Different Combinations Of Tests Research Articles

Variation in liver function testing and the effect of pyridoxal-5-phosphate on ALT, AST and FIB-4 results.

Background As one of the most requested profiles of blood tests, there is a need for standardisation among liver function tests (LFT). Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are key markers of hepatocellular injury. ALT and AST are used to calculate a Fibrosis-4 (FIB-4) score for assessing liver fibrosis. Despite recommendations by the International Federation of Clinical Chemistry (IFCC) to include pyridoxal-5-phosphate in ALT and AST assay methodologies, most laboratories continue to omit this. Methods Data from the UK NEQAS for Clinical Chemistry Scheme, Distribution 1160 (November 2023), was reviewed to investigate variation in practice regarding liver blood tests in relation to ALT, AST and FIB-4. In addition, a series of questions audited laboratory practice in relation to liver enzymes. Results Wide variation was seen in LFT profiles offered by laboratories, with 32 different combinations of tests used. The IFCC-recommended methods for ALT and AST are used by one-third of laboratories, and give significantly higher results than non-IFCC methods. Laboratories using IFCC methods also reported significantly higher FIB-4 scores. Reference ranges and cut-offs for these tests also varied, and did not account for method-related differences in results. Conclusions The lack of standardisation of LFTs can have a significant impact on patient care. The difference in results for ALT, AST and FIB-4 in laboratories not using IFCC-recommended methods may lead to misdiagnosis. This issue should be addressed by laboratories using methods including pyridoxal-5-phosphate. Until then, method-related reference ranges and cut-offs for ALT, AST and FIB-4 are required.

Advancing Perioperative Neurocognitive Health: A Critical Review of Predictive Tools, Diagnostic Methods, and Interventional Strategies.

Perioperative neurocognitive disorders (PNDs) affecta large percentage of people who undergo surgeries that need general anesthesia. There is an increased risk of death and a major disruption to postoperative self-care as a result of this. This study compiles all the relevant materials that the authors have found to investigate postnatal depression and its causes, as well as the methods used to determine the probability and severity of PNDs and how to reduce their risk before surgery. Postnatal depression can have many causes, and this text explores some of them. These include a history of alcohol or opiate use, immunological dysregulation, advanced age, educational background, infections, neurocognitive impairment, and pre-existing chronic inflammatory disorders. It also delves into various methods used to gauge the likelihood and severity of postpartum depression. The following assessment tools were covered: the Clock Drawing Test, Domain-Specific Tests, the Mini-Mental State Examination, and the Montreal Cognitive Assessment. In addition to biochemical markers, neuroimaging techniques play an important role in diagnosis. The Frailty Fried assessment, which measures inertia, sluggishness, lack of physical activity, fatigue, and unintentional weight loss, is a key prognostic sign that is highlighted. There is strong evidence that the index, which is derived from these five characteristics, may accurately predict the likelihood of PNDs. Risk mitigation strategies are also covered in this research. Preoperative brain plasticity-based therapies, such as physical exercise and intensive cognitive training, can significantly reduce the incidence and severity of postoperative neurocognitive disorders. A peripheral nerve block, monitoring cerebral oxygen saturation, dexmedetomidine, and a reduction in anesthesia depth are all ways to improve anesthetic procedures. Methods that lower blood pressure should be avoided, the body temperature should be kept down during surgery, or the time without liquids should be lengthened; all of these raise the risk of postoperative nausea and vomiting and make it worse. Potential approaches include a Mediterranean diet, physical activity, cognitive stimulation, smoking cessation, alcohol reduction, avoidance of anticholinergic medications, and non-steroidal anti-inflammatory drug stewardship, although there is no definitive evidence for successful postoperative neurocognitive rehabilitation procedures. More standardized diagnostic criteria, evaluation methods, and PND classification are urgently needed, according to this study. Different cases of PNDs are characterized by different combinations of tests, cutoff values, and methods because there is a broad variety of diagnostic tests used to make the diagnosis.Until now, PNDs and pre-existing neurocognitive disorders have been diagnosed using the Diagnostic and Statistical Manual of Mental Disorders (DSM-V). With an aging population comes an increase in the occurrence and prevalence of PNDs, which calls for a specific way to classify and describe the condition.

