Hypophosphataemia in old patients is associated with the refeeding syndrome and reduced survival

Objectives. Previous studies found that hypophosphataemia (HP) a common finding in hospitalised patients associated with unfavourable outcome, but they did not focus on old patients. The aim of the current study was to determine the prevalence, associated risk factors and potential clinical consequences of HP detected during hospitalisation in a geriatric medical centre. Design. Case-control study. Setting. A total of 312-bed geriatric division. Subjects. We compared 325 patients aged >= 65 years with at least one episode of HP-group defined by serum phosphate <= 0.77 mmol L-1 with 326 patients without HP (non-HP group). Measurements. Evaluation included baseline anamnesis, demographic and laboratory data. Patients in both groups were followed up to 2.7 years and clinical outcome recorded included length of hospitalisation, in-hospital and long-term survival. Results. About 14.1% of 2307 elderly had HP. Patients in the HP-group compared with the non-HP group had significantly more weight loss, lower albumin levels, more sepsis and received threefold more glucose-containing infusions and twofold more food supplementations (P < 0.0001). HP was detected on average on the 10.9 +/- 21.5 days of hospitalisation. Patients in the HP-group compared with the non-HP group, had significantly longer hospitalisation period (P < 0.0001) and reduced long-term survival (P = 0.003) with threefold increased mortality rates. In a multivariate analysis, HP was not found to be an independent predictor of mortality. Conclusions. The HP was common among old hospitalised patients. Clinical characteristics of the HP-group, the time-course and strong association with glucose and food supplementation, are compatible with the refeeding syndrome, described previously in malnourished patients. HP was associated with significantly reduced survival.