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PubMed1987

Outpatient evaluation of a rapid, direct test for detection of group A streptococci in throat swabs.

A latex agglutination test (Marion Laboratories) was compared with standard culture methods for the detection of Group A streptococci in two studies of 500 throat swabs each. Swabs were first inoculated to sheep blood agar and then tested for Group A streptococcal antigen. The direct test performed with nearly identical sensitivity and specificity in the two phases of the study. Overall, Group A streptococci were isolated from 91 specimens, and 81 (89%) of these were detected by the direct latex test. The predictive value positive for the latex test was 90%, and the accuracy was 98%. The sensitivity of the latex test for detection of specimens having ten or more colonies of Group A streptococci was 95%. Non-Group A beta-hemolytic streptococci were isolated from 65 specimens, and all of these specimens had negative latex tests. The authors' findings suggest that this direct latex agglutination test is a reliable screening method for rapid detection of Group A streptococci in outpatient throat specimens.

Ambulatory Care↗
PubMed2002

Bee-venom allergy in children: long-term predictive value of standardized challenge tests.

Venom immunotherapy (VIT) is able to protect insect venom-allergic patients against life-threatening sting reactions. Standardized sting challenges can be used as a diagnostic tool to check whether VIT is required. No data are available on the long-term predictive value of sting challenge tests. The purpose of this study was to investigate the long-term predictive value of sequential bee-sting challenges with respect to the ability to predict future sting reactions in bee-venom (BV) allergic children. Between 1988 and 1992, 92 BV-allergic children had been challenged with sequential bee stings at intervals of 2-6 weeks to determine the necessity of VIT. In 1996, all 92 families were followed-up using standardized telephone interviews. Until the follow-up, 61 children (66.3%) had experienced at least one natural bee sting. Based on the results of the initial challenge tests, 13 of the 61 patients had been started on VIT. Two of these 13 (15.4%) developed systemic reactions 1 year after VIT of 5 years, of which one was mild and one was severe. Among the 48 re-stung patients who were not treated with VIT, three children (6.3%) experienced mild systemic reactions, whereas 45 children reported no more than a local reaction. The long-term predictive value of sequential bee-sting challenge tests for systemic reactions in children not treated with VIT remained at a level of 93.8% (95% confidence interval: 82.8-98.7%) even over a period of more than 6 years. Based on this data, we conclude that sequential bee-sting challenges are a powerful tool to determine the necessity for VIT in BV-allergic children.

Adolescent↗
PubMed1986

Predictive value of a screening test for antibodies to HTLV-III.

A test for the detection of antibodies to HTLV-III is available and will be widely used to screen donated blood to prevent transfusion-associated acquired immunodeficiency syndrome (AIDS). Based upon the sensitivity and specificity, the authors calculated the expected predictive values for different groups of asymptomatic individuals using Bayes' theorem. The prevalence of HTLV-III infection has great impact upon the positive and negative predictive values of the test. For a member of the general population there is a less than 3% chance that a positive test represents a true positive. High-risk patients, such as hemophiliacs, with a positive test will have a greater than 95% chance of actually having antibodies to HTLV-III, but the negative predictive value of the test in this group is less than ideal. The authors recommend that all positive tests for HTLV-III be confirmed by more specific methods when obtained in low-risk people. Members of high-risk groups for AIDS should continue to refrain from donating blood, despite the availability of the screening test.

Acquired Immunodeficiency Syndrome↗
PubMed2006

[Predictive value of an ischemia test in men and women with stable angina pectoris in clinical practice. Results of the heart catheter registry of the Working Society of Senior Hospital Cardiologists].

BACKGROUND AND OBJECTIVE: Symptoms of coronary artery disease (CAD) and the accuracy of non-invasive tests differ between men and women. This study sought to evaluate the difference between the predictive value of a stress test in clinical practice for the diagnosis of significant coronary heart disease (CHD: stenosis > 50%) between women and men with stable angina. PATIENTS AND METHODS: 143,848 consecutive patients undergoing diagnostic coronary angiography at 99 hospitals during 2002 were included in the prospective cardiac catheter registry of the Working Party of Senior Hospital Cardiologists (Arbeitsgemeinschaft Leitende Kardiologische Krankenhausärzte [ALKK]). All patients with stress test and stable angina CCS class I-III (n=27387; 20.4%) were included, 10,911 (39.8%) of them female. 70.6% of women and 73.2% of men had a positive stress test. RESULTS: In 46.1% of women and 71.5% of men with positive test and stable angina had relevant CHD (p<0,001). Diabetes increased the prevalence of CHD in patients with a positive test both in women (65.5%) and men (80.5%), with CCS class III angina to 63.3% and 85.8%, respectively. CONCLUSIONS: In clinical practice a positive stress test in women with stable angina is associated significantly less often with clinically relevant CHD than in men. The low positive predictive value of 46.1% underlines the need for additional clinical features like diabetes or cardiac symptoms (CCS class) before invasive diagnosis is performed.

