The Norton scale is an independent prognostic marker for mortality in critically ill patients

Abstract

The Norton scale (NS) is a widely used instrument to estimate the risk for pressure ulcers in adult, hospitalized patients. Lower NS scores, with the cut-off less than 15, indicate higher risk for pressure ulcer development. The NS assesses 5 domains: mental condition, physical condition, mobility, activity in daily living and incontinence. However, its discriminatory power to predict pressure ulcers is rather low. Since the NS reflects the patients' daily functioning it might be an independent risk factor of outcome of patients in the Intensive Care Unit (ICU), apart from the severity of acute critical illness scores. We therefore performed a single center retrospective study in critically ill patients who were admitted to a tertiary intensive care unit in 2021. NS scores and patients' characteristics and outcomes were collected from computerized databases. The primary outcome was 90-day mortality. Of the 2271 patients who were admitted to the ICU in 2021, 1889 patients were included, of which the NS was measured upon admission (83%). In this cohort, the mean age was 64 years, the Apache III score 59 and the Charlson Comorbidity index 4.4. Increased risk for pressure ulcers (NS <= 14) was detected in 9.7% of patients. Patients with a NS <= 14 were older, more severely ill upon admission and had more comorbidities. The 90-day mortality was 32% in the NS <= 14 group and 11.6% in the NS of more than 14 group (p<0.0001). A reduction in one point in the NS score was inversely associated with a relative increase in mortality by 13%. Furthermore, when corrected for disease severity and comorbidity, NS <= 14 was still independently associated with lower survival (OR 0.47 (0,32-0,70). NS may be an independent prognostic marker for mortality in critically ill patients and could be used in prognostication for critically ill patients. These findings need to be confirmed in prospective, multicentric observational studies.