COMBAT: Clinical- and cost-effectiveness, safety and acceptability of COMBined phacovitrectomy, versus sequentiAl viTrectomy and cataract surgery, for the management of rhegmatogenous retinal detachment: A Randomised Equivalence Clinical Trial.
A large UK trial will test whether combining two eye surgeries into one procedure works just as well as doing them separately for people with a detached retina. Retinal detachment is an emergency where the light-sensitive layer at the back of the eye peels away, causing vision loss. Surgeons typically repair it with a vitrectomy, but this almost always triggers a cataract—a clouding of the eye’s natural lens—that requires a second operation months later. Patients find two surgeries stressful, and the NHS performs thousands of extra cataract procedures each year as a result. The COMBAT trial will randomly assign 276 adults aged 50 or older to either a single combined operation (phacovitrectomy) or the current two-step approach. The primary measure is whether vision after one year is equivalent—within a margin of seven letters on an eye chart—between the two groups. If the combined procedure proves as safe and effective, it could save around 6,000 cataract surgeries annually across the NHS, reduce hospital visits for patients, and lower healthcare costs. The trial also tracks complications, quality of life, and patient preferences to guide future clinical guidelines.
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Research question: In people with non-highly myopic phakic rhegmatogenous retinal detachment (RRD) (Population) is phacovitrectomy (Intervention) equivalent (equivalence margin +/- 7 letters) or superior to vitrectomy and subsequent phacoemulsification (Comparator)? Background: In RRD, the retina detaches from the eye wall. As a result, sight is lost. Most RRD are treated with vitrectomy surgery. A common complication of vitrectomy is cataract, the opacification of the crystalline lens of the eye. Currently, patients presenting with phakic (no previous cataract surgery) non-highly myopic RRD are not routinely offered phacoemulsification (cataract surgery; phaco in short) at the same time as vitrectomy (phacovitrectomy). Following vitrectomy, most (if not all) will develop a cataract requiring phaco. The COMBAT patient and public involvement (PPI) group voiced that surgery is stressful for patients; if phacovitrectomy were as safe and successful as vitrectomy and subsequent phaco, patients would likely prefer it. Phacovitrectomy may reduce visits/admissions to hospital and costs to patients and NHS. Aims: To determine clinical and cost-effectiveness, safety and patient experience and acceptability of phacovitrectomy, compared with vitrectomy and subsequent cataract surgery (if/when needed), for non-highly myopic phakic RRD and to set basis for its implementation. Methods: Design/Setting: Pragmatic, allocation-concealed, single-masked (outcome assessors), multicentre, randomised equivalence trial at 30 UK sites. Population: Adults 50 years or older with non-highly myopic phakic RRD of any gender, ethnicity, religion, sexual orientation or socioeconomic status. Health technology assessed: Phacovitrectomy. Comparator: Vitrectomy and subsequent phaco (if/when needed) (current standard care). Primary outcome: Change in best-corrected visual acuity (BCVA) from baseline to month 12. Secondary outcomes (at or by 12 months): Primary and final retinal reattachment (i.e. proportion of eyes with an attached retina after one, or two or more surgeries, respectively); complications; number of surgeries; refractive error; use of health and social care services and non-health care costs; health and visual related quality of life; participant’s preference and experience; proportion of participants with BCVA <69 letters and with <34 letters; time to achieve ‘best vision’; change in BCVA. Sample size: COMBAT is powered to demonstrate treatment equivalence for the primary outcome. Based on two one-sided t-tests, 2.5% significance level, 15.2-letter standard deviation[13] and an equivalence margin of +/- 7 letters (a difference of 7 or fewer is not considered clinically meaningful)[14,15], 248 participants are required to be 90% sure the 95% confidence interval will exclude a difference in means of more than 7 letters. Allowing for 10% dropout, we will need a minimum of 276 participants. Timelines: Set-up 6 months(m); recruitment 24m; follow-up 12m; analysis/write-up 6m. Anticipated impact and dissemination: No patients in the COMBAT PPI group who had phakic RRD were offered phacovitrectomy. COMBAT will provide evidence base to guide care on this regard. Adding a phaco to the vitrectomy adds around 8 minutes surgical time[8] but could save 6000 cataract surgeries or more a year to the NHS. The research team/PPI group will ensure visibility of COMBAT and national/international dissemination of findings.
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