Diagnostic performance indices for immunofluorescent tests and enzyme immunoassays of leishmaniasis sera from northern and north-eastern Brazil

A total of 341 sera were screened for anti-Leishmania IgA, IgG, and IgM antibodies by immunofluorescent (IF) tests and enzyme immunoassay (ELISA). Altogether, 292 of the sera originated from patients with clinically as well as parasitologically diagnosed (positive lesion imprint or the Montenegro skin test) cutaneous leishmaniasis; 49 of the sera were from controls from the same base population. In terms of diagnostic performance, the ELISAs for IgG and IgM yielded indices of diagnostic utility, and the positive predictive value for the IgG-ELISA was 94.6%. A remarkably high specificity (100%) was obtained with the IgA-IF test, but its sensitivity was very low.     

IgM抗体捕捉ELISA法在麻疹血清学诊断上的优越性

本文用ACELISA法、ELISA-IgG法、HI法测定了临床诊断为麻疹的100对患者双份血清,其中8份三种方法都为阴性。余92对血清的三种方法诊断阳性率分别为ACELISA法98.9%,ELISA-IgG法82.6%,HI法69.4%,证明ACELISA法是诊断麻疹较好的方法,有敏感、特异、早期、多数仅需单份血清就能诊断等的优点。IgM抗体发病第二天开始出现,病后第2周达到高峰,一个月后明显下降或阴转,故ACELISA法诊断的适宜采血时期为发病第3~25天。     

LEPTO Dipstick: a rapid and simple method for serodiagnosis of acute leptospirosis.

The LEPTO Dipstick assay is a newly developed test for the diagnosis of leptospirosis and uses a broadly reactive antigen for detecting IgM antibodies. The test was evaluated in the Andaman and Nicobar Islands, using 867 serum samples from known cases of leptospirosis and controls. The efficacy of IgM ELISA was also tested for comparison. The LEPTO Dipstick had a sensitivity of 78.7%, a specificity of 88.3% and a positive predictive value of 91.0%. The test had a good level of agreement with the standard criteria for diagnosis using paired microscopic agglutination tests (kappa = 0.64). These indices were similar to those of IgM ELISA (sensitivity 78.5%, specificity 87.6%, positive predictive value 90.5%, kappa 0.63). Both the LEPTO Dipstick and IgM ELISA had the highest sensitivity during the second, third and fourth weeks of illness (87.6% and 88.2%, respectively). Sensitivities during the first week and after 4 weeks were relatively low but acceptable. The test is very easy to perform and does not require any special skills for its performance. The reagents and dipsticks have a long shelf-life even at room temperature. As the test can be performed without the aid of sophisticated equipment, it is suitable for use at the peripheral level as a rapid screening test for the diagnosis of leptospirosis.     

Waist circumference a good indicator of future risk for type 2 diabetes and cardiovascular disease

ABSTRACT: BACKGROUND: Abdominal obesity is a more important risk factor than generalised obesity for the development of type 2 diabetes and cardiovascular disease. For preventive and public health purposes it is vital that risk factors are detected as early as possible, in order to affect the lifestyle choices at an individual level. METHODS: We used the data from a community based study assessing the risk for type 2 diabetes and cardiovascular disease and the prevalence of the metabolic syndrome among middle-aged men in Helsinki. From the data we performed sensitivity and specificity analysis including positive and negative predictive values, and corresponding 95% CI for eleven different cut-off points with 1 cm intervals (92 to 102 cm) of waist circumference to identify those with increased risk for type 2 diabetes and/or cardiovascular disease. RESULTS: Waist circumference => 94 cm in middle-aged men, identified subjects with increased risk for type 2 diabetes and/or for cardiovascular disease with a sensitivity of 84.4% (95% CI 76.4% to 90.0%), and specificity of 78.2% (95% CI 68.4% to 85.5%). The respective positive predictive value is 82.9% (95% CI 74.8% to 88.8%), and negative predictive value 80.0% (95% CI 70.3% to 87.1%). CONCLUSIONS: Measurement of waist circumference in middle-aged men is a reliable test to identify individuals at increased risk for type 2 diabetes and cardiovascular disease. This measurement should be used more in daily practice in primary health care to identify individuals at risk and when planning health counselling and interventions.     

