92.6-98.7]。使用BLCM模型I估计微丝病的患病率为9.7%[6.2-13.7]。BLCM模型I的输出显示灵敏度为78.9%[65.3-90.3],特异性为100.0%[99.3-100.0],阳性预测值为99.1%[87.2-100.0],直接血液检查/TBS-50的阴性预测值为93.0%[87.3-97.7]。
    结论:TBS-50相对于其他两种技术显示出低灵敏度。在五分之一的案例中,使用这些方法,结果将被错误地声明为否定。然而,这种方法可以用有限的资金来部署。
    BACKGROUND: The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies-Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques-direct examination of 10 µl blood and a leukoconcentration of 5 ml-for the diagnosis of microfilaremic loiasis.
    METHODS: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM-the BLCM model I and alternative models II and III-for sensitivity analysis.
    RESULTS: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7-14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2-18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3-90.2], specificity was 100.0% [97.8-100.0], the positive predictive value was 100.0% [81.5-100.0], and the negative predictive value was 96.5% [92.6-98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2-13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3-90.3], specificity of 100.0% [99.3-100.0], a positive predictive value of 99.1% [87.2-100.0], and a negative predictive value of 93.0% [87.3-97.7] for direct blood examination/TBS-50.
    CONCLUSIONS: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds.
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  • 文章类型: Journal Article
    背景:意识,知识,信仰,和身体活动行为意向(PA)指南可能是促进PA的重要中介因素。然而,这些心理过程到PA行为的途径尚未研究。这些途径可能因健康素养水平而异。这项研究调查了PA的途径,从准则意识到行为,并进一步检查了它们是否因健康素养而有所不同。
    方法:对7,000名20-69岁的日本参与者进行了横断面研究。参与者在一家互联网调查公司注册。参与者的意识,知识,信仰,以及关于日本PA指南的行为意图,中等强度至剧烈强度PA的体积,活动水平,和健康素养通过问卷调查。PA途径,从准则意识到行为,通过结构方程模型(SEM)进行检验,以PA行为为因变量。采用多组扫描电镜观察健康素养对PA通路的调节作用。在多组建模中,健康素养得分按中位数划分为高低组。
    结果:SEM揭示,PA指南意识直接影响PA行为,并通过知识的调解具有一定的间接作用,信仰,和行为意图。此外,多组SEM显示,在高健康素养组中,间接效应(路径系数[PC]:0.11,95%置信区间[CI]:0.10-0.13)的比例高于直接效应(PC:0.07,95CI:0.03-0.11)。相比之下,在低健康素养组中,直接效应(PC:0.22,95CI:0.15-0.30)的比例高于间接效应(PC:0.06,95CI:0.05-0.07)。
    结论:PA指南意识与PA行为直接或间接相关,由知识的心理途径介导,信仰,和行为意图,并受到健康素养的影响。这些结果表明,在实施基于PA指南的干预措施时应考虑健康素养。
    Awareness, knowledge, beliefs, and behavioral intentions of physical activity (PA) guidelines may be important mediating factors for promoting PA. However, these pathways of the psychological process to PA behavior have not been examined. These pathways may differ depending on health literacy levels. This study investigated the pathways to PA, from guideline awareness to behavior, and further examined whether they differed by health literacy.
    A cross-sectional study was conducted with 7,000 Japanese participants aged 20-69 years. The participants were registered with an Internet survey company. Participants\' awareness, knowledge, beliefs, and behavioral intentions regarding the PA guidelines of Japan, the volume of moderate-to-vigorous intensity PA, activity level, and health literacy were examined through a questionnaire. The PA pathways, from guideline awareness to behavior, were examined by structural equation modeling (SEM), with PA behavior as the dependent variable. Multi-group SEM was conducted to examine the moderating effect of health literacy on PA pathways. Health literacy scores were dichotomized into high and low groups in multi-group modeling by the median split.
