Title: Cataract Surgery: Measuring and predicting patient level vision related health benefits and harms
Funder: Department of Health and Social Care

Abstract: Cataract is an extremely common potentially blinding age related condition with cataract surgery the most frequently undertaken surgical procedure on the NHS. Currently pre- and postoperative vision assessments are based on monocular (one eye at a time) letter recognition tasks of limited relevance to a person s everyday vision with both eyes open. UK relevant patient reported measures of visual disability from cataract and its relief from surgery are lacking. This research programme will address a series of issues of direct relevance to the perceptions of people with cataract undergoing surgery in 4 work packages (WP). WP1: Measuring Visual Disability Development of a cataract patient-reported outcome measure (Cat-PROM) A self-reported visual disability measurement instrument for cataract and its relief through surgery will be developed based on our published and pilot work. Iterative development in typical cataract patients will take place in 4 NHS service settings in England. Robust methodology, including Rasch analysis, will deliver an interval scaled instrument with the ordinal response options (and respondents) positioned along the same underlying continuous latent scale of cataract visual disability measured in units of Logits. Cat-PROM will be relevant to the UK population and suitable for routine NHS use. Benefits Patients: A measure of cataract visual disability of direct relevance to patients self-reported experience of their vision before and after cataract surgery. NHS: A patient reported outcome measure for cataract. WP2: Predicting Harm Validation of risk models for complications and vision loss from surgery In parallel, we will obtain from the National Ophthalmology Database (NOD) project electronically extracted detailed data on ~250,000 cataract procedures from 30 NHS trusts. We will validate or update (if needed) our existing risk model for prediction of surgical complications (intraoperative posterior capsular rupture, PCR) and postoperative monocular visual acuity loss (visual harm). Benefits Patients: Personalised risk prediction for surgical complication or adverse acuity outcome based on individual risk factor profile; more relevant preoperative consenting. NHS: Ensure most experienced surgeons operate on high risk cases; ability to assess case-mix adjusted outcomes of surgeons for revalidation. WP3: A cohort study of 1500 people undergoing cataract surgery Predicting Visual Benefit Quantification of indicators for Cat-PROM self-reported benefit from cataract surgery (favourable and less favourable outcomes). Known and suspected predictors of benefit from cataract surgery will be assessed in relation to pre- and postoperative Cat-PROM self-reports. Patients approaching cataract surgery recruited to undergo enhanced research clinic preoperative assessment. Detailed phenotypic profiling to include known and suspected indicators of outcome variation. Cat-PROM used as the primary postoperative outcome measure. Predictors of levels of benefit investigated with statistical modelling. Benefits Patients: Personalised prediction of expected self-reported benefit based on a visual disability measure of direct relevance to patients. NHS: Patient centred measures of benefit in people undergoing cataract surgery; predictors of surgical benefit. Decision-Support From the statistical models for prediction of benefit, surgical complications and visual loss/harm, integrated calculator tools constructed for personalised predictions based on patients individual risk factor profiles. Calculator outputs referenced in patient decision-support Option Grids formatted as frequently asked questions (FAQ). Benefits Patient: Accessible decision-support information with personalised prediction of likely self-reported visual benefit, intraoperative complications and visual harm from cataract surgery. NHS: Better informed patients able to make informed choices regarding cataract surgery; strengthened consenting processes with greater relevance to individual people and their eyes. Health Utilities Established health utility measures are unresponsive for moderate visual disability, including for cataract. We will evaluate the ability of well-established (EQ-5D-3L) and recently developed (EQ-5D-5L, ICECAP-O) preference based health utility measures to detect changes in vision-related quality of life or wellbeing related to cataract surgery and where appropriate to map or co-calibrate instruments with the Cat-PROM. Benefits Patient: Recognition of the relevance and importance of appropriate provision for surgical treatment of visual disability from cataract. NHS: Greater equity of health resource allocation across conditions and boundaries. WP4: Implementation Pilot / Feasibility Trial of Decision-Support A combined feasibility and pilot randomised trial exploring the impact on decision making, acceptability and cost-effectiveness of the Cataract Option Grid decision-support tool developed in WP3 will be undertaken in 4 NHS service settings. In parallel the Cat-PROM prediction model will be assessed for validity based on predicted and observed levels of postoperative visual benefit. Investigation of outcome mismatches including in-depth qualitative case-study approaches will be used to try to understand the basis for mismatches in unusual situations where clinical expectations of benefit are inconsistent with patient perceptions of outcome. Benefits Patient: Pilot RCT of Option Grid decision-support impact identified; Costs of additional data collection defined; Mismatches between clinical expectations and patient perceptions better understood. NHS: Pilot data on the performance, impact, acceptability and cost of Option Grid enhanced decision-support including benefits and risks prediction for cataract surgery; Feasibility for forward planning of possible fully powered RCT of decision-support.

Lay abstract: Cataract is an extremely common potentially blinding age related condition. Cataract surgery is the most frequently undertaken surgical procedure on the NHS (~330,000 annually in England). Before and after surgery vision testing is normally done one eye at a time using the (opticians) letter chart. Although useful, testing in this way does not capture people s everyday experience of their vision. Asking patients about everyday vision, in a structured way, allows the patient s perception of their eyesight to be measured . Measuring: Our first objective will be to develop and test a suitable set of questions (Cat-PROM) for eliciting self-reported vision information from people with cataract. Testing will be done both before and after surgery to check that the questions work as intended. We have already done work towards this (published and pilot for application, see appendix). Harm: All surgery can have complications and cause harm to patients. Although fairly uncommon in cataract surgery (1-2 per 100) harmful events must be avoided whenever possible. From our studies of 55,567 operations we know that the averages can hide a lot of variation depending on patient factors, with a small proportion of complex patients being at very high risk. If there is a complication then there is a 6x higher likelihood of vision loss following surgery. We will check our results for prediction of adverse events using ~200,000 fresh electronic patient cataract care records. Statistically, big numbers are needed to analyse these uncommon adverse events. Benefit: Understanding the risk of harm is just one aspect of weighing things up when considering possible surgery. Patients also need to know how likely it is that surgery will be successful. Statistically, smaller numbers are required to study this because favourable outcomes are more frequent. To understand different gradations of benefit however, additional preoperative details not routinely collected are needed e.g. cataract severity. From detailed clinical assessments of 1500 people before and after surgery we will identify important preoperative features associated with better or poorer self-reported Cat-PROM outcomes. Health Economics: The National Institute for Health and Clinical Excellence (NICE) uses a patient Quality-of-Life self-report questionnaire (EQ5D) when deciding on NHS spending. Moderate vision problems are not adequately detected by the EQ5D. We will ask subgroups of the 1500 people to complete it along with other Quality-of-Life questionnaires, and link these to Cat-PROM scores for future health economics studies. Decision Support: Empowerment of patients considering cataract surgery will be achieved through clear presentation of personalised information on risks of harm and likely patient-reported visual benefit from cataract surgery using a frequently asked question style of Option Grid . The usefulness of this information for patients and health care providers will be evaluated in regard to shared patient-clinician decision making.

Research activity codes: 7.3 MANAGEMENT AND DECISION MAKING;7.1 INDIVIDUAL CARE NEEDS
Health categories: EYE