Is the observed lowering of intraocular pressure due to treatment?

Thomas, Ravi and Mengersen, Kerrie (2013) Is the observed lowering of intraocular pressure due to treatment?. Indian Journal of Ophthalmology, 61 3: 119-121. doi:10.4103/0301-4738.107908

Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads

Author Thomas, Ravi
Mengersen, Kerrie
Title Is the observed lowering of intraocular pressure due to treatment?
Journal name Indian Journal of Ophthalmology   Check publisher's open access policy
ISSN 0301-4738
Publication date 2013-03
Sub-type Article (original research)
DOI 10.4103/0301-4738.107908
Open Access Status DOI
Volume 61
Issue 3
Start page 119
End page 121
Total pages 3
Place of publication India
Publisher Medknow Publications and Media
Collection year 2014
Language eng
Formatted abstract
Objective: Use Bayes' theorem to estimate the intraocular pressure (IOP) lowering effect of medical treatment initiated for glaucoma and determine if IOP comparisons to the baseline IOP of the same eye is clinically useful.

Materials and Methods: The probability that treatment with prostaglandin is responsible for an observed 20% decrease in IOP with prostaglandin treatment was calculated using Bayes' theorem using the following available information: the probability of a 20% decrease in IOP given treatment with prostaglandin, the probability of a treatment effect using prostaglandin and the overall probability of a 20% decrease in IOP. The calculations were repeated to account for a possible 2 mmHg overestimation of effect caused by measurement error in performing applanation tonometry.

Results: The probability that treatment is responsible for an observed 20% decrease in IOP following initiation of treatment with a prostaglandin was 99%. After adjusting for measurement error this probability was 98%. Obtaining two IOP measurements marginally increased the probability.

Conclusion: Following initiation of treatment with prostaglandin, Bayes' theorem allows us to infer that treatment effect is the most likely explanation for an observed 20% decrease in IOP from the baseline; this inference remains even after adjusting for known measurement error. The high probability of a treatment effect is due to the high prior odds of treatment effect and the high likelihood ratio for prostaglandin producing such an effect. If data is available, similar calculations can be used for other percentage decreases, other medications and for the monocular trial.
Keyword Bayes's theorem
Initiating treatment
Monocular trial
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Medicine Publications
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 0 times in Thomson Reuters Web of Science Article
Scopus Citation Count Cited 0 times in Scopus Article
Google Scholar Search Google Scholar
Created: Sun, 12 May 2013, 01:06:27 EST by System User on behalf of School of Medicine