Organ involvement in newly diagnosed sarcoidosis patients in the Netherlands: The first large European multicentre prospective study.

Background: Clinical presentation and prevalence of organ involvement is highly variable in sarcoidosis and depends on ethnic, genetic and geographical factors. These data are not extensively studied in a Dutch population.

Aim: To determine the prevalence of organ involvement and the indication for systemic immunosuppressive therapy in newly diagnosed sarcoidosis patients in the Netherlands.

Methods: Two large Dutch teaching hospitals participated in this prospective cohort study. All adult patients with newly diagnosed sarcoidosis were prospectively included and a standardized work-up was performed. Organ involvement was defined using the WASOG instrument.

Results: Between 2015 and 2020, a total of 330 patients were included, 55% were male, mean age was 46 (SD 14) years. Most of them were white (76%). Pulmonary involvement including thoracic lymph node enlargement was present in 316 patients (96%). Pulmonary parenchymal disease was present in 156 patients (47%). Ten patients (3%) had radiological signs of pulmonary fibrosis. Cutaneous sarcoidosis was present in 74 patients (23%). Routine ophthalmological screening revealed uveitis in 29 patients (12%, n = 256)). Cardiac and neurosarcoidosis were diagnosed in respectively five (2%) and six patients (2%). Renal involvement was observed in 11 (3%) patients. Hypercalcaemia and hypercalciuria were observed in 29 (10%) and 48 (26%, n = 182) patients, respectively. Hepatic involvement was found in 6 patients (2%). In 30% of the patients, systemic immunosuppressive treatment was started at diagnosis.

Conclusions: High-risk organ involvement in sarcoidosis is uncommon at diagnosis. Indication for systemic immunosuppressive therapy was present in a minority of patients.