Incidence and prevalence of psoriatic arthritis in Buenos Aires, Argentina: a 6-year health management organization-based study

Methods. Population: for incidence calculation, the population at risk was all adult members of the HIMCP, with continuous affiliation for at least 1 year from January 2000 to January 2006. Each person was followed until he/she voluntarily left the HIMCP, death or finalization of the study (final dates) contributing time at risk since January 2000 or enrolment date (whichever occurred later) to that final date. Case ascertainment: medical records of all patients with the problem psoriasis and/or PsA in the HIMCP problem-oriented computer-based patient record system, or registered in rheumatologists and/or dermatologists databases, were revised. Patients fulfilling CASPAR criteria were included. Statistical analysis: incidence rate (IR) was calculated with 95% CIs. Cumulative prevalence was estimated on 1 January 2006 (denominator population = 88 112). Results. In the study period, 138 288 persons contributed a total of 558 878 person-years, of whom 35 developed PsA (IR 6.26; 95% CI 4.2, 8.3 cases per 100 000 person-years). There were 12 females: IR 3.64 (95% CI 1.6, 5.7) cases per 100 000 person-years; and 23 males: IR 10.02 (95% CI 5.9, 14.1) cases per 100 000 person-years. On 1 January 2006, 65 prevalent cases were identified: prevalence 74 (95% CI 57, 94) cases per 100 000 members. Conclusions. The incidence and prevalence of PsA in this Latin American country was similar to that reported in other studies from Europe and the USA.