To assess the incidence and prevalence of rheumatoid arthritis (RA) in Poland for the period 2013–2021, total and dependent on gender, age, region and serological status. Information on reported National Health Fund (NHF) health services and reimbursed prescriptions were used, defining an RA patient as a person who had at least two visits in different quarters with ICD-10 code M05 or M06 and at the same time filled at least one reimbursed prescription for a drug whose active substance is methotrexate, sulfasalazine, leflunomide or was treated with biologic disease-modifying anti-rheumatic drugs (bDMRDs) or targeted synthetic DMARDs (tsDMARDs) as part of a drug program financed by the National Health Fund. The nationwide standardised incidence rate of RA in 2021 was 29 persons per 100,000 population (18 per 100,000 population of seropositive vs. 11 per 100,000 population of seronegative RA). The prevalence of RA in Poland in 2021 was 689.0 people per 100,000 population, a total of 0.7% (1.1% in women and 0.3% in men). The incidence of seronegative RA was approximately 38%. The majority of new RA diagnoses were in the sixth and seventh decades of life, irrespective of patients’ gender. The results allow RA to be classified as a disease with a significant social impact. A trend of later onset of RA has been observed, which requires special consideration of the needs of patients over 55 years of age.

To estimate the actual incidence and prevalence of psoriatic arthritis (PsA) within a 9-year timeframe in Poland. Patients were defined as having PsA if they had at least two visits more than 90 days apart with ICD-10 codes M07.0, M07.1, M07.2, M07.3, or L40.5 and filled at least one reimbursed prescription for peripheral or axial PsA-specific treatments during this period (including methotrexate, sulfasalazine, ciclosporin, leflunomide, biologics, targeted synthetic drugs, or non-steroidal anti-inflammatory drugs). Data was obtained from the nationwide public payer database, considering gender, age, and region of residence. We observed an incidence rate of 1.1 per 100,000 inhabitants in 2021, compared to 13.2 in 2013. Regarding the age of the first diagnosis, the peak incidence rate decreased, with a more pronounced decline in men. The prevalence of PsA rose from 72.5 individuals per 100,000 in 2013 to 95.5 in 2021, representing approximately 0.1% of the total population in Poland, with a significant predominance of women among patients over 55 years of age. The decline in PsA incidence may be influenced by a strict case definition and improved access to treatment. Higher prevalence in older women suggests potential gender-related differences. The lower peak incidence and younger diagnosis age in men raise questions about whether lower PsA prevalence in older males is linked to higher mortality due to longer disease duration and comorbidities. Further research is needed to clarify these findings.

Multiple sclerosis (MS) is most often diagnosed in women of childbearing age. Therefore, it is important to examine the impact of pregnancy on the course of MS and to enable patients to make decisions about motherhood based on reliable data. The main objective of this study was to assess the impact of pregnancy on the course of MS by comparing the frequency of MS-related hospitalizations during pregnancy and 40 weeks postpartum versus 40 weeks before pregnancy. We used administrative health claims to identify female patients with MS, their deliveries, and their MS-related hospital admissions and calculated the frequency of MS-related hospital admissions before, during, and after pregnancy. We observed that MS is diagnosed approximately three times less often during pregnancy than before or after pregnancy. The number of MS-related hospital admissions decreased during pregnancy, especially in the third trimester. In contrast with other studies, we did not observe an increased level of MS-related admissions postpartum. The number of hospitalizations reported with steroid injections and emergency department visits also decreased during pregnancy. Our results show that pregnancy has a protective effect on the course of MS.

Background: Nationwide epidemiologic data on comorbidity burden in early rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are limited. We compared coded diagnoses for concurrent disorders in incident RA and PsA based on administrative healthcare data (AHC). Methods: This retrospective cohort study used AHCs from the National Health Fund between 2009 and 2021. Using composite proxy definitions for RA and PsA diagnosis (combination of ICD-10 codes and prescription data), we identified all new cases of RA and PsA between 2019 and 2021. We utilized a ten-year lookback window for the accrual of concurrent disorder claims. Age-, sex-, serostatus- and calendar year-adjusted models were considered. Crude, relative and adjusted prevalence estimates were calculated using generalized linear models. Results: Using NHF data, we identified 36,285 and 1603 patients with incident RA/PsA, respectively. We estimated the burden of 31 multisystem comorbidities. Most disorders (N = 23, 74.2%) were more frequently coded among RA patients, while only liver diseases were significantly more prevalent in PsA. Chronic back pain (+21.2 pp) and osteoarthritis (+18.3 pp) were tied to the greatest absolute differences, likely mirroring medical contact patterns throughout the differential diagnostic process. Hospitalization due to heart failure and stroke, but not myocardial infarction, was more common in RA vs. PsA. Conclusions: Newly diagnosed patients with RA and PsA show distinct patterns of healthcare utilization for multiple organ disorders. Early RA may be tied to higher comorbidity rates not fully explained by age and sex, as compared to PsA; further studies are necessary to clarify these observations.