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The scored patient-generated subjective global assessment is an effective nutrition assessment tool in subjects with chronic obstructive pulmonary disease
e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism 6 (2011) e27ee30
Contents lists available at ScienceDirect
e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism journal homepage: http://www.elsevier.com/locate/clnu
Original Article
The scored patient-generated subjective global assessment is an effective nutrition assessment tool in subjects with chronic obstructive pulmonary disease Judith Bauer a, *, Elizabeth Egan b, Alexandra Clavarino a a b
University of Queensland, Brisbane, Australia The Wesley Hospital, Brisbane, Australia
a r t i c l e i n f o
s u m m a r y
Article history: Received 25 January 2008 Accepted 28 October 2010
Background & Aims: To evaluate the scored patient-generated subjective global assessment (PG-SGA) as a nutrition assessment tool in subjects with chronic obstructive pulmonary disease. Methods: Seventy-two participants attending a pulmonary rehabilitation program (22M, 50F; mean age 66.6 8.6 y). Nutritional status was assessed using the scored PG-SGA e global categorisation and score; fat free mass index. Results: According to the subjective global assessment, 61 participants were well-nourished and 11 were moderately malnourished. Well-nourished participants had significantly lower PG-SGA scores (5.9 3.0 vs 12.1 5.4), higher % oxygen saturation (94.9 2.8 vs 93.6 2.4) and higher BMI (27.8 6.1 vs 19.5 3.2) than malnourished. There was a significant correlation between PG-SGA score and % oxygen saturation (r ¼ 0.275, p ¼ 0.026) and 6-min walking distance (r ¼ 0.245, p ¼ 0.044). The PG-SGA score had an 82% sensitivity and 79% specificity of predicting the global categorisation of nutritional status. Conclusions: The scored PG-SGA identifies malnutrition in participants with chronic obstructive pulmonary disease. The nutritional status of subjects attending pulmonary rehabilitation programs could be assessed and tracked with the scored PG-SGA. Ó 2010 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.
Keywords: Nutrition assessment Patient-generated subjective global assessment Chronic obstructive pulmonary disease
1. Introduction Malnutrition is common in patients with chronic obstructive pulmonary disease (COPD), with prevalence depending on the method of nutrition assessment, timing of the assessment and severity of disease.1e5 In COPD, malnutrition has been found to be associated with increased morbidity (increased dyspnoea, decreased exercise capacity, impaired quality of life) and mortality.2,4,6 As there is no gold standard for the assessment of nutritional status in patients with COPD, a variety of objective nutrition parameters (anthropometric, biochemical and immunological) have been used in the literature either alone or in combination to diagnose malnutrition. The use of single objective nutrition parameters to assess nutritional status has been questioned due to
* Corresponding author. Tel.: þ61 7 334 67703; fax: þ61 7 3365 6877. E-mail address: [email protected] (J. Bauer).
lack of sensitivity and specificity as many non-nutritional factors affect the results.7 The scored patient-generated subjective global assessment (PG-SGA) is a method of nutrition assessment developed by Ottery.8 In common with subjective global assessment,9 nutritional status is determined on the basis of a combination of a medical history (weight loss, oral intake, nutrition impact symptoms, functional capacity) and physical examination (loss of subcutaneous fat, muscle wasting, oedema), which are combined subjectively into the global categories of well nourished, moderately or suspected of being malnourished or severely malnourished. The scored PG-SGA provides additional information regarding shortterm weight loss, more extensive nutrition impact symptoms and a numerical score. It has been demonstrated to be a valid method of nutrition assessment in oncology, renal and stroke specialties as well as general patients in the acute care setting.10e15 The PG-SGA score correlates with objective nutrition parameters (% weight loss, BMI), quality of life, morbidity (survival, length of stay), has a high degree of inter-rater reproducibility and a high sensitivity and
1751-4991/$36.00 Ó 2010 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.eclnm.2010.10.003
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J. Bauer et al. / e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism 6 (2011) e27ee30
specificity when compared with other validated nutrition assessment tools.10e15 The aim of this study was to assess the validity of the scored PG-SGA as a nutrition assessment tool in participants attending a pulmonary rehabilitation program.
Table 1 Participant characteristics (n ¼ 72).
