Preoperative medical testing in Medicare patients undergoing cataract surgery

Abstract

Background: Routine preoperative testing is not recommended for patients undergoing cataract surgery, because testing neither decreases adverse events nor improves outcomes. We sought to assess adherence to this guideline, estimate expenditures from potentially unnecessary testing, and identify patient and health care system characteristics associated with potentially unnecessary testing.

Methods: Using an observational cohort of Medicare beneficiaries undergoing cataract surgery in 2011, we determined the prevalence and cost of preoperative testing in the month before surgery. We compared the prevalence of preoperative testing and office visits with the mean percentage of beneficiaries who underwent tests and had office visits during the preceding 11 months. Using multivariate hierarchical analyses, we examined the relationship between preoperative testing and characteristics of patients, health system characteristics, surgical setting, care team, and occurrence of a preoperative office visit.

Results: Of 440,857 patients, 53% had at least one preoperative test in the month before surgery. Expenditures on testing during that month were $4.8 million higher and expenditures on office visits $12.4 million higher (42% and 78% higher, respectively) than the mean monthly expenditures during the preceding 11 months. Testing varied widely among ophthalmologists; 36% of ophthalmologists ordered preoperative tests for more than 75% of their patients. A patient's probability of undergoing testing was associated mainly with the ophthalmologist who managed the preoperative evaluation.

Conclusions: Preoperative testing before cataract surgery occurred frequently and was more strongly associated with provider practice patterns than with patient characteristics. (Funded by the Foundation for Anesthesia Education and Research and the Grove Foundation.).

Figure 1. Preoperative Testing during the Preoperative Month as Compared with Baseline

Panel A shows the percentage of Medicare beneficiaries who underwent testing, stratified according to the number of tests performed. Among all beneficiaries, 13% had one test, 11% had two tests, 10% had three tests, 7% had four tests, and 13% had five or more tests during the preoperative month; the corresponding mean percentages of beneficiaries who had these numbers of tests during the baseline period were 10%, 8%, 5%, 3%, and 7%. The proportion of beneficiaries who did not undergo any testing decreased from 67% during the baseline period to 47% during the preoperative month. We calculated the baseline percentages by averaging the percentage of beneficiaries undergoing the specified number of tests each month over the 11-month baseline period. Panel B shows the mean number of tests and office visits per beneficiary per month. Patients underwent a mean of 1.09 tests per beneficiary per month during the 11-month baseline period, as compared with 1.81 tests per beneficiary in the preoperative month — a 66% increase. Office visits increased by 63%, from 0.43 visits per beneficiary per month during the baseline period to 0.70 visits per beneficiary in the preoperative month. The total number of beneficiaries in the denominator includes all patients in the cohort. The number of tests includes only tests commonly requested for a preoperative evaluation (complete blood count, chemical analysis, coagulation studies, urinalysis, electrocardiography, echocardiography, cardiac stress tests, chest radiography, and pulmonary-function tests). The number of office visits includes only office visits to providers commonly asked to give preoperative clearance (general practice, anesthesiology, cardiology, family practice, internal medicine, and geriatric medicine physicians, nurse practitioners, and physician assistants). Office visits to ophthalmologists or optometrists were not included. Panel B was created with data from the subgroup of beneficiaries with 6 months of follow-up after the index surgery (222,741 patients), to show that testing levels returned to baseline after the index surgery. The percentage of testing and office visits during the baseline period and preoperative month in this subcohort were virtually identical to the results in the full cohort.

Figure 2. Variation among Ophthalmologists in the Prevalence of Preoperative Testing and Office Visits

Using data on ophthalmologists who performed five or more surgeries in 2011, we graphed the percentage of each ophthalmologist’s patients who underwent testing during the 30 days before index cataract surgery. Of the 9253 ophthalmologists who operated on five or more patients in 2011, more than one third (36%) had 75% or more of their patients undergo preoperative testing, and 8% ordered at least one preoperative test for every patient. The 36% of ophthalmologists who ordered testing for 75% or more of their patients treated only 26% of the total number of patients, but their patients accounted for 84% of all testing above the baseline level of testing. The variation in preoperative office visits was similar in magnitude to the variation in testing, and the use of office visits paralleled that of testing across providers. During the baseline period, the mean monthly prevalence of testing and office visits was 33% and 32%, respectively.