Findings from a study published in Ophthalmology Science reviewed the current literature on diabetic retinopathy (DR) with codified DR definitions to analyze discrepancies in DR terminologies.
Give me some background.
As one of the leading causes of preventable blindness in working adults, minimizing disparities in DR screening and treatment outcomes is of paramount interest to researchers.
The broad adoption of electronic health records (EHRs) has increased data accessibility in clinical practice, billing, and research—necessitating standardization in datasets.
How does this connect to defining DR?
For example, EHR data has allowed for the development of big data studies and artificial intelligence (AI) models with generalizable outcomes, which have been useful for automated DR diagnosis and screening.
Yet, these systems need diverse datasets—requiring standardized representation of data—such as definitions of the disease, associated severity, visual acuity, and images, to facilitate data sharing.
Now talk about the study.
In this literature review, a research team from the University of California San Diego reviewed PubMed and Google Scholar for peer-reviewed studies that used codified definitions of DR (ex., billing codes).
Subsequently, quantitative analyses of the codified definitions were performed to describe the variation between DR cohort definitions.
Findings?
Overall, 43 studies met the inclusion criteria (i.e., having codified definitions of DR), with the earliest study published in July 2008 and the most recent in March 2023.
The research team reported three key findings from the study:
- There is substantial variation in coding systems utilized to define DR cohorts.
- Even within studies using the same coding systems, different definitions were used.
- The majority of studies used provider-defined billing diagnosis codes; only a minority of them used procedure codes or other clinical data elements.
Tell me more.
Half of the included studies utilized datasets based on structured EHR data (i.e., data registries, institutional EHR review), and the other half used claims data.
All but one of the studies used billing codes such as the International Classification of Diseases 9th or 10th edition (ICD-9 or ICD-10) either solely or in addition to another terminology for defining disease.
Go on…
Of the 27 included studies that used ICD-9 and the 20 studies that used ICD-10 codes, the most commonly used codes related to the full spectrum of DR severity.
DR complications (i.e., vitreous hemorrhage [VH]) were also used to define some DR cohorts.
Expert opinion?
According to the study authors, “There exists a secondary need for standardizing disease definitions within a coding system for various DR entities (i.e., proliferative DR [PDR], center-involving diabetic macular edema [DME], DR with VH, and DR with tractional retinal detachment) among other ophthalmic diseases.”
Of note, investigators used DR as a case study to elucidate the discrepancies between studies in defining ophthalmic diseases.
Keep going…
The authors noted that, “Although there have been attempts to create standardized definitions of chronic diseases and DR,” the overall lack of universally-accepted DR standardized definitions affects the ability to:
- Compare outcomes between studies
- Assess generalizability of multi-study findings in reviews
- Adversely affects the reproducibility of studies in other settings
Take home.
Significant variation exists in codified definitions for DR cohorts in retrospective studies, and fluctuating definitions diminish generalizability and reproducibility in studies.
Consequently, standardizing DR coding systems is key to improving data-sharing capabilities and uncovering health disparities to optimize patient care and develop treatments to manage DR.