Objective: To identify individuals with antinuclear antibodies (ANA) not fulfilling criteria for systemic lupus erythematosus (SLE) or other connective tissue diseases (CTD); to describe their clinical and serological features, to identify factors indicating evolution to SLE.
Methods: A case-control study, based on retrospective evaluation of clinical files. The cases were ANA positive individuals (n = 50) examined in a medical outpatient setting, for symptoms compatible with SLE, but not fulfilling SLE classification criteria. Two patients with SLE were matched to each case in terms of age at initial symptom onset and sex. Thyroid autoimmunity was assessed by detecting antithyroid antibodies. Fisher's exact test and conditional logistic regression were used to evaluate the predictive ability of initial findings for SLE development.
Results: ANA positive individuals suspected of having a CTD present a wide variety of symptoms and findings, usually at the 4th to 5th decade of life. Antibodies to Sm and U1RNP were absent; anti-Ro(SSA) and anti-La(SSB) occurred in 6%, while anti-dsDNA occurred in less than 10% of the cases. Arthritis, butterfly and discoid rash, Raynaud's phenomenon, and anti-Ro/SSA antibodies are the initial findings indicating evolution to SLE. Hematological abnormalities such as leukopenia and thrombocytopenia as well as constitutional symptoms such as easy fatigue and arthralgias are not associated with evolution to SLE. Antithyroid antibodies were detected in 16% of the cases and 2.3% of controls.
Conclusion: ANA may connote a form of systemic autoimmunity that is expressed as a wide variety of complaints, even in the absence of a definite diagnosis of CTD. Arthritis, rash, Raynaud's phenomenon, and anti-Ro/SSA antibodies indicate evolution to SLE. Autoimmune thyroid disease occurs in ANA positive individuals not fulfilling SLE classification criteria rather than in patients with SLE.