    SEM revealed that PA guideline awareness directly affects PA behavior and has certain indirect effects through the mediation of knowledge, beliefs, and behavioral intentions. Furthermore, the multi-group SEM showed that the proportion of indirect effects (path coefficient [PC]: 0.11, 95% confidence interval [CI]: 0.10-0.13) was higher than direct effects (PC: 0.07, 95%CI: 0.03-0.11) in the high-health literacy group. In contrast, the proportion of direct effects (PC: 0.22, 95%CI: 0.15-0.30) was higher than indirect effects (PC: 0.06, 95%CI: 0.05-0.07) in the low-health literacy group.
    PA guideline awareness is both directly and indirectly associated with PA behavior, mediated by psychological pathways of knowledge, beliefs, and behavioral intentions, and influenced by health literacy. These results suggest that health literacy should be considered when implementing PA guideline-based interventions.
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  • 文章类型: Journal Article
    BACKGROUND: Actuarial and statistical methods have been proposed as alternatives to conventional methods of diagnosing mild cognitive impairment (MCI), with the aim of enhancing diagnostic and prognostic validity, but have not been compared in racially diverse samples.
    OBJECTIVE: We compared the agreement of consensus, actuarial, and statistical MCI diagnostic methods, and their relationship to race and prognostic indicators among diverse older adults.
    METHODS: Participants (N = 354; M age = 71; 68% White, 29% Black) were diagnosed with MCI or normal cognition (NC) according to clinical consensus, actuarial neuropsychological criteria (Jak/Bondi), and latent class analysis (LCA). We examined associations with race/ethnicity, longitudinal cognitive and functional change, and incident dementia.
    RESULTS: MCI rates by consensus, actuarial criteria, and LCA were 44%, 53%, and 41%, respectively. LCA identified three MCI subtypes (memory; memory/language; memory/executive) and two NC classes (low normal; high normal). Diagnostic agreement was substantial, but agreement of the actuarial method with consensus and LCA was weaker than the agreement between consensus and LCA. Among cases classified as MCI by actuarial criteria only, Black participants were over-represented, and outcomes were generally similar to those of NC participants. Consensus diagnoses best predicted longitudinal outcomes overall, whereas actuarial diagnoses best predicted longitudinal functional change among Black participants.
    CONCLUSIONS: Consensus diagnoses optimize specificity in predicting dementia, but among Black older adults, actuarial diagnoses may be more sensitive to early signs of decline. Results highlight the need for cross-cultural validity in MCI diagnosis and should be explored in community- and population-based samples.
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  • 文章类型: Journal Article
    BACKGROUND: Prevalence figures for health-related behaviors disguise the existence of behavioral clusters. A growing body of work indicates the potential effectiveness of using simultaneous (versus sequential) approaches to targeting health-related behaviors to make deeper inroads into addressing non-communicable diseases. To inform future interventions designed to simultaneously address multiple risk factors, the aim of the present study was to identify behavioral clusters including nine behaviors relating to smoking, alcohol consumption, nutrition, physical activity, and sleep.
    METHODS: A latent class analysis was applied to a nationally representative sample of 1849 adult Australians.
    RESULTS: Of the four identified segments, one was characterized by a relatively healthy behavioral profile and another demonstrated poor results across multiple lifestyle domains. The other two groups comprised individuals who demonstrated healthy behaviors in some domains (e.g., substance use) but not in others (primarily physical inactivity and junk food consumption, respectively).
    CONCLUSIONS: Results suggest the opportunity to encourage individuals in the latter two groups to build on existing positive behaviors to achieve greater overall compliance with health recommendations. Particularly intensive interventions are likely needed for those in the unhealthiest group to address the potentially reinforcing effects of their multiple unhealthy behaviors.
