Zinc Depletion Increases Readmission in Older Patients: An Example of Interactions Between Nutrition and Disease

Abstract

Abstract. Background: ill health may lead to poor nutrition and poor nutrition to ill health, so identifying priorities for management still remains a challenge. The aim of this report is to present data on the impact of plasma zinc (Zn) depletion on important health outcomes after adjusting for other poor prognostic indicators in hospitalised patients. Methods: Hospitalised acutely ill older patients who were part of a large randomised controlled trial had their nutritional status assessed using anthropometric, hematological and biochemical data. Plasma Zn concentrations were measured at baseline, 6 weeks and at 6 months using inductively- coupled plasma spectroscopy method. Other clinical outcome measures of health were also measured. Results: A total of 345 patients assessed at baseline, 133 at 6 weeks and 163 at 6 months. At baseline 254 (74%) patients had a plasma Zn concentration below 10.71 μmol/L indicating biochemical depletion. The figures at 6 weeks and 6 months were 86 (65%) and 114 (70%) patients respectively. After adjusting for age, co-morbidity, nutritional status and tissue inflammation measured using CRP, only muscle mass and serum albumin showed significant and independent effects on plasma Zn concentrations. The risk of non-elective readmission in the 6-months follow up period was significantly lower in patients with normal Zn concentrations compared with those diagnosed with Zn depletion (adjusted hazard ratio 0.62 (95% CI: 0.38 to 0.99), p = 0.047. Conclusions: Zn depletion is common and associated with increased risk of readmission in acutely-ill older patients, however, the influence of underlying comorbidity on these results can not excluded.