Diagnostic Value of Urine Strip Testing for White Blood Cells: an Implication for Screening in Individuals with Spinal Cord Injury

Urinary tract infection (UTI) is an important health problem affecting millions of people each year. A significant high incidence of UTI can be seen in individuals with disabilities, especially those with paralysis due to spinal cord injury. Dip stick screening tests may offer promise as an early warning system of UTI since they are easy to perform and can be self-administered. Here, we report our experience of the diagnostic value of the urine strip test for white blood cell count in medical laboratory practice. The sensitivity of urine strip test was 100%, the specificity 92.2%, the positive predictive value 33.8% and the negative predictive value 100%. False positive was 7.8% and false negative 0%. This can confirm the needs for further examination in cases with positive urine strip screening test. Hence, the usage of urine strip examination as a screening tool for pyuria, an early sign of UTI among people with disabilities is recommended.     

Basophil activation test in the diagnosis of allergy to medicines

In this paper we study the reliability of the basophil activation test (BAT) in the "in-vitro" diagnosis of allergy to betalactams and to metamizol, and the sensitivity and specificity of the technique are analyzed. To this end, we studied 58 patients allergic to betalactam antibiotics with a positive cutaneous test facing any derivative of penicillin and 30 healthy controls who tolerated betalactams, and 26 patients allergic to metamizol with an immediate reaction and 30 healthy controls who tolerated the medicine. Sensitivity to BAT in allergy to betalactams was 52.8%, and specificity was 92.6%. For metamizol, sensitivity was 42.3% and specificity was 100%. The positive predictive value of BAT in allergy to betalactams was 18.9% and the negative predictive value was 98.4%. For metamizol, the positive predictive value of the technique was 100% and the negative predictive value was 99.4%. The joint use of BAT and CAP (specific IgE) makes it possible to diagnose some 65% of patients allergic to betalactams. The combined use of cutaneous tests and BAT in allergy to metamizol detects 70% of the cases. BAT is a useful, non-invasive technique in the "in-vitro" diagnosis of allergy to betalactams and metamizol.     

A simplified screening strategy for thalassaemia and haemoglobin E in rural communities in south-east Asia

OBJECTIVE: To evaluate a simple screening strategy for thalassaemia and haemoglobin (Hb) E in a prevention and control programme for thalassaemia in rural communities with limited resources. METHODS: Blood samples from 301 Thai-Khmer participants were screened for thalassaemia and Hb E using a combined modified one-tube osmotic fragility (OF) test and a modified dichlorophenolindophenol (DCIP) precipitation test. Results were evaluated with standard haematological analyses including erythrocyte indices, Hb typing and quantification and polymerase chain reaction (PCR) analysis of alpha-globin and beta-globin genes. FINDINGS: Participants were divided into four groups according to the results of the combined tests. Altogether, 104 of 301 participants (34.6%) had negative results on both tests; 48 (15.9%) were positive on the OF test but not the DCIP test; 40 (13.3%) were negative on the OF test but positive on DCIP test; and 109 (36.2%) were positive on both tests. No carrier of clinically significant forms of thalassaemia (alpha(o)-thalassaemia, beta-thalassaemia) or Hb E was found among the group that had negative results for both tests. All participants with Hb E had positive DCIP tests. Carriers of alpha+-thalassaemia or Hb Constant Spring could generate either positive or negative OF test results but they all had negative DCIP tests. Using both tests as a preliminary screening for the three important groups of carriers gave a sensitivity of 100% and a specificity of 69.8%. The positive predictive value of the combined test was 77.2%. The negative predictive value was 100%. Further evaluation of the screening system by local staff at three community hospitals found a sensitivity of 98.1-100% and a specificity of 65.4-88.4% with positive predictive values of 75.0-86.9% and negative predictive values of 98.1-100%. CONCLUSION: A combined test using OF and DCIP could be used as an effective preliminary screening alternative to an electronic blood cell count for identifying carriers with alpha(o)-thalassaemia, beta-thalassaemia and Hb E. The strategy should prove useful for population screening in prevention and control programmes in rural communities in south-east Asia where laboratory facilities and economic resources are limited.     

