Can the use of a rapid nutrition screening tool facilitate timely dietetic referrals on the acute renal wards? : A validation study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics at Massey University, Albany, New Zealand
Background: The percentage of malnourished patients in the acute renal hospital wards
has been reported as 52.6% and associated with increased hospital stay and morbidity.
There are currently no published nutrition screening tools that are sensitive enough to
detect undernutrition risk in this patient group.
Aim: To develop and validate a rapid nutrition screening tool that is sensitive and
specific to recognise renal inpatients at undernutrition risk.
Method: The renal nutrition screening tool (R-NST) was modified from the malnutrition
screening tool (MST) that has been validated in the acute care setting. It includes the
traditional risk variables such as involuntary weight loss and reduction in food intake, as
well as biochemical measures to increase the effectiveness of recognising undernutrition
risk. It was designed in three simple, accumulative steps. The new R-NST was validated
using a prospective, blind comparison to a gold standard study design (N = 122). The
undernutrition risk of each participant identified by the research assistants using the RNST
was compared to the nutritional status independently assessed by the researchers
using the 7-point subjective global assessment (SGA) as a gold standard and hand grip
strength (HGS) as a functional indicator. The R-NST was autonomously undertaken by
nursing staff to determine its feasibility as a routine screening on ward level.
Results: The SGA and R-NST tools classified 63.9% and 68.0% of participants as
malnourished or at undernutrition risk, respectively. The R-NST was valid to detect
undernutrition risk (sensitivity = 97.3%, specificity = 74.4%, positive predictive value
(PPV) = 88.0%, negative predictive value (NPV) = 93.6%) compared to the SGA. The HGS
in malnourished participants were lower than those that are well nourished in either
women (p = 0.001) or participants aged under 65 years (p = 0.009). The R-NST showed
ability to recognise participants requiring dietetic intervention due to their renal
conditions. The compliance rate in the R-NST screening by the nursing staff was low
Conclusion: The R-NST is a good diagnostic tool for identifying acute renal patients at
undernutrition risk and facilitating timely dietetic referral. Further research is warranted
to explore innovative yet effective interventions to enhance nutrition screening
compliance in ward practice.