Cataract Surgery Rates Vary Greatly Among US Communities

Ricki Lewis, PhD

January 04, 2016

Patient age at first cataract surgery and the age-standardized surgery rate vary considerably among some US communities, according to results of a study published online December 30 in JAMA Ophthalmology.

The rate of cataract surgery has increased during the last 2 decades, in parallel to the aging of the US population. A study published in 1995 of cataract surgery rates in US communities using Medicare claims data from the late 1980s revealed little variability compared with other surgical procedures and identified communities that had the lowest and highest cataract surgery rates. Variables associated with cataract surgery rate included age, sex, race, latitude, and density of optometrists.

Courtney Y. Kauh, MD, from the Department of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, and colleagues revisited the study from the 1980s. They used a retrospective cross-sectional design to assess cataract surgery among patients of a large, managed-care network. Patients were at least 40 years of age and lived in 306 US communities ("hospital referral regions"). The study period covered from 2001 to 2011.

The study assessed median age at initial cataract extraction, age-standardized cataract surgery rate, and time from initial diagnosis to first surgery. The researchers checked whether the communities that had the lowest and highest rates of cataract surgery matched those identified in the earlier study. They also evaluated present-day relevance of the factors found to affect cataract surgery rates in the 1980s.

Of 1,050,815 patients diagnosed with cataracts, 243,104 (23.1%) had surgery in one or both eyes during the time of the study. Communities with the youngest and oldest patients at initial surgery differed in age by nearly 2 decades: 59.9 to 60.1 years in Lansing, Michigan, and Aurora, Illinois, compared with 77.0 to 79.6 years in Marquette, Michigan, and Rochester and Binghamton, New York. Overall median age at first surgery was 67.7 years.

The lowest age-standardized cataract surgery rate was 7.5%, seen in Honolulu, Hawaii. That was five times lower than the highest age-standardized cataract surgery rate, which was 37.3% in Lake Charles, Louisiana. Because of the small numbers of enrollees, 82 communities were excluded from the age-standardized rate calculation.

The median time from initial cataract diagnosis to date of first surgery ranged widely, from 17 days in Victoria, Texas, to 367 days in Yakima, Washington.

Each year of age at initial cataract diagnosis was associated with increased hazard for surgery by 2.5% (adjusted hazard ratio [HR], 1.02; 95% confidence interval [CI], 1.02 - 1.03). Black patients had a 15% decreased hazard for surgery (HR, 0.85; 95% CI, 0.83 - 0.87) compared with white patients, whereas Latino patients (HR, 1.08; 95% CI, 1.05 - 1.10) and Asian patients (HR, 1.09; 95% CI, 1.05 - 1.12) had an increased hazard. The researchers suggest that possible explanations for black patients' lower hazard for surgery include racial differences in type of lens opacification, less use of healthcare resources, less awareness of the value of cataract surgery, and practical matters such as lack of transportation and accessibility to ophthalmologists' offices for treatment and follow-up care.

"For every 1° increase in latitude, the likelihood of cataract surgery decreased by 1% (adjusted HR, 0.99 [95% CI, 0.98-0.99])," the authors write. Higher latitudes are exposed to lower levels of ultraviolet light.

"For every additional optometrist in the community per 100 000 enrollees, the hazard increased by 0.1% (adjusted HR, 1.001 [95% CI, 1.001-1.001])," the authors add. Both the old and the new studies found that cataract surgery rates were associated with the number of optometrists in a community, but not with the number of ophthalmologists.

Patients living in rural communities had a 5% to 7% increased hazard of surgery compared with those living in cities (P < .001), which the researchers suggest could reflect greater exposure to sunlight.

A major limitation of the study is that it identifies variation in age of first cataract surgery, but not the reasons behind the differences. Factors might include availability of eye care professionals and how assertively they recommend surgery, lifestyle factors, and differing visual demands of living in a particular environment, such as whether public transportation is available or workers must drive in traffic in the dark. A second limitation of the study is the generalizability of data from one managed care organization.

In an invited commentary, Scott D. Smith, MD, MPH, from the Cleveland Clinic Abu Dhabi in the United Arab Emirates, considered the greater effects of random variation in smaller populations. "The observation that the highest rate of cataract surgery was found in Lake Charles, Louisiana, in 2 data sources separated in time by nearly 20 years makes a compelling argument that specific underlying factors may be involved. In contrast, random variation may be the explanation for the observation that Billings, Montana, the region with the lowest rate of cataract surgery in the earlier study, falls among the highest in the more recent data," he writes.

The researchers and commentator have disclosed no relevant financial relationships.

JAMA Ophthalmol. Published online December 30, 2015. Article abstract, Commentary extract

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