Validation of a questionnaire for epilepsy diagnosis in primary care services]

OBJECTIVE: To evaluate the usefulness of a questionnaire in primary health care services for establishing the diagnosis of epilepsy in children from 1 to 10 years old and for classifying their epileptic seizures. METHODS: This cross-sectional observational study was conducted in 2004. There were 204 children in the study (102 diagnosed with epilepsy and 102 without epilepsy). The children were randomly selected at the Regional Center of Epilepsies and the Vincent Corral Moscoso Hospital, which are both in the city of Cuenca, Ecuador. For the study, each child with epilepsy was matched with a child without epilepsy, in two age groups: 1 to 5 years old and 6 to 10 years old. Four students who were in their last academic year in the School of Medicine of Cuenca and who did not know the child's diagnosis utilized the questionnaire with a family member or other guardian of the child. The validity, sensitivity, specificity, positive predictive value, and negative predictive value of the questionnaire were calculated, with 95% confidence intervals (95% CIs). The clinical diagnosis carried out by specialists was used as the gold standard. RESULTS: The assessment showed that the questionnaire had good sensitivity (95.10%; 95% CI: 94.58%-95.61%) and good specificity (97.06%; 95% CI: 96.58%-97.59%). Validity was 96.08% (95% CI: 95.84%-96.36%), with a positive predictive value of 97.00% (95% CI: 96.48%-97.52%) and a negative predictive value of 95.19% (95% CI: 94.74%-95.74%). The level of agreement in the classification of the epileptic seizures carried out by the neurologists and by the medical students who used the questionnaire was satisfactory for the generalized seizures (kappa = 0.67). Upon testing for interobserver agreement among the specialists, the kappa value for the diagnoses was 0.80 among the neurologists and 0.89 among the pediatricians. CONCLUSIONS: The diagnostic questionnaire that was assessed has good sensitivity and adequate specificity, and, after brief training, primary health care general practitioners can use it to help them diagnose epileptic seizures.     

Evaluation of antigen detection and antibody detection tests for Trypanosoma evansi infections of buffaloes in Indonesia.

Two Ag-ELISAs, an IgG-specific antibody detection ELISA (IgG ELISA) and a card agglutination test (CATT) for the detection of Trypanasoma evansi infections in buffaloes in Indonesia, were compared. Diagnostic sensitivity estimates were obtained by testing sera from 139 Indonesian buffaloes which had been found to be infected by parasitological tests. Diagnostic specificity was estimated by testing sera from 263 buffaloes living in Australia. Response-operating characteristic curves were constructed, and optimal ELISA cut-off values, which minimized the number of false-negative and false-positive results, were chosen. The IgG ELISA had the highest sensitivity (89%) and the CATT had the highest specificity (100%). There was a significant difference between the sensitivities (71 and 81%), but not between the specificities (75 and 78%), of the two Ag-ELISAs. The four tests were further compared by calculation of post-test probabilities of infection for positive and negative test results using a range of prevalence values, and likelihood ratios. The results suggested that the CATT was the best test to 'rule-in' infection (i.e. the highest probability of infection in test-positive animals) and the IgG ELISA was the best test to 'rule-out' infection (i.e. the lowest probability of infection in test-negative animals).     

Sensitivity, specificity and predictive value of hearing complaints

This study assessed the sensitivity, specificity and predictive value of hearing complaints in outpatients attending an university ear, nose and throat clinic. A cross-sectional study was carried out in Canoas, Southern Brazil, from 1999 to 2002. Seven-hundred and ninety-five subjects who underwent the audiometric test were analyzed. The results showed that the complaint of hearing loss presented 80.9% sensitivity, 69.6% specificity and 86.5% positive predictive value and 60.4% negative predictive value. Despite its subjective character, the audiometric test can be considered a reliable diagnostic tool and should be used due to its low cost compared to the new technologies.     

