Transcript screening for retinopathy & nephropathy

SCREENING FOR RETINOPATHY &
NEPHROPATHY
Prof.V.Mohan.,M.D.,Ph.D.,D.Sc.
DIRECTOR
M.V.DIABETES SPECIALITIES CENTRE,
VISITING PROFESSOR OF DIABETOLOGY
SRI RAMCHANDRA MEDICAL COLLEGE, PORUR
PRESIDENT
MADRAS DIABETES RESEARCH FOUNDATION,
CHENNAI
PROFESSOR OF INTERNATIONAL HEALTH
1
UNIVERSITY OF MINNESOTA, USA
CARDINAL PRINCIPLES FOR SCREENING
(WHO)
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
THE SCREENING PATHWAY
Healthy
Disease or precursor
detectable
Screening possible
Symptoms
develop
Advanced
disease
Death
Intervention to avert
disease
development or its
consequence
Life prolonged
CLASSIFICATION
DIABETIC RETINOPATHY
NON - PROLIFERATIVE
DIABETIC RETINOPATHY
WITHOUT
MACULOPATHY
WITH
MACULOPATHY
PROLIFERATIVE
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?
Yes, because retinopathy….
is an important health problem
has a known natural history
has effective treatment
screening is
simple to perform
acceptable to patients
cost effective
comprehensive
DIABETIC RETINOPATHY - SCREENING
 A simple diagnostic procedure, to identify
those patients in whom prompt treatment is
needed to prevent loss of vision
 It is not a complete clinical examination in
itself
EYE EXAMINATION - ROUTINE
 History
 Visual acuity
 Clinical examination of retina
 Direct ophthalmoscopy
 Indirect ophthalmoscopy
 Retinal color photography
 Fluorescein angiography
OCULAR FUNCTION EXAMINATION
 Visual acuity (corrected), distance, reading
 Colour vision
 Visual field test - to test confrontation
eye movements
 After dilation
 Lens
 Vitreous
 Fundus including disc and macula
RETINAL EXAMINATION
Ophthalmoscopy
Retinal photography
Polaroid photographs
35mm colour slides
Digital images
- Scanner
- Video
- Digital camera
OPHTHALMOSCOPY
Direct ophthalmoscopy and
indirect ophthalmoscopy
through dilated pupil
inexpensive, rapid, efficient
OPHTHALMOSCOPY
 Direct ophthalmoscopy enables adequate examination
of only the posterior pole
 Indirect ophthalmoscopy provides insufficient
magnification
 Slit lamp examination using either indirect
ophthalmoscopy with convex aspheric lens or
diagnostic contact lens yields more information on
retinal thickening and proliferative retinopathy
RETINAL PHOTOGRAPHY
 Seven 30 degree fields
 Two 45 degree fields
 Three photographs
spread across the posterior
pole
OPHTHALMOSCOPY vs PHOTOGRAPHY
OPHTHALMOSCOPY
No documentation
PHOTOGRAPHY
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
Retinal photography is the gold standard
for screening diabetic retinopathy
Seven 30 - degree field of stereoscopic
photographs taken by a trained technician
Photographs can be taken by a mobile
unit with a camera and later assessed by a
trained reader
Suited to serve even rural communities
SPECIFICITY AND SENSITIVITY OF
OPHTHALMOSCOPY AND PHOTOGRAPHY
Ophthalmoscopy
(%)
Sensitivity
Specificity
65.7
93.8
Photography
(%)
87.3
84.8
Owens et al, Diabetic Medicine, 1998
WHO CAN DO SCREENING ?
 General practitioner
 Optometrists
 Clinicians in a hospital - based diabetes
centre
 Ophthalmologists

Diabetologists

Retinal photography services

Combination of all these
ERROR RATES FOR DIAGNOSING DIABETIC
EYE DISEASE - OPHTHALMOSCOPY
Overall
errors (%)
Serious
errors (%)
Internist
74
70
Senior medical resident
69
52
Diabetologist
66
50
Ophthalmologist
48
11
Retinal specialist
13
0
NATURAL HISTORY OF NEPHROPATHY
IN TYPE 1 DIABETES
Normo
albuminuria
Stage of
hyperfiltration
Micro
albuminuria
15 - 20 yrs
Macro
albuminuria
Azotemia End stage
(Renal
Renal
failure)
disease
4 - 5 yrs
1 yrs
PREVALENCE OF DIABETIC NEPHROPATHY
Diabetic Nephropathy

Develops in 35 - 45% of Type 1 diabetic
patients
 20 - 30% 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
5 - 60% of type 2 diabetes depending on ethnic origin
Caucasians - 5 - 10%
African Americans - 10 - 20%
Pima Indians - 60%
Asian Indians - 10%
Even with 10%, 1.7 million Indian diabetics will
have Nephropathy
SCREENING FOR MICROALBUMINURIA
Routine urinalysis for protein
Overt nephropathy
- For protein
+ For protein
Quantitative
protein
begin treatment
Repeat in
1 year
Condition that may
Yes
invalidate urine
Wait until resolved
albumin excretion
No
No
Test for microalbumin > 30 mg/24h
Yes
Repeat microalbumin test twice
within 3 months period
2 of 3 tests > 30 mg/24h ?
Yes
Microalbuminuria, begin treatment
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
Three methods
Albumin to creatinine ratio in random spot
collection
24 - h urine collection with creatinine
Timed collection (4-h or overnight)
DEFINITION OF MICROALBUMINURIA
Stage
Normoalbuminuria
Microalbuminuria
Clinical albuminuria
24h
collection
< 30 mg/24h
Timed
collection
<20g/min
Spot
collection
<30g/mg creat
30-300 mg/24h 20-200g/min 30-300g/mg creat
>300 mg/24h
>200g/min
>300g/mg creat
ADA, Diabetes Care, 1998
ADVANTAGES AND DISADVANTAGES
METHODS OF MICROALBUMINURIA ANALYSIS
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
SPECIFICITY AND SENSITIVITY FOR MICROALBUMINURIA
Timed urine collection - gold standard
Sensitivity
(%)
Specificity
(%)
Random spot specimen
89
85
First morning void
70
93
Schwab et al, Diabetes Care, 1992
SHORTENED TIMED CLEARANCES
SUGGESTIONS …..
3 -hour
collections
4 -hour
collections
Brodows et al, Diabetes Care, 1981
Steno study group, Lancet, 1982
1 -hour
timed
collections
Sochett et al, J.Pediatr,1988
Overnight
collections
Viberti et al , Lancet, 1982
ASSAYS FOR MICROALBUMINURIA
Qualitative
Dipstick method
Quantitative
Radioimmuno assay
Immunoturbidometric assay
Enzyme linked Immunosorbant assay
MICRAL STRIPS
Micral strip screening tests offer a costeffective 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
For preventing blindness due to diabetes
 Screening
 Diagnosis
 Treatment
 Counseling
 Education
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
For preventing nephropathy due to diabetes
 Annual screening of Microalbuminuria
 Glycemic control
 Treatment modalities to slow down
the rate of progression of nephropathy
in all diabetic patients