Impact of hypophosphatemia on outcome of patients in intensive care unit: a retrospective cohort study

BackgroundHypophosphatemia generally occurs in Intensive Care Units (ICUs), but its impact is often ignored. The aim of this study was to investigate whether hypophosphatemia can be a risk factor for ICU 28-day mortality.MethodsA single-center retrospective cohort study was conducted by collecting data from 1073 patients admitted to general ICU and then presented to the Sixth Affiliated Hospital, Sun Yat-sen University (Guangzhou City, Guangdong Province, China) from 1 January 2016 to 31 December 2017. The patients were divided into a normal control group (serum phosphate levels 0.80-1.60mmol/L) and a hypophosphatemia group (serum phosphate levels <0.80mmol/L), based on the concentration of phosphorus at the time of ICU admission. The association between phosphate levels and ICU 28-day mortality was evaluated by binary logistic regression analysis. Multivariate logistic regression was employed to predict the ICU 28-day mortality.ResultsThe cohort included 946 patients with a median phosphate concentration of 0.77mmol/L (interquartile range 0.55-1.03mmol/L). Patients with hypophosphatemia had a higher ICU 28-day mortality than the normal control group (33.3% vs 24.0%, P<0.05). Patients with hypophosphatemia had a longer ICU and hospital stays, and prolonged duration of mechanical ventilation (all P<0.05). Hypophosphatemia was an independent risk factor for ICU 28-day mortality (adjusted OR=1.5, 95% CI=1.1-2.1, P=0.01) in the multivariate logistic regression analysis.ConclusionsHypophosphatemia at admission is an independent risk factor for 28-day mortality in general ICU patients.Trial registrationThe medical study was approved by the Institutional Ethics Committee of the Six Affiliated Hospital, Sun Yat-sen University (Approval number: 2017ZSLYEC-110). No consent was given as the data were analyzed anonymously.