Renal disease in sarcoidosis patients in a German multicentric retrospective cohort study.

INTRODUCTION: Sarcoidosis is a systemic granulomatous disease potentially affecting every organ system. Renal involvement is reportedly rare, and the evidence consists of case reports and cohort studies. Systematic investigations are scarce and show a varying prevalence ranging from <1% to 30-50%. METHODS: We retrospectively analyzed data from patients with a recent diagnosis of sarcoidosis from five tertiary care centers focusing on renal sarcoidosis. RESULTS: We analyzed data from 327 patients with sarcoidosis between 2001 and 2021. Of 327 patients, 109 (33.3%) had probable or definite renal sarcoidosis. 90 (27.5%) had histopathologic confirmation. 57 (64%) had an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2. The most prominent associated finding was an elevated soluble interleukin-2 receptor. Patients with renal sarcoidosis more frequently received glucocorticoids than other non-renal sarcoidosis patients (92% vs. 78%, p < 0.01). Also, azathioprine (38% vs. 16%, p < 0.001) and mycophenolate mofetil (5% vs. 1%, p < 0.05) were more frequently used in renal sarcoidosis compared to non-renal sarcoidosis, whereas methotrexate was used less frequently (7% vs. 17%, p < 0.05). CONCLUSIONS: Our data of the largest cohort with biopsy-confirmed renal sarcoidosis demonstrate a higher prevalence (27.5% of all patients) than previously published with a relevant disease burden. The urinary findings in most cases were only mildly abnormal, and some patients did not have renal biopsy despite abnormal urinary results. A renal workup should be performed in all patients with a new diagnosis of sarcoidosis.

The continuous measurement of anti-CCP-antibodies does not help to evaluate the disease activity in anti-CCP-antibody-positive patients with rheumatoid arthritis.

Anti-cyclic citrullinated peptide antibody (CCP-AB) are used for diagnosis of rheumatoid arthritis (RA). It is still unknown if the extent of CCP-AB levels is useful to assess the disease activity or the individual follow-up as an individual activity parameter. We investigated 40 patients with a known RA who were positive for CCP-AB. Correlation between disease activity (DAS 28) and the amount of levels of CCP-AB in all patients over time as well as the individual follow-up were analysed. A weak correlation between CCP-AB and DAS 28 [r = 0.19; p = 0.001] was found. The individual correlation between CCP-AB titre and DAS 28 ranged between r = -1 and r = 1, so a strong positive and also a strong negative correlation was seen in single patients. In patients with erosive RA the correlation was significantly more positive than in patients with non-erosive RA. Because the correlation between CCP-AB levels and parameters of disease activity measured by DAS 28 is very low, we conclude for monitoring the disease activity to use simply and established parameters like morning stiffness, HAQ or ESR. The individual follow-up of the levels of CCP-AB is by the moment not useful for monitoring the disease activity.