Meta-analysis of prostate-specific antigen and digital rectal examination as screening tests for prostate carcinoma

BACKGROUND: Physicians commonly screen for prostate cancer by using prostate-specific antigen (PSA) and digital rectal examination (DRE). The usefulness of these screening mechanisms is not well established, however. A meta-analysis of PSA and DRE to detect prostate carcinoma was conducted with a focus on sensitivity, specificity, and positive predictive value. METHODS: A literature search of OVID database (1966 to November 1999) using the medical subject headings "prostate-specific antigen" and "mass screening," as well as "prostate carcinoma," was performed. Thirteen articles were selected for the meta-analysis in this study. Most studies included asymptomatic men older than 50 years from various countries. Pooled results were calculated from the individual reports for sensitivity, specificity, and positive predictive value for PSA and DRE based on biopsy result as the reference standard. RESULTS: The overall detection rate of prostate carcinoma was 1.8% based on a positive biopsy. Of the prostate carcinoma detected, 83.4% was localized. The pooled sensitivity, specificity, and positive predictive value for PSA were 72.1%, 93.2% and 25.1%, respectively; and for DRE were 53.2%, 83.6% and 17.8%, respectively. CONCLUSIONS: There were two major outcomes of this meta-analysis. One was the potential for detecting early-stage prostate cancer with these screening tests, because 83.4% of total cancers detected were localized. The second important outcome was that the overall sensitivity, specificity, and positive predictive value for PSA were higher than those for DRE when used as a screening tool to detect prostate cancer. When a patient has abnormal findings using PSA and DRE, the chance of cancer is 1 in 4 or 5. Conversely, when findings from PSA and DRE are normal, the chance of missing a cancer is about 10%.     

Serological tests in leprosy. The sensitivity, specificity and predictive value of ELISA tests based on phenolic glycolipid antigens, and the implications for their use in epidemiological studies

This paper examines the sensitivity and specificity of two ELISA assays for IgM antibodies to Mycobacterium leprae, one employing natural phenolic glycolipid and the other employing a synthetic disaccharide glycoconjugate as antigen. Estimates of sensitivity and specificity are derived, based on a panel of sera from leprosy cases in Malawi and various non-leprosy controls from the UK. Though both assays were able to identify a high proportion of multibacillary patients, neither was able to detect a high proportion of paucibacillary patients without considerable loss of specificity. The implications of the inverse relationship between sensitivity and specificity are discussed with reference to the predictive value of such tests in such areas as Malawi, where the large majority of cases are paucibacillary.     

Seroepidemiology of Strongyloides infection in the Southeast Asian refugee population in Canada

As part of a screening and treatment program for intestinal parasite infections offered to newly arrived Southeast Asian refugees in Canada between July 1982 and February 1983, a total of 232 sera were tested for Strongyloides infection using an enzyme-linked immunosorbent assay (immunoglobulin G). These results were compared with coprologic results and eosinophil counts. The seroprevalence was 76.6% (131 of 171) among Kampucheans, 55.6% (15 of 27) among Laotians, and 11.8% (4 of 34) among Vietnamese. A statistically significant relation (p less than 0.001) was found between Strongyloides serology and Strongyloides infection on stool examination (prevalence, 24.7%) among Kampucheans. Eosinophilia (greater than or equal to 10%) was found to be significantly associated with both infection measures. Using coprologic results as the "gold standard," the properties of the serologic test were estimated to be: sensitivity (95%), specificity (29%), positive predictive value (30%), and negative predictive value (95%). These estimates should be regarded as minimal values, as stool examination for Strongyloides infection can be an unreliable diagnostic reference. Further evaluation of the discrepancies observed between coprologic and serologic testing is required to determine the usefulness of these tests in epidemiologic studies.     

