Objective: To perform a systematic literature review on the diagnostic and predictive value of conventional radiographs (CR) in patients with undifferentiated arthritis (UA).
Methods: We performed an extended search using Medline, Embase, the Cochrane Library, and abstracts from the 2007 and 2008 meetings of the American College of Rheumatology and the European League Against Rheumatism. Articles were included based on predefined inclusion criteria, and quality was assessed by using validated quality scales.
Results: In total, 25 articles were included from 6003 retrieved references. Five articles described a pure UA population, 20 articles described a mixed population [mostly rheumatoid arthritis (RA) and UA]. In studies on UA, erosions on CR were strong predictors of RA diagnosis [positive likelihood ratio (LR+) 3.5-10.9; odds ratio 7.6 and 8.7). In a more heterogeneous mixed population, 20 studies reporting on 11 cohorts found a relationship between CR findings and subsequent diagnosis of RA. LR+ for erosions and/or bony decalcifications ranged from 1.8 to 9.7, and there was greater prevalence of erosions and higher Sharp-van der Heijde score in the RA group at followup. With regard to prognosis in both UA and mixed populations, an association was found between number of abnormalities on CR and poor outcome.
Conclusion: Several studies, in pure UA and mixed populations, clearly demonstrate that CR are helpful in predicting future diagnosis of RA or worse prognosis. However, absence of abnormalities on CR does not sufficiently exclude RA or other unfavorable outcome.