Tips for learners of evidence-based medicine: 5. The effect of spectrum of disease on the performance of diagnostic tests

Montori, Víctor M.; Wyer, Peter C.; Newman, Thomas B.; Keitz, Sheri A.; Guyatt, Gordon

doi:10.1503/cmaj.1031666

Cited by 47 publications

(35 citation statements)

References 10 publications

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“…[4][5][6] Likelihood ratios associated with a positive response to the motor or sensory questions 'rule in' S4-5 sensory and motor function, whereas negative likelihood ratios 'rule out' S4-5 sensory and motor function. [6][7][8] RESULTS Overall, 34 of 116 consecutive people attending a SCI outpatient clinic between November 2010 and June 2011 were recruited. The reasons for exclusion were refusal to participate (21), impaired cognition or drug dependency (3), inability to contact the participant before appointment (17), multiple co-morbidities or other medical issues (12), less than 1 year post injury (20), limited English (5) or failure to attend an appointment (4).…”

Section: Discussionmentioning

confidence: 99%

The diagnostic accuracy of self-report for determining S4–5 sensory and motor function in people with spinal cord injury

et al. 2011

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Study design: A diagnostic accuracy study. Objectives: The objective was to determine the ability of people with SCI to accurately self-report S4-5 sensory and motor function. Setting: Outpatient clinic, Sydney, Australia. Methods: A consecutive series of thirty-four people who had sustained a SCI more than 1 year before the study, and who were attending an outpatient medical clinic were recruited. They were assessed on two occasions. On the first occasion, ability to self-report S4-5 sensory and motor function was assessed with four questions. On the second occasion, a rehabilitation physician performed a physical examination to determine participants' S4-5 sensory and motor function. The rehabilitation physician was unaware of the results of participants' self-report. Participants' self-reports were compared with results from the physical examination using likelihood ratios. Results: The likelihood ratios (95% CI) associated with a positive response to the sensory and motor questions were 1.92 (1.0-3.6) and 2.4 (1.2-4.9), respectively. The likelihood ratios associated with a negative response to the sensory and motor questions were 0.1 (0.0-0.6) and 0.4 (0.1-1.2), respectively. Conclusion: People with SCI are reasonably accurate at self-reporting S4-5 sensory and motor function, although there is a high rate of false positives for S4-5 motor in those with motor levels below T10. In some situations it may be appropriate to use self-report rather than a physical examination to determine S4-5 sensory and motor function. It is used to determine S4-5 sensory and motor function, and alone determines whether a person has a complete or incomplete SCI. It is also used to distinguish between different types of SCI and, importantly, to distinguish an American Spinal Injuries Association Impairment Scale (AIS) B lesion from an AIS C, D or E lesion. The reliance of the classification on S4-5 is based on its prognostic value. Those with S4-5 sensory or motor function have a better chance of neurological recovery than those without. 1 There is little doubt that appropriately trained staff need to carefully undertake the S4-5 examination in people with recent SCI or in those receiving interventions which may influence the neurological recovery. However, there are situations where it may be reasonable to compromise on accuracy and rely on self-report. For example, it may be reasonable to rely on self-report if trying to classify a person's neurological status for a community-based research project which is not targeting neurological recovery. A small degree of inaccuracy may be inconsequential and warranted to avoid rectal examinations. Of course at issue is the extent of inaccuracy in classification when relying on self-report: the focus of this study.It is worth exploring ways of avoiding rectal examinations where possible because they are invasive and unpleasant examinations with associated risks. For example, they can cause rectal bleeding and stimulate bowel motions. There are also logistical and practical problems asso...

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Section: Discussionmentioning

confidence: 99%

The diagnostic accuracy of self-report for determining S4–5 sensory and motor function in people with spinal cord injury

et al. 2011

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“…Thus, these measures of diagnostic accuracy cannot be used interchangeably. Some measures largely depend on disease prevalence, and all of them are sensitive to the spectrum of the disease in the population studied [4]. It is therefore of great importance to know how to interpret them, as well as when and under what circumstances to use them.…”

Section: Diagnostic Accuracy Measuresmentioning

confidence: 99%

Diagnostic Accuracy Measures

Eusebi¹

2013

Cerebrovasc Dis

254

199

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Background: An increasing number of diagnostic tests and biomarkers have been validated during the last decades, and this will still be a prominent field of research in the future because of the need for personalized medicine. Strict evaluation is needed whenever we aim at validating any potential diagnostic tool, and the first requirement a new testing procedure must fulfill is diagnostic accuracy. Summary: Diagnostic accuracy measures tell us about the ability of a test to discriminate between and/or predict disease and health. This discriminative and predictive potential can be quantified by measures of diagnostic accuracy such as sensitivity and specificity, predictive values, likelihood ratios, area under the receiver operating characteristic curve, overall accuracy and diagnostic odds ratio. Some measures are useful for discriminative purposes, while others serve as a predictive tool. Measures of diagnostic accuracy vary in the way they depend on the prevalence, spectrum and definition of the disease. In general, measures of diagnostic accuracy are extremely sensitive to the design of the study. Studies not meeting strict methodological standards usually over- or underestimate the indicators of test performance and limit the applicability of the results of the study. Key Messages: The testing procedure should be verified on a reasonable population, including people with mild and severe disease, thus providing a comparable spectrum. Sensitivities and specificities are not predictive measures. Predictive values depend on disease prevalence, and their conclusions can be transposed to other settings only for studies which are based on a suitable population (e.g. screening studies). Likelihood ratios should be an optimal choice for reporting diagnostic accuracy. Diagnostic accuracy measures must be reported with their confidence intervals. We always have to report paired measures (sensitivity and specificity, predictive values or likelihood ratios) for clinically meaningful thresholds. How much discriminative or predictive power we need depends on the clinical diagnostic pathway and on misclassification (false positives/negatives) costs.

