Guidelines for immunologic laboratory testing in the rheumatic diseases: anti-DNA antibody tests.

Introduction This paper is part of a series on immunologic testing guidelines. The series introduction (1) outlines the full methodology for obtaining data, grading the literature, combining the information from multiple sources, and developing recommendations. Briefly, MEDLINE and Healthstar were searched using a variety of search terms, and all relevant available literature was reviewed. All papers were critically reviewed using published standards for studies of diagnostic tests. Test use was categorized as primarily diagnostic or prognostic (which also included monitoring). Information was extracted from each paper to allow for calculation of a weighted average for sensitivity and specificity; likelihood ratios (LRs) were then derived from these values (positive LR sensitivity/[1 specificity]; negative LR [1 sensitivity]/specificity). Recommendations for use of tests were based on the LRs, where a test was considered to be “very useful” for a given disease if the weighted average positive LR was 5 or negative LR was 0.2. A test was considered “useful” if the weighted average positive LR was 2 and 5 or negative LR was 0.2 and 0.5. A test was considered “not useful” if the positive LR was 2 or the negative LR was 0.5. Antibodies capable of binding double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), Z-DNA, and various other proteins associated with DNA (e.g., histones) can be detected in the serum of patients with systemic lupus erythematosus (SLE). In this analysis, the term antiDNA antibody will refer only to antibodies specific for dsDNA (also referred to as native DNA). A number of studies have shown that antibodies to ssDNA (also referred to as denatured DNA) are less specific for the diagnosis of SLE than anti-dsDNA antibodies. While anti-ssDNA antibodies may be a useful research tool, they are an infrequently used clinical test, and will not be addressed further in this analysis.