SCREENING FOR RETINOPATHY & NEPHROPATHY 1 Prof.V.Mohan.,M.D.,Ph.D.,D.Sc. DIRECTOR M.V.DIABETES SPECIALITIES CENTRE, PROFESSOR OF INTERNATIONAL HEALTH UNIVERSITY OF MINNESOTA, USA VISITING PROFESSOR OF DIABETOLOGY SRI RAMCHANDRA MEDICAL COLLEGE, PORUR PRESIDENT MADRAS DIABETES RESEARCH FOUNDATION, CHENNAI CARDINAL PRINCIPLES FOR SCREENING 1. Important health problem with a presymptomatic state 2. Acceptable screening procedures (both by public and health care professional) 3. Safe, effective and universally agreed treatment 4. Economic cost of screening and treatment should be less than that for diagnosis and treatment (WHO) THE SCREENING PATHWAY Healthy Disease or precursor detectable Symptoms develop Advanced disease Death Screening possible Intervention to avert disease development or its consequence Life prolonged CLASSIFICATION NON - PROLIFERATIVE DIABETIC RETINOPATHY PROLIFERATIVE DIABETIC RETINOPATHY WITHOUT MACULOPATHY WITH MACULOPATHY DIABETIC RETINOPATHY VISUAL IMPAIRMENT AND RETINOPATHY By the year 2020 the number of blind people world-wide, over 60 years of age will reach 54 million (Practical Optometry,1996) 90% of the blindness in the world occurs in developing countries Diabetic retinopathy is seventh cause of blindness in India Timely treatment can prevent up to 98% of vision loss from diabetic retinopathy Less than half of those with diabetes have their eyes examined for retinopathy at the recommended frequency BJO, 2001 IS SCREENING FOR RETINOPATHY JUSTIFIED? is an important health problem has a known natural history has effective treatment screening is simple to perform acceptable to patients cost effective comprehensive Yes, because retinopathy. DIABETIC RETINOPATHY - SCREENING M A simple diagnostic procedure, to identify those patients in whom prompt treatment is needed to prevent loss of vision M It is not a complete clinical examination in itself EYE EXAMINATION - ROUTINE M History M Visual acuity M Clinical examination of retina M Direct ophthalmoscopy M Indirect ophthalmoscopy M Retinal color photography M Fluorescein angiography OCULAR FUNCTION EXAMINATION D Visual acuity (corrected), distance, reading M Colour vision M Visual field test - to test confrontation eye movements D After dilation M Lens M Vitreous M Fundus including disc and macula Ophthalmoscopy Retinal photography Polaroid photographs 35mm colour slides Digital images - Scanner - Video - Digital camera RETINAL EXAMINATION OPHTHALMOSCOPY Direct ophthalmoscopy and indirect ophthalmoscopy through dilated pupil inexpensive, rapid, efficient D Direct ophthalmoscopy enables adequate examination of only the posterior pole D Indirect ophthalmoscopy provides insufficient magnification OPHTHALMOSCOPY D Slit lamp examination using either indirect ophthalmoscopy with convex aspheric lens or diagnostic contact lens yields more information on retinal thickening and proliferative retinopathy Seven 30 degree fields Two 45 degree fields Three photographs spread across the posterior pole RETINAL PHOTOGRAPHY OPHTHALMOSCOPY vs PHOTOGRAPHY OPHTHALMOSCOPY PHOTOGRAPHY No documentation Can be documented is possible Errors cannot be Photographs can be detected regraded Observer bias Mutiple grading is possible RETINAL PHOTOGRAPHS RETINAL PHOTOGRAPHY GOLD STANDARD FOR RETINAL SCREENING Seven 30 - degree field of stereoscopic photographs taken by a trained technician Photographs can be taken by a mobile unitwith a camera and later assessed by a trained reader Suited to serve even rural communities Retinal photography is the gold standard for screening diabetic retinopathy SPECIFICITY AND SENSITIVITY OF OPHTHALMOSCOPY AND PHOTOGRAPHY Ophthalmoscopy Photography (%) (%) Sensitivity Specificity Owens et al, Diabetic Medicine, 1998 WHO CAN DO SCREENING ? M General practitioner M Optometrists M Clinicians in a hospital - based diabetes centre M Ophthalmologists M Diabetologists M Retinal photography services M Combination of all these ERROR RATES FOR DIAGNOSING DIABETIC EYE DISEASE - OPHTHALMOSCOPY Overall Serious errors (%) errors (%) Internist Senior medical resident Diabetologist66 50 Ophthalmologist48 11 Retinal