“…The method of assessing fluid intake or hydration status was judged low risk of bias in 4 studies, 14,20,22,25 high risk in 16, 10e13,15e19,21,23,24,26,28,32,33 and unclear in 3. 29e31 Of 4 studies judged low risk, 2 assessed serum osmolality, 20,22 1 used International Classification of Diseases, Ninth Revision (ICD-9) codes only, 25 and 1 measured all fluid intake over 24 hours using referenced methodology with good interrater reliability (r ¼ 0.98).…”