Adult↗
PubMedDate not supplied

On tests for equality of predictive values for t diagnostic procedures.

This paper concerns comparisons of the efficiency of several diagnostic tests, as characterized by the measures of sensitivity (xi), specificity (eta) and predictive value (rho). We show that hypotheses concerning the equality of predictive values relate only to hypotheses concerning xi and eta and that we can test these by approximate chi 2 statistics. Data for the cases of t = 2 or 3 diagnostic tests illustrate the method.

Diagnosis↗
PubMed1987

Perendoscopic gastric pH determination. Simple method for increasing accuracy in diagnosing chronic atrophic gastritis.

The endoscopic diagnosis of chronic atrophic gastritis is often underestimated, and most of the procedures adopted to increase diagnostic accuracy are time consuming and complex. In this study, we evaluated the usefulness of the determination of gastric juice pH by means of litmus paper. Values obtained by this method correlate well with gastric acid secretory capacity as measured by gastric acid analysis (r = -0.64, p less than 0.001) and are not affected by the presence of bile. Gastric juice pH determination increases sensitivity and other diagnostic parameters such as performance index (Youden J test), positive predictive value, and post-test probability difference by 50%. Furthermore, the negative predictive value is very high, the probability of missing a patient with chronic atrophic gastritis with this simple method being 2% for fundic and 15% for antral atrophic change. We conclude that gastric juice pH determination, which substantially increases diagnostic accuracy and is very simple to perform, should be routinely adopted.

Female↗
PubMed2006

Prediction of driving ability after stroke and the effect of behind-the-wheel training.

The aim of this study was to examine the predictive value of a neuropsychological test battery relating to an on-the-road driving evaluation and to determine whether patients who failed the driving test could improve their driving through behind-the-wheel training. Thirty-four stroke patients were compared with 20 healthy, matched controls. Patients who failed the driving test were offered driving practice at a driving school and were then reassessed (neuropsychologically and practically). On most of the cognitive tests, patients performed significantly less well than control subjects. Almost 50% of the controls and the patients failed the driving evaluation. None of the neuropsychological tests was able to predict the driving outcome. Of the patients who failed the first driving evaluation, 85% passed the second evaluation after driving practice. There are few controlled studies focusing on the stroke population and the effect of behind-the-wheel training. It is suggested that more controlled studies are needed with more homogenous patient-groups and reliable and quantitative outcome measures.

Adult↗
PubMedDate not supplied

Lower extremity deep venous thrombosis: vascular laboratory quality assurance without correlation between ultrasound and venography.

Venography is rarely available for comparison with ultrasonography (US) as a means for quality assurance (QA) in the detection of lower extremity venous thrombosis. New QA methods must be implemented. We compared results of multiple serial studies performed in the same extremity as a QA indicator. From a 3-year sample of close to 9,000 venous tests, we obtained a subset of 44 patients who had 331 tests in 71 lower extremities throughout the years. A positive or negative study preceded or followed by another positive or negative study was considered as a confirmed study. A negative or positive study not preceded or followed by a negative or positive study was considered as unconfirmed. Explanations were then sought to explain unconfirmed results. There were 169 (51%) and 124 (37%) confirmed positive and negative studies, respectively, and 13 (4%) and 25 (8%) unconfirmed positive and negative studies, respectively. Of the 13 unconfirmed positive tests, 2 were preceded by negative tests, 3 were preceded and followed by negative tests, and 8 were followed by negative tests. Of these 13 tests, 4 documented extensive venous thrombosis. Of the 25 unconfirmed negative tests, 11 followed treatment for venous thrombosis, 6 had recurrent thrombosis with intermittent lysis, and 8 were followed by positive tests. Considering the low probability of extensive thrombosis being a false-positive test, positive predictive value was 95% (173/182). Excluding 11 negative tests following treatment for venous thrombosis, negative predictive value was 90% (124/138) and accuracy was 93% (297/320). US versus US and literature US versus venography comparisons of these statistics were similar.

Female↗
PubMed1994

The predictive value of a nonstress test taken 24 h before delivery in high-risk pregnancies.

OBJECTIVES: A series of 180 cases of high risk pregnancies were studied in order to assess if a nonstress test taken 24 h before delivery is of any prognostic significance. METHODS: To assess the predictability of the NST (reactive or nonreactive) in terms of fetal outcome, the following variables were taken into consideration: fetal distress during labor, low Apgar score (< 7) and perinatal mortality rate. RESULTS: A reactive test was found to be a good predictor of the healthy fetus (negative predictive value = 91.2%). Also, specificity of the test was found to be 85.4%. CONCLUSIONS: The nonreactive test could identify a population at risk but it was not helpful as a 'stand alone' modality in decision making, because of the low sensitivity and positive predictive value rates (40.9% and 28.1%, respectively).

Apgar Score↗
PubMed1988

Evaluation of a direct identification method for Staphylococcus aureus from blood culture broth.

