Adverse events show decline after cataract surgery among Medicare patients

Older patients, white men, patients with proliferative diabetic retinopathy and those who had combined procedures had a higher risk for complications.

Rates of adverse events after cataract surgery among Medicare beneficiaries diminished steadily between 1994 and 2006, a large study found.

Postoperative complications fell significantly among three patient cohorts over the study period, the study authors said.

“We found that individuals who underwent cataract surgery during 1994 and 1995 had a 21% increased risk of being diagnosed with a severe postoperative complication relative to the group of Medicare beneficiaries who underwent cataract surgery during the 2005 to 2006 period. Those who underwent surgery in 1999 and 2000 had a 20% increased risk of experiencing a severe adverse event relative to the 2005 to 2006 group,” Joshua D. Stein, MD, MS, the corresponding author, said in an interview with Ocular Surgery News.

The study was published in Ophthalmology.

Population and methods

The retrospective longitudinal cohort analysis included 221,594 Medicare beneficiaries who underwent a first cataract surgery between 1994 and 2006. Beneficiaries were classified into three cohorts: those who had cataract surgery in 1994 and 1995 (57,780 patients), 1999 and 2000 (73,064 patients) and 2005 and 2006 (90,750 patients).

Diagnosis codes from the International Classification of Diseases 9th Revision, Clinical Modification (ICD-9-CM) were used to identify severe complications after cataract surgery.

Investigators determined 1-year rates of endophthalmitis, suprachoroidal hemorrhage and rhegmatogenous retinal detachment or tractional retinal detachment.

Cox regression analysis was used to determine the odds of each cohort developing severe adverse events. Data were adjusted for age, gender and race, medical comorbidities, and surgeon case mix.

Records showed that 214,468 cataract surgeries (97%) were not combined with other intraocular procedures on the same day as the cataract surgery; 7,126 surgeries (3%) were combined with other procedures.

Patients were followed up for 1 year postoperatively.

Results and conclusions

Results showed that 1,086 patients (0.5%) experienced at least one severe postoperative complication. Patients who had cataract surgery in 1994 to 1995 had a 21% higher risk of severe postoperative complications than those who had surgery in 2005 to 2006. Patients who had surgery in 1999 to 2000 had a 20% higher risk than those treated in 2005 to 2006.

The probability of a severe complication was 0.6% in 1994 to 1995, 0.5% in 1999 to 2000 and 0.4% in 2005 to 2006. The first two cohorts had a significantly higher probability of complications than the third cohort (both P < .001), the authors said.

Mean age was 77.8 years among patients who experienced severe postoperative complications and 77.5 years among those who experienced no complications. The difference was statistically insignificant.

White men had a 25% higher risk of complications than white women, Dr. Stein said.

Patients who underwent same-day cataract surgery combined with another intraocular surgery had a more than twofold higher risk of severe complications than those who had cataract surgery alone. Dr. Stein attributed this difference to increased time in the operating room, increased patient exposure to surgical instruments, multiple incisions in the eye, use of retrobulbar anesthesia and fluctuations in IOP.

Diabetic patients with no diabetic retinopathy and those with nonproliferative diabetic retinopathy had no increased risk of complications. However, those with proliferative or advanced diabetic retinopathy had a 62% higher risk, Dr. Stein said.

Surgeon case mix was also an important factor.

“A patient who underwent cataract surgery by a surgeon whose mix of patients tend to experience more complications is herself at elevated risk for developing a serious complication relative to another patient who underwent cataract surgery by a surgeon whose patients in general tend to have fewer such complications,” Dr. Stein said.

Innovation, future study

It was unclear from the data whether the transition to sutureless clear corneal incisions in the mid- to late-1990s led to increased risk for endophthalmitis.

“There have been some papers suggesting that rates of endophthalmitis went up with that transition. Other papers suggest that they didn’t,” Dr. Stein said. “In the present analysis, we are not observing higher rates of endophthalmitis in the 1999 to 2000 or 2005 to 2006 cohorts compared with the 1994 to 1995 cohort, which suggests that the transition to clear corneal incisions is not having a major impact on rates of postoperative endophthalmitis.”

It is unclear whether ongoing innovations such as femtosecond laser technology affects the safety profile of cataract surgery. However, the ability to adequately analyze this in the future using claims data would depend on significant adoption of the technology, Dr. Stein said.

“If it’s so expensive that there are only a handful of surgeons using it, then it may be difficult to replicate this study in a few years,” he said. “But if it’s a technology that becomes widespread, like a lot of the newer technologies, and it’s certainly being marketed that way, then hopefully it will lead to continued improvement in the safety profile of cataract surgery if we replicate our analysis in a few years.” – by Matt Hasson

Reference:

• Stein JD, Grossman DS, Mundy KM, Sugar A, Sloan FA. Severe adverse events after cataract surgery among Medicare beneficiaries. Ophthalmology. 2011;118(9):1716-1723.

• Joshua D. Stein, MD, MS, can be reached at University of Michigan, Kellogg Eye Center, 1000 Wall St., Ann Arbor, MI 48105; email: jdstein@med.umich.edu.
• Disclosure: Dr. Stein has no relevant financial disclosures.