A recombinant antigen-based IgG4 ELISA for the specific and sensitive detection of Brugia malayi infection

An IgG4 ELISA based on a novel recombinant antigen was evaluated for detection of Brugia malayi infection, using 2487 sera from various institutions: 2031 samples from Universiti Sains Malaysia, 276 blinded sera from 2 other institutions in Malaysia, 140 blinded sera from India and 40 blinded sera from Thailand. These sera were from various groups of individuals, i.e., microfilaraemics, chronic patients, endemic normals, non-endemic normals and individuals with other parasitic and bacterial infections. Based on a cut-off optical density reading of 0.300, the IgG4 ELISA demonstrated specificity rates of 95.6-100%, sensitivity rates of 96-100%, positive predictive values of 75-100% and negative predictive values of 98.9-100%. These evaluation studies demonstrated the high specificity and sensitivity of this test for the detection of active B. malayi infection. Thus, the IgG4 ELISA would be very useful as a tool in diagnosis and in elimination programmes for brugian filariasis.     

G试验和GM试验联合痰真菌培养对ICU患者侵袭性真菌感染的早期诊断

目的探讨血清1,3-β-D葡聚糖检测(G试验)及半乳甘露聚糖抗原检测(GM试验)联合痰真菌培养在重症监护病房(ICU)患者侵袭性真菌感染(IFI)早期诊断中的价值。方法选取徐州医科大学附属医院2015年1月—2016年12月重症监护病房(ICU)有高危IFI因素的住院患者,根据IFI的诊断标准将患者分成3组:IFI组(包括确诊及临床诊断)、拟诊IFI组、非IFI组。分析三组患者血清G试验、GM试验和痰真菌培养的结果,评价三者联合检测对IFI的早期诊断价值。结果共调查ICU住院患者264例,其中IFI组56例,拟诊IFI组43例,非IFI组165例。56例诊断IFI患者中,血清G试验阳性46例,GM试验阳性39例,真菌培养阳性34例;三者联合检测的敏感性98.2%、特异性82.4%、阳性预测值65.5%、阴性预测值99.3%、阳性似然比5.58、阴性似然比0.02、Youden指数0.98。三者联合检测的敏感性、阴性预测值均高于G试验、GM试验和痰真菌培养的单独检测,差异均有统计学意义(均P0.05);但是,三者联合检测的特异性、阳性预测值与单独检测G试验、GM试验和痰真菌培养比较,差异均无统计学意义(均P0.05)。结论 G试验、GM试验和痰真菌培养三者联合检测能提高ICU患者IFI早期诊断的敏感性,从而指导临床医生早期治疗IFI。     

Comparison of a supplemented Rose Questionnaire to exercise thallium testing in men and women

The Rose Questionnaire has had high specificity and variable sensitivity when compared to physician identification of the symptom complex of angina pectoris. We assessed the accuracy of a supplemented Rose Questionnaire in a series of 198 patients by comparing the Questionnaire to exercise thallium test evidence of coronary artery disease. The Rose diagnosis of angina had 26% sensitivity, 79% specificity, 42% positive predictive value, and 65% negative predictive value. The Rose diagnosis of myocardial infarction had 26% sensitivity and 90% specificity. The Rose diagnosis of angina or infarction yielded a sensitivity of 44%, specificity of 72%, positive predictive value of 67%, and negative predictive value of 50%. Supplemental questions designed to identify atypical ischemic pain led to increased sensitivity of up to 68% that was offset by decreased specificity. While the Questionnaire's sensitivity for coronary disease was greater for women than men (57 vs 40%), the overall accuracy was the same because specificity was lower (63 vs 80%).     

Publications on diagnostic test evaluation in family medicine journals: an optimal search strategy

Search strategies for articles reporting on diagnostic test evaluations have been subjected to less research than those in the domain of clinical trials. We set out to develop an optimal search strategy for publications on diagnostic test evaluations in general, that could be added to keywords describing the specific diagnostic test at issue. Nine Family Medicine journals were searched from 1992 through 1995 for primary publications on diagnostic test evaluation by hand searching and a Medline search strategy published earlier. Additionally, new search strategies have been developed with stepwise logistic regression, using Mesh terms and free text words related to diagnosis and test evaluation as independent variables. Hand searching identified 75 primary publications on diagnostic test evaluation from a total of 2467 primary publications. The previously published search strategy had a sensitivity of 73%, a specificity of 94%, and a positive predictive value of 29%. The most accurate new search strategy had a sensitivity of 80.0% (60/75; 95% CI: 71.0-89.1), a specificity of 97.3% (2327/2392; 95% CI; 96.6-97.9%), a positive predictive value of 48% (95% CI: 40-56) and diagnostic odds ratio of 149. All four new strategies used the Mesh term "sensitivity and specificity" (exploded with the Mesh terms "predictive value" and "ROC")and cumulatively added the text words "specificity," "false negative," "accuracy," and "screening." The search strategy using the Mesh term "sensitivity and specificity" (exploded) and the text words "specificity," "false negative," and "accuracy" has both higher sensitivity and specificity than the previously published strategy. The increase in specificity in three strategies reduces the absolute number of false-positive articles that have to be screened by 50-75%, compared to the number of false positives in the earlier strategy.     

