SPECIAL ARTICLENutritional risk screening (NRS 2002): a new method based on an analysis of controlled clinical trials
Introduction
Undernutrition is common in hospitals and one study showed that among the 40% of the patients, who were undernourished at admission, about 75% lost further weight during hospitalization (1). The deterioration of nutritional status is probably linked to several factors concerning food supply, apart from the disease process itself 2., 3.. However, the lack of a widely accepted screening system which will detect patients who might benefit clinically from nutritional support may be considered a major factor. A survey among doctors and nurses in Danish hospitals showed that the lack of a proper screening tool was seen as one of the major reasons for not initiating nutritional support (4).
Up to the present, the available screening systems, however, have not been validated with respect to clinical outcome, as also stated recently by the ASPEN board of directors (5). They also suggested that, in the absence of an outcomes validated approach, a combination of clinical and biochemical parameters should be used to assess the presence of malnutrition. They suggest to use the subjective global assessment, SGA (6), which classifies patients subjectively on the basis of data obtained from history and physical examination, since this system has been validated in several ways other than with respect to clinical outcome. On the other hand, a number of randomized controlled trials (RCTs) have been carried out to investigate the clinical effect of nutritional support, and some of these have shown a positive effect, while others have not. In most of these studies, some measure of nutritional status was used as a criterion for inclusion, stratification or description, but commonly used screening systems were seldom used as inclusion criteria 7., 8..
We therefore attempted to establish a screening system2 using a retrospective analysis of controlled trials and the nutritional criteria or characteristics and clinical outcome in these studies. The system was developed on the assumption that the indications for nutritional support are the severity of undernutrition and the increase in nutritional requirements, resulting from the disease, i.e. that severe undernutrition or severe disease by themselves or in varying combinations may indicate the need for nutritional support. This will also include patients who are not undernourished at the time but are at risk of becoming so because of disease and/or its treatment, e.g. major trauma, surgery or chemotherapy, since both may cause impairment of food intake and increased stress-metabolism. The concept of relating nutritional status to severity of disease is well-recognized, as displayed for example in the decision box (2), which emphasizes the need for acting on possible further impairment of nutritional status during the clinical course of the disease. These concepts are illustrated both by the study of Bastow et al. (9) in elderly women with fractured neck of femur, which showed that nutritional support was effective only in those who were particularly undernourished, but not in those who were less undernourished, and the study by Müller et al. (10) which showed that the positive effect of preoperative nutritional support disappeared when the surgical technique was changed from a transthoracic procedure to a less invasive stapling procedure.
Our screening system which was designed to include measures of current potential undernutrition as well as disease severity was then validated against all controlled trials of nutritional support known to us, in order to evaluate whether it was capable of distinguishing those with a positive clinical outcome from those that showed no benefit from nutritional support. The analysis and the recommendations were reviewed and discussed with an ESPEN ad hoc working group under the auspices of the ESPEN Educational Committee.
Section snippets
Screening system
Table 1 shows the screening system, developed as explained in detail in the appendix. Patients are scored in each of the two components (1) undernutrition and (2) disease severity, according to whether they are absent, mild, moderate or severe, giving a total score 0–6. Patients with a total score of ≥3 are classified as nutritionally at-risk. Undernutrition was estimated using three variables used in most screening tools: BMI, percent recent weight loss and change in food intake, since these
Results
A total of 128 studies containing a total of 8944 patients were analyzed. Table 2 shows the categorization of studies, outcome variables, patient categories and mode of feeding. Only one study was in category 0 with respect to severity of disease (126) and only one study was in category 3 with respect to undernutrition (134), and therefore these categories are not shown in the table. Some studies, using predominantly parenteral nutrition, showed a negative effect on outcome: more major
Discussion
The screening system was developed on the basis of intervention studies that were illustrative of the overall concept. However, dietary history was included among the variables defining undernutrition with the same weight as the other variables, despite the fact that only few studies used dietary history as part of the initial characterization of the patients. Also, the definition of the categories of inadequate intake as mild, moderate, or severe was estimated due to lack of accurate
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- 1
Members of the ad hoc working group under the auspices of the ESPEN Educational Committee: Maria Camilo, Lisbon, Portugal; Rosemary Richardson, Edinburgh, UK; Marinos Elia, Southampton, UK; Simon Allison, Nottingham, UK; Remy Meier, Liestal, Switzerland; Mathias Plauth, Dessau, Germany. 2By our definitions, a screening system is a rapid identification of patients who require nutritional support, carried out by the admitting staff and organized by the ward staff. A nutritional assessment is performed by a nutrition expert in the few patients who may have particular metabolic or nutritional problems and may require special feeding techniques.