Cataract Audit Data Validation FAQs

To validate the data, look at the unadjusted complication rates on the NOD website, and see if the number of cases of Posterior Capsular Rupture (PCR) and Visual Acuity (VA) loss fit with what you were expecting. Individual cases cannot be listed as the NOD does not hold patient identification details, but you can cross check the number with you own local surgical record (from where the NOD obtained the data). The data is presented as a funnel plot and your individual surgeon or centre outcome will be represented with an amber colour asterisk (*) on each graph. If there is any discrepancy between your local records of PCR or VA loss for the audit period, and what has been presented on the NOD then please contact the audit team via email, noa.project@rcophth.ac.uk within the validation period so that necessary changes can be made before publication.

The most common reasons for this are: 

1. If the audit data collection period selected is noton the results pages of the website is different to the date period  selected on the EMR (Electronic Medical Record) system, your data will not match the published results.
2. TheIn addition to this, the audit excludes operations that are not eligible for analysis (e.g. combined procedures, detailed inclusion and exclusion criteria available at www.nodaudit.org.uk/resources/methodology).
3. On the RCOphth NOD audit website we report both unadjusted and case complexity adjusted rates (adjusted for risk) while the EMR systems show the unadjusted rates. If you are using OpenEyes the case definition is not identical to that used in the national audit which includes zonule rupture with vitreous prolapse.  

If the case complexity (risk factors) information has not been accurately recorded on the data collection tool (EMR systems/in-house databases), the audit analysis team are unable to account for unrecorded risk factors. It is important that surgeons collect accurate and complete data for each cataract operation undertaken. Please see the statistical analysis plan and the guide for EMR users on the RCOphth NOD website for more information about the risk factors. 

See answer to Q3 above. Please note that the audit receives all VA data recorded on the EMR system which includes measurements from other eye clinics the surgeon may not be aware the patient was attending. If you are a Medisoft or OpenEyes EMR user you can check these data yourself using the cataract audit tool for pre- vs. post-op VA. 

The audit team uses pseudonymised/ anonymised data and we do not know the identity of your cases. Your local EMR audit functionality should allow you to find the cases with complications. This is the best place to begin in terms of checking your data. Once you have identified your complications locally you can refer to the inclusion / exclusion criteria at https://nodaudit.org.uk/healthcare-professionals/resources to check that they are eligible for the national audit. Once you have checked through all your complications, if you still believe that there is an error then email noa.project@rcophth.ac.uk and we will try to assist

Where data errors are confirmed the audit team can amend or remove your data from the public facing section of the NOD website.

The risk factors used in PCR adjustment were updated in 2024 using a sample of around 960,000 operations performed over six NHS years with the analysis published in EYE (https://doi.org/10.1038/s41433-024-03344-2). The risk factors used in VA loss were identified from analysis of around 160,000 operations performed over four NHS years. See https://nodaudit.org.uk/healthcare-professionals/resources.  To be statistically significant these risks need to be both sufficiently common and sufficiently important to appear in the model. There will always be rare high-risk cases which are missed by the model but these would be expected to be evenly spread across surgeons and centres. It is possible that there are risks which have not been recorded on the Medisoft EMR (which was used for development of the VA loss model) and which are therefore absent in the model. Please contact the RCOphth NOD audit team via email at noa.project@rcophth.ac.uk if you require more information. 

This can occur when your recorded case complexity is less complex than the average across all surgeons and centres. Our analysis gives credit for undertaking complex cases but we can only do so if you provide us with the correct information about your case complexity. It is important for surgeons who take on the most difficult cases to not be penalised for doing so and the risk adjustment is designed to do exactly that. Conversely, where a surgeon or centre only agrees to operate on straightforward cases, then that surgeon’s or centre’s results should reflect the fact that only ‘easy’ cases are being undertaken. The accuracy of these adjustments depends on accurate data being recorded by surgeons.

Identifiable outcomes of individual centres and independent surgeons will be published on the NOD Audit website. Centre level results are supplied to the Care Quality Commission (CQC) and Getting it Right First Time (GIRFT).

These results are the unadjusted (observed) rates with no adjustment for the complexity of the surgery. These values are considered when setting the benchmark values used in the audit, which are derived from aggregate samples. These rates reflect all patients included in the sample used to derive the value with the full range of co-morbidities. For centres the sample is all eligible operations in the latest audit year (NHS year), and for surgeons all eligible operations performed by non-trainee surgeons within the latest 3 NHS years. For Visual Acuity loss the samples rules also include only eyes with both a preoperative and postoperative VA data from centres/non-trainee surgeons respectively with at least 60% of their operations with both preoperative and postoperative VA data.

For the April 2023 – March 2024 audit year, the time window used for pre-operative VA is the better measurement of Corrected Distance Visual Acuity (CDVA) or Uncorrected Distance Visual Acuity (UDVA) that is closest to the date of surgery, including the day of surgery and within 6 months prior to surgery. Pin Hole Visual Acuity (PHVA) measurements are not used for pre-operative VA. For post-operative VA, we use the best measurement of CDVA, UDVA or PHVA between 8 days and 6 months after cataract surgery.