Discriminative value of different combinations of tests to detect unilateral neglect in patients with right hemisphere damage.

This study was undertaken to assess the most sensitive combination of tests to detect peripersonal unilateral neglect (UN) after stroke. The present study is a secondary analysis of a previously reported multicentric study of 203 individuals with right hemisphere damage (RHD), mainly subacute stroke, 11 weeks postonset on average, and 307 healthy controls. A battery of seven tests, providing 19 age- and education-adjusted z-scores, were given: the bells test, line bisection, figure copying, clock drawing, overlapping figures test, and reading and writing. Statistical analyses used a logistic regression and a receiver operating characteristic (ROC) curve after adjustment on demographic variables. A combination of four z-scores based on the following three tests provided good discrimination of patients with RHD from matched healthy controls: the starting point and the difference between the number of omissions on left and right sides from the bells test, rightward deviation in bisection of long lines (20 cm), and left-sided omissions in a reading task. The area under the ROC curve was 0.865 (95% confidence interval = 0.83-0.901), with sensitivity = 0.68, specificity = 0.95, accuracy = 0.85, positive predictive value = 0.90, and negative predictive value = 0.82. The most sensitive and parsimonious combination of tests to detect UN after stroke relies on four scores from three simple tests (bells test, line bisection, and reading). Future study is warranted to assess its ability to account for the functional difficulties of UN in daily life in the patient's actual environment.

Comparative analysis of Modified Thorington to the prism cover, von Graefe and Maddox rod tests

Background: Heterophoria measurement is important in the evaluation of binocular vision. There are many different methods of heterophoria measurement. There are various methods of heterophoria measurements, and studies have compared different methods, some reporting little difference between the methods while others reported that measures can be significantly different.Aim: The purpose of this study was to compare heterophoria measurements obtained using four clinical methods, that is, the modified Thorington test (MTT) on the Bernell Muscle Imbalance Measure (MIM) with those obtained from the prism cover test (PCT), Von Graefe test (VGT) and Maddox rod test (MRT), and thereby to establish their interchangeability.Setting: The study was performed at an optometric clinic within a South African university.Methods: Dissociated near horizontal heterophoria was measured on a sample of 30 optometry students (ages 19–25 years) using the PCT, VGT, MRT and MTT. Three measurements for each of the four tests per participant were obtained, and thereafter the means were applied in analysis of the results. Agreement between paired tests was assessed using Bland–Altman plots.Results: The means for near or proximal heterophoria obtained using the four tests were −2.63 ± 1.9Δ, −2.90 ± 1.7Δ, −3.37 ± 2.0Δ and −2.47 ± 1.9Δ, with a strong correlation for each pair (p = 0.00) (minus signs indicate exophoria [XOP]). Among the different combinations of tests, the MTT and PCT showed the best agreement, although the reliability was good for all four tests.Conclusion: The measurement of near heterophoria can best be quantified either using the MTT or PCT because they showed the greatest level of agreement.

Diagnostic value of the SARC-f questionnaire and muscle strength tests for the detection of sarcopenia in patients with rheumatoid arthritis

