Bryan J. Winn, M.D., associate residency program director for ophthalmology Columbia University, New York
The Columbia University ophthalmology residents Source: Department of Ophthalmology, Columbia University
This month, I asked the Columbia
residents to analyze the conclusions from this study of the EUREQUO
database for cataract surgery.
David F. Chang, M.D.,
chief medical editor
In an effort to create evidence-based guidelines for cataract surgery and ultimately improve the quality of cataract and refractive surgery, the European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO) was created. This 3-year project (January 2009-August 2011) involved the creation of a database for documentation of information pertaining to cataract surgeries performed throughout Europe, including the European Society of Cataract and Refractive Surgeons and 11 other national societies. In total, the database included 523,921 reported surgeries. In their recent article, "Evidence-based guidelines for cataract surgery: Guidelines based on data in the European Registry of Quality Outcomes for Cataract and Refractive Surgery database," Lundström et al. provide both a summary of this surgical data and evidence-based
recommendations for surgical standards in cataract surgery. The following data were collected for the EUREQUO: first- versus second-eye surgery, outpatient versus inpatient surgery, demographic data, pre-op corrected distance visual acuity (CDVA) and refraction, ocular comorbidity, level of complexity, type of anesthesia, surgical technique, IOL type, surgical complications,
visual outcome, refractive outcome, and post-op complications. Analysis of the acquired data was used to develop evidence-based guidelines for cataract surgery that can be summarized as follows: All patients with visual disability from cataract should be treated regardless of age, generally in an outpatient setting. No specific CDVA limit can be given for patient selection. Ocular comorbidities are not a contraindication to cataract surgery, but the likelihood of worse visual outcomes must be discussed with the patient. Local anesthesia is generally sufficient, and phacoemulsification should be considered the standard technique. Hydrophobic acrylic lenses are the most commonly used lenses, although all lenses have strengths and weaknesses. Capsular complications, while unavoidable, should be rare, and a rate under 2% should be possible to achieve. 97% of eyes with no comorbidity should have a final CDVA outcome of 6/12 or better, and the final refractive outcome should fall within 0.6 diopters of the target. Post-op complications, which may be related to factors such as
surgeon experience and pre-existing ocular comorbidities, should be minimized. Limiting complications such as a capsule rupture, introducing prophylactic intracameral antibiotics, and creating watertight incisions are key steps to preventing post-op endophthalmitis, which should occur no more often than 1 in 2,000 surgeries.
The goal of creating evidence-based guidelines for cataract surgery is a worthy one, and the number of cases in this database is impressive. The data provided in this prospective study are further strengthened by the diversity of countries represented. In an effort to ensure fair comparison of surgical standards between countries, only those with greater than 1,000 surgeries in the database were included when inter-country comparisons were made. Despite this feat of data collection and analysis, we find that the recommendations for standards of care may be limited by multiple factors ranging from data entry to data analysis and subsequent applicability in different economic environments and health systems. First, while the different countries contributed the same types of data to the EUREQUO database, there was no clear standardization for reporting among the countries. Therefore, the data may be inconsistent across the different studied outcomes. For example, for post-op endophthalmitis, data from the U.K. were not included because the authors stated that the variable was missing from the electronic medical records system. The complication of posterior capsular opacity (PCO) affecting vision was not reported by Holland and Sweden, two of the largest contributors to the overall data set. These two countries also did not report the complication of uveitis requiring medication. For both of these complication categories, the number of eligible cases therefore dropped from 241,136 to 35,553. Second, with regard to reporting, it appears that data were voluntarily entered by physicians. In describing capsular complications, the authors reported that the between-country variation in capsule complications was 0.1-1.79%, with an average overall surgical complication rate of 2.3%. It seems likely that the true capsular complication rate is higher than 0.1%, and in fact, the authors did concede that the numbers should be interpreted carefully because only a few centers were represented for some countries. These centers could be treating a more complex or healthier eye population, resulting in data skewed toward more or fewer complications, respectively. Reporting bias was also likely to be a weakness in this kind of database, as physicians may have underreported the number of complications that they experienced. A third weakness of this study was the definition of "long-term" visual outcomes as results occurring between 7 and 60 days post-op. This is particularly problematic when considering the fact that two common post-op complications, PCO and cystoid macular edema (CME), can take more than 60 days to develop. Although the study reported specifically on short-term PCO (less than 2 months), the variability of "long-term" follow-up as any time between 7 and 60 days make the results difficult to interpret. Furthermore, because there was no true long-term follow-up, the authors did not consider CME, another post-op complication that can lead to further intervention and worse long-term visual outcomes. Interestingly, countries that had records of fewer than 1,000 cases were excluded from inter-country analysis. However, the exclusion begs several questions: Did these countries really have so few cataract surgeries per year? Is it possible that economically disadvantaged countries were therefore less likely to have contributed to the database? If so, does this restrict this article's application of standards of care to more advantaged healthcare and economic environments? The authors reported that Belgium and Germany had higher rates of good pre-op visual acuity in the operative eye, as well as higher rates of good pre-op visual acuity in the better eye. As standards of living are relatively high in these two countries, this type of patient selection can be expected. However, it would have been interesting to report countries with worse average pre-op visual acuities as well and to determine if the average post-op CDVA was correspondingly lower. It is reasonable to assume that countries with poorer access to healthcare have cases with worse average pre-op visual acuities and a higher overall rate of complexity. These difficult cases would be more likely to result in more surgical complications and lower post-op CDVA. However, this information was not provided in the study and may be skewing the benchmark standards introduced in this study. The authors had long-term follow-up data for only 241,136 of the 523,921 cases, and they presented it as a binary choice of vision of better or worse than 6/12. While they reported many interesting facts, such as approximately 40% of surgeries are for a second eye, or approximately 60% are performed on women, they did not relate these data with outcomes or complications. Furthermore, they did not present data about the visual outcomes in patients with complicated surgeries. It seems odd to be crafting guidelines without relating the variables to outcomes. In summary, this large, multi-country, multi-year data accrual and analysis offers a compelling description of modern standards of cataract surgical management throughout Europe. The major strength of this study is the large amount of data, which provides benchmarks for post-op visual acuity and refractive outcomes. While the results will surely be used as international guidelines for surgical standards of care, one must temper the value of the study, and validity of the benchmarks, with an understanding of the study's limitations and internal biases. Standardization of data reporting across countries as well as correlation between reported variables and outcomes would strengthen the validity of similar future studies.