2. Materials and methods Subjects with COPD were recruited at the first session of a sixweek pulmonary rehabilitation program over an 18-month period. The inclusion criteria for this group were as follows: age > 18 years, moderate to severe COPD based on Forced Expiratory Volume (FEV1) < 60%, cognitive function and ability to communicate adequately to provide informed consent and understand and respond to questions. Seventy-seven subjects enrolled in the pulmonary rehabilitation program and seventy-two participants participated in this study. Nutritional status was assessed by a dietitian experienced at using the scored PG-SGA. A global rating of nutritional status (well nourished, suspected or moderately malnourished or severely malnourished) and an overall PG-SGA score was calculated. Body weight and resistance were measured in light clothing using a footto-foot single frequency bioelectrical impedance analyser (Tanita Inc, Tokyo, Japan, Model 300GS). Fat free mass (FFM) was estimated using a BIA prediction formula developed by Shols in patients with COPD using the deuterium oxide dilution technique as the reference method.5 FFM index (FFMI) was calculated as FFM/height2 and classified as low (15 females or 16 males) based on the standard criteria developed by VanItallie et al.17 Exercise capacity was measured by a physiotherapist using a standard 6-min walk protocol which assesses the individual’s capacity to cover as much distance as they can in 6-min.18 The multidisciplinary ethics committee of the hospital approved the conduct of this study. Voluntary signed informed consent was obtained from each subject prior to commencement of the study. 3. Statistical analysis Statistical analysis was carried out using SPSS for Windows (Version 11.0.1, 2001, SPSS Inc., Chicago, USA) statistical software package. Continuous variables were normally distributed except % oxygen saturation, which was transformed (natural log) to improve distribution. Characteristics of well-nourished and malnourished participants were compared by independent sample t-tests for continuous variables and Fisher’s Exact test for categorical variables. Correlation analysis was used to examine the association between PG-SGA score and % oxygen saturation and 6-min walking distance. A contingency table was used to determine the sensitivity, specificity and predictive value of the PG-SGA score compared to the global categorisation of nutritional status (well-nourished or malnourished). Statistical significance was set at the conventional p < 0.05 level (two-tailed), however results were also interpreted for clinical significance. 4. Results The characteristics of participants are shown in Table 1. According to the global categorisation, 61 of 72 participants were well nourished, 11 were moderately malnourished and none were severely malnourished. The PG-SGA score, BMI, FFM, FFMI, measurement of respiratory function and exercise capacity of wellnourished and malnourished participants are shown in Table 2. Well-nourished participants had a significantly lower mean PGSGA score and higher BMI than malnourished participants, and a trend towards lower FFMI in the malnourished group, although
Variable
Mean standard deviation
Gender Male: Female Age (years) Height (cm) Weight (kg) BMI (kg/m2) FEV1 (%) FFM (kg)* Male Female FFMI (kg/m2)* Male Female
22:50 66.4 166.5 73.3 26.5 47.8
*
8.7 8.0 17.4 6.5 19.7
59.1 8.5 45.2 6.8 19.4 2.6 16.9 2.6
n ¼ 63.
this did not reach statistical significance. Well-nourished participants had significantly higher % oxygen saturation but there was no difference in FEV1 or 6 min walking distance between the groups. There were significant negative correlations between nutritional status (PG-SGA score) and both % oxygen saturation (r ¼ 0.275, p ¼ 0.026) and 6-min walking distance (r ¼ 0.245, p ¼ 0.044). In this study, six participants were underweight (BMI < 18.5), 31 within the acceptable range (BMI 18.5e24.9), 16 were overweight (BMI 25.0e29.9 kg/m2) and 19 were obese (BMI 30 kg/m2). There was a significant difference in FEV1% between participants with BMI < 18.5 (30.0 6.6), BMI 18.5e24.9 (46.4 19.1) and BMI 25 (51.4 19.9) (p ¼ 0.041). There was no significant difference between 6-min walking distances based on BMI categorisation. A low FFMI was found in 16 participants (15 female and 1 male), four participants with low FFMI were underweight (BMI <18.5) and 12 participants within the acceptable range (BMI 18.5e24.9), whereas 11 participants with low FFMI were classified as malnourished and 5 classified as well-nourished. There was no significant difference between FEVI, % oxygen saturation or 6-min walking distances based on FFMI categorisation. Based on triage recommendations of Ottery8 that a PG-SGA score 9 requires critical nutrition intervention, the ability of the PG-SGA score to predict the global classifications of well-nourished or malnourished was determined. Forty-eight of 72 participants were correctly classified by the PG-SGA as being well-nourished (true negatives) and 9 participants were correctly classified as being malnourished (true positives). Two participants were misclassified as being well nourished (false negatives) and 13 participants were misclassified as being malnourished (false positives). The scored PG-SGA had a sensitivity of 82% and a specificity of 79%. Concurrent validity was determined from a Receiver Operating Characteristic (ROC) curve plotting the sensitivity and 1-specificity of the PG-SGA score against identification of malnutrition by low FFMI. The area under the curve of 63.8% (95% CI 49.1e78.4%) indicated the PG-SGA score estimates low FFMI with fair accuracy.