specialist13 0 Stage of hyper- filtration Micro albumi- nuria Macro albumi- nuria Azotemia (Renal failure) End stage Renal disease Normo albumi- nuria NATURAL HISTORY OF NEPHROPATHY IN TYPE 1 DIABETES yrs 1 yrs yrs PREVALENCE OF DIABETIC NEPHROPATHY Diabetic Nephropathy Develops in % of Type 1 diabetic patients % of Type 2 diabetic patients Leading cause of ESRD in United States PREVALENCE OF DIABETIC NEPHROPATHY IN DIFFERENT ETHNIC GROUPS 19 million Indians with diabetes % of type 2 diabetes depending on ethnic origin Caucasians % African Americans % Pima Indians - 60% Asian Indians - 10% Even with 10%, 1.7 million Indian diabetics will haveNephropathy SCREENING FOR MICROALBUMINURIA Routine urinalysis for protein - For protein + For protein Overt nephropathy Quantitative protein begin treatment Condition that may invalidate urine albumin excretion Wait until resolved Test for microalbumin > 30 mg/24h Repeat microalbumin test twice within 3 months period 2 of 3 tests > 30 mg/24h ? Microalbuminuria, begin treatment Repeat in 1 year Yes No Yes No Yes SPECIMEN COLLECTION Collect freshly voided urine in a clean, dry container Preservatives should be avoided Samples which cannot be tested within 3 days of collection should be refrigerated Samples should not be frozen The test should be free from significant interference from glucosuria, pH, ketonuria or bacterial contamination SCREENING FOR MICROALBUMINURIA Albumin to creatinine ratio in random spot collection 24 - h urine collection with creatinine Timed collection (4-h or overnight) Three methods DEFINITION OF MICROALBUMINURIA Stage 24h Timed Spot collection collection collection Normoalbuminuria < 30 mg/24h 200 g/min >300 g/mg creat ADA, Diabetes Care, 1998 Random spot collection First void or morning collection Timed collection Easy to perform Generally provides accurate information Preferred due to diurnal variation in albumin excretion Gold standard Notoriously labour and time intensive Patients co-operation difficult ADVANTAGES AND DISADVANTAGES METHODS OF MICROALBUMINURIA ANALYSIS SPECIFICITY AND SENSITIVITY FOR MICROALBUMINURIA Sensitivity Specificity (%) (%) Random spot specimen First morning void Schwab et al, Diabetes Care, 1992 Timed urine collection - gold standard 3 -hour collections 4 -hour collections Overnight collections Brodows et al, Diabetes Care, 1981 Steno study group, Lancet, 1982 Viberti et al, Lancet, 1982 SHORTENED TIMED CLEARANCES SUGGESTIONS .. 1 -hour timed collections Sochett et al, J.Pediatr,1988 Qualitative Dipstick method Quantitative Immunoturbidometric assay Enzyme linked Immunosorbant assay Radioimmuno assay ASSAYS FOR MICROALBUMINURIA MICRAL STRIPS Micral strip screening tests offer a cost- effective method of screening Dip sticks show acceptable sensitivity (95%) and specificity (93%) All positive tests should be confirmed by more specific methods FALSE POSITIVES FOR ALBUMINURIA Hyperfiltration (Newly diagnosed diabetes) Exercise Marked hypertension Congestive Heart Failure Urinary Tract Infection Acute febrile illness CONCLUSIONS Screening for retinopathy Sensitive, specific and safe screening tests are available for retinopathy Retinal photography is the gold standard, which can be modified from seven to four field Training is necessary to grade retinal photographs Newer technologies including digital imaging may reduce the cost of screening PRIORITIES ` Screening ` Diagnosis ` Treatment ` Counseling ` Education For preventing blindness due to diabetes For all diabetic patients CONCLUSIONS Screening for nephropathy Screening tests for microalbuminuria are safe, simple at the same time specific and sensitive Timed urine collection is the gold standard. However spot urine testing has also proved to be equally sensitive Micral dip sticks are cost effective Microalbuminuria provides information not only about nephropathy,but also generalized vascular disease (endothelial dysfunction) PRIORITIES ` Annual screening of Microalbuminuria ` Glycemic control ` Treatment modalities to slow down the rate of progression of nephropathy For preventing nephropathy due to diabetes in all diabetic patients