Volume of Cataract Surgery and Surgeon Gender: The Florida Ambulatory Surgery Center Experience 2005 Through 2012

Background

Cataract is the most common surgically reversible cause of vision loss in the United States, and the most common major surgical procedure performed in the United States, with direct medical costs for treatment approaching $7 billion annually.(1,2) The incidence of cataract surgery has been increasing over the last several decades,(3-5) due to improved technologies and techniques, greater safety, and the convenience of outpatient surgery.(6,7) During this same period there has been a change in the composition of the ophthalmic workforce, characterized by a steady rise in the number of women entering the field.(8) From 2004 to 2008, the proportion of women ophthalmologists in the United States increased by 16% as the total workforce declined by 1%.(8) This trend in composition should continue in the foreseeable future, as the proportion of female residents in ophthalmology is plateauing at over 40%.(9) To understand how gender composition might affect differences in health services we examined the surgeon gender–specific rates of routine cataract surgery performed in ambulatory surgical centers in Florida.

Methods

Data Sources

CPT code 66984 was used to identify surgeons who performed routine cataract surgery in Florida from 2005 through 2012 through the Agency for Health Care Administration (AHCA) ambulatory surgery center database. The publicly accessible database is available to researchers in a multi-year format under a limited dataset agreement with Florida AHCA.(10) The dataset contains no patient identifiers. Florida statute (§408.061) and administrative codes require all hospitals and ambulatory surgery centers to report patient-level information to AHCA for the purposes of disease surveillance and to track cost trends.(11) All public and private Florida ambulatory surgery centers, free-standing or hospital-based, are required to comply with AHCA regulations, except military and Veterans Administration hospitals. Financial penalties are levied against institutions that fail to observe deadlines within specified timeframes. Historically, statewide compliance rates approach 100% six months after the end of the calendar year (Nancy Tamariz, program administrator AHCA office of data collection, written communication, May 29, 2014). The Northwestern University Investigational Review Board exempted the study.

The dataset was downloaded into Microsoft Excel (Redmond, Washington) and transferred into Statistical Analysis Software (Version 9.3; SAS, Cary, North Carolina) for sorting and analysis. Routine cataract surgery was linked to individual surgeon provider for each calendar year. Physician providers can be linked to surgical CPT codes through their medical license number. The medical license of each surgeon was verified through the Florida Health Care Practitioner Data Portal.(12) Two investigators (DDF and CEM) independently extracted the following information on each provider from the public website: postgraduate training in ophthalmology; dates of completion of residency and, when applicable, post-residency fellowship. We excluded surgeons if they had not completed a 36-month residency in ophthalmology; we also excluded cataract surgery performed during residency training.

Definitions

From information available on the Florida Health Care Practitioner Data Portal, an ophthalmic surgeon was defined as a graduate from an allopathic or osteopathic medical school who completed 36 months of residency in ophthalmology. The end of this 36-month residency was recorded as the completion date of training. Fellowship was defined as a minimum of 12 months of training occurring after residency. The training included anterior segment surgery, glaucoma, neuro-ophthalmology, oculoplastic surgery, oncology, pathology, pediatrics, retina, and uveitis. For ophthalmologists with more than one fellowship, only the first 12-month program was recorded. Because the state does not have established categorical descriptions for post-residency training in ophthalmology, physicians vary in how they describe fellowships. A sizeable number listed “ophthalmology” without further clarification. This was recorded as “ophthalmology, not otherwise specified (NOS).” Fellowships in cornea, refractive surgery, cataract surgery, and anterior segment surgery often were described in overlapping terms. These fellowships were consolidated as anterior segment surgery. Surgeon gender was determined by first name. When gender-ambiguous names were encountered, gender was established through an Internet search. Ophthalmologists with state licenses who performed routine cataract surgery during a fellowship year of training were credited as surgeons if they listed staff privileges at any hospital or medical care institution that year.