Table 2 Difference in measures of nutritional status and respiratory function in COPD participants (n ¼ 72). Well-nourished (n ¼ 61) PG-SGA score BMI (kg/m2) Oxygen saturation (%) FEV1 (%) FFM (kg)* FFMI (kg/m2)* Six minute walk distance (m) *
n ¼ 63.
5.3 27.1 95.4 51.1 48.8 17.7 349.2
3.0 5.1 2.3 19.3 9.8 2.8 122.6
Malnourished (n ¼ 11) 12.3 20.4 93.8 43.2 47.3 15.9 346.3
6.0 3.5 2.9 28.6 7.9 2.2 100.3
p value 0.003 0.000 0.039 0.078 0.655 0.066 0.943
J. Bauer et al. / e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism 6 (2011) e27ee30
5. Discussion This study showed that the scored PG-SGA is a suitable method for assessing the nutritional status of subjects with COPD and there were significant associations between nutritional status and measures of respiratory function and exercise capacity. According to the global categorisation of nutritional status, 11 patients were moderately malnourished. In addition to factors such as different methods and criteria used to diagnose malnutrition, the relative low prevalence of malnutrition found in this study may be reflective of the higher socioeconomic status of the participants as all were attending a private physician and had private health insurance. Well-nourished participants had significantly lower PG-SGA scores (5.9 3.0) compared to malnourished participants (12.1 5.4). These findings are in agreement with studies using this assessment tool in patients with cancer,11e13,20 chronic kidney disease,14 stroke15 and general medical patients.14 An advantage of the scored PG-SGA as a nutrition assessment tool is that it yields both a global categorisation (well nourished, moderately or suspected of being malnourished and severely malnourished) and a numerical score. The global categorisation can be used to determine the nutritional status of the individual or group. The score can be used to triage nutrition intervention,19 as an outcome measure to demonstrate change in nutritional status12,20 or as a surrogate measure of change in quality of life.16 The score is more sensitive to smaller changes in nutritional status than the global categorisation.20 Construct validity of the PG-SGA score has been measured from several perspectives. Firstly based on triage recommendations,8 a PG-SGA score of 9 had a sensitivity of 82% and a specificity of 79% at predicting nutritional status (well-nourished or malnourished). Although a lower sensitivity, these findings are consistent with the sensitivity and specificity of the tool in oncology.11,13 Secondly, based on the ROC of PG-SGA score against low FFMI, the PG-SGA score estimates low FFMI with fair accuracy. Thirdly, there was a significant negative correlation between PG-SGA score and % oxygen saturation and 6-min walking distance. These findings are in agreement with other studies, which have demonstrated that malnourished subjects have decreased muscle mass, which has a negative influence on oxygen saturation and walking distance.3,21 There was no difference in 6-min walk between the global categorisation of well nourished and malnourished, yet significant but weak correlation was observed with 6-min walk and the PG-SGA score. This highlights the advantage of using a continuous measure such as the PG-SGA score, which may be more sensitive to changes than a categorical variable such as SGA. In this study 16 participants were classified as overweight (BMI 25e<30 kg/m2) and 19 were classified as obese (BMI 30 kg/ m2). These results are not surprising as in Australia over 50% of adults are classified as overweight or obese.22 Other studies have shown that a low BMI increases mortality and morbidity in this patient group.1,4,23,25 In patients with COPD receiving long-term oxygen therapy, nutritional depletion (BMI<20) was an independent risk factor for mortality and hospitalisation and the best prognosis was observed in the overweight and obese patients.4 Shols et al.24 showed that low BMI had a negative effect on survival in COPD patients admitted to a rehabilitation centre. In this study, there was a significant difference between FEV1 based on BMI categorisation, which is consistent with previous findings.1 Several studies in patients with COPD have recommended measurement of FFMI as BMI alone underestimates depletion of FFM.23,26 Our results are in agreement with these findings, as 12 of the 16 participants with low FFMI were within the healthy BMI range. There are several potential limitations of this study. Selection bias that may have been introduced by the convenience sample of patients attending a rehabilitation program and the exclusion of