We evaluated the reliability of Staphaurex (Wellcome Diagnostics, Dartford, England) for the direct identification of staphylococci from blood culture broth with evidence of positivity and a suggestive Gram-stained smear. Our evaluation indicates that this application is of limited sensitivity, thus reducing the value of a negative test. However, since the test is highly specific, a positive test is significant in predicting the isolation of Staphylococcus aureus.

Blood↗
PubMed2004

Recovery of nerve injury after mandibular sagittal split osteotomy. Diagnostic value of clinical and electrophysiologic tests in the follow-up.

The diagnostic value of several clinical, quantitative sensory tests (brush-stroke directional discrimination (BSD), touch detection threshold (TD), warm/cold (W/C) and sharp/blunt discrimination (S/B)), and electrophysiologic tests (mental nerve blink reflex (BR), nerve conduction study (NCS), cold (CDT), and warm (WDT) detection thresholds) in the recovery of inferior alveolar nerve (IAN) injury was evaluated in a prospective 1-year follow-up study of 20 patients after bilateral sagittal split osteotomy (BSSO). The subjective sensory alteration was assessed from patients' drawings. The predictive values of different tests at 2 weeks were determined in relation to the subjective sensory recovery at 12 months. The most pronounced recovery of the nerve damage occurred during the first 3 months according to all measures used. After 3 months, the electrophysiologic tests, especially the NCS, indicated significant further improvement. Except for the TD test, all other clinical test results were normal already at 3 months postoperatively. At early and late controls, the NCS and the thermal quantitative sensory testing could best verify the subjective sensory alteration, and most accurately assess the degree of thick and thin fibre dysfunction. At 1 year, the nerve dysfunction, as revealed by the NCS, corresponded with the figures of sensory alteration reported by the patients (35% R, 40% L). The W/C, BSD, S/B and WDT tests had the best early positive predictive values. Electrophysiologic tests had higher negative predictive values compared to clinical tests.

Adolescent↗
PubMed1990

Epidemiology of cervical cancer in the screened population in Taiwan, 1979-1984.

This study was based on the screening data of April 1979-June 1984 to provide descriptive epidemiology of cervical cancer in Taiwan. During the 63 months, 175,823 women were screened and 1988 (1.13%) suspicious cases were found. The predictive value of a positive test was 50.14% and the specificity of the screening test was 99.44%. The estimated cancer rate among the screened population was 0.57%. The ratio of carcinoma in situ to invasive carcinoma was 1.91. The mean ages were 37.5 years for screened population, 44.1 years for suspects, 46.3 years for cancer cases (44.1 years for carcinoma in situ and 50.8 years for invasive carcinoma), 57.3 years for cervical cancer deaths in 1981 and 58.1 years for uterine cancer deaths in 1981. Univariate descriptive analyses on all women screened revealed the following variables to be positively associated (p less than 0.05) with suspicious Pap smears and cancer confirmed cases: age, number of years married, number of full-term deliveries, number of abortions/miscarriages, and abnormal vaginal bleeding. Negative associations were found with age at first marriage, education level, previous Pap smear and use of condom for contraception. Suspicious rates (but not detected cancer rates) were significantly higher for those women who themselves or whose husbands worked in mining, salt production, fishery or agriculture occupations. They were lowest for those (self or husband) employed in civil service, teaching, military service or police. By residence, suspicious rates were highest for those residing in the most urbanized areas (cities) and lowest for those in the second most urbanized areas (country cities). Thus urbanization level was not significantly involved. Other risk variables reported in the literature such as family history of uterine and other cancers were not significantly associated with either the suspicious or the cancer rate in this study.

Adult↗
PubMed1997

Prediction of head-up tilt test result by analysis of early heart rate variations.

BACKGROUND: Head-up tilt testing is a useful test for investigating vasovagal syncope. The determination of early, accurate, predictive criteria for a negative result would permit a reduction in the duration of the tilt test. METHODS AND RESULTS: Patients with no drug use and no illnesses other than recurrent unexplained syncope were recruited. In an initial study (110 consecutive patients), we aimed to determine a predictive criterion based on heart rate variations during the first minutes of upright tilting that could distinguish between patients with positive and negative tilt tests (patients with an early continual decrease in heart rate or blood pressure were excluded). Then we tested the predictive value of the established criterion in a second independent sample of patients with unexplained syncope (109 consecutive patients). An early sustained increase in heart rate < or = 18 bpm during the first 6 minutes of upright tilting at a 60 degree angle allowed us to predict negative tilt tests with 100% specificity, 100% positive predictive value, and 88.6% sensitivity. This criterion was validated in the second, prospective arm of the study (96.4% specificity, 98.4% positive predictive value, and 87.3% sensitivity), even with subsequent use of isoproterenol in low doses. CONCLUSIONS: In patients with no drug use and no illnesses other than recurrent unexplained syncope, a simple clinical criterion identifies patients who will not develop syncope during a prolonged upright tilt.

Adult↗