The aim of the study was to determine the diagnostic significance of the SARC-F (A Simple Questionnaire to Rapidly Diagnose Sarcopenia) questionnaire for sarcopenia screening and tests for assessing muscle strength in patients with rheumatoid arthritis. Material and methods . The study included 87 women aged 40-75 years who completed the SARC-F screening questionnaire. All patients underwent muscle strength assessment tests - wrist dynamometry and “Rising from a chair”, as well as dual X-ray absorptiometry (DXA) to quantify muscle mass. Sensitivity, specificity, diagnostic accuracy, positive predictive value and negative predictive value were determined for the SARC-F questionnaire and muscle strength tests. Results . Significant sarcopenia was diagnosed in 20 (23%) women. The sensitivity, specificity and diagnostic accuracy of the SARC-F questionnaire was 30, 42 and 39%, respectively, of the wrist dynamometry - 95, 34 and 48%, of the “Rising from a chair” test - 50, 21 and 28%, respectively. Paired use of different combinations of tests did not lead to an improvement in diagnostic value. With all three tests, the sensitivity, specificity and diagnostic accuracy were 71, 20, and 33%, respectively. Conclusion . The SARC-F questionnaire used to screen for sarcopenia has a rather low diagnostic value for identifying patients with rheumatoid arthritis in need of further evaluation. Among muscle strength tests, hand dynamometry was found to be a highly sensitive, but insufficiently specific method, which can lead to overdiagnosis of probable sarcopenia. All this indicates the need to develop a screening method specific for rheumatoid arthritis and to improve the methods of stage I of sarcopenia diagnosis.

Monitoring of noninvasive ventilation: comparative analysis of different strategies

BackgroundNoninvasive ventilation (NIV) represents an effective treatment for chronic respiratory failure. However, empirically determined NIV settings may not achieve optimal ventilatory support. Therefore, the efficacy of NIV should be systematically monitored. The minimal recommended monitoring strategy includes clinical assessment, arterial blood gases (ABG) and nocturnal transcutaneous pulsed oxygen saturation (SpO2). Polysomnography is a theoretical gold standard but is not routinely available in many centers. Simple tools such as transcutaneous capnography (TcPCO2) or ventilator built-in software provide reliable informations but their role in NIV monitoring has yet to be defined. The aim of our work was to compare the accuracy of different combinations of tests to assess NIV efficacy.MethodsThis retrospective comparative study evaluated the efficacy of NIV in consecutive patients through four strategies (A, B, C and D) using four different tools in various combinations. These tools included morning ABG, nocturnal SpO2, TcPCO2 and data provided by built-in software via a dedicated module. Strategy A (ABG + nocturnal SpO2), B (nocturnal SpO2 + TcPCO2) and C (TcPCO2 + builtin software) were compared to strategy D, which combined all four tools (NIV was appropriate if all four tools were normal).ResultsNIV was appropriate in only 29 of the 100 included patients. Strategy A considered 53 patients as appropriately ventilated. Strategy B considered 48 patients as appropriately ventilated. Strategy C misclassified only 6 patients with daytime hypercapnia.ConclusionMonitoring ABG and nocturnal SpO2 is not enough to assess NIV efficacy. Combining data from ventilator built-in software and TcPCO2 seems to represent the best strategy to detect poor NIV efficacy.Trialregistration Institutional Review Board of the Société de Pneumologie de Langue Française (CEPRO 2016 Georges)

Assessment of the Feasibility and Cost of Hepatitis C Elimination in Pakistan

Chronic hepatitis C virus (HCV) infection is a global health problem. The World Health Assembly recently pledged to eliminate HCV by 2030. However, in Pakistan, a country with one of the highest prevalence rates, the feasibility and cost of HCV elimination are not known. To investigate whether and under what conditions HCV elimination is feasible in Pakistan and to estimate the cost of such elimination. This decision analytical model study used a microsimulation model of the HCV epidemic in Pakistan from 2015 to 2030. Using Pakistan-specific variables, the model simulated the landscape of HCV in Pakistan and evaluated the minimum required screening and treatment rates needed to eliminate HCV in Pakistan. The study used simulated individuals chronically infected with HCV from 2015 to 2030. The analysis was performed in 2018. The status quo and 7 scenarios that can lead to HCV elimination in Pakistan by 2030, which were defined by different combinations of tests for screening, detection of viremia before treatment, and confirmation of treatment response. Temporal trends in HCV infection prevalence, mortality, and disability-adjusted life-years and total cost of HCV infection care under the status quo and scenarios that can eliminate HCV by 2030. Under the status quo, from 2015 to 2030, 1.44 million people are projected to die of HCV infection; 48% of deaths would be among people younger than 50 years. To achieve HCV elimination in Pakistan, HCV testing would need to be scaled up to at least 25 million people to diagnose 900 000 persons and treatment to 700 000 people per year. Compared with the status quo, the elimination scenario would avert 323 000 liver-related deaths and 13.0 million HCV-associated disability-adjusted life-years from 2015 to 2030. The elimination scenario was associated with cost savings of $2.6 billion from 2018 to 2030 with use of a point-of-care test for population-wide antibody screening and detection of viremia and treatment response. Substantial scale-up of HCV testing and treatment may be essential to eliminate HCV infection in Pakistan, and such a strategy may be associated with cost savings in the near future. Although HCV elimination in Pakistan may be ambitious, strategic planning and strong support from the government may aid in its elimination.