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  • 文章类型: Journal Article
    报告根据新的Delphi共识定义诊断的选择性胎儿生长受限(sFGR)的结局。并确定潜在的生存预测因子,在一组未经选择的单绒毛膜双胎妊娠中。
    这是一项从头三个月开始的单绒毛膜双胎妊娠的回顾性研究,在妊娠16、20或30周被诊断为sFGR。根据新的Delphi共识标准将sFGR定义为在一个双胞胎中存在估计的胎儿体重(EFW)<3百分位数或以下至少两个:一个双胞胎的EFW<10百分位数,一对双胞胎的腹围<10百分位数,EFW不一致≥25%或较小双胞胎的脐动脉搏动指数>95百分位。主要结果是总体生存率(直到出生后第28天)和失去一个或两个双胞胎的风险。我们使用单和多变量广义估计方程模型进一步确定了可能的生存预测因子。
    我们分析了675例怀孕,其中177例(26%)在16、20或30周时被诊断为sFGR。总体生存率为313/354(88%)和146/177(82%)怀孕导致两个双胞胎的存活。一对双胞胎的存活率为21/177(12%),而两个双胞胎的存活率为10/177(6%)。随后的双胎贫血-红细胞增多症序列(TAPS)在6/177(3%)妊娠中发生,双胎-双胎输血综合征(TTTS)在17/177(10%)妊娠中发生。所有TAPS胎儿都存活了下来。随后发展为TTTS的sFGR妊娠的存活率为65%(22/34),与分离的sFGR(没有随后的TAPS或TTTS)的91%(279/308)相比(P<0.001)。大多数sFGR病例为I型(110/177(62%)),生存率为96%(212/220),与II型(P<0.001)和III型(P=0.006)sFGR患者的生存率分别为55%(12/22)和83%(55/66)。大多数sFGR妊娠(130/177(73%))在16或20周(早期发作)首次诊断。存活率为85%(221/260),与首次诊断为30周(迟发)的sFGR的98%(92/94)生存率相比(P=0.04)。在28/177(16%)sFGR病例中,至少有一个双胞胎存在重大异常。在这些怀孕中,生存率为39/56(70%),无异常者为274/298(92%)(P<0.001)。TTTS的后续发展(比值比(OR),0.18(95%CI,0.06-0.52)),II型sFGR(或,0.06(95%CI,0.02-0.24))和III型sFGR(OR,0.21(95%CI,0.07-0.60))和至少一个双胞胎中存在重大异常(OR,0.12(95%CI,0.04-0.34)),但不是第一次诊断时的胎龄,与生存率下降独立相关。
    在单绒毛膜双胎妊娠中,分离的sFGR与90%的存活率相关。TTTS的后续发展,较小的双胞胎的脐动脉中缺乏或逆转的舒张末期血流以及主要异常的存在对sFGR的存活率产生不利影响。版权所有©2020ISUOG。由JohnWiley&SonsLtd.发布.
    To report the outcome of selective fetal growth restriction (sFGR) diagnosed according to the new Delphi consensus definition, and determine potential predictors of survival, in a cohort of unselected monochorionic diamniotic twin pregnancies.
    This was a retrospective study of monochorionic diamniotic twin pregnancies followed from the first trimester onward, which were diagnosed with sFGR at 16, 20 or 30 weeks\' gestation. sFGR was defined according to the new Delphi consensus criteria as presence of either an estimated fetal weight (EFW) < 3rd centile in one twin or at least two of the following: EFW of one twin < 10th centile, abdominal circumference of one twin < 10th centile, EFW discordance ≥ 25% or umbilical artery pulsatility index of the smaller twin > 95th centile. The primary outcomes were the overall survival rate (up to day 28 after birth) and risk of loss of one or both twins. We further determined possible predictors of survival using uni- and multivariate generalized estimated equation modeling.
