Key result
Higher preoperative anion gap was inversely associated with primary open-angle glaucoma (OR 0.90; 95% CI 0.80-1.00), whereas higher chloride and red blood cell counts were positively associated.
Why the study?
Are there differences in routine preoperative blood test biomarkers between primary open-angle glaucoma patients and cataract surgery patients?
Case-Control (n=300)
No
Are there differences in routine preoperative blood test biomarkers between primary open-angle glaucoma patients and cataract surgery patients?
Odds Ratio: 0.9 (95% CI 0.8–1)
Primary open-angle glaucoma patients have a lower anion gap, higher chloride levels, and higher red blood cell counts compared to age-related cataract surgery patients.
Preoperative biomarker differences should not change practice; leaves open hypothesis-generating links to POAG pathophysiology in case-control data.
PURPOSE: To investigate biomarker differences in routine preoperative blood tests performed on primary open-angle glaucoma (POAG) case and control patients presenting for anterior segment eye surgery. METHODS: POAG cases and age-related cataract surgery patients (controls) who underwent anterior segment surgery at Massachusetts Eye and Ear from January 2009 through March 2012 were identified by retrospective record review. Patients with diabetes mellitus, secondary glaucoma, and cataract due to trauma or steroid exposure were excluded. Data on demographic features, preoperative ophthalmological and medical diagnosis, blood pressure, anthropometric measures, basic metabolic panel, and complete blood count were extracted from the medical records. Univariate differences in lab values between POAG cases and controls were assessed using unpaired t tests. Multivariate logistic regression analysis was completed to determine the independent associations of biomarkers with POAG. RESULTS: A total of 150 cases and 150 age-related controls were included. In multivariate analysis, higher AG was inversely associated with POAG (odds ratio [OR] = 0.90; 95% confidence interval [CI], 0.80-1.00), and higher Cl- level was positively associated with POAG (OR = 1.15; 95% CI, 1.02-1.29). The lower AG in POAG patients could be explained by higher IgG levels as the available data in post hoc analysis showed a nonsignificant trend toward higher IgG in cases compared to controls (17 vs 23; 1142 ± 284 mg/dl vs 1028 ± 291 mg/dl; P = 0.22). Furthermore, in multivariable analysis, a higher red blood cell count was also associated with POAG (OR = 1.91; 95% CI, 1.11-3.28). CONCLUSIONS: Patients with POAG presenting for anterior segment surgery had a lower AG compared to age-related cataract surgery patients. The etiology of this reduced gap is unclear but the possible contribution of IgG warrants further exploration. The etiology of higher red blood cell counts in POAG cases is unknown and deserves further exploration.
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Cohen et al. (2014) conducted a case-control in Primary open-angle glaucoma (POAG) (n=300). Preoperative blood biomarkers (anion gap, chloride, red blood cell count) vs. Age-related cataract surgery patients (controls) was evaluated on Primary open-angle glaucoma (POAG) (OR 0.90, 95% CI 0.80-1.00). Higher preoperative anion gap was inversely associated with primary open-angle glaucoma (OR 0.90; 95% CI 0.80-1.00), whereas higher chloride and red blood cell counts were positively associated.
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