Bioelectrical impedance analysis and other hydration parameters as risk factors for delirium in rural nursing home residents

Background: The study investigators conducted a vigorous screening protocol for delirium in rural long-term care (LTC) facilities for a period of 28 days focusing on Bioelectrical Impedance Analysis (BIA) and other hydration parameters as risk factors.

Methods: A two-stage cluster sampling procedure was used to randomly select participants (n = 313) from 13 LTC facilities located in southeastern Iowa, stratified on facility bed size. BIA was used to estimate intracellular water (ICW), extracellular water (ECW), and total body water (TBW) on four occasions--baseline and follow-up days 7, 14, and 28. Volume estimates were calculated as a percent of body weight (%WT). Serum electrolytes and hematology were also measured. Delirium was measured with four strict criteria: a NEECHAM Confusion Scale score < 25, Vigilance "A" score > 2, a Mini-Mental Status Examination < baseline, and a positive Confusion Assessment Method score.

Results: There were n = 69 delirium cases (22.0%). Blood urea nitrogen/creatinine ratios greater than 21:1 (odds ratio = 1.76, 95% confidence interval 1.02-3.06). No significant risk for delirium was associated with ICW, ECW, or TBW as a percent of body weight.

Conclusions: Some changes were observed with a slight decrease in ICW between day 7 and day 14 of follow-up that tended to follow an increase in delirium events, but in general the BIA measures did not predict delirium events.