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Understanding the effects of conditional dependence in research studies involving imperfect diagnostic tests

, : Understanding the effects of conditional dependence in research studies involving imperfect diagnostic tests. Statistics in Medicine (): -

NlmCategory="UNASSIGNED">When two imperfect diagnostic tests are carried out on the same subject, their results may be correlated even after conditioning on the true disease status. While past work has focused on the consequences of ignoring conditional dependence, the degree to which conditional dependence can be induced has not been systematically studied. We examine this issue in detail by introducing a hypothetical missing covariate that affects the sensitivities of two imperfect dichotomous tests. We consider four forms for this covariate, normal, uniform, dichotomous and trichotomous. In the case of a dichotomous covariate, we derive an expression showing that the conditional covariance is a function of the product of the changes in test sensitivities (or specificities) between the subgroups defined by the covariate. The maximum possible covariance is induced by a dichotomous covariate with a very strong effect on both tests. Through simulations, we evaluate the extent to which fitting a latent class model ignoring each type of covariate but including a general covariance term can adjust for the correlation induced by the covariate. We compare the results to when the conditional dependence is ignored. We find that the bias because of ignoring conditional dependence is generally small even for moderate covariate effects, and when bias is present, a model including a covariance term works well. We illustrate our methods by analyzing data from a childhood tuberculosis study. Copyright © 2016 John Wiley & Sons, Ltd.


PMID: 27730659

DOI: 10.1002/sim.7148

Other references

Nahas, G.G.; Ligou, J.C.; Mehlman, B., 1960: Effects of pH changes on O2 uptake and plasma catecholamine levels in the dog. During hypercapnic acidosis induced by "apneic oxygenation", one observes in the dog a rise in plasma catecholamine levels in the presence of a constant oxygen uptake (0.O2) and a rise in mean blood pressure. When pH is maintained consta...

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Brokensha, G.; Westbury, D.R., 1974: Adaptation of the discharge of frog muscle spindles following a stretch. 1. Stretching a frog muscle spindle evoked a discharge of action potentials in its sensory axon. As the rate of this discharge decreased during the adaptation that followed the dynamic phase of a stretch, the variability of the interspike interval...

Pillutla, R.C.; Sharer, J.D.; Gulati, P.S.; Wu, E.; Yamashita, Y.; Lerner, C.G.; Inouye, M.; March, P.E., 1995: Cross-species complementation of the indispensable Escherichia coli era gene highlights amino acid regions essential for activity. Era is an essential GTP binding protein in Escherichia coli. Two homologs of this protein, Sgp from Streptococcus mutans and Era from Coxiella burnetii, can substitute for the essential function of Era in E. coli. Site-specific and randomly genera...

Fialkow, A., 1933: The Geometry of Degenerate Heat Families. Proceedings of the National Academy of Sciences of the United States of America 19(5): 543-548

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Smith H.G., 1973: The signy island terrestrial reference sites part 2 the protozoa. British Antarctic Survey Bulletin (33-34): 83-87

Das, S.N.; Chatterjee, S., 1996: Long term toxicity study of Optiliv. The effects were studied of a daily dose of Optiliv, a polyherbal product used for its hepatoprotective properties, at 18 or 60 mg/kg (3 and 10 times recommended therapeutic dose) for 30 days on rats. Optiliv up to 10 times higher than the recomme...

Mccall, K.; Bender, W., 1996: Probes for chromatin accessibility in the Drosophila bithorax complex respond differently to Polycomb-mediated regression. The Polycomb group (PcG) of genes are required for maintenance of the repressed state of the homeotic genes in Drosophila. There are similarities between the PcG repression and mating-type silencing in yeast or heterochromatic position effect in D...

Verheyen, R., 1947: Notes sur le faune ornithologique de 1'Afrique cen-trale. VI. Description d'un nouveau Strigide du Congo belge, 22 211946p. 1-2. Notes sur la faune ornithologique de 1'Afrique Centrale. VII. Liste d'une collection d'oiseaux rares. Bull Mus Hist nat Belg, 2310: 1-14