Alberto Narváez

Publications (4)40.58 Total impact

• Source

  Available from: Monica Taljaard

  Article: Intracluster correlation coefficients from the 2005 WHO Global Survey on Maternal and Perinatal Health: implications for implementation research.

  Monica Taljaard, Allan Donner, José Villar, Daniel Wojdyla, Alejandro Velazco, Vicente Bataglia, Anibal Faundes, Ana Langer, Alberto Narváez, Eliette Valladares, Guillermo Carroli, Nelly Zavaleta, Archana Shah, Liana Campodónico, Mariana Romero, Sofia Reynoso, Karla Simônia de Pádua, Daniel Giordano, Marius Kublickas, Arnaldo Acosta
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  ABSTRACT: Cluster-based studies involving aggregate units such as hospitals or medical practices are increasingly being used in healthcare evaluation. An important characteristic of such studies is the presence of intracluster correlation, typically quantified by the intracluster correlation coefficient (ICC). Sample size calculations for cluster-based studies need to account for the ICC, or risk underestimating the sample size required to yield the desired levels of power and significance. In this article, we present values for ICCs that were obtained from data on 97,095 pregnancies and 98,072 births taking place in a representative sample of 120 hospitals in eight Latin American countries. We present ICCs for 86 variables measured on mothers and newborns from pregnancy to the time of hospital discharge, including 'process variables' representing actual medical care received for each mother and newborn. Process variables are of primary interest in the field of implementation research. We found that overall, ICCs ranged from a minimum of 0.0003 to a maximum of 0.563 (median 0.067). For maternal and newborn outcome variables, the median ICCs were 0.011 (interquartile range 0.007-0.037) and 0.054 (interquartile range 0.013-0.075) respectively; however, for process variables, the median was 0.161 (interquartile range 0.072-0.328). Thus, we confirm previous findings that process variables tend to have higher ICCs than outcome variables. We demonstrate that ICCs generally tend to increase with higher prevalences (close to 0.5). These results can help researchers calculate the required sample size for future research studies in maternal and perinatal health.
  Paediatric and Perinatal Epidemiology 04/2008; 22(2):117-25. · 2.31 Impact Factor
• Source

  Available from: José Villar

  Article: Maternal and neonatal individual risks and benefits associated with caesarean delivery: multicentre prospective study.

  José Villar, Guillermo Carroli, Nelly Zavaleta, Allan Donner, Daniel Wojdyla, Anibal Faundes, Alejandro Velazco, Vicente Bataglia, Ana Langer, Alberto Narváez, Eliette Valladares, Archana Shah, Liana Campodónico, Mariana Romero, Sofia Reynoso, Karla Simônia de Pádua, Daniel Giordano, Marius Kublickas, Arnaldo Acosta
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  ABSTRACT: To assess the risks and benefits associated with caesarean delivery compared with vaginal delivery. Prospective cohort study within the 2005 WHO global survey on maternal and perinatal health. 410 health facilities in 24 areas in eight randomly selected Latin American countries; 123 were randomly selected and 120 participated and provided data 106,546 deliveries reported during the three month study period, with data available for 97,095 (91% coverage). Maternal, fetal, and neonatal morbidity and mortality associated with intrapartum or elective caesarean delivery, adjusted for clinical, demographic, pregnancy, and institutional characteristics. Women undergoing caesarean delivery had an increased risk of severe maternal morbidity compared with women undergoing vaginal delivery (odds ratio 2.0 (95% confidence interval 1.6 to 2.5) for intrapartum caesarean and 2.3 (1.7 to 3.1) for elective caesarean). The risk of antibiotic treatment after delivery for women having either type of caesarean was five times that of women having vaginal deliveries. With cephalic presentation, there was a trend towards a reduced odds ratio for fetal death with elective caesarean, after adjustment for possible confounding variables and gestational age (0.7, 0.4 to 1.0). With breech presentation, caesarean delivery had a large protective effect for fetal death. With cephalic presentation, however, independent of possible confounding variables and gestational age, intrapartum and elective caesarean increased the risk for a stay of seven or more days in neonatal intensive care (2.1 (1.8 to 2.6) and 1.9 (1.6 to 2.3), respectively) and the risk of neonatal mortality up to hospital discharge (1.7 (1.3 to 2.2) and 1.9 (1.5 to 2.6), respectively), which remained higher even after exclusion of all caesarean deliveries for fetal distress. Such increased risk was not seen for breech presentation. Lack of labour was a risk factor for a stay of seven or more days in neonatal intensive care and neonatal mortality up to hospital discharge for babies delivered by elective caesarean delivery, but rupturing of membranes may be protective. Caesarean delivery independently reduces overall risk in breech presentations and risk of intrapartum fetal death in cephalic presentations but increases the risk of severe maternal and neonatal morbidity and mortality in cephalic presentations.
  BMJ (Clinical research ed.). 12/2007; 335(7628):1025.
• Source

  Available from: José Villar

  Article: Caesarean delivery rates and pregnancy outcomes: the 2005 WHO global survey on maternal and perinatal health in Latin America.