Analyses

Calculations of population parameters were performed with SAS. The total routine cataract surgeries in AHCA datasets each year was considered equivalent to all routine ambulatory cataract surgeries performed in Florida except for military and Veterans Administration hospitals.

To examine how years of clinical practice (i.e., beyond residency training) affected surgical volume, a nested controlled study was performed. In year 2012, women were matched with male surgeons who had completed residency training the same calendar year. Mean or average surgical volumes by gender were analyzed using the pooled test with  = 0.05.

Results

The mean number of annual routine cataract surgeries performed in ambulatory surgery centers from 2005 through 2012 was 214,753 (standard deviation (Table 1). The annual totals ranged from a low of 205,889 in 2011 to a high of 224,761 in 2009. The number of ophthalmologists performing routine cataract extraction each year averaged 739 (SD: 4.1). Although the number of “new” or first-time surgeons in the AHCA dataset each year exceeded 100, it was offset by a nearly equal number of physicians who dropped off the list. Total surgeons remained relatively stable over eight years, differing from zenith to nadir by just 14 (Table 1). The number of women increased steadily from a low of 77 in 2005 to a high of 105 in 2012 (36% increase). In 2005, women represented 10.5% of all surgeons performing routine cataract surgery; by 2012, they represented 14.2%.

The mean number of routine cataract surgeries performed by men each year was roughly twice that of women (Table 1). These means showed no clear trend; the highest annual mean for women was 152 surgeries in 2005, while the highest annual mean for men was 329 surgeries in 2009.

Using 1000 routine cataract surgeries annually as an arbitrary threshold for high-volume surgery, approximately 30 surgeons reached this level each year (Table 2). The average time from residency training among this group just exceeded 20 years. Three to six surgeons each year had completed residency in the previous 10 years. Women rarely were represented in the high-volume group. Two women performed 1000 or more surgeries in 2005, but over the next seven years women reached this threshold just four times.

Approximately half of ophthalmologists who performed routine cataract surgery in Florida had some type of fellowship training (Table 3). Because some fellowships lend themselves more readily to cataract surgery than others, annual gender-specific rates of surgery were examined according to subspecialty background. In each subspecialty men substantially exceeded women in cataract surgery volume. Women trained in glaucoma came closest to parity, where some years they achieved two-thirds the volume of men.

Over the eight years of this study, the mean time from residency training increased slightly for male surgeons, ranging from a low of 18.0 years in 2005 to a high of 20.3 years in 2012. Years beyond residency for women also trended upward, from 10.4 years in 2005 to 11.7 years in 2012.

Women trained in glaucoma came closest to parity.

The nested controlled study involved 105 female surgeons and 379 male surgeons from 2012. The 105 women were matched by graduation date of residency to men who performed cataract surgery that year. Women from this cohort had a mean of 139.8 (SD = 187.7) surgeries compared with men, with a mean of 312.3 (SD = 375.2) cases (p < .0001).

Discussion

This study linked over 1.7 million routine cataract surgeries over eight years to individual surgeons in Florida. Because a substantial proportion of all cataract surgeries in the United States are performed in Florida, this sample should provide insight into how routine cataract surgery is apportioned nationally by surgeon gender. The overall number of ophthalmologists performing routine cataract surgery remained relatively stable during the period of observation, as the loss of men was offset by a gain in women. Women made up a minority of surgeons, but grew from a low of 77 (10.5%) in 2005 to a high of 105 (14.2%) in 2012. The slow increase in absolute numbers of women suggests any gender-related impact on overall cataract surgery patterns will likely be gradual, particularly because the mean number of surgeries women performed remained unchanged over eight years, at roughly half the rate of men. The magnitude of this gender-volume disparity merits further investigation, particularly the potential roles that choice and professional barriers might play.