Identification of suitable combinations of in vitro sperm-function test for the prediction of fertility in buffalo bull

The present study assessed sperm functional characteristics in the frozen-thawed semen of buffalo bulls and estimated their relationship with field fertility. Frozen semen samples from three different freezing operations each from nine Murrah buffalo bulls were used for the assessment of different sperm functions related to fertilizing potential. Bulls were classified into high (n = 2), medium (n = 5), and low (n = 2) fertile based on adjusted field fertility. The sperm functions estimated included membrane integrity using carboxyfluorescein diacetate-propidium iodide, acrosome reaction status using fluorescein isothiocyanate peanut agglutinine, status of apoptosis using Annexin-V, protamine deficiency using Chromomycin A3, membrane stability using Merocyanine 540 and lipid peroxidation status using 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene. The relationship between the proportion of live acrosome-intact spermatozoa and fertility was positive and significant (r = 0.59; P = 0.001). The proportion of moribund spermatozoa showed a significantly negative correlation with fertility (r = −0.50; P = 0.008). Similarly, the relationship of spermatozoa with unstable membrane (r = −0.51; P = 0.007), necrotic (r = − 0.42; P = 0.028), early necrotic (r = −0.42; P = 0.031), and apoptotic spermatozoa (r = −0.39; P = 0.046) with bull fertility was negative and significant. The correlation between the protamine-deficient spermatozoa and fertility was negative, but not significant. Among different combinations of tests, live acrosome-intact spermatozoa and lipid peroxidation status of spermatozoa revealed high positive correlation with buffalo bull fertility (adjusted R2 = 0.73, C[p] = 0.80). These preliminary findings may help in developing tools for assessing fertility of buffalo bulls, once validated in more animals.

Repeatability of the modified Thorington card used to measure far heterophoria.

To determine the interexaminer and intraexaminer repeatability of the modified Thorington test (TH) for distance vision in young adults and to compare these results with those observed for the heterophoria tests most commonly used in clinical practice. Agreement among tests was also assessed. Distance heterophoria was quantified on two separate occasions by two examiners in 110 subjects aged 18 to 32 years (mean, 19.74 years; SD, 2.5 years) using four different tests: cover test (CT) Von Graefe, Maddox rod, and modified TH. The repeatability of the tests and agreement between them was estimated by the Bland and Altman method whereby the mean difference and the 95% limits of agreement were determined as the coefficient of repeatability (COR) and coefficient of agreement. The Thorington test showed best interexaminer repeatability (COR = ±1.43Δ), followed closely by CT (COR = ±1.65Δ), whereas best intraexaminer repeatability was observed for CT (COR = ±1.28Δ) followed by TH (COR = ±1.51Δ). Among the different combinations of tests, TH and CT showed best agreement indicated by the lowest coefficient of agreement (±2.23Δ) and a low mean difference (-0.63Δ) between measurements. Good interexaminer and intraexaminer repeatability was observed for both TH and CT, and agreement between the two tests was also good. Given the simple administration of the TH, we recommend its clinical use to quantify distance horizontal heterophoria.

