Prevalence and incidence of psoriatic arthritis: A systematic review and meta-analysis.

BACKGROUND: Psoriatic arthritis (PsA) is a specific form of inflammatory arthritis associated with psoriasis affecting in the same measure men and women but with a consistent geographic variability. Since the burden of PsA frequency has important implications in the definition of the healthcare policies, it is important to measure the frequency of disease in the general population.

OBJECTIVE: To quantify the global health burden of PsA summarizing the data provided by the population-based available studies investigating prevalence and incidence of the disease.

METHODS: A MEDLINE search was performed to identify all studies reporting the prevalence or incidence of PsA. Fixed- and random-effect models were fitted to estimate the prevalence and incidence pooled estimates. Between-study heterogeneity was evaluated using the Q statistic and the I2 index and Publication bias using Egger's asymmetry test.

RESULTS: Twenty-eight studies were included in the meta-analysis, 17 retrieved from the literature search and 11 from the meta-analysis of Alamanos et al. The random effect pooled PsA prevalence and incidence rates are respectively 133 every 100,000 subjects (95% CI, 107-164 every 100,000 subjects) and 83 every 100,000 PY (95% CI, 41-167 every 100,000 PY). High between-study heterogeneity was found for both prevalence and incidence estimates.

CONCLUSIONS: This study allowed the estimation of a global average prevalence and incidence rates of PsA and the evaluation of the geographic variability. The high between-study heterogeneity suggests the importance to look not only at the pooled estimates but also at the study-specific estimate.