A study recently published in the Advances in Ophthalmology Practice and Research journal evaluated the association between red blood cell distribution width to albumin ratio (RAR) and cataract risk among U.S. adults.
Back up a minute … what is RAR?
RAR is an emerging composite biomarker integrating two independent biological indicators (i.e., the ratio of red blood cell distribution width to serum albumin concentration) reflecting systemic inflammation and nutrition-related status.
Note: RAR levels increase under conditions of chronic inflammation, oxidative stress, and nutritional deficiency.
And how does this relate to cataracts?
Recent studies have implicated systemic chronic inflammation in cataract pathogenesis, wherein inflammatory states activate oxidative stress pathways, thereby accelerating lens protein denaturation and aggregation.
Plus: A growing body of literature has demonstrated the superior prognostic and risk stratification value of RAR across multiple chronic diseases, including:
- Age-related macular degeneration (AMD)
- Diabetic retinopathy (DR)
- Cardiovascular events
- Cancer
- Depression
However: The association between RAR and cataract development remains unexplored.
Now talk about the study.
Investigators performed a cross-sectional study using the National Health and Nutrition Examination Survey (NHANES) from 1999-2008.
- Note: All but one of the above-mentioned studies utilized the NHANES to evaluate the association between RAR and chronic diseases.
Additional study details to keep in mind:
- Self-reported history of cataract surgery served as a proxy for cataract diagnosis
- Covariates included sociodemographic factors, lifestyle variables, and comorbidities
- Propensity score matching was implemented to reduce confounding bias
Findings?
The analytical cohort comprised 26,397 participants (mean age: 49.5 years, 50.7% female), of which 2,295 (8.70%) had cataract.
- Cataract patients exhibited significantly higher RAR values (3.22±0.47) compared to non-cataract participants (3.06±0.46).
After adjustment for all covariates, a positive association between RAR and cataract was observed—both when RAR was treated as a continuous variable (odds ratio [OR]: 1.41, 95% confidence interval [CI]: 1.21-1.65, p < 0.001) and when analyzed categorically by quartiles.
- Participants in the highest RAR quartile had significantly increased cataract risk relative to the lowest quartile (OR: 1.57, 95% CI: 1.26-1.96, p < 0.001).
Anything else?
Subgroup analysis revealed no significant interaction effects across the covariates listed below, with the RAR-cataract association remaining statistically significant in most subgroups:
- Age
- Gender
- Race/ethnicity
- Education level
- Marital status
- Economic status
- Body mass index (BMI)
- Smoking/alcohol
- Hypertension
- Hyperlipidemia
- Diabetes
Expert opinion?
“Given its cost-effectiveness and ease of measurement, RAR may serve as a routine monitoring marker for cataract,” the study authors explained.
Moreover: “For patients with chronic inflammatory conditions, in addition to managing comorbidities and improving lifestyle, future research should focus on evaluating the potential effects of anti-inflammatory therapies and albumin supplementation for cataract prevention,” they added.
Any limitations?
A few to note, including:
- The cross-sectional nature of the study precludes further investigation on the causal relationship between RAR and cataract
- Self-reported surgery history by participants does not accurately reflect the prevalence of cataract, considering the existence of untreated patients and recall bias
- Data limitations prevented detailed investigation into associations between RAR and specific cataract types or severity grades
Take home.
These findings suggest that elevated RAR is independently associated with higher cataract prevalence, implicating systemic inflammation and nutritional deficiency as modifiable risk factors.