Biomedical subjects
J G Thornton
Publications and source records attributed to J G Thornton.
Vitamin K and childhood cancer.
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Effect of presentation of partogram information on obstetric decision-making.
The way in which medical information is presented may affect doctors' decision-making. We have assessed whether changing the appearance of the same information on the partogram affects clinical decisions during labour. Sixteen junior obstetricians were asked about how they would manage six hypothetical cases of difficult labour. Information was given by partogram, in which we varied either the relative scales of the x and y axes or whether the latent phase of labour had been included. Doctors were more likely to intervene and to intervene more actively if the progress of labour curve appeared flat and if the latent phase was included. The shape and point of origin of the partogram probably influence intervention rates in practice and may partly explain the low rates of caesarean section in some hospitals.
Routine weighing during antenatal visits.
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Decision analysis in medicine.
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Uteroplacental flow velocity waveforms after CVS.
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Convulsions in pregnancy in related gorillas.
Two related gorillas, the second the granddaughter of the first, had pregnancies complicated by convulsions and edema. They may have suffered from eclampsia, indicating that this is not an exclusively human disease and that in gorillas, as in humans, there is a familial factor.
Immunohistochemistry in pelvic nodes of patients with cervical cancer.
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Recurrent idiopathic non-immunologic hydrops fetalis: a report of two families, with three and two affected siblings.
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Pre-eclampsia: discordance among identical twins.
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Tables for estimation of individual risks of fetal neural tube and ventral wall defects, incorporating prior probability, maternal serum alpha-fetoprotein levels, and ultrasonographic examination results.
Tables are provided for estimation of the risk of open spina bifida in patients who have elevated maternal serum alpha-fetoprotein levels but normal results on detailed anatomy ultrasonographic scan. Risks are provided for various prior population risks, for various levels of elevated maternal serum alpha-fetoprotein, and for various assumptions about the sensitivity of ultrasonographic examination. The formula used is based on sequential multiplication of odds with the use of Bayes' theorem, but an arbitrary reduction (to the power of 0.5) in the degree to which ultrasonographic information modifies the odds has been made to allow for the nonindependence of ultrasonography and maternal serum alpha-fetoprotein tests. The wide range of resulting risks shows that the decision to offer amniocentesis after a negative scan should be individualized.
Clinical experience with the triple test for Down's syndrome screening.
The introduction of maternal serological screening for chromosome disorders in pregnancy in women aged over 30 years at the estimated date of delivery was monitored in two hospitals. The test used involved measurement of three substances in maternal serum combined with maternal age (the triple test). This is the first report of such screening applied to an unselected antenatal clinic population. Test uptake was high but there was no overall increase in amniocentesis numbers because the increase in younger mothers was compensated for by a decrease in older women who previously, without serological testing, might have gone directly to amniocentesis. It is anticipated that widespread introduction of such testing will lead to improved detection of Down's syndrome as predicted from retrospective studies.
Efficacy and long-term effects of antenatal prophylaxis with anti-D immunoglobulin.
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Identification of the cystic fibrosis gene.
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Hospital admission in twin pregnancy.
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Decision analysis in obstetrics and gynaecology.
Decision analysis has its weaknesses: it may oversimplify problems, and probability and utility estimates may be biased. However, the alternative--decision-making by intuition--is likely to oversimplify problems even more and to be subject to even greater bias. Clinicians and patients often ignore major items of data, they handle probabilistic information badly, and their decisions are subject to a number of well-documented biases (Tversky and Kahnemann, 1974). Concern over these problems is not a reason to avoid decision analysis. Probably the greatest virtue of the decision tree and the other components of decision analysis is that the method forces decision-makers to make the bases for their decisions explicit. Generating the information often clarifies problems, and the source of difference of opinion can then be elucidated. Most of the benefits of decision analysis come to the decision-maker in the early part of the analysis as the problem is formulated and probabilities and values are estimated. Only occasionally is it necessary to perform new research, formally measure experts' opinions by the Delphi method, or do elaborate sensitivity analysis.