Assessment of Children With Suspected Auditory Processing Disorder

To identify the factors that may underlie the deficits in children with listening difficulties, despite normal pure-tone audiograms. These children may have auditory processing disorder (APD), but there is no universally agreed consensus as to what constitutes APD. The authors therefore refer to these children as children with suspected APD (susAPD) and aim to clarify the role of attention, cognition, memory, sensorimotor processing speed, speech, and nonspeech auditory processing in susAPD. It was expected that a factor analysis would show how nonauditory and supramodal factors relate to auditory behavioral measures in such children with susAPD. This would facilitate greater understanding of the nature of listening difficulties, thus further helping with characterizing APD and designing multimodal test batteries to diagnose APD. Factor analysis of outcomes from 110 children (68 male, 42 female; aged 6 to 11 years) with susAPD on a widely used clinical test battery (SCAN-C) and a research test battery (MRC Institute of Hearing Research Multi-center Auditory Processing "IMAP"), that have age-based normative data. The IMAP included backward masking, simultaneous masking, frequency discrimination, nonverbal intelligence, working memory, reading, alerting attention and motor reaction times to auditory and visual stimuli. SCAN-C included monaural low-redundancy speech (auditory closure and speech in noise) and dichotic listening tests (competing words and competing sentences) that assess divided auditory attention and hence executive attention. Three factors were extracted: "general auditory processing," "working memory and executive attention," and "processing speed and alerting attention." Frequency discrimination, backward masking, simultaneous masking, and monaural low-redundancy speech tests represented the "general auditory processing" factor. Dichotic listening and the IMAP cognitive tests (apart from nonverbal intelligence) were represented in the "working memory and executive attention" factor. Motor response times to cued and noncued auditory and visual stimuli were grouped in the "processing speed and alerting attention" factor. Individuals varied in their outcomes in different tests. Poor performance was noted in different combinations of tests from the three factors. Impairments solely related to the "general auditory processing" factor were not common. The study identifies a general auditory processing factor in addition to two other cognitive factors, "working memory and executive attention" and "processing speed and alerting attention," to underlie the deficits in children with susAPD. Impaired attention, memory, and processing speed are known to be associated with poor literacy and numeracy skills as well as a number of neurodevelopmental disorders. Individuals with impairments in the "general auditory processing" tests along with tests from the other two cognitive factors may explain the co-occurrence of APD and other disorders. The variation in performance by individuals in the different tests noted was probably due to a number of reasons including heterogeneity in susAPD and less-than ideal test-retest reliabilities of the tests used to assess APD. Further research is indicated to explore additional factors, and consensus is needed to improve the reliability of tests or find alternative approaches to diagnose APD, based on the underlying factors.

Evaluating the Correspondence of Different Cognitive Batteries

It is widely accepted that abilities are a meaningful level of abstraction for distinguishing among individuals with respect to their levels of cognitive functioning. However, relatively little is known about the extent to which different combinations of tests reflect the same cognitive abilities, or about the relation of cognitive abilities in one test battery with specific tests in another battery. Data from two cognitive batteries were analyzed to determine the correspondence of ability factors in the two batteries, and to evaluate the relative influence of cognitive abilities from one battery on the subtest scores in the other battery. Although the batteries involved different combinations of tests, correlations between the theoretically similar ability factors in the two batteries were very high (i.e., r > .84). Furthermore, with only a few exceptions, the primary influences on the subtest scores in one battery were from the theoretically relevant ability factor in the other battery.

Red flags to screen for malignancy in patients with low-back pain.