Practice patterns have been shown to differ substantially between male and female ophthalmologists in New Zealand, Australia, and Canada, as they have in other fields of medicine and surgery in various industrialized countries.(13,14) In academic ophthalmology, gender disparities in funded grants, peer-reviewed publications, and positions of editorial leadership have fueled discussions over personal and professional priorities and gender bias.(15-17)

The volume of cataract surgery is likely to increase with increasing time beyond training as surgeons become established in clinical practices. Because male ophthalmologists in Florida, on average, had been out of training about nine years longer than women, this might account for some disparity in surgical rates. We investigated this possibility by performing a nested controlled study, where women in 2012 were matched by year of residency graduation with men. The results showed that men attained on average more than a two-fold greater volume of cases (312.3 vs 139.8 [p <. 0001]). These findings argue that greater time from residency training for men would not explain their higher annual rates of surgery.

Could lower surgical volumes for women be due to having worked fewer hours than men, perhaps because of greater family responsibilities or maternity leave? We know of no objective data documenting that women ophthalmologists in the United States spend fewer hours in clinical practice than their male counterparts. However, surveys of surgeons in North America suggest that women surgeons work similar hours and take similar call to men.(18-20) In a recent survey of Canadian ophthalmologists, there was no difference between men and women in terms of full- and parttime work, but there was a statistically significant percentage of men that operated two or more days per month more than women (64% versus 49% [p = .01]).(18) A survey of members of the American College of Surgeons, using a 2:1 random male-to-female sample, found that there was no difference in total hours worked by gender, either in private or academic practices.(19) In another survey conducted by the American College of Surgeons dealing with professional burnout, the results showed no differences in the hours worked or number of nights on call per week between men and women.(20) Given the available information on practice patterns, it would be difficult to implicate less work time as a major contributing factor to the lower rates of cataract surgery documented in this study.

The Florida Department of Health collects information on the state’s medical workforce each year, with some annual variation in question format. Because the workforce survey is a mandatory component of the medical license renewal process, response rates are excellent. In the 2009–2010 survey, physicians were queried about the number of patient-care hours they work each week. Only 8.3% of the 37,375 responders (90.3% of 41,274 actively licensed doctors) worked 21 hours or fewer.(21) Responses, however, were not broken down according to gender or subspecialty. These data suggest that a minority of all physicians in Florida work part time. Unless women in ophthalmology differ substantially from women in other areas of clinical practice, work hours alone would not explain the nearly 50% reduction in annual surgical volume.(21)

One weakness of this study is its reliance on administrative data collected by Florida for the purposes of medical licensure and tracking of outpatient surgery. Although the falsification or distortion of these records is proscribed by state regulations, we cannot guarantee how carefully medical licensure applications or ambulatory surgery center questionnaires are examined for accuracy. The results also may not be generalizable to other parts of the country, because the practice of ophthalmology might differ elsewhere. With over 700 ophthalmologists performing routine cataract surgery in Florida each year, and dozens exceeding 1000 cases, ophthalmology may be more competitive than it is in other states. The potential role—if any—that market forces may play in determining patterns of care related to surgeon gender has not been studied.

Conclusions

From 2005 through 2012, women eye surgeons performed cataract surgery at approximately half the rate of men each year. This pattern was observed among women with and without subspecialty training, and displayed no tendency to change. The disparity persisted when women surgeons were matched with men by the year they completed residency. Given the available information on practice patterns, it would be difficult to implicate less work time as a major contributing factor to lower rates of cataract surgery documented in this study.

No persuasive reason for this gender disparity can be supported from the data at hand or the scientific literature. This type of gender phenomenon in medicine, however, is not restricted to eye surgery. An article in The New York Times in October 2014 reported that 21 of the 22 physicians who earned over $500,000 in speaking and consulting fees from drug companies were men.(22) The lopsided representation of men could not be accounted for by the proportion of qualified women in clinical practice or research. The author of the article explored a variety of theories informally through interviews with key leaders in medicine and industry and found no compelling answer.

Although Florida might not be representative of ophthalmic practices in other states, the large difference in surgical volume between men and women surgeons argues against this finding being spurious or purely regional. Further study is necessary to uncover the reasons for this gender disparity.

References

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