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Resumen OBJETIVO: Calcular y ajustar los múltiplos de la mediana para el índice de pulsatilidad medio de las arterias uterinas, presión arterial media materna, factor de crecimiento placentario y proteína plasmática A asociada al embarazo, a fin de valorar el desempeño diagnóstico del modelo corregido de preeclampsia de la Fetal Medicine Foundation en población mexicana. MATERIALES Y MÉTODOS: Estudio de casos y controles anidado en una cohorte prospectiva efectuado en el Centro de Salud Dr. Galo Soberón y Parra entre el 1 de octubre de 2015 y el 30 de junio de 2016. Criterio de inclusión: pacientes con embarazo de 11-13.6 semanas. Criterio de exclusión: pacientes de riesgo no seleccionado, con embarazo único, entre 11 y 13.6 semanas calculadas por ecografía mediante longitud cráneo cauda. Criterio de eliminación: pacientes que abandonaron el estudio. Se evaluaron el índice de pulsatilidad medio de las arterias uterinas, la presión arterial media, los valores séricos del factor de crecimiento placentario y la proteína plasmática A asociada al embarazo. Se comparó la diferencia en la distribución de los biomarcadores entre la observada en población mexicana y la esperada según la formula original de la Fetal Medicine Foundation. Cuando la diferencia fue mayor a 0.2 múltiplos de la mediana, se utilizó la mediana del observado como coeficiente de ajuste a la fórmula original del esperado. RESULTADOS: De las 300 pacientes reclutadas, 292 concluyeron el estudio. La media de semanas de embarazo al momento del tamizaje fue de 12.4 (desviación estándar 0.72). La prevalencia de preeclampsia fue de 4.5% (13 de 292). Se encontraron diferencias importantes en la distribución de múltiplos de la mediana para el índice de pulsatilidad medio de las arterias uterinas, factor de crecimiento placentario y proteína plasmática A asociada al embarazo. Posterior a la corrección de los biomarcadores, la sensibilidad, falsos positivos y área bajo la curva del modelo ajustado para detectar cualquier preeclampsia fue de 92% (12 de 13), 5.7% (16 de 279) y 93.3%, respectivamente. CONCLUSIONES: La distribución de los múltiplos de la mediana en población mexicana es distinta para los biomarcadores: factor de crecimiento placentario, proteína plasmática A asociada al embarazo e índice de pulsatilidad medio de las arterias uterinas. El ajuste de estos biomarcadores para población mexicana resulta en un buen desempeño diagnóstico del modelo de preeclampsia.
Abstract OBJECTIVE: Calculate and adjust the multiples of the median (MoMs) for the mean pulsatility index of uterine arteries (IPm Aut), mean arterial pressure (PAM), placental growth factor (PlGF) and plasma protein associated with pregnancy (PAPP-A), in order to assess the diagnostic performance of the corrected preeclampsia model of the fetal medicine foundation in the Mexican population. MATERIALS AND METHODS: Case-control study nested in a prospective cohort conducted at the "Dr. Galo Soberón y Parra "from October 1, 2015 - June 30, 2016. Patients with pregnancy of 11-13.6 weeks were included, multiple pregnancies or older than 14 weeks were excluded and patients with medication intake prior to pregnancy; Patients who decided to leave the study were eliminated. Autm IPm, PAM, PlGF and PAPP-A serum values were evaluated. The difference in the distribution of biomarkers between that observed in the Mexican population and that expected was compared according to the original formula of the Fetal Medicine Foundation. When the difference was greater than 0.2 MoMs, the median observed was used as an adjustment coefficient to the original expected formula. RESULTS: Of the 300 patients recruited, 292 concluded the study. The average gestational age at the time of screening was 12.4 weeks (standard deviation [SD] 0.72). The prevalence of preeclampsia was 4.5% (13/292). Important differences were found in the distribution of multiples of the median (MoMs) for IPm Aut, PlGF and PAPP-A. After correction of the biomarkers, the sensitivity, false positives and area under the curve (AUC) of the model adjusted to detect any preeclampsia was 92% (12/13), 5.7% (16/279) and 93.3%, respectively . CONCLUSIONS: The distribution of MoMs in the Mexican population is different for the PlGF, PAPP-A and IPm Aut biomarkers. The adjustment of these biomarkers to the Mexican population results in a good diagnostic performance of the preeclampsia model.
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OBJECTIVE: To demonstrate that specificity to diagnose gestational diabetes increases when the end point diminishes from 180 to 170 mg/dL. MATERIAL AND METHODS: We made a transversal study based on the collection of 200 files randomly chosen, and whose diagnose was gestational diabetes identified by screening test. We established two end points: 180 and 170 mg/dL. The statistical analysis was based on the efficacy values for each one of them. Likelihood ratios for both tests were compared with the gold standard of the oral glucose tolerance test, 3 h with 100 g of glucose. A hundred patients were chosen for each group (the end point of the first and second group was greater than 180 and 170 mg/dL, respectively). RESULTS: The screening test results of the first group varied between 130 and 180 mg/dL. Fifty tolerance curves of four samples were negative and 50 were abnormal; 30 of these had diagnosis of gestational diabetes and 20 carbohydrate intolerance. In the second group the screening test results varied from 130 to 170 mg/dL. Sixty four tolerance curves of four samples were normal and 36 were abnormal; 24 of these had diagnosis of gestational diabetes and 12 carbohydrate intolerance. CONCLUSIONS: Modifying the superior end point of the glucose screening test, from 180 to 170 mg/dL, maintains the test sensitivity and improves its specificity.