The identification of serious pathologies, such as spinal malignancy, is one of the primary purposes of the clinical assessment of patients with low-back pain (LBP). Clinical guidelines recommend awareness of "red flag" features from the patient's clinical history and physical examination to achieve this. However, there are limited empirical data on the diagnostic accuracy of these features and there remains very little information on how best to use them in clinical practice. To assess the diagnostic performance of clinical characteristics identified by taking a clinical history and conducting a physical examination ("red flags") to screen for spinal malignancy in patients presenting with LBP. We searched electronic databases for primary studies (MEDLINE, EMBASE, and CINAHL) and systematic reviews (PubMed and Medion) from the earliest date until 1 April 2012. Forward and backward citation searching of eligible articles was also performed. We considered studies if they compared the results of history taking and physical examination on patients with LBP with those of diagnostic imaging (magnetic resonance imaging, computed tomography, myelography). Two review authors independently assessed the quality of each included study with the QUality Assessment of Diagnostic Accuracy Studies (QUADAS) tool and extracted details on patient characteristics, study design, index tests, and reference standard. Diagnostic accuracy data were presented as sensitivities and specificities with 95% confidence intervals for all index tests. We included eight cohort studies of which six were performed in primary care (total number of patients; n = 6622), one study was from an accident and emergency setting (n = 482), and one study was from a secondary care setting (n = 257). In the six primary care studies, the prevalence of spinal malignancy ranged from 0% to 0.66%. Overall, data from 20 index tests were extracted and presented, however only seven of these were evaluated by more than one study. Because of the limited number of studies and clinical heterogeneity, statistical pooling of diagnostic accuracy data was not performed.There was some evidence from individual studies that having a previous history of cancer meaningfully increases the probability of malignancy. Most "red flags" such as insidious onset, age > 50, and failure to improve after one month have high false positive rates.All of the tests were evaluated in isolation and no study presented data on a combination of positive tests to identify spinal malignancy. For most "red flags," there is insufficient evidence to provide recommendations regarding their diagnostic accuracy or usefulness for detecting spinal malignancy. The available evidence indicates that in patients with LBP, an indication of spinal malignancy should not be based on the results of one single "red flag" question. Further research to evaluate the performance of different combinations of tests is recommended.

Targeting Asymptomatic Term and Late Preterm Newborns at Risk for Early Sepsis: C Reactive Protein 20mg/L Threshold

Identification of sepsis is a major issue due to limitations in diagnosis and severity of outcome. Different combinations of tests are used to screen babies at risk for infection, none specific enough to avoid treatment of non- infected newborns. 193 newborns with � 35 weeks of gestational age admitted in the maternity were screened for infection using a protocol scoring system involving haematological values and CRP � 10mg/l. Blood-cultures were taken after treatment decision, before antibiotics were started. No microbiological exam was included in the screening. Treatment decisions were taken by the staff irrespectively of the ongoing observational study. Newborns were classified by the authors in 4 groups: infected (culture verified), strongly suspected infection (SSI), no sepsis but treated (NST), no sepsis-no treatment (NSNT). Treatment decision was revaluated by the authors according to different cut-off levels of CRP. 40 newborns (20.7%) received antibiotics. 2 had positive blood-cultures. 13 were classified as SSI (all treated) and 178 as not infected (25 treated). All infected babies were identified but the error of the positive predictive value reached 62.5%. Revaluation of treatment decisions with CRP cut-off levels of 15, 20 and 25 mg/l showed respectively 60.5%, 51.6 and 48% of error of the positive predictive value, the first two cut-offs missing no infected newborns but the last one missing two. A new scoring system including CRP at 20mg/l has been in use since then without readmissions for infection and an estimated reduction of 24% antibiotic treatment.

A reply to the discussion by H. Un of the paper “Use of zeolite, coal bottom ash and fly ash as replacement materials in cement production”

In this article, the authors of a recent study (Canpolat et al, 2004) that used three different combinations of tests to investigate the effects of zeolite, coal bottom ash, and fly ash as Portland cement (PC) replacement materials reply to a commentary published about their study. The study investigated properties including setting time, volume expansion, compressive strength, and water consistency of the mortar. Results showed that replacement materials have some effects on the mechanical properties of the cement. In the commentary, Un (July 2005) contended that some of the study authors' interpretations about zeolites are misleading. Indeed, Un maintained that the cements produced in this study were not appropriate for comparing the effect of zeolite on the initial strength of specimens. To investigate the clear effect of zeolite replacement, cements with similar fineness have to be produced. The study authors reply that zeolite is similar to other pozzolanic materials such as silica fume and fly ash. Zeolite substitution can improve the strength of concrete by the pozzolanic reaction with CaOH2.

