Rate of endophthalmitis after cataract surgery in US shows slight decrease

Medicare claims data showed that patient age, surgeon experience and surgical volume correlated strongly with the risk of postop endophthalmitis.

Issue: July 10, 2012

The rate of endophthalmitis after cataract surgery in the United States declined slightly between 2003 and 2004, according to a study.

However, the postoperative endophthalmitis rate was markedly higher in the United States than in Sweden over the same time period, the study authors said.

Patient age, gender, race, surgery location, and surgeon experience and volume emerged as key risk factors for postoperative endophthalmitis, the authors said.

“We found here for the first time that there were differences in rates of endophthalmitis by surgeon-specific factors, namely that surgeons who had a higher volume, more years of experience or were working in an ambulatory surgical center had lower rates of endophthalmitis,” Emily W. Gower, PhD, the corresponding author, said in an interview with Ocular Surgery News.

A previous study conducted from 1994 to 2001 showed a somewhat higher rate of endophthalmitis, suggesting a possible correlation between evolving surgical techniques and lower endophthalmitis rates, Dr. Gower said.

Emily W. Gower

“There were some changes in surgical practice, and we wonder whether or not those changes in surgical practice may have affected these rates,” she said. “This is a first step in investigating that finding.”

The study was supported by a grant from the National Eye Institute and published in Ophthalmology.

Patients and parameters

Investigators acquired Medicare beneficiary fee-for-service claims data from the Centers for Medicare and Medicaid Services Research Data Distribution Center. International Classification of Diseases-9 Clinical Modification Codes were used to identify cases of presumed postoperative endophthalmitis that occurred within 42 days after cataract surgery.

The data showed 4,006 cases of presumed endophthalmitis that occurred after about 3.2 million cataract procedures.

Annual endophthalmitis rates were calculated for each state individually and for the 48 contiguous states; Alaska and Hawaii were excluded from the analysis.

The study authors conducted a multivariate analysis that included surgeon-related factors and patient-related variables such as age, gender, state of residence and comorbidities.

Data and findings

Study results showed a national postoperative endophthalmitis rate of 1.33 per 1,000 surgeries in 2003 and 1.11 per 1,000 surgeries in 2004. Adjusted data showed that surgeries performed in 2004 were 13% less likely to result in endophthalmitis than those performed in 2003.

Age correlated strongly with postoperative endophthalmitis; patients older than 85 years had a 53% higher risk of endophthalmitis than those between 65 and 74 years.

“Obviously, those factors are important, with age being a primary factor. Older individuals are less likely to have good wound healing than younger individuals,” Dr. Gower said.

Adjusted data showed that lower annual surgical volume and less surgeon experience were linked with an elevated risk of postoperative endophthalmitis.

“[Surgical] volume and number of years of experience are playing key roles here,” Dr. Gower said.

Surgeries performed in hospital outpatient centers had a 23% higher risk of endophthalmitis than those performed in ambulatory surgical centers.

According to a Swedish study, the rate of postoperative endophthalmitis was 0.48 cases per 1,000, significantly lower than in the United States, the study authors said.

“There are a few factors we could speculate about. One of those is that in Sweden a primary anti-infective measure is the use of cefuroxime, whereas in the U.S. we don’t use that drug,” Dr. Gower said.

Many U.S. surgeons are reluctant to inject cefuroxime because of concerns about contamination during drug preparation and allergic reactions, she said.

“This study highlights that we have had a reduction in endophthalmitis rates, but we’re still nowhere near the rate in Sweden,” Dr. Gower said. “It more highlights the need for future research questions to be answered, looking at why our rate has gone down and how we can get it to go down more.” – by Matt Hasson

Reference:

Keay L, Gower EW, Cassard SD, Tielsch JM, Schein OD. Postcataract surgery endo-phthalmitis in the United States: analysis of the complete 2003 and 2004 Medicare database of cataract surgeries. Ophthalmology. 2012;119(5):914-922.

For more information:

Emily W. Gower, PhD, can be reached at Departments of Epidemiology and Prevention and Ophthalmology, Wake Forest School of Medicine, Medical Center Blvd., Winston Salem, NC 27157; 336-716-2184; fax: 336-713-4300; email: egower@wakehealth.edu.
Disclosure: Dr. Gower has no relevant financial disclosures.