羊水板层小体计数对预测早产儿肺成熟度的价值研究

【目的】 探讨板层小体对预测早产儿肺成熟度的临床价值。 【方法】 对早产儿进行板层小体计数,找出反应肺成熟度的判定界值,并统计其对肺成熟度的阳性预测值、阴性预测值、敏感性、特异性以及对34周以下早产儿的预测情况。 【结果】 成熟判定界值≥98 000/μL时其阴性预测值100%;阳性预测值 27.1%;敏感性100%;特异性41.9%;34周以下早产儿的阴性预测值100%,阳性预测值53.6%,敏感性100%,特异性23.5%,可以避免23.5%早产儿气管插管和使用PS;不成熟判定界值≤33 000/μL时阴性预测值96.7%;阳性预测值46.7%;敏感性87.5%;特异性78.4%;34周以下早产儿的阴性预测值85.7%,阳性预测值72%,敏感性100%,特异性70.6%;可使70.6%的早产儿避免气管插管和肺表面活性物质使用;33 000~98 000/μL之间为可疑值时此范围的发病率为20%。 【结论】 板层小体的计数对于预测新生儿肺成熟度是一个较好的筛选试验。     

空腹血糖与糖化血红蛋白在2型糖尿病诊断中的应用

目的评估空腹血糖（FPG）和糖化血红蛋白（HbAlc）诊断2型糖尿病（T2DM）的敏感性和特异性。探讨FPG、HbAlc及联合指标诊断T2DM的最佳切点。方法采用WHO糖尿病诊断标准,将423例研究对象分为T2DM组（n=60）和非T2DM组（n=363）,所有受试者均行口服葡萄糖耐量试验（OGTT）,同时测定其FPG及HbAlc。绘制FPG和HbAlc诊断糖尿病的受试者工作曲线（ROC曲线）。结果①HbAlc诊断T2DM的切点为6．1％,此时灵敏度为91．7％,特异度为78．5％,曲线下面积0．910（95％CI,0．873～0．946）,阳性预测值（＋PV）为41．4％,阴性预测值（-PV）为98．3％,You＆n指数为O．702,正确率为80．4％,Kappa值为0．465。HbAlc≥6．5％时,灵敏度为61．7％,特异度为93．7％,＋PV为61．7％、-Py为93．7％,Youden指数为0．553,正确率为89．1％,Kappa值为O．553。②FPG诊断T2DM的切点为6．09mmol／L,此时灵敏度83．3％,特异度89．3％,曲线下面积0．898（95％CI,0．885-0,957）,＋PV50．5％,一州96．9％。Youden指数0．726,正确率86．1％,Kappa值0．549。当FPG≥7．00mmol／L时,灵敏度33．3％,特异度99．2％,＋w87．0％、-PV90．0％、Youden指数0．325、正确率89．8％、Kappa值0．438。③HbAlc≥6．1％和FPG≥6．09mmol／L联合指标具有较好的诊断性能。且优于单个指标,此时的灵敏度83．3％．特异度93．7％,＋PV68．5％,-PV97．1％,Youden指数0．770,正确率92．2％,Kappa值0．706。结论HbAlc≥6．1％和FPG≥6．09mmol／L联合指标具有很好的灵敏度和特异度,且Youden指数、正确率、Kappa值都高于其他指标,与OGTT有很好的一致性,对T2DM的诊断有较好应用价值。