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However, a key criticism of observational studies is selection bias due to the inability to adjust for unobserved patient characteristics
Signs You Might Have a Vitamin B12 Deficiency Vitamin B12 plays a key role in many bodily functions, and a deficiency can show up in a variety of ways
Mov Disord Clin Pract 3:156160 Fanciulli A, Jordan J, Biaggioni I, Calandra-Buonaura G, Cheshire WP, Cortelli P, Eschlboeck S, Grassi G, Hilz MJ, Kaufmann H, Lahrmann H, Mancia G, Mayer G, Norcliffe-Kaufmann L, Pavy-Le Traon A, Raj SR, Robertson D, Rocha I, Struhal W, Thijs R, Tsioufis KP, van Dijk JG, Wenning GK (2018) Consensus statement on the definition of neurogenic supine hypertension in cardiovascular autonomic failure by the American Autonomic Society (AAS) and the European Federation of Autonomic Societies (EFAS): endorsed by the European Academy of Neurology (EAN) and the European Society of Hypertension (ESH)