1. Anti-Nuclear Antibody Tests
Regan Arendse FCP(SA), PhD
Rheumatologist
Saskatoon

2. Case study

3. Questions Is the ANA a useful clinical tool?
What causes a false positive ANA?
When should an ANA test be requested?

4. Rates of positive ANA in healthy and ill
Wandstrat et al., J Autoimmun 2006; 27:

5. Gender and positive ANA
Quan-Zhen et al., Arth Res Ther 2011

6. Age and positive ANA
No association between age (20-60 years) and ANA positivity
Quan-Zhen et al., Arth Res Ther 2011
Tan et al., Arth & Rheum 1997; 40:

7. Accumulated % + antibodies over 10 years before diagnosis with SLE
Erikson et al., Arth Res Ther 2011; 13

8. Antibody presence predating disease
Erikson et al., Arth Res Ther 2011; 13

9. Predictive value of ANA for SLE
Incidence rate of SLE, lupus develops in <1% positive ANA individuals
None of 24 ANA asymptomatic children developed disease over mean 61 month follow up period
Predictive value of ANA increases in the at risk population with clinical disease
Aho et al., J Rheum 1992; 19:
Cabral et al., Pediatrics 1992; 89: 441-4

10. Answer
The ANA is not a good screening tool for auto-immune disease in the absence of convincing clinical signs
Long time interval between ANA positivity and onset of disease does not warrant screening
Lack of any effective pre-emptive or prophylactic treatment emphasizes that the argument not to routinely request an ANA

11. What causes a false positive ANA?

12. HEp-2 indirect immunofluorescence

13. Antigens with similar structure to pathologic antigens
Viruses (Herpes viruses and HIV)
Drugs which alter proteins (Procainamide, INH, Phenytoin)
Malignant cells
Environmental toxins (silicone)

14. When should an ANA test be requested?
Yes if strong clinical suspicion of autoimmune disease
Scleroderma
Lupus
Dermatomyositis
Sjogren’s disease
Mixed connective tissue disease

15. When should an ANA test be requested?
No if not a strong clinical suspicion of autoimmune disease
Chronic pain
Chronic fatigue
Chilblains
Raynaud’s phenomenon
Rosacea

16. When should an ANA test be requested?
8.8% of fibromyalgia patients have +ANA
8.9% of controls have +ANA
In prospective study over 4 years, in 12 with FMS and 12 controls, one in FMS group developed SLE and one in controls developed Sjogren’s syndrome
Al Allaf et al., Clin Rheuma 2002; 21: 472-7

17. Conclusion ANA should not be routinely requested
ANA should not be requested for non-specific symptoms
ANA should only be requested in patients with clinical features strongly suggestive of an auto-immune disease
Causes of false positives are many and varied