Early Endophthalmitis Incidence and Risk Factors Following Glaucoma Surgery in the Medicare Population from 2016 to 2019.

OBJECTIVE: To determine early endophthalmitis incidence and risk factors following glaucoma surgeries in the Medicare population.

DESIGN: Retrospective, longitudinal study.

SUBJECTS AND PARTICIPANTS: Eyes that had glaucoma surgery among Medicare Fee-For-Service and Medicare Advantage beneficiaries in the US aged 65 years or older.

METHODS: Medicare Fee-For-Service and Medicare Advantage claims were used to identify all patients who underwent glaucoma surgery, combined cataract/glaucoma surgery, and cataract surgery alone from 2016 to 2019. Endophthalmitis cases within 42 days of the index surgery were identified using the International Classification of Diseases, Tenth Revision-Clinical Modification (ICD-10 CM) codes. Multivariable logistic regression models were used to evaluate factors associated with postoperative endophthalmitis.

MAIN OUTCOME MEASURES: The 42-day postoperative endophthalmitis incidence and risk factors associated with endophthalmitis following glaucoma surgery.

RESULTS: There were 466,928 glaucoma surgeries, of which 310,823 (66.6%) were combined with cataract surgery. Cataract surgeries alone (n=8,460,360) served as a reference group. Microinvasive glaucoma surgeries constituted most glaucoma procedures performed (67.8%), followed by trabeculectomy (14.0%), tube shunt (10.9%), and Other procedures (7.3%). There were 572 cases of endophthalmitis identified following all glaucoma surgeries. Endophthalmitis incidence following glaucoma, combined cataract/glaucoma, and cataract surgeries alone were 1.5 (95% confidence interval [CI]; 1.3-1.7), 1.1 (95% CI; 1.0-1.2), and 0.8 (95% CI; 0.8-0.8) per thousand procedures, respectively. The median day of diagnosis of endophthalmitis was later for glaucoma surgeries at 16.5 days compared to combined cataract/glaucoma or cataract surgeries alone at 8 and 6 days, respectively. Compared to MIGS, Tube shunts were the only surgery type to be a significant risk factor for endophthalmitis for both standalone (aOR 1.8, p=0.002) and combined surgery (aOR 1.8, p=0.047). The other risk factor for both standalone (aOR 1.1, p=0.001) and combined (aOR 1.06, p=0.049) was Charlson comorbidity index (CCI). Age (aOR 1.03, p=0.004) and male gender (1.46, p=0.001) were significant risk factors only for combined cataract and glaucoma surgeries.

CONCLUSIONS: Compared to cataract surgery alone, early endophthalmitis incidence was higher for both glaucoma surgeries and combined cataract/glaucoma surgeries, with the highest incidence among tube shunts. There were differing demographic risk factors for combined cataract/glaucoma surgeries compared to glaucoma surgeries alone.