Submitted: February 15, 2013 Posted: March 16, 2013

Transcription

1 1 Submitted: February 15, 2013 Posted: March 16, 2013 TITLE: The results of the validation process of a Modified SGA (Subjective Global Assessment) Nutrition Assessment and Risk Level Tool designed by the Clinical Nutrition Service of St. Luke s Medical Center, a tertiary care hospital in the Philippines AUTHORS: Lacuesta- Corro, Leia MD (1,2) Paguia, Grace MD (1,2) Navarette, Donnabelle RND (2) Llido, Luisito MD (1,2) INSTITUTION WHERE RESEARCH WAS PERFORMED: 1) Clinical Nutrition Fellowship Training Program, St. Luke s Medical Center, Quezon City, Philippines 2) Clinical Nutrition Service, St. Luke s Medical Center, Quezon City, Philippines ABSTRACT: Background: There is a need to validate the modified SGA nutritional assessment form designed by PhilSPEN for use in the clinical nutrition process. Methodology: The form was subjected to sensitivity and specificity tests which also include the positive and negative predictive values as well as the diagnostic accuracy. ROC (Receiver Operating Characteristic) curves were also created to show the visual quality of the diagnostic tool. Results: Sensitivity = 94.7% Specificity = 95.2% Positive Predictive Value = 95.7% Negative Predictive Value = 94.1% Diagnostic Accuracy = 95% Conclusion: The modified SGA nutrition assessment and risk level tool (form) is shown by the validation tests to be an acceptable for performing nutrition assessment and risk level determination.

2 2 INTRODUCTION Nutrition assessment is the process where a patient, who is identified to be nutritionally at risk through the nutrition screening process [1,2] will undergo a more intensive body composition analysis in order to determine if he is malnourished or not and if malnourished if he is mild, moderate, or severely malnourished. [1-3] The degree of malnutrition has a major influence in outcome from an injury or traumatic event especially on the quality of management whether medical or surgical, thus there is a need to have a reliable and accurate tool for nutritional assessment in order to provide a more rational and adequate treatment for the patient. There is a lot of nutritional assessment tools available worldwide, but one of the most commonly used tool is the Subjective Global Assessment developed by Dr. Jeejeeboy and his team. [4] The St. Luke s Medical Center, a tertiary care hospital in the Philippines, has a nutrition program and one of its goals for achieving optimum standards of patient care is to develop its own simple to use, but validated, nutritional assessment tool for the nutritionally at risk patient. Through its partnership with the Philippine Society of Parenteral and Enteral Nutrition (PHILSPEN) [5-7] it adopted the modified- SGA form developed for use by both the society and the major institutions of care throughout the country (Philippines). The Clinical Nutrition Service of this institution decided to validate the modified- SGA form in order to have a nutritional assessment tool that can be used in this institution. This is the report on the result of the validation process. METHODOLOGY The modified SGA form (Figure 1) is filled up by members of the Clinical Nutrition Team of St. Luke s Medical Center, Quezon City, Philippines, with the final reference diagnosis of nutritional status determined by the senior members of the team. Since there is no gold standard as to the diagnosis of malnutrition it was decided to define the reference standard for malnutrition based on these criteria: a) the use of a formal SGA done by a member of the clinical nutrition team on the same patient, b) final diagnosis of malnutrition by an experienced member of the clinical nutrition service a senior consultant who has been the service for more than 10 years and c) diagnosis of malnutrition in a clinical nutrition service which has defined malnutrition in its overall context for the past 10 years. The forms were examined and evaluated by one senior clinical nutrition physician (Dr. L.O.L.) and two junior clinical nutrition physicians, Dr. L.L- C and Dr. G.P.). Table 1 also lists the criteria as to the consideration of the finding as False Positive and Negative. The combined assessments or diagnosis is considered the reference value as to whether the patient is malnourished or not.

3 3 Figure 1: The modified SGA form The validation process was done by the following procedures. The sensitivity and specificity of the modified- SGA form was determined using 2 x 2 tables. The tables contain the True Positive, True Negative, False Positive and False negative values. Receiver Operating Characteristic (ROC) curves were also created to show the strength of the sensitivity and specificity of the tool. Finally the Positive and Negative Predictive Values were also determined. The software used was the NCSS- PASS software designed by J. Hintze [8] and the explanations of the process were taken from the 4 th edition of Basic and Clinical Biostatistics. [9]

4 4 Table 1: SGA grade and malnutrition diagnosis criteria SGA grade criteria SGA C SGA A SGA B with +1 or +2 fat / muscle loss SGA B with no fat/muscle loss Malnutrition Diagnosis True positive for malnutrition (TP) True negative for malnutrition (TN) False negative (FN) False positive (FP) The SGA grades of the subjects were identified (A, B or C). Those with SGA grade C were designated as true positive for malnutrition risk. Those with SGA grade A were designated as true negative cases. Finally for those with SGA grade B, they were designated as false negative if with subcutaneous fat or muscle loss (+1/+2) as shown in Table 1. A false positive diagnosis was designated to those with SGA grade B without subcutaneous fat or muscle loss using the guide shown in Table 1. However, the final decision as to which category the patient belongs rests on the one doing the nutritional assessment. The ultimate decision in designating the patient as malnourished or not rests on the senior members of the clinical nutrition team who have either seen the patients assessed or have reviewed the accomplished forms this is the reference standard or diagnosis. Only patients with complete records and fully accomplished modified SGA forms were included in the study. RESULTS: A total of 179 subjects were included in the study. Table 2 shows the 2 x 2 tables and Table 3 shows the validation results of the modified- SGA form. Table 2 Malnutrition Modified SGA tool Yes No Total Positive for malnutrition TP = 90 FP = 4 94 Negative for malnutrition FN = 5 TN = Total Table 3: Validation Results Result Sensitivity = TP / (TP+FN) 94.7% Specificity = TN / (TN+FP) 95.2% Positive Predictive Value (PPV) = TP / (TP+FP) 95.7% Negative Predictive Value (NPV) = TN / (TN+FN) 94.1% Prevalence = (TP+FN) / Total N 53.1% Diagnostic accuracy = (TP+TN) / Total N 95%