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participants with cognitive or communication problems. A further limitation was that FFMI could not be calculated for all participants due to the presence of oedema or a pacemaker. Body composition was determined using foot-to foot BIA. This may underestimate fat mass compared to other BIA devices such as hand-to-foot and bioimpedance spectroscopy and these differences may increase with higher BMI.26 The high false positive rate raises the question as to whether the moderately malnourished patients are indeed malnourished. Detsky9originally termed SGA B as suspected or moderately malnourished; therefore there may be some patients in this category who are well nourished. This is consistent with the concept of nutritional status as a continuum from well nourished to severely malnourished. In summary, the scored PG-SGA is a valid tool for the assessment of nutritional status in an ambulatory COPD population. It enables nutritional status to be quickly determined for appropriate medical nutrition therapy to be commenced. Authors contribution JDB participated in the study design, performed data collection, performed the statistical analysis and drafted the manuscript. EE assisted with data collection, supervision of the study and assisted with the manuscript draft. AC devised the study protocol, assisted with the statistical analysis and the interpretation and the writing of the manuscript. Source of funding The authors would like to thank The Wesley Research Institute for sponsorship of the study. Conflict of interest The authors have no conflict of interest to declare. References 1. Sahebjami H, Doers JT, Render ML, Bond TL. Anthropometric and pulmonary function test profiles of outpatients with stable chronic obstructive pulmonary disease. Am J Med 1993;94(5):469e74. 2. Landbo C, Prescott E, Lange P, Vestbo J, Almdal TP. Prognostic value of nutritional status in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1999;160(6):1856e61. 3. Schols AM, Soeters PB, Dingemans AM, Mostert R, Frantzen PJ, Wouters EF. Prevalence and characteristics of nutritional depletion in patients with stable COPD eligible for pulmonary rehabilitation. Am Rev Respir Dis 1993;147 (5):1151e6. 4. Chailleux E, Laaban JP, Veale D. Prognostic value of nutritional depletion in patients with COPD treated by long-term oxygen therapy: data from the ANTADIR observatory. Chest 2003;123(5):1460e6. 5. Steiner MC, Barton RL, Singh SJ, Morgan MD. Bedside methods versus dual energy X-ray absorptiometry for body composition measurement in COPD. Eur Respir J 2002;19(4):626e31. 6. Foley RJ, ZuWallack R. The impact of nutritional depletion in chronic obstructive pulmonary disease. J Cardiopulm Rehabil 2001;21(5):288e95. 7. Gibson R. Principles of nutrition assessment. New York: Oxford University Press; 1990. 8. Ottery F. Patient-Generated subjective global assessment. In: McCallum P, Polisena C, editors. The clinical Guide to oncology nutrition. Chicago: American Dietetic Association; 2000. p. 11e23. 9. Detsky AS, McLaughlin JR, Baker JP, Johnston N, Whittaker S, Mendelson RA, et al. What is subjective global assessment of nutritional status? J Parenteral Enteral Nutr 1987;11(1):8e13. 10. Janda M, Obermair A, Laky B, Cleghorn G. Comparison of different nutritional assessments and body-composition measurements in detecting malnutrition among gynecologic cancer patients. Am J Clin Nutr 2008;87(6):1678e88. 11. Chasen MR, Bhargava R. A rehabilitation program for patients with gastroesophageal cancerda pilot study. Support Care Cancer 2010;18(2):35e6. 12. Bauer J, Capra S, Ferguson M. Use of the scored Patient-Generated Subjective Global Assessment (PG-SGA) as a nutrition assessment tool in patients with cancer. Eur J Clin Nutr 2002;56(8):779e85. 13. Isenring E, Thomas JM, Kellett E. Nutritional status and length of stay in patients admitted to an acute assessment unit. J Hum Nutr Dietetics 2007;20 (4):320e9.
