Prognostic factors of thymectomy in patients with myasthenia gravis: a cohort of 132 patients.

OBJECTIVE: To identify the response to thymectomy and the factors associated with a poor response, a nested case-control study was performed on 132 patients with an established diagnosis of myasthenia gravis who had had a thymectomy between 1987 and 1997 and had been followed up for at least 3 years. METHODS: In order to assess the response to thymectomy, the following two points were taken into account: (a) the dose of pyridostigmine and other drugs (steroids, azathioprine) that the patient took before and after thymectomy, and (b) the Osserman classification before and after thymectomy. The patients were divided into 4 groups: (1) patients in remission; (2) patients with improvement; (3) patients with no change, and (4) patients who were worse. RESULTS: 91 patients had a good response (69%) and 41 patients had a poor response (31%). The response by groups was as follows: 50 patients were found to be in remission; 41 patients had improved; 34 patients had no changes, and 7 got worse. Being more than 60 years old was associated with a poor prognosis (odds ratio 4.6, CI 1.11-20.32, p 0.01). The patients who had the disease for more than 3 years (odds ratio 2.97, CI 0.79-5.39, p 0.09) had a tendency towards a bad prognosis even though there was no statistical significance, and for those who had it for more than 4 years (odds ratio 2.58, CI 0.89-0.96, p 0.02) the bad prognosis was statistically significant. The patients who had the disease for more than 3 years between diagnosis and thymectomy (odds ratio 2.02, CI 0.69-5.90, p 0.15) and those with it for more than 4 years (odds ratio 2.53, CI 0.83-7.7, p 0.06) had a tendency towards a poor prognosis even though there was no statistical significance. In addition, having Osserman I was associated with a bad prognosis. Referring to the pathological findings, patients with thymoma (odds ratio 3.51, CI 0.43-31.5, p 0.15) and those with thymic atrophy (odds ratio 2.19, CI 0.93-5.16, p 0.04) had a poor prognosis. Finally, the use of steroids before thymectomy (odds ratio 2.26, CI 0.99-5.18, p 0.03) was associated with a worse prognosis. CONCLUSIONS: The response to thymectomy was high (69%). The variables that had the most prognostic importance were age and the Osserman stage. Other variables of poor prognosis were: high doses of pyridostigmine and use of steroids before surgery; the total duration of the disease and the duration of the disease between diagnosis and the surgical procedure; history of previous thymectomy; use of plasmapheresis after surgery, and the discovery of thymic atrophy and thymoma in the histopathological result.

Pruebas diagnósticas en miastenia gravis. Conformación de un estándar diagnóstico mediante un método de consenso / Diagnostic test in myasthenia gravis. Creation of a standard for diagnosis using a method of consensus

Introducción. En la actualidad la mejor prueba para el diagnóstico de miastenia gravis (MG) es la electromiografía de fibra única (EFU). Debido al coste de la prueba, pocos hospitales en el mundo la pueden tener para uso rutinario para confirmar el diagnóstico de MG. Objetivo. Identificar un estándar de oro aceptable para hospitales que no cuenten de manera habitual con EFU mediante la utilización de una metodología de consenso realizado en tres etapas. Sujetos y métodos. Las dos primeras etapas del estudio se realizaron mediante encuestas prolectivas y la tercera etapa mediante una metodología Delfos. En la primera etapa se aplicó un instrumento a 55 neurólogos generales donde se preguntaba cuál era la mejor combinación de pruebas y la mejor prueba aislada con las que habitualmente realizaban el diagnóstico de MG. En la segunda etapa se aplicó un segundo instrumento de recolección a 15 expertos de unidad motora (EUM), quienes analizaron cuatro situaciones clínicas frecuentes en la práctica (cuadro clínico clásico de MG generalizada, paciente con cuadro de miastenia ocular, cuadro de MG generalizada de mediana probabilidad y cuadro clínico de baja probabilidad), identificando la mejor prueba aislada y el mejor conjunto de pruebas para el diagnóstico de miastenia gravis con y sin el uso de EFU. Finalmente, se crearon cuatro flujogramas de las cuatro situaciones clínicas analizadas que fueron consensuados mediante una metodología Delfos con ocho neurólogos EUM. Resultados. Hemos identificado un estándar de oro aceptable para hospitales que no cuenten de manera general con EFU mediante una metodología de consenso. También hemos consensuado cuatro flujogramas diagnósticos de las situaciones clínicas más frecuentes a las que nos enfrentamos en la práctica clínica habitual. Conclusión. Hemos encontrado una serie de resultados con una utilidad importante para el diagnóstico de MG aplicables a médicos generales, médicos internistas y neurólogos que no cuenten con todas las pruebas disponibles para el diagnóstico de esta enfermedad (AU)

[Diagnostic tests in myasthenia gravis. Creation of a standard for diagnosis using a method of consensus]. / Pruebas diagnósticas en miastenia gravis. Conformación de un estándar diagnóstico mediante un método de consenso.

INTRODUCTION: Nowadays the best test for the diagnosis of myasthenia gravis (MG) is the single fiber electromyography (SFEMG). Due to the cost of the test it has not become routine in most part of the hospitals to confirm the diagnosis of MG. OBJECTIVE: To identify an acceptable gold standard for hospitals which do not have access to SFEMG, but have access to some other classical test through the use of a consensus methodology. SUBJECTS AND METHODS: The study was realized in three stages. The first two stages were done through a prolective survey and the third stage through a Delfos methodology. During the first stage 59 general neurologist were interviewed, applying an instrument in which they were asked which were the best test and the best group of tests to diagnose MG without using the SFEMG. During a second stage, a second collection instrument was applied to 15 experts in motoneuron diseases to identify the best isolated test and the best test scheme with and without using the SFEMG in four frequent clinical situations in clinical practice (typical clinical case of generalized MG, patient with ocular myasthenia, patient with generalized MG of medium and low probability). Finally four flowcharts were created of the four analyzed clinical situations and were approved through a Delfos methodology with 8 neurologist motoneuron disease. RESULTS: We identified an acceptable gold standard for hospitals which do not have access to SFEMG through the use of a consensus methodology. We have also completed four diagnostic flowcharts about the most frequent clinical situations that we have faced in the ordinary practice. CONCLUSIONS: We have found a series of important results for the diagnosis of MG available to general physicians, internists and neurologist that do not have all the test for the diagnosis of MG.

[The consistency and validity of a measurement in clinical pediatric research. Its definition, evaluation and interpretation]. / Consistencia y validez de una medición en la investigaciíon clínica pediátrica. Definición, evaluación y su interpretación.

In clinical pediatric research as in all research, one of the fundamental characteristics is the measurement of the studied features, either clinical, of laboratory or cabinet. A measurement must have two fundamental characteristics, for it to be considered as scientific: consistency and validity. The first one is centered on the variability of the measurement, which is due to the measuring instrument, to the subject or entity which is measured and to the individual or individuals who carry out the measuring, this is known as intra or interobserver variability, respectively. Validity is the fact of "actually" measuring what we want to measure. Both characteristics of measurement, are often mixed, between them and with other concepts, and this is the reason of not having a clear idea of what is the real meaning. This paper discusses the different terms that have been used for consistency and validity of a measurement. Also it points out how to assess consistency, from the validity, taking into account the measuring scale of the variables and the number of observers. Easy examples are used for the application of different formulas and for the interpretation of the results.