RESUMEN
STUDY OBJECTIVES: Serum ferritin levels are used to determine the need for iron supplementation in patients with RLS. The purpose of the study was to determine whether immunoassay measurement of serum ferritin yields varying levels according to different manufacturer assays, with resultant variation in cut off values. METHODS: We compared serum ferritin levels using 116 clinical samples assessed by the Beckman and Roche methods. RESULTS: While there was a high correlation between results obtained from the 2 methods (R2 = 0,99), the absolute values differed. The equivalent ferritin measures determined by Beckman, Roche were: 50 mcg/dL, 83 mcg/dL; 75 mcg/dL, 121 mcg/dL; 100 mcg/dL, 158 mcg/dL; and 300 mcg/dL, 457 mcg/dL. CONCLUSIONS: It is uncertain which assays were used to measure serum ferritin in the seminal studies on which current guidelines for iron therapy for RLS are based. In view of this uncertainty, as well as the limited data on which current recommendations are based, clinicians should be flexible in using recommended serum ferritin cut off values, also utilizing percentage transferrin saturation. Assuming that Beckman or equivalent assays were used, centers using the Roche method need to adjust the cut offs for administration of oral iron and intravenous iron recommended by current practice guidelines to avoid withholding treatment for RLS patients who might benefit from iron supplementation.
RESUMEN
Sleep patterns vary widely between individuals. We explore methods for identifying populations exhibiting similar sleep patterns in an automated fashion using polysomnography data. Our novel approach applies unsupervised machine learning algorithms to hypnodensities graphs generated by a pre-trained neural network. In a population of 100 subjects we identify two stable clusters whose characteristics we visualize graphically and through estimates of total sleep time. We also find that the hypnodensity representation of the sleep stages produces more robust clustering results than the same methods applied to traditional hypnograms.