    We analyzed 675 pregnancies, of which 177 (26%) were diagnosed with sFGR at 16, 20 or 30 weeks. The overall survival rate was 313/354 (88%) with 146/177 (82%) pregnancies resulting in survival of both twins, 21/177 (12%) in survival of one twin and 10/177 (6%) in loss of both twins. Subsequent twin anemia-polycythemia sequence (TAPS) developed in 6/177 (3%) and twin-twin transfusion syndrome (TTTS) in 17/177 (10%) pregnancies. All TAPS fetuses survived. The survival rate in sFGR pregnancies that subsequently developed TTTS was 65% (22/34), compared with 91% (279/308) in those with isolated sFGR (no subsequent TAPS or TTTS) (P < 0.001). The majority of sFGR cases were Type I (110/177 (62%)) and had a survival rate of 96% (212/220), as compared with a survival of 55% (12/22) in those with Type-II (P < 0.001) and 83% (55/66) in those with Type-III (P = 0.006) sFGR. The majority of sFGR pregnancies (130/177 (73%)) were first diagnosed at 16 or 20 weeks (early onset), with a survival rate of 85% (221/260), as compared with a survival of 98% (92/94) in sFGR first diagnosed at 30 weeks (late onset) (P = 0.04). A major anomaly in at least one twin was present in 28/177 (16%) sFGR cases. In these pregnancies, survival was 39/56 (70%), compared with 274/298 (92%) in those without an anomaly (P < 0.001). Subsequent development of TTTS (odds ratio (OR), 0.18 (95% CI, 0.06-0.52)), Type-II sFGR (OR, 0.06 (95% CI, 0.02-0.24)) and Type-III sFGR (OR, 0.21 (95% CI, 0.07-0.60)) and presence of a major anomaly in at least one twin (OR, 0.12 (95% CI, 0.04-0.34)), but not gestational age at first diagnosis, were independently associated with decreased survival.
    Isolated sFGR is associated with a 90% survival rate in monochorionic diamniotic twin pregnancies. The subsequent development of TTTS, absent or reversed end-diastolic flow in the umbilical artery of the smaller twin and the presence of a major anomaly adversely affect survival in sFGR. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.
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  • 文章类型: Journal Article
    阿拉伯国家的大学生缺乏对健康行为的研究,例如体育锻炼和健康营养及其结合。当前的调查评估了健康的营养,埃及6266名学生的中等/剧烈体力活动(PA),利比亚,和巴勒斯坦。我们使用世卫组织的建议计算了营养指南成就指数,以及使用美国心脏协会指南的成人指南实现PA建议。潜在班级回归分析确定了同质的男女学生群体,基于他们对这两个准则的成就。我们检查了组成员资格与指南成就之间的关联。三级解决方案模型最好地拟合了数据,产生三个学生群体:“健康饮食者”(7.7%的女性,10.8%的男性),“身体活跃”(21.7%的女性,25.8%的男性),和“低健康行为”(70.6%的女性,63.4%的男性)。我们没有观察到一个潜在的类别,表现出相结合的健康行为(身体活跃和健康的饮食),国家之间没有重大差异。我们观察到健康营养的比率非常低(约10%的学生达到了八项营养指南中的四项以上),各国的性别差异很小。大约18-47%的学生达到了PA指南,根据国家和性别,更多的是男性。很少有女性达到PA指南,特别是在利比亚和巴勒斯坦。文化适应的多行为干预需要鼓励健康的生活方式,营养和PA行为。国家政策需要促进积极生活,同时解决文化、地理,以及其他阻碍年轻人参与PA的障碍。
    Research on healthy behaviour such as physical activity and healthy nutrition and their combination is lacking among university students in Arab countries. The current survey assessed healthy nutrition, and moderate/vigorous physical activity (PA) of 6266 students in Egypt, Libya, and Palestine. We computed a nutrition guideline achievement index using WHO recommendation, as well as the achievement of PA recommendations using guidelines for adults of the American Heart Association guidelines. Latent class regression analysis identified homogenous groups of male and female students, based on their achievements of both guidelines. We examined associations between group membership and achievement of guidelines. A three-class solution model best fitted the data, generating three student Groups: \"Healthy Eaters\" (7.7% of females, 10.8% of males), \"Physically Active\" (21.7% of females, 25.8% of males), and \"Low Healthy Behaviour\" (70.6% of females, 63.4% of males). We did not observe a latent class that exhibited combined healthy behaviours (physically active and healthy eaters), and there were no major differences between countries. We observed a very low rate of healthy nutrition (≈10% of students achieved greater than four of the eight nutrition guidelines), with little gender differences across the countries. About 18-47% of students achieved the PA guidelines, depending on country and gender, more often among males. Few females achieved the PA guidelines, particularly in Libya and Palestine. Culturally adapted multi-behavioural interventions need to encourage healthy lifestyles, nutrition and PA behaviours. National policies need to promote active living while addressing cultural, geographic, and other barriers to young adults\' engagement in PA.
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  • 文章类型: Journal Article
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