Incidence of seropositive rheumatoid arthritis in population-based studies in Northern Savo, Finland, during 1980-2020.

The objective is to evaluate the incidence of seropositive rheumatoid arthritis (RA) over 40-year period in Northern Savo, Finland. Data on new seropositive RA patients according to the American College of Rheumatology (ACR) 1987 classification criteria were collected in 2020-2021. In 2020 data on tobacco exposure, patient-reported dental health and living in residences with fluoridated tap water were gathered. Incidence rates were estimated and age- and gender-adjusted to Northern Savo population. The results were compared with data acquired in studies from 1980, 1990, 2000, and 2010. In 2020, 46 seropositive RA patients (21 females and 25 males) were recorded. The crude incidence of seropositive RA fulfilling the ACR 87 criteria in 2020 was 22.3 (95% CI 16.3 to 29.8)/100 000 and age and gender-adjusted 22.3 (95% CI 15.9 to 28.8)/100 000. Tobacco exposure > 5 pack years occurred 18% of females and 56% of males. Only 16% of males were full dentate. A total of 242 incident seropositive RA (age ≥ 16 years, 55% females) were identified in all study years. No differences in the gender-specific incidence rates in each cohort or in incidence between the studies every 10 years were recorded. The incidence of seropositive RA decreased in the age group < 55 years, p = 0.003. There was no change in the incidence of seropositive RA between genders or the study years. A declining trend for occurrence of seropositive RA in the young and early middle-aged population may reflect change in risk factors.

Transferrin receptor expression on reticulocytes as a marker of iron status in dialyzed patients.

BACKGROUND: Erythropoietin therapy should be accompanied by an adequate iron supply in order to avoid functional iron deficiency (FID) related to enhanced erythropoiesis. Therefore, accurate monitoring of the body's iron homeostasis is needed. This study was conducted to investigate whether transferrin receptor (TfR) expression on reticulocytes can reflect iron status in patients with chronic renal failure (CRF). METHODS: TfR expression [antibody binding capacity (ABC)] and the proportion of TfR positive reticulocytes (%TfR+ Ret) relative to all reticulocytes were measured by a quantitative flow cytometric method at baseline and at 3 weeks in 34 dialysis patients. Iron status (plasma ferritin and soluble TfR) and hemoglobin (Hb) with advanced cellular indices, such as the percentage of hypochromic reticulocytes (%HYPOr) and cellular Hb in reticulocytes (CHr), were also analyzed. RESULTS: Patients with FID had significantly higher TfR ABC and %TfR+ Ret compared with patients with replete iron status (p=0.034 and p=0.006, respectively). In patients whose Hb concentrations showed a reduction, the mean increase (3 weeks- baseline) in TfR ABC was four-fold higher and %TfR(+)Ret was three-fold higher when compared with patients whose Hb was stable or had increased. The changes in TfR expression correlated significantly with the changes in reticulocyte indices [CHr (negatively), %HYPOr (positively)] and plasma ferritin (negatively). CONCLUSIONS: Reticulocyte TfR expression reflected the changes in the Hb level and the iron availability at the cellular level, and therefore it might be useful in the assessment of iron status in patients with CRF.