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Stat Biopharm Res. Author manuscript; available in PMC 2017 June 02. Published in final edited form as: Stat Biopharm Res. 2016 ; 8(2): 151–160. doi:10.1080/19466315.2015.1133453.
Commensurate Priors on a Finite Mixture Model for Incorporating Repository Data in Clinical Trials Byron J. Gajewski, Department of Biostatistics, University of Kansas Medical Center C. Shane Reese, Department of Statistics, Brigham Young University
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John Colombo, and Schiefelbusch Institute for Life Span Studies and Department of Psychology, University of Kansas Susan E. Carlson Department of Dietetics and Nutrition, University of Kansas Medical Center
Abstract
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Docosahexaenoic acid (DHA) is a good source of fat that can be taken up through food, such as fish, or taken as a supplement. Evidence is building that DHA provides a high yield, low risk strategy to reduce preterm birth and/or low birth weight. These births are great costs to society. A recently completed phase III trial revealed that higher birth weight and gestational age were associated with DHA dosed at 600 mg/day. In this paper we take a posterior predictive approach to assess impacts of these findings on public health. Simple statistical models are not adequate for accurate posterior predictive distribution estimation. Of particular interest is a paper by Schwartz et al. (2010) who discovered that the joint distribution of birth weight and gestational age is well modeled by a finite mixture of three normal distributions. Data from our own clinical trial exhibit similar features. Using the mean and variance-covariance matrices from Schwartz et al. (2010) and flexible commensurate priors (Hobbs et al., 2012) for the mixing parameters, we estimate the effect of DHA supplementation on the over 20,000 infants born in hospitals demographically similar to the hospital where the clinical trial was conducted.
Keywords
Author Manuscript
Healthcare costs; Public policy; Dichotomization; Mixture models; Historical controls; Commensurate priors
Introduction National hospital costs for infant admissions are much higher for preterm birth/low birth weight infants versus uncomplicated births (Russell et al., 2007). Using 2001 dollars, it is estimated that preterm (< 37 weeks gestation) or low birth weight (
Stat Biopharm Res. Author manuscript; available in PMC 2017 June 02. Published in final edited form as: Stat Biopharm Res. 2016 ; 8(2): 151–160. doi:10.1080/19466315.2015.1133453.
Commensurate Priors on a Finite Mixture Model for Incorporating Repository Data in Clinical Trials Byron J. Gajewski, Department of Biostatistics, University of Kansas Medical Center C. Shane Reese, Department of Statistics, Brigham Young University
Author Manuscript
John Colombo, and Schiefelbusch Institute for Life Span Studies and Department of Psychology, University of Kansas Susan E. Carlson Department of Dietetics and Nutrition, University of Kansas Medical Center
Abstract
Author Manuscript
Docosahexaenoic acid (DHA) is a good source of fat that can be taken up through food, such as fish, or taken as a supplement. Evidence is building that DHA provides a high yield, low risk strategy to reduce preterm birth and/or low birth weight. These births are great costs to society. A recently completed phase III trial revealed that higher birth weight and gestational age were associated with DHA dosed at 600 mg/day. In this paper we take a posterior predictive approach to assess impacts of these findings on public health. Simple statistical models are not adequate for accurate posterior predictive distribution estimation. Of particular interest is a paper by Schwartz et al. (2010) who discovered that the joint distribution of birth weight and gestational age is well modeled by a finite mixture of three normal distributions. Data from our own clinical trial exhibit similar features. Using the mean and variance-covariance matrices from Schwartz et al. (2010) and flexible commensurate priors (Hobbs et al., 2012) for the mixing parameters, we estimate the effect of DHA supplementation on the over 20,000 infants born in hospitals demographically similar to the hospital where the clinical trial was conducted.
Keywords
Author Manuscript
Healthcare costs; Public policy; Dichotomization; Mixture models; Historical controls; Commensurate priors
Introduction National hospital costs for infant admissions are much higher for preterm birth/low birth weight infants versus uncomplicated births (Russell et al., 2007). Using 2001 dollars, it is estimated that preterm (< 37 weeks gestation) or low birth weight (