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“…Esto podría explicar la gran sensibilidad que presenta Shamoon 2004 (22) , cuyos pacientes fueron enrolados en un hospital de referencia con un espectro de enfermedad más severo y, probablemente, con mayor bagaje sintomático que aquellos que fueron evaluados en centros comunitarios. En otras palabras, el proceso de referencia y transferencia al hospital podría haber seleccionado los casos más graves o los casos persistentes, mientras que los leves o con resolución espontánea no habrían acudido al hospital, incrementando así la sensibilidad y especificidad de la prueba (26) . Además, la alta prevalencia de neumonía que muestran los estudios incluidos sugiere cierto sesgo de selección o referencia.…”

Section: Discussionunclassified

“…Una revisión sistemática publicada en el 2005 encontró que la ausencia de síntomas y signos respiratorios, como rinorrea, tos, retracciones, taquipnea, murmullo vesicular disminuido, aleteo nasal, y quejido espiratorio, descartaban el diagnóstico de neumonía con un LR negativo de 0,0 (IC 95% 0,0-0,4), mientras que la presencia de al menos uno de estos presentaba un LR positivo de 1,6 (IC95% 1,3-31) (26) . Estos hallazgos pueden ser aplicados solo en países desarrollados por su baja prevalencia de NAC (27) .…”

Section: Discussionunclassified

Precisión de la taquipnea y las retracciones subcostales como signos clínicos para diagnóstico de neumonía adquirida en la comunidad en niños: revisión sistemática y metaanálisis

Domecq

Prutsky

Lazo

et al. 2012

Rev Peru Med Exp Salud Publica

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Objetivos. Evaluar si la taquipnea y las retracciones subcostales son predictoras eficientes para el diagnóstico de neumonía adquirida en la comunidad (NAC) en niños. Materiales y métodos. Se revisaron las bases de datos: PubMed, LILACS, The African Journal Database y The Cochrane Central Library. Se incluyeron estudios originales que evaluaron el rendimiento diagnóstico de los criterios clínicos de taquipnea o retracciones subcostales, definidos según los criterios de la Organización Mundial de la Salud (OMS) para el diagnóstico de NAC en niños de hasta cinco años de edad con tos y fiebre. Se estimaron las razones de probabilidades (LR), el odds ratio diagnostico (DOR) y sus respectivos intervalos de confianza al 95% (IC95%) para cada prueba clínica evaluada. Resultados. Se encontraron 975 estudios, incluyendo ocho en la revisión. Se enrolaron 4740 pacientes y analizaron 3584 (75%), de los cuales 916 (19%) tuvieron el diagnóstico de NAC. Al combinar los datos, la taquipnea obtuvo una LR positiva de 3,16, (IC95% 2,11-4,73) y una LR negativa de 0,36 (IC95% 0,23-0,57). El DOR fue de 10,63 (IC95% 4,4-25,66, I 2 =93%). Al realizar el análisis para retracciones subcostales se obtuvo un LR positivo de 2,49 (IC95% 1,41-4,37) y un LR negativo de 0,59 (IC95% 0,4-0,87). El DOR fue de 5,32 (IC95% 1,88-15,05, I 2 =89%). Conclusiones. Se puede tomar en cuenta la presencia o ausencia de taquipnea y retracciones subcostales en el diagnóstico de NAC, cabe considerar la incertidumbre relativa en su poder diagnóstico y los LR relativamente modestos. La confianza en estos resultados es baja por la inadecuada calidad de la evidencia en este tema.Palabras clave: Frecuencia respiratoria; Neumonía; Niños; Metanálisis; Revisión sistemática (fuente: DeCS BIREME). IDENTIFICATION OF TACHYPNEA AND SUBCOSTAL RETRACTIONS AS CLINICAL SIGNS FOR THE DIAGNOSIS OF COMMUNITY-ACQUIRED PNEUMONIA AMONG CHILDREN: SYSTEMATIC REVIEW AND META-ANALYSIS ABSTRACTObjectives. Determine whether tachypnea and subcostal retractions can be efficient predictors for the diagnosis of Community-Acquired Pneumonia (CAP) among children. Materials and methods. These were the databases used: PubMed, LILACS, The African Journal Database and The Cochrane Central Library. Original studies were included which assessed the diagnostic performance of the clinical criteria for tachypnea or subcostal retraction defined in accordance with the criteria of the World Health Organization (OMS) for CAP diagnosis in children ≤ 5 with cough and fever. The likelihood ratio (LR), the diagnosis odds ratio (DOR), and their respective confidence intervals at 95% (IC95%) were estimated for each clinical test. Results. 975 studies were found, eight were included in the review. 4740 patients were enrolled and 3584 (75%) were analyzed, 916 (19%) of which had a CAP diagnosis. When data were combined, tachypnea had a positive LR of 3.16, (95% CI 2.11-4.73) and a negative LR of 0.36 (95% CI 0.23-0.57). The DOR was 10.63 (95% CI 4.4-25.66, I2=93%). When subcostal retractions were analyzed, a positive...

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Tips for learners of evidence-based medicine: 5. The effect of spectrum of disease on the performance of diagnostic tests

Cited by 47 publications

References 10 publications

The diagnostic accuracy of self-report for determining S4–5 sensory and motor function in people with spinal cord injury

The diagnostic accuracy of self-report for determining S4–5 sensory and motor function in people with spinal cord injury

Diagnostic Accuracy Measures

Precisión de la taquipnea y las retracciones subcostales como signos clínicos para diagnóstico de neumonía adquirida en la comunidad en niños: revisión sistemática y metaanálisis

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