A discussion of the paper “Use of zeolite, coal bottom ash and fly ash as replacement materials in cement production” by F. Canpolat, K. Yılmaz, M.M. Köse, M. Sümer, M.A. Yurdusev

This brief article comments on a research study (Canpolat et al, 2004) that used three different combinations of tests to investigate the effects of zeolite, coal bottom ash, and fly ash as Portland cement (PC) replacement materials. The study investigated properties including setting time, volume expansion, compressive strength, and water consistency of the mortar. Results showed that replacement materials have some effects on the mechanical properties of the cement. In this commentary, Un contends that some of the study authors' interpretations about zeolites are misleading. Indeed, Un maintains that the cements produced in this study are not appropriate for comparing the effect of zeolite on the initial strength of specimens. To investigate the clear effect of zeolite replacement, cements with similar fineness have to be produced.

Use of zeolite, coal bottom ash and fly ash as replacement materials in cement production

In this research, the effects of zeolite, coal bottom ash and fly ash as Portland cement replacement materials on the properties of cement are investigated through three different combinations of tests. These materials are substituted for Portland cement in different proportions, and physical properties such as setting time, volume expansion, compressive strength and water consistency of the mortar are determined. Then, these physical properties are compared with those of PC 42.5. The results showed that replacement materials have some effects on the mechanical properties of the cement. The inclusion of zeolite up to the level of 15% resulted in an increase in compressive strength at early ages, but resulted in a decrease in compressive strength when used in combination with fly ash. Also, setting time was decreased when zeolite was substituted. The results obtained were compared with Turkish Standards (TS), and it was found that they are above the minimum requirements.

Sensitivity, Specificity, and Predictive Values of Screening Tests for Eye Conditions in a Clinic-based Population

To assess four commonly available visual function tests to detect visually disabling or vision-threatening eye conditions among new patients of a large, urban, public, general ophthalmology clinic. Three hundred seventeen patients were tested for contrast sensitivity, Amsler grid abnormalities, and visual acuity at near and at distance. A complete eye evaluation found the prevalence of serious eye diseases, allowing determination of the sensitivity (Sn), specificity (Sp), likelihood ratio (LR), and other characteristics of each test. Of 317 patients, most were Hispanic (77%), women (60%), and middle-aged (44 +/- 17 years). Normal findings were reported in 18%; refractive error in 43%; cataracts in 16%; glaucoma in 7.3%; and macular degeneration in 4.1%. Near visual acuity of 20/40 or worse (Sn = 0.75; Sp = 0.74; LR = 2.8); and distance visual acuity testing of 20/30 or worse (Sn = 0.74; Sp = 0.73; LR = 2.7) correlated significantly with ocular disease, whereas contrast sensitivity testing (Sn = 0.62; Sp = 0.41; LR = 1.1) and Amsler grid test (Sn = 0.19; Sp = 0.92; LR = 2.4) did not. Test performance decreased when refractive errors were excluded and among those younger than 40 years of age relative to those 40 years of age or older. Of the four screening tests studied, distance and near threshold visual acuities as defined above were judged to have the best correlations of an abnormal result with ocular disease, both including or excluding refractive error. Different combinations of tests did not result in more accurate detection of ocular disease. More efficient screening tools for detecting ocular disease need to be developed.

