This page is provided by Thomas J. A. Lehman MD
Delivering the
best care - with great care
Dr. Lehman is the
author of many textbook chapters and articles on the care of children and young
adults with SLE. He practices in
THE ANA
DILEMMA!
A common rheumatic
disease related problem faced by pediatricians is the child with a positive test for antinuclear antibodies (ANA). In ‘the old days’ this test was done using a
rat liver substrate. A positive test of
So we should ignore low titer positive ANAs – right?
Well unfortunately some of the people with low titer positive ANAs do have diseases.
How does a sensible physician
cope? If you go to the textbooks you
will read about sensitivity, specificity, positive predictive value, and
negative predictive value. These are
important to understand for every test we do. Sensitivity – the goal is no false negatives – percentage of those
tested with positive tests over number with disease. Does it detect every case? Specificity
– the goal is no false positives – percentage of those tested who test negative
over number who do not have disease. Positive predictive value – how likely
is it that a positive test means you do have the disease. Negative
predictive value – how likely is it a negative test means you don’t have
disease. An example from the literature*
1010 patients were tested for ANA. 153
were ANA positive, 17 had lupus. Sensitivity 100% - all the patients
with SLE were positive. Specificity 86% - 857/1010 tested negative
and did not have disease. Positive predictive value was only 11% 17 positive with disease out of 153 positive
– oops not so good. Negative predictive value 100% no one who was ANA negative had
disease.
Well that’s useful information except for one
thing. The results depend entirely on the population being tested. If you are testing people with symptoms who
you suspect have disease you get entirely different results than if you
randomly test people on the street with no reason to suspect they have
disease. Thus the sensitivity,
specificity, etc all depend on the clinical situation in which the testing is
being done. So is there anything useful
here when you are out in private practice?
General guidelines I use. 1) If
the patient has symptoms of rheumatic disease they should be evaluated no
matter what the ANA result.
2) If the patient has an ANA of
Typical example
from my practice; a seven year old girl had a recurrent itchy rash. The allergist ordered a panel of tests and
the ANA was 1:320. The rash went
away. A follow-up ANA was done and was
even higher. The girl felt fine, no
rash. A few months later another ANA was
done which was > 1:320 so she was referred for ‘reassurance.’ CBC, ESR, and Chemistries were all normal,
but on full evaluation she turned out to be IgA
deficient and have high titer anti-thyroid antibodies and unsuspected mildly
symptomatic hypothyroidism.
In the late 70s
at Childrens of LA, I had 90 families with children
with lupus. I tested every family member
and discovered 30 sisters of teenagers with lupus who were themselves ANA
positive. Two of these sisters had SLE
when examined carefully. I followed the
remaining 28, examining them every six months.
In two years nothing happened.
But by five years 2 had lupus and by ten years 7 did. It would not have been appropriate to start
treating any of these sisters until they had diagnosable disease. But ignoring them after the initial negative
exam wouldn’t have been right either.
Conservative monitoring will prove to have been unnecessary for many,
but may save the lives of others. None
of us know for sure who is who.
We’re at
Burke Rehab in
My
book –click here to order at a discount from Amazon.com
at
Amazon.com
“Dr. Tom Lehman’s experience and compassion are evident on every page of this
book, and they help guide the reader—child, parent,
and healthcare professional alike – through the
world of childhood arthritis. This book
is an absolute gem written with a single goal in mind: improve the lives of kids with arthritis.” -- Jack Klippel, M.D. President and
CEO of the Arthritis Foundation
“Dr. Lehman has given parents and families of children with
arthritis the first book that speaks to the parent and child as equals. His book explains the illnesses, the
medications, the lab tests, and the disease course in simple, understandable
lay language and givens them valuable insight into how a pediatric
rheumatologist thinks. Bravo!”-- Charles Spencer, M.D.,
Professor of Clinical Pediatrics,
It’s not just
growing pains.
A guide to childhood muscle, bone, and joint pain,
rheumatic diseases and the latest treatments
Click here to see the table of contents
It
has always been a frustration trying to answer the many questions I have
received from people over the web. I can’t
take the time and give them the detail I would like to. I have to take care of my patients. This book is a distillation of my experience
answering questions for parents and health professionals over 25 years of
practice. If you want to know about the
diseases, the tests, the medications, or how to be sure you are getting the
best care– If you are the family member of a child with joint pains, this book will
give you the answers. If you are a general physician, a
pediatrician, or a nurse who cares for children with these diseases it will
answer many of the questions families ask you, and you can recommend it to
them. It will also answer many of your
questions about what shots to give, what precautions to take, and the other
questions families, pediatricians, and other health care providers have asked
me over the years.
Dr. Lehman is
the author of many textbook chapters and articles on the care of children and
young adults with SLE. He practices in
New York City. Click
here for more information about Dr. Lehman or the
Hospital for Special Surgery.
Click here
for The Lupus Foundation web page
The Arthritis Foundation also works with
children with lupus.
Click for BOOKS dealing with SLE
This site provided by Thomas J. A. Lehman MD
Chief, Division of Pediatric Rheumatology
The Hospital for Special
Surgery
535 E 70 St,
212-606-1151, fax 212-606-1938, e-mail goldscout@aol.com
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