title: Extending the diabetic retinopathy screening interval beyond 1 year: systematic review.
abstract: To determine whether the recommended screening interval for diabetic retinopathy (DR) in the UK can safely be extended beyond 1 year. Systematic review of clinical and cost-effectiveness studies. Nine databases were searched with no date restrictions. Randomised controlled trials (RCTs), cohort studies, prognostic or economic modelling studies which described the incidence and progression of DR in populations with type 1 diabetes mellitus or type 2 diabetes mellitus of either sex and of any age reporting incidence and progression of DR in relation to screening interval (vs annual screening interval) and/or prognostic factors were included. Narrative synthesis was undertaken. 14,013 papers were identified, of which 11 observational studies, 5 risk stratification modelling studies and 9 economic studies were included. Data were available for 262,541 patients of whom at least 228,649 (87%) had type 2 diabetes. There were no RCTs. Studies concluded that there is little difference between clinical outcomes from screening 1 yearly or 2 yearly in low-risk patients. However there was high loss to follow-up (13-31%), heterogeneity in definitions of low risk and variation in screening and grading protocols for prior retinopathy results. Observational and economic modelling studies in low-risk patients show little difference in clinical outcomes between 1-year and 2-year screening intervals. The lack of experimental research designs and heterogeneity in definition of low risk considerably limits the reliability and validity of this conclusion. Cost-effectiveness findings were mixed. There is insufficient evidence to recommend a move to extend the screening interval beyond 1 year.
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Sian
authors.initials: S
authors.lastname: Taylor-Phillips
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Hema
authors.initials: H
authors.lastname: Mistry
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Leslie
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Dan
authors.initials: D
authors.lastname: Todkill
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tsertsvadze
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Connock
authors.affiliation: Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Aileen
authors.initials: A
authors.lastname: Clarke
mesh_terms: D000367:Age Factors; D003362:Cost-Benefit Analysis; D003922:Diabetes Mellitus, Type 1 / Q000150:complications*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000191:economics / Q000209:etiology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000191:economics; D013997:Time Factors
keywords: Diabetes Mellitus; Diabetic Retinopathy; Mass Screening; Screening Interval; Systematic Review