Factores predictores del estado libre de cálculos en la primera ureteroscopia flexible con litotricia láser / Predictors of stone-free status in the first flexible ureteroscopy with laser lithotripsy

Resumen Introducción: La ureteroscopia flexible con litotricia láser (URSLL) es una modalidad mínimamente invasiva de tratamiento quirúrgico de cálculos renales. La selección inadecuada de pacientes para este procedimiento genera un desbalance de costo-efectividad. Objetivo: Conocer los factores predictores de estado libre de litos en un solo tiempo quirúrgico en pacientes sometidos a URSLL. Método: Cohorte retrospectiva de pacientes sometidos a URSLL. Se realizó un análisis univariado y multivariado (regresión logística) de los predictores de estado libre de cálculos en la primera URSLL, global y categorizado por sexo. Resultados: EL estado libre de cálculos en la primera URSLL fue de 73.62 %. Los predictores de estado libre de cálculos en hombres fueron edad y tamaño, densidad y multiplicidad del cálculo; en las mujeres, el índice de masa corporal y la multiplicidad del cálculo. Conclusiones: Los factores pronósticos de estado libre de cálculos en la primera URSLL son distintos en hombres y mujeres. Las mujeres con obesidad y sobrepeso probablemente tengan cálculos de fácil fragmentación y extracción asociados con ácido úrico.

Abstract Introduction: Flexible ureteroscopy and laser fragmentation (FURSL) is a minimally invasive modality for surgical treatment of renal stones. Inadequate selection of patients for this treatment generates a cost-effectiveness unbalance. Objective: To know the stone-free rate predictors in a single surgical time in patients undergoing FURSL. Method: Retrospective cohort of patients undergoing FURSL. Global and gender-categorized univariate and multivariate (logistic regression) analyses were performed to identify stone-free predictors at first FURSL. Results: Stone-free rate at first FURSL was 73.62%. Predictors in males were patient age and stone size, density and multiplicity; in females, body mass index and multiplicity of stones. Conclusions: Stone-free rate predictors at first FURSL are different in males and females. Women with overweight and obesity probably have easy-to-fragment and easy-to-extract stones associated with uric acid.

Tasa libre de litos sin complicación mayor como definición de éxito en nefrolitotomía percutánea / Stone-free rate without major complication as a definition of success in percutaneous nephrolithotomy

Resumen Introducción: El éxito en nefrolitotomía percutánea (NLP) se define como estatus libre de litos, sin embargo, las complicaciones mayores se presentan con alta frecuencia y han sido reportadas como resultado secundario. Objetivo: Presentar una nueva definición de éxito en NLP que comprenda la tasa libre de litos sin complicaciones mayores y una escala de riesgo para predecir este desenlace. Método: Cohorte histórica de pacientes sometidos a NLP. Las variables incluidas fueron edad, sexo, urocultivo, índice de comorbilidad de Charlson (ICC) y lito complejo. Se definió éxito: sin litos, sin o con complicación Clavien ≤ 2; éxito intermedio: con litos sin o con complicación Clavien ≤ 2; fracaso: con o sin litos con complicación Clavien > 2. Se realizó análisis bivariado para identificar los factores asociados con el desenlace. Por regresión logística múltiple se calculó el peso independiente de cada factor. Resultados: Se incluyeron 568 procedimientos, 59 % en el sexo femenino. La mediana de edad fue de 49 años; 65, 22 y 13 % de los casos tuvieron éxito, éxito intermedio y fracaso. El sexo femenino, urocultivo positivo, lito complejo e ICC severo se asociaron con fracaso. Conclusión: La probabilidad de éxito fue directamente proporcional al número de factores de riesgo.

Abstract Introduction: Success in percutaneous nephrolithotomy (PCNL) is defined as a stone-free status; however, major complications are highly common and have been reported as a secondary outcome. Objective: To propose a new definition of PCNL success that comprises a stone free rate without major complications and a risk scale to predict this outcome. Methods: Historical cohort of patients undergoing PCNL. The included variables were age, gender, urine culture, Charlson's comorbidity index (CCI) and complex stones. Success was defined as a stone free status with or without Clavien grade ≤ 2 complication; intermediate success: with stones, with or without Clavien grade ≤ 2 complication; and failure: with or without stones with Clavien grade ≤ 2 complication. Bivariate analysis was performed to identify which factors are associated with the outcome. The independent weight of each factor was calculated by multiple logistic regression analysis. Results: 568 procedures were included, 59% of which were in females. Median age was 49 years; 65%, 22% and 13% of cases were classified as success, intermediate success and failure, respectively. Female sex, positive urine culture, complex stones and severe CCI were associated with failure. Conclusions: The likelihood of success was directly proportional to the number of risk factors.

