NRS-2002 components, nutritional score and severity of disease score, and their association with hospital length of stay and mortality


Malnutrition is a substantial issue in hospitals, leading to prolonged length of hospital stay, increased perioperative morbidity and increased mortality. There are several validated screening tools for malnutrition, one of which is the Nutritional Risk Screening 2002 (NRS). It screens patients based on recent weight loss, reduction of recent food intake, body mass index (BMI), severity of disease and age. Higher NRS scores have been shown to be negatively associated with patients’ outcomes such as increased morbidity and mortality.

The aim of the study was to evaluate how the two NRS components Nutritional Score (NS) and Severity of Disease Score (SDS) are associated with patients’ length of hospital stay and mortality.

All patients admitted to the medical department of a large community hospital in Switzerland were screened for malnutrition using the nutrition screening NRS during the years 2014 to 2017. Data on patients’ NRS, primary diagnosis, number of secondary diagnoses, mortality, length of stay (LOS), discharge, sex and age were collected. The association between the NRS components and LOS/mortality was estimated using a linear mixed-effects regression model and a logistic regression model, respectively, with adjustment for confounders (age, sex, comorbidity, diagnosis group, mode of discharge and year of hospitalisation).

The evaluation of the outcomes of 21,855 hospitalisations demonstrated that the NS was associated with an increment in the LOS of 5.5–12.3% per score point, depending on the diagnosis group. An increase in the SDS by one point was associated with an increase in the LOS of 2.2–11.3%. The odds for all-cause in-hospital mortality were increased by 44.1% (95% confidence interval [CI] 33.7–55.2%) per point in the NS, and by 73% (95% CI 57.5–90.1%) per point in the SDS.

Increases in both components of the NRS are associated with longer LOS. The NS has a slightly stronger impact on LOS compared to the SDS and its effect is dependent on the patient’s diagnosis group. Increases in the SDS are linked to a higher mortality than increases in the NS.

Introduction Background

Malnutrition and patients at risk for malnutrition are a considerable issue in hospitals with a prevalence ranging from 20% to 60% at the time of hospital admission, depending on the investigated population and diagnostic tools used . Until 2019 there existed no international consensus on the exact definition and diagnosis of malnutrition. It is now agreed that the diagnosis requires either unintentional weight loss, low body mass index (BMI), or reduced muscle mass by either reduced food intake/assimilation or disease burden [9].
Malnutrition can be categorised into three major groups: disease-related malnutrition with inflammation by acute or chronic disease; disease-related malnutrition without inflammation; and malnutrition without disease, resulting from starvation or psychological factors [10].
Malnutrition negatively affects patients by decreasing quality of life, prolonging length of hospital stay (LOS), causing functional impairment [11] and increasing the incidence of comorbidities such as nosocomial infections [12] and mortality. In addition, malnutrition-related effects are an economic burden in the diagnosis-related group healthcare system [13], if malnutrition is not identified and subsequently treated [14]. This further highlights the need for early and consistent screening, diagnosis and treatment of patients at risk or already manifesting malnutrition, and an understanding of the tools used for identifying malnutrition.
In the hospital setting, one of the validated tools used to screen patients at risk for malnutrition is the Nutritional Risk Screening 2002 (NRS) [15]. The NRS screens the nutritional status, the severity of disease and the age of the patient. The nutritional status is based on nutrition-related information acquired from patient interviews and/or the patient’s weight or body mass index (BMI). The scoring system for severity of disease was created on the basis of how well patients’ outcomes with certain diagnoses improved as a response to meeting daily caloric and protein requirements with nutritional support. It has been established that a higher NRS score is strongly associated with longer LOS [16], increased number of complications [6], higher morbidity, increased mortality and increased hospital costs [61619].
However, as the NRS encompasses a patient’s severity of disease, it might be challenging to determine to what degree the disease itself, regardless of the patient’s nutritional state, is responsible for the above-mentioned association between NRS scores and LOS. The NRS has been well validated, but only a few studies have analysed its two components, namely the Nutrition Score (NS) and the Severity of Disease Score (SDS), separately in relation to LOS and/or clinical outcome.

The aim of this study was to evaluate how the two NRS components, the NS and the SDS, are associated with a patient’s LOS across different diagnosis groups. As a secondary endpoint, we assessed how the all-cause in-hospital mortality was associated with the NRS.

Patients and methods 

Patient data were collected from the hospital records and made anonymous by the hospital patient data management. All patients aged ≥18 years admitted to the department of general internal medicine of the Kantonsspital Winterthur in Switzerland during the years 2014–2017 were eligible for inclusion in the study. Kantonsspital Winterthur is a large community hospital covering urban as well as rural regions. Patients who were admitted to day-care units, underwent elective procedures or did not stay in hospital for more than one day were excluded. Patients who were discharged against a doctor’s recommendation or transferred to another institution were also excluded.