  José Villar, Eliette Valladares, Daniel Wojdyla, Nelly Zavaleta, Guillermo Carroli, Alejandro Velazco, Archana Shah, Liana Campodónico, Vicente Bataglia, Anibal Faundes, Ana Langer, Alberto Narváez, Allan Donner, Mariana Romero, Sofia Reynoso, Karla Simônia de Pádua, Daniel Giordano, Marius Kublickas, Arnaldo Acosta
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  ABSTRACT: Caesarean delivery rates continue to increase worldwide. Our aim was to assess the association between caesarean delivery and pregnancy outcome at the institutional level, adjusting for the pregnant population and institutional characteristics. For the 2005 WHO global survey on maternal and perinatal health, we assessed a multistage stratified sample, comprising 24 geographic regions in eight countries in Latin America. We obtained individual data for all women admitted for delivery over 3 months to 120 institutions randomly selected from of 410 identified institutions. We also obtained institutional-level data. We obtained data for 97,095 of 106,546 deliveries (91% coverage). The median rate of caesarean delivery was 33% (quartile range 24-43), with the highest rates of caesarean delivery noted in private hospitals (51%, 43-57). Institution-specific rates of caesarean delivery were affected by primiparity, previous caesarean delivery, and institutional complexity. Rate of caesarean delivery was positively associated with postpartum antibiotic treatment and severe maternal morbidity and mortality, even after adjustment for risk factors. Increase in the rate of caesarean delivery was associated with an increase in fetal mortality rates and higher numbers of babies admitted to intensive care for 7 days or longer even after adjustment for preterm delivery. Rates of preterm delivery and neonatal mortality both rose at rates of caesarean delivery of between 10% and 20%. High rates of caesarean delivery do not necessarily indicate better perinatal care and can be associated with harm.
  The Lancet 07/2006; 367(9525):1819-29. · 38.28 Impact Factor
• Article: Tasas de cesáreas y resultados perinatales: estudio global WHO 2005 sobre salud materna y perinatal en América Latina

  José Villar, Eliette Valladares, Daniel Wojdyla, Nelly Zavaleta, Guillermo Carroli, Alejandro Velazco, Arcana Shah, Liana Campodónico, Vicente Bataglia, Aníbal Faundes, Ana Langer, Alberto Narváez, Allan Donner
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  ABSTRACT: Las tasas de cesáreas continúan incrementándose en todo el mundo. Nuestro objetivo fue investigar la asociación entre frecuencia de cesáreas y resultados del embarazo en el ámbito institucional ajustado a la población de embarazadas y a las características institucionales. Métodos: para el estudio de la OMS del 2005 sobre salud materna y perinatal realizamos un estudio multiestratificado comprendiendo 24 regiones geográficas en 8 países de Latinoamérica. Se obtuvieron datos individuales de todas las mujeres admitidas para el parto durante 3 meses en 120 instituciones seleccionadas aleatoriamente de 410 instituciones identificadas. También se obtuvieron datos del nivel institucional. Conclusiones: Obtuvimos datos de 97.095 partos entre 106.546 (Cobertura del 91%). La mediana de cesáreas fue del 33% (Rango intercuartilos 24 al 43%) con las tasas mas elevadas en hospitales privados, 51% (Rango 43 al 57%). Las tasas de cesáreas especificas de cada institución fueron afectadas por primiparidad, cesárea previa y complejidad institucional. Las tasas de cesáreas fueron positivamente asociadas con tratamiento antibiótico post-parto, severa morbilidad materna y mortalidad, aun ajustándose a los factores de riesgo. El incremento en las tasas de cesáreas fue asociada con aumento en la tasa de mortalidad fetal y mayor número de bebes admitidos en la unidad de cuidados intensivos por 7 días aun después de ajustarse con prematurez. Las tasas de partos pretérminos y muerte neonatal aumentaron en la frecuencia de cesáreas de entre 10 y 20%. Interpretación: Las altas tasas de cesáreas no necesariamente indican mejor cuidado perinatal y pueden asociarse con daños.
  Revista del Hospital Materno Infantil Ramón Sardá. 01/2006;