Diabetic macular oedema and diode subthreshold micropulse laser (DIAMONDS): study protocol for a randomised controlled trial
Noemi Lois,
Evie Gardner,
Norman Waugh,
Augusto Azuara-Blanco,
Hema Mistry,
Danny McAuley,
Nachiketa Acharya,
Tariq M. Aslam,
Clare Bailey,
Victor Chong,
Louise Downey,
Haralabos Eleftheriadis,
Samia Fatum,
Sheena George,
Faruque Ghanchi,
Markus Groppe,
Robin Hamilton,
Geeta Menon,
Ahmed Saad,
Sobha Sivaprasad,
Marianne Shiew,
David H. Steel,
James Stephen Talks,
Catherine Adams,
Christina Campbell,
Matthew Mills,
Mike Clarke,
On behalf of the DIAMONDS Study Group
Affiliations
Noemi Lois
From The Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast
Evie Gardner
The Northern Ireland Clinical Trials Unit (NICTU)
Norman Waugh
The Division of Health Sciences, University of Warwick
Augusto Azuara-Blanco
the Centre for Public Health, Queens University
Hema Mistry
The Division of Health Sciences, University of Warwick
Danny McAuley
From The Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast
Nachiketa Acharya
Sheffield Teaching Hospitals NHS Foundation Trust
Tariq M. Aslam
The Manchester Academic Health Science Centre, Manchester Royal Eye Hospital and Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester
Clare Bailey
Bristol Eye Hospital
Victor Chong
Royal Free Hospital NHS Foundation Trust
Louise Downey
Hull and East Yorkshire Hospital, Hull and East Yorkshire NHS Trust
Haralabos Eleftheriadis
Kings College Hospital NHS Foundation Trust
Samia Fatum
John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust
Abstract Background In the UK, macular laser is the treatment of choice for people with diabetic macular oedema with central retinal subfield thickness (CST) < 400 μm, as per National Institute for Health and Care Excellence guidelines. It remains unclear whether subthreshold micropulse laser is superior and should replace standard threshold laser for the treatment of eligible patients. Methods DIAMONDS is a pragmatic, multicentre, allocation-concealed, randomised, equivalence, double-masked clinical trial that aims to determine the clinical effectiveness and cost-effectiveness of subthreshold micropulse laser compared with standard threshold laser, for the treatment of diabetic macular oedema with CST < 400 μm. The primary outcome is the mean change in best-corrected visual acuity in the study eye from baseline to month 24 post treatment. Secondary outcomes (at 24 months) include change in binocular best corrected visual acuity; CST; mean deviation of the Humphrey 10–2 visual field; change in percentage of people meeting driving standards; European Quality of Life-5 Dimensions, National Eye Institute Visual Functioning Questionnaire-25 and VisQoL scores; incremental cost per quality-adjusted life year gained; side effects; number of laser treatments and use of additional therapies. The primary statistical analysis will be per protocol rather than intention-to-treat analysis because the latter increases type I error in non-inferiority or equivalence trials. The difference between lasers for change in best-corrected visual acuity (using 95% CI) will be compared to the permitted maximum difference of five Early Treatment Diabetic Retinopathy Study (ETDRS) letters. Linear and logistic regression models will be used to compare outcomes between treatment groups. A Markov-model-based cost-utility analysis will extend beyond the trial period to estimate longer-term cost-effectiveness. Discussion This trial will determine the clinical effectiveness and cost-effectiveness of subthreshold micropulse laser, when compared with standard threshold laser, for the treatment of diabetic macular oedema, the main cause of sight loss in people with diabetes mellitus. Trial registration International Standard Randomised Controlled Trials, ISRCTN17742985. Registered on 19 May 2017 (retrospectively registered).
