Best Tests June 2006
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A pragmatic decision was made to include ANA testing in our framework for the investigation of ongoing fatigue as GPs told us they were concerned about missing connective tissue disease in people with tiredness. The feedback we have is that this is not a good idea because of the likely high yield of false positives. To clarify the issue we have reproduced the useful, clear guideline on ANA testing promulgated by the British Columbia Medical Association.
Antinuclear Antibody (ANA) Testing for Connective Tissue Disease
This guideline describes appropriate use of antinuclear antibody (ANA) testing in the diagnosis of connective tissue disease (CTD), also referred to as “systemic rheumatic disease”. It applies only to individuals 17 years of age and over. The guideline does not address ANA testing in the investigation of unexplained infertility, adverse pregnancy outcomes, liver disease or thrombotic disorders.
RECOMMENDATION 1: ANA testing not indicated
ANA testing should not be ordered unless a connective tissue disease is a significant clinical possibility.
ANA testing is not helpful in confirming a diagnosis of rheumatoid arthritis or osteoarthritis.
ANA testing should not be used to evaluate fatigue, back pain or other musculoskeletal pain unless accompanied by one or more of the clinical features listed in Recommendation 2.
RECOMMENDATION 2: ANA testing indicated
ANA testing is a useful diagnostic adjunct if the clinical history and physical examination show symptoms and signs of CTD consistent with systemic lupus erythematosus (SLE), scleroderma, Sjögren’s syndrome or polymyositis/dermatomyositis. Such patients typically* present with at least one of the following clinical criteria, unexplained by other causes:
CTD is uncommon, occurs almost exclusively in women, and typically presents before 50 years of age.
RECOMMENDATION 3: Repeat testing rarely indicated
ANA testing should usually be ordered only once.
Positive ANA tests do not need to be repeated. Changes in the ANA titre do not correlate with disease activity. Negative tests rarely need to be repeated. If there is a strong suspicion of an evolving CTD or a change in the patient’s illness suggesting the diagnosis should be revised, repeat testing may be indicated.
This guideline was developed by the Guidelines and Protocols Advisory Committee, approved by the British Columbia Medical Association and adopted by the Medical Services Commission.
http://www.health.gov.bc.ca/msp/protoguides/gps/ana.pdf (Accessed May 2006).