Avoiding erroneously high levels of detection in combinations of semi-independent tests

A randomization procedure is proposed which allows statistical tests to be combined into a single test to maintain specified and acceptable levels of false detection. This method was applied to the problem of detecting density dependence in 135 unpublished time-series (of ≥10 generations) from insect populations, and to simulated density-dependent and density-independent data, so that the correctness of observed levels of detection from the published data could be verified. To allow the application of the randomization procedure to Bulmer's (1975) tests and Varley and Gradwell's (1960) test, these were recast as randomization tests. The randomization procedure was tested with 39 combinations of tests for density dependence (and limitation/attraction); it generally producedcombined tests with levels of detection that were intermediate between detection levels of the constituent tests (and hence was limite by these). The specified rate of false detection (5%) was never exceeded (by more than 1%) when combined tests were applied to time-series from a random-walk model. Two different combinations of tests produced levels of detection from the published time-series which were slightly greater than their constituent tests when they were combined into single tests. These were the randomized form of Bulmer's (1975) first test with the tests of Pollard et al. (1987) and Reddingius and den Boer (1989) with the randomized form of Bulmer's second test. The combination of Bulmer's first and Pollard et al.'s test produced a greater level of detection (21.5%) than any other single test or combination of tests. These results were confirmed by the analysis of modelled density dependent data. Although the increase in power of combinations of tests over single tests is small with the data we used, the combined tests (listed above) had rates of detection that were less influenced by the form of data (of two forms of density-dependent data) than were their constituent tests. Hence, it appears that the combined tests are of greater generality than single test statistics. The method presented here for combining several statistical tests into a single randomization test is applicable in many other areas of ecology where we wish to apply several tests and take the most probable result of these; and if the tests being conducted are, or can be expressed as, randomization tests.

Incorporating new technologies in periodontal diagnosis into training programs and patient care: a critical assessment and a plan for the future.

New diagnostic technologies may be capable of providing the dental practitioner with powerful tools that can assist in the early identification of periodontal disease that can result in expediated treatment. In this paper, clinical, host, and microbiological parameters will be evaluated for their ability to assess disease activity and to assist in the treatment decision-making process. The discussion will focus on: 1) the perceived need for markers of disease activity; 2) the most commonly proposed markers of disease activity currently under consideration for clinical application; and 3) a plan for future use of disease activity markers. The review concludes that: 1) tooth loss and most forms of rapid disease progression is limited to a small subset of patients within the periodontally diseased population; 2) no single parameter will stand alone as a measure of disease activity; 3) different aspects of treatment may require different combinations of tests to successfully intercept disease in this vulnerable patient group; and 4) early diagnosis can affect long-term periodontal status. Best estimates are presented for: 1) pre-disease identification of high-risk population groups; 2) early diagnosis of disease activity on a site and patient basis; and 3) assistance in the therapeutic decision-making process. It is further concluded that the complexity of the problem may require a re-examination of priorities such that more time and money is allocated to early diagnosis as opposed to treatment in this highly vulnerable patient population.

Rapid and specific diagnosis of HIV-1 and HIV-2 infections

To identify cost-effective testing strategies for HIV-1 and HIV-2 infections, we evaluated different combinations of tests on serum specimens from 1134 consecutive patients attending tuberculosis treatment centers in Abidjan, Côte d'lvoire. Virus-specific whole-virus enzyme-linked immunosorbent assay (WVE), Western blot (WB) and synthetic peptide enzyme-linked immunosorbent assay (SPE) were used in sequential fashion to determine the true prevalence of infection; 27% were reactive to HIV-1, 5% to HIV-2, and 10% to both viruses. Of 239 specimens positive on WB for both HIV-1 and HIV-2, SPE diagnosed 38% as HIV-1-reactive and 16% as HIV-2-reactive, while 46% remained reactive to both viruses. Using WVE or one of two rapid (5-10 min) mixed (HIV-1 and HIV-2) antigen tests (RMATs) as a screening test, followed by SPE as a supplemental test, gave results with sensitivity of 97.3-99.2%, specificity of 99.5-99.7%, and positive predictive value for diagnosing HIV infection of 99.4-99.6%, with important savings in time and reagent costs. SPE allows more specific distinction between HIV-1 and HIV-2 infections than WB, and could replace it as a supplemental test in many settings. WB may be required for specimens reactive on screening tests but negative on SPE, until sensitivity of the SPE is further evaluated. A mixed antigen screening test followed by SPE seems to be an efficient testing strategy for diagnosing HIV-1 and HIV-2 infections.