Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2024 Jan 1;33(1):8-14.
doi: 10.1097/IJG.0000000000002262. Epub 2023 Jul 20.

Examining Bias in Published Surgical Glaucoma Clinical Trials

Reinemary Michael  1 , Hiuxin Zhang  2 , Sarah McIntyre  2 , Leila Cape  2 , Andrew Toren  3
Affiliations
Review

Examining Bias in Published Surgical Glaucoma Clinical Trials

Reinemary Michael et al. J Glaucoma. .

Abstract

Prcis: Our results demonstrate that, among randomized clinical trials examining the use of surgical treatments for glaucoma, the majority were not registered. Publication bias (PB) was less likely. More than a third of registered trials presented outcome reporting bias (ORB).

Purpose: Despite the optimum of quality evidence provided by randomized controlled trials (RCTs), biases may be introduced and hinder their application. The primary objective of this study was to investigate ORB and PB in RCTs assessing surgical treatments of glaucoma, as well as their registration status.

Materials and methods: A literature review was conducted in MEDLINE, EMBASE, and CENTRAL databases. Inclusion criteria were RCTs published in English between 2007 and 2021 that focused on surgical treatments of patients of all ages with glaucoma or elevated intraocular pressure. Exclusion criteria included cadaveric and animal studies. Registration status was correlated with entries from clinical trial registries. PB was determined by the proportion of trials presenting statistically significant results. ORB was evaluated by comparing the study's primary outcome with that listed in the trial registry. Trials quality was assessed using the Jadad score.

Results: After deleting duplicates, 7561 citations were screened. One hundred sixty-one RCTs were eligible and included between 13 and 556 participants. Of the total, 91% studied an adult population and 71% included patients suffering from primary open angle glaucoma. Among included studies, 63% were not registered and 47% had statistically significant results. An upward trend in registration was observed with time. However, 37% of the studies showed discrepancies between objectives in cited clinical trial registries and the published results.

Conclusion: PB in surgical glaucoma trials was not obvious. Among the minority of trials that were registered, more than a third presented ORB. Unregistered trials had lower quality. RCT registration is crucial for the transparent interpretation of studies, improved patient care in surgery, and informed decision-making.

PubMed Disclaimer

Conflict of interest statement

Disclosure: The authors declare no conflict of interest.

References

    1. Steinmetz JD, Bourne RR, Briant PS, et al. Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study. Lancet Global Health. 2021;9:e144–e160.
    1. Tham Y-C, Li X, Wong TY, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology. 2014;121:2081–2090.
    1. Szigiato A-A, Trope GE, Jin Y, et al. Trends in glaucoma surgical procedures in Ontario: 1992–2012. Can J Ophthalmol. 2015;50:338–344.
    1. Storgaard L, Tran TL, Freiberg JC, et al. Glaucoma clinical research: trends in treatment strategies and drug development. Front Med. 2021;8:733080.
    1. Storgaard L, Tran TL, Freiberg JC, et al. Glaucoma clinical research: trends in treatment strategies and drug development. Front Med. 2021;8:733080.