Page 40 - Recognizing axial spondyloarthritis - Janneke de Winter

CHAPTER THREE
dactylitis) and/or extra-articular (uveitis, IBD, psoriasis) disease. In AS, previous studies reported an arthritis prevalence of 18-58% (9,11,25–27), an enthesitis prevalence of 34-74% (9,25,26) and a dactylitis prevalence of 6-8% (9,26,28) (reported at any time during the disease course). Reported uveitis occurring at some point in time during the course of the disease varies from 22-37% (25– 27,29–31), IBD prevalence is estimated at 4-16% (27,30–34), and psoriasis prevalence at 4-9% (6,27,30,31,33,34).
In contrast, the prevalence of peripheral and extra-articular disease manifestations in nr-axSpA remains less well defined. Hypothesizing that AS and nr-axSpA reflect subsets of a single disease entity and have similar disease burden, we performed a meta-analysis of published studies of axial SpA in order to assess if the best available estimate of the prevalence of peripheral and extra- articular disease manifestations is similar in AS and nr-axSpA.
METHODS
We conducted a literature search by database searching, citation searching, ‘pearl growing’ (35) and reference list checking. We performed this systematic review and meta-analysis in accordance with the PRISMA guidelines (36).
Search methods
One of the authors (JdW) performed a systematic literature search with the assistance of an experienced librarian (RS). We used the following electronic bibliographical databases: Medline, the Cochrane Central Register of Controlled Trials (CENTRAL) and The Cochrane Library on October 1st 2015 (see supplemental Table 1 for participants, intervention, control and outcome (PICO) and search strategy). The search was performed without language restrictions. In order to retrieve additional references, we used Citation Pearl Growing (35). Furthermore, primary and secondary references from retrieved publications were manually checked to identify additional studies.
One review author (JdW) screened each title and abstract and selected potentially eligible studies. Thereafter, two review authors (JdW, LvM) independently selected eligible articles according to pre-determined selection criteria. If there was any doubt, the full text article was read by the review authors. Consensus of inclusion was in all cases achieved by discussion. If multiple publications presented data from the same study population, only the publication with the largest sample size was included. Reviews were only included if they presented original data.
Selection criteria for studies
Studies were included in this meta-analysis if data on prevalence of peripheral and extra-articular disease manifestations in both AS and nr-axSpA were available. We included both longitudinal as well as cross-sectional studies. Randomized controlled trials, as well as retrospective studies were not included to avoid
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