RESUMO
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.
Assuntos
Miastenia Gravis/cirurgia , Timectomia , Corticosteroides/administração & dosagem , Adulto , Azatioprina/administração & dosagem , Estudos de Casos e Controles , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Miastenia Gravis/classificação , Miastenia Gravis/diagnóstico , Exame Neurológico/efeitos dos fármacos , Prognóstico , Brometo de Piridostigmina/administração & dosagem , Resultado do TratamentoRESUMO
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.