Preoperative dehydration is a well-known predictor of in-hospital complications and poor functional outcomes in older patients with hip fractures. In an orthopedic and geriatric cooperative setting, we aimed to investigate whether preoperative dehydration was associated with frailty, prolonged hospital stays and short-term mortality in older patients with hip fractures.

This retrospective cohort study was conducted in a Danish university hospital. The study population consisted of patients 65+ years surgically treated for hip fracture. Dehydration was defined as serum calculated osmolarity above 295 mmol/L. Outcomes were frailty at discharge measured by the Multidimensional Prognostic Index, hospital stay of 7 days or more and 90-day mortality.

In total, 214 patients were consecutively included in the study from March 11, 2018, to August 31, 2020. The mean age was 81.2 (SD: 7.6) and 69% of the patients were women. The prevalence of preoperative dehydration was 40%. It was associated with severe frailty (Odds Ratio (OR): 2.08 [95% confidence interval (CI): 1.11-3.90]; p=0.02) and prolonged hospital stay (OR: 2.28 [95% CI: 1.29-4.04]; p=0.02). Seven percent died when dehydrated compared to 5% in the non-dehydrated (p=0.91).

Prevalence of preoperative dehydration is high among older patients with hip fractures and is associated with severe frailty and length of hospital stay. Systematic screening for dehydration on admission is advisable and may contribute to more adequate fluid management in the perioperative phase.