Alcances de una estrategia educativa desde una perspectiva participativa de la educación en el desarrollo de lectura crítica de informes de investigación en médicos residentes de medicina nuclear / Developing critical skills to analyze research reports in nuclear medicine

Objetivo: Estimar los alcances de una estrategia educativa en el desarrollo de la lectura crítica de informes de investigación en médicos residentes de medicina nuclear. Métodos: Estudio de intervención entre mayo y junio de 2007 para medir el grado de desarrollo de lectura crítica en médicos residentes de medicina nuclear. Se elaboró un instrumento con cinco resúmenes de informes de investigación en medicina nuclear, con 96 enunciados que exploraron cuatro indicadores (interpretar, enjuiciar, proponer y valoración de aspectos técnicos y tecnológicos). Se estimó la confiabilidad interna con la prueba de Kuder-Richardson 20 (0.89). Se conformaron cinco categorías: muy bajo (17-32), bajo (33-48), medio (49-64), alto (65-80) y muy alto (81-96). El análisis estadístico se realizó con estadística no paramétrica. Resultados: Al inicio de la estrategia, 80 % de los residentes mostró un grado de dominio de lectura crítica muy bajo e incluso calificaciones dentro de lo explicable por efecto del azar; al final de la misma, 90% alcanzó un dominio medio. Las diferencias fueron estadísticamente significativas (p=0.02). Conclusiones: La estrategia educativa propició un avance en el desarrollo de lectura crítica de informes de investigación en medicina nuclear.

OBJECTIVE: To estimate the impact of an educational strategy aimed at developing critical reading of research reports among medical residents enrolled in a nuclear medicine course. METHODS: We carried out an intervention study to measure the degree to which students developed critical reading skills in a one month period (May-June, 2007). We developed an instrument that included five summaries of research articles in nuclear medicine and 96 sentences that measured four indicators (interpret, judge, propose, and assessment of technical and technological aspects). The instrument's internal validity was measured using the Kuder-Richardson test (KR 20 = 0.89) stratified in five scores: very low (17-32), low (33-48), medium (49-64), high (65-80) and very high (81-96). Non-paramentric statistics was employed to determine significant differences. RESULTS: At the beginning of the intervention, 0.80 of participating residents scored in the [quot ]very low[quot ] domain of critical reading even after controlling for a random effect. At the end of the study, 0.90 scored in the [quot ]medium[quot ] category. Results were statistically significant (p = 0.02). CONCLUSIONS: The educational strategy tested, fostered the development of critical reading skills among a sample of nuclear medicine residents.

Dos métodos para la toma de biopsia transrectal de próstata ecodirigida: sistemática versus ecosospechosa / Two methods for transrectal ultrasound-guided biopsy of the prostate: systematic vs guided for suspect echogenic lesion

OBJECTIVE: We undertook this study to determine the efficiency of ultrasound-guided transrectal prostate biopsy applying two techniques: systematic extended vs. suspicious sonographic areas. METHODS: Medical files and histopathological reports were reviewed of patients who were treated at the Specialties Hospital of the 21st Century Medical National Center in Mexico City with suspicion of prostate cancer (T1, T2 and PSA <10 ng/ml). Patients had ultrasound-guided transrectal prostate biopsy applying two techniques: systematic extended vs. hypoechoic suspicious sonographic areas. Studies were carried out from January 1, 2005 to July 2006. RESULTS: Of 145 selected patients submitted to ultrasound-guided transrectal prostate biopsy, systematic extended biopsy (group I) was carried out in 73 (50.3%), taking on average 11.75 cylinders per patient. In 72 (49.6%) patients, biopsies were taken on suspicious sonographic areas (group II), taking on average 4.02 cylinders. In group I, 36 (49.3%) patients were positive vs. group II, where 20 (27.7%) patients were positive (p <0.01) with an estimation of risk in favor of group I, determining a probability 2.5 times higher of positivity with this technique (95% confidence interval: range 1.2-5) and a better performance in 22%. CONCLUSIONS: Systematic extended ultrasound-guided transrectal prostate biopsy represents a technique with a higher rate of efficiency than using ultrasound-guided transrectal prostate biopsy in suspicious sonographic areas and has proven over time to be the superior prostate biopsy technique for diagnosis of prostate cancer. It must be considered the method of choice.