Diagnostic and Prognostic Value of Genetics in Undifferentiated Peripheral Inflammatory Arthritis: A Systematic Review

Objective. To evaluate the diagnostic and prognostic utility of genetic testing in undifferentiated peripheral inflammatory arthritis (UPIA). Methods. A systematic literature search was performed in Medline. Embase, the Cochrane Library, and abstracts presented at the 2007 and 2008 meetings of the American College of Rheumatology and the European League Against Rheumatism. The target studies were those evaluating diagnostic or prognostic value of genetic markers specifically in UPIA. Two reviewers independently screened titles and abstracts and reviewed included articles in detail. All data were collected using ad hoc standard forms, permitting the calculation of positive and negative likelihood ratios of each genetic marker for diagnoses of different rheumatic diseases and for the development of relevant outcomes. Results. Of the 3109 articles retrieved, 26 original studies fulfilled criteria of the systematic review. The most frequent diagnosis tested was rheumatoid arthritis, followed by inflammatory polyarthritis, and spondyloarthropathies. The main prognostic outcome evaluated was development of erosions, followed by median Larsen score, remission, Health Assessment Questionnaire (HAQ) score, and persistent synovitis. In total, 122 genetic markers were tested. No genetic marker had a high likelihood ratio for the diagnosis of a specific rheumatic disease. The shared epitope was associated with poor prognosis (erosions, HAQ > 1, mortality, and persistent synovitis). Other genes did not predict outcome in undifferentiated arthritis. Other outcomes for persistent disease or disability were not studied in depth. Conclusion. In isolation, no studied genetic marker is very informative of a future diagnosis in patients with UPIA. The shared epitope has a slight association with poor prognosis of UPIA. (J Rheumatol 2011;38 Suppl 87:38-44; doi:10.3899/jrheum.101073)