5 5 Table 3 data also show high values indicative of the quality of the diagnostic capabilities of the form through its positive and negative predictive values and diagnostic accuracy. Figure 2 shows that the True Positive and True Negative curves were closest to the superior characteristics of a diagnostic test with the true negative result having a better quality compared to the true positive result [10] DISCUSSION It is shown by this validation process that the modified SGA tool is an effective tool in identifying the severely malnourished patient with a sensitivity of 94.7%, specificity of 95.2%, a positive predictive value of 95.7%, and a diagnostic accuracy of 95%. The ROC curves further show the value of the modified SGA form as a good diagnostic tool in the area of ruling in malnutrition which is the true positive curve and even better in ruling out malnutrition which is the true negative curve. Although the clinical nutrition service had to determine its own reference standard for the diagnosis of malnutrition, the use of the formal SGA and the expertise and experience of the clinical nutrition physicians deciding on the diagnosis of the presence or absence of malnutrition is considered adequate enough.

6 6 When this nutrition assessment tool was compared with the NRS 2002 (Nutrition Risk Screening year 2002) which was developed by the Denmark group of ESPEN [11] and the MUST (Malnutrition Universal Screening Tool) developed for Great Britain [12], in the area of sensitivity, sensitivity and positive predictive value, both were validated using the formal SGA designed by Jeejeeboy et al [4], the results are as follows: [13] Table 4 Nutrition assessment Tool Validating tool Sensitivity Specificity Positive Predictive Value NRS 2002 of ESPEN [11] SGA 74% 87 82% [13] MUST of BAPEN [12] SGA 72% 90 84% [13] Modified SGA of PhilSPEN SGA 94.7% 95.2% 95.7% Legend: NRS 2002 Nutrition Risk Screening tool published in year 2002 ESPEN European Society of Parenteral and Enteral Nutrition MUST Malnutrition Universal Screening Tool BAPEN British Association of Parenteral and Enteral Nutrition SGA Subjective Global Assessment PhilSPEN Philippine Society of Parenteral and Enteral Nutrition The modified SGA version of this institution came up with better results as to sensitivity, specificity, and positive predictive values compared to these two already accepted nutrition screening and assessment tools. [13] Since the report by Young et al [13] were on the utilization of NRS 2002 and MUST as nutrition screening tools, it stands to reason that the higher value or score of the PhilSPEN modified SGA tool is due to its design as a nutrition assessment tool thus providing a more in- depth analysis of the nutritional status of the patient. The validation process thus shows that the PhilSPEN modified SGA nutrition assessment and risk levelling tool is a good and acceptable tool for the diagnosis of the presence or absence of malnutrition and its attendant risks. However, the ability of the tool to define the level of nutrition risk status of the patient is still to be evaluated. CONCLUSION The modified SGA nutrition assessment tool is an acceptable tool for nutritional assessment for adult and elderly patients in the Philippines, whether out- patient or in- patient.

7 7 REFERENCES: 1. Pesce- Hammond K, Wessel J. Nutrition assessment and decision making. The ASPEN Nutrition Support Practice Manual 2 nd ed; Merritt R, editor- in- chief; A.S.P.E.N., Silver Spring, MD; 2005: How does clinical nutrition run? The value of implementing a clinical nutrition program and nutrition support team (NST) to address the problem of malnutrition in the hospitals of the Philippines. PhilSPEN Online Journal of Parenteral and Enteral Nutrition. Available at POJ_PositionPaper.html#NT_mechanics2. Accessed January30, A.S.P.E.N. Board of Directors and Task Force on Standards for Specialized Nutrition Support for Hospitalized Adult Patients. Standards for specialized nutrition support: Adult hospitalized patients. Nutr Clin Pract 2002; 17: Detsky AS, McLaughlin JR, Baker JP, et al. What is Subjective Global Assessment of nutritional status? J Parenter Enteral Nutr 1987; 11 (1): The history of clinical nutrition in the Philippines. The PHILSPEN website. Available at Accessed February 21, Ocampo R B, Camarse CM, Kadatuan Y, et al. Predicting post- operative complications based on surgical nutritional risk level using the SNRAF in colon cancer patients - a Chinese General Hospital & Medical Center experience. Phil J Surg Spec 2008; 63 (4): Also available at accessed February 26, Del Rosario DC, Inciong J, Sinamban R, Llido L. The effect of adequate energy and protein intake on morbidity and mortality in surgical patients nutritionally assessed as high risk and low risk: report from a tertiary care private hospital in the Philippines. PhilSPEN Online Journal of Parenteral and Enteral Nutrition. Available at Accessed March 1, NCSS software. Available at Accessed March 1, Dawson B, Trapp R. Basic and Clinical Biostatistics 4 th edition; McGraw- Hill 2004: Lang T, Secic M. How to report statistics in medicine 2 nd edition; American College of Physicians, Philadelphia 2005: NRS Velasco et al. Eur J Clin Nutr 2011; 65: MUST - Kyle UG et al. Clin Nutr 2006; 25: Young AM, Kidston S, Banks MD, Mudge AM, Isenring EA. Malnutrition screening tools: comparison against two validated nutrition assessment methods in older medical inpatients. 1 Nutrition 2013; 29(1):