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14. Desbrow B, Bauer J, Blum C, Kandasamy A, McDonald A, Montgomery K. Assessment of nutritional status in hemodialysis patients using patientgenerated subjective global assessment. J Ren Nutr 2005;15(2):211e6. 15. Martineau J, Bauer JD, Isenring E, Cohen S. Malnutrition determined by the patient-generated subjective global assessment is associated with poor outcomes in acute stroke patients. Clin Nutr 2005;24(6):1073e7. 16. Isenring EA, Capra S, Bauer JD. Nutrition intervention is beneficial in oncology outpatients receiving radiotherapy to the gastrointestinal or head and neck area. Br J Cancer 2004;91(3):447e52. 17. VanItallie TB, Yang MU, Heymsfield SB, Funk RC, Boileau RA. Height-normalized indices of the body’s fat-free mass and fat mass: potentially useful indicators of nutritional status. Am J Clin Nutr 1990;52(6):953e9. 18. Stevens D, Elpern E, Sharma K, Szidon P, Ankin M, Kesten S. Comparison of hallway and treadmill six-minute walk tests. Am J Respir Crit Care Med 1999;160(5 Pt 1):1540e3. 19. Ottery F. Supportive nutritional management of the patient with pancreatic cancer. Oncology (Huntington) 1996;10(9 Suppl):26e32. 20. Bauer JD, Capra S. Nutrition intervention improves outcomes in patients with cancer cachexia receiving chemotherapyea pilot study. Support Care Cancer 2005;13(4):270e4.
21. Nishimura Y, Tsutsumi M, Nakata H, Tsunenari T, Maeda H, Yokoyama M. Relationship between respiratory muscle strength and lean body mass in men with COPD. Chest 1995;107(5):1232e6. 22. National Preventative Health Taskforce. 2008. Australia: the healthiest country by 2020 A discussion paper: Commonwealth of Australia; 2003. 23. Vestbo J, Prescott E, Almdal T, Dahl M, Nordestgaard BG, Andersen T, et al. Body mass, fat-free body mass, and prognosis in patients with chronic obstructive pulmonary disease from a random population sample: findings from the Copenhagen City Heart Study. Am J Respir Crit Care Med 2006;173 (1):79e83. 24. Schols AM, Slangen J, Volovics L, Wouters EF. Weight loss is a reversible factor in the prognosis of chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1998;157(6 Pt 1):1791e7. 25. Kyle UG, Janssens JP, Rochat T, Raguso CA, Pichard C. Body composition in patients with chronic hypercapnic respiratory failure. Respir Med 2006;100 (2):244e52. 26. Bosy-Westphal A, Later W, Hitze B, Sato T, Kossel E, Gluer CC, et al. Accuracy of bioelectrical impedance consumer devices for measurement of body composition in comparison to whole body magnetic resonance imaging and dual X-ray absorptiometry. Obes Facts 2008;1(6):319e24.
Contents lists available at ScienceDirect
e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism journal homepage: http://www.elsevier.com/locate/clnu
Original Article
The scored patient-generated subjective global assessment is an effective nutrition assessment tool in subjects with chronic obstructive pulmonary disease Judith Bauer a, *, Elizabeth Egan b, Alexandra Clavarino a a b
University of Queensland, Brisbane, Australia The Wesley Hospital, Brisbane, Australia
a r t i c l e i n f o
s u m m a r y
Article history: Received 25 January 2008 Accepted 28 October 2010
Background & Aims: To evaluate the scored patient-generated subjective global assessment (PG-SGA) as a nutrition assessment tool in subjects with chronic obstructive pulmonary disease. Methods: Seventy-two participants attending a pulmonary rehabilitation program (22M, 50F; mean age 66.6 8.6 y). Nutritional status was assessed using the scored PG-SGA e global categorisation and score; fat free mass index. Results: According to the subjective global assessment, 61 participants were well-nourished and 11 were moderately malnourished. Well-nourished participants had significantly lower PG-SGA scores (5.9 3.0 vs 12.1 5.4), higher % oxygen saturation (94.9 2.8 vs 93.6 2.4) and higher BMI (27.8 6.1 vs 19.5 3.2) than malnourished. There was a significant correlation between PG-SGA score and % oxygen saturation (r ¼ 0.275, p ¼ 0.026) and 6-min walking distance (r ¼ 0.245, p ¼ 0.044). The PG-SGA score had an 82% sensitivity and 79% specificity of predicting the global categorisation of nutritional status. Conclusions: The scored PG-SGA identifies malnutrition in participants with chronic obstructive pulmonary disease. The nutritional status of subjects attending pulmonary rehabilitation programs could be assessed and tracked with the scored PG-SGA. Ó 2010 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.
Keywords: Nutrition assessment Patient-generated subjective global assessment Chronic obstructive pulmonary disease
1. Introduction Malnutrition is common in patients with chronic obstructive pulmonary disease (COPD), with prevalence depending on the method of nutrition assessment, timing of the assessment and severity of disease.1e5 In COPD, malnutrition has been found to be associated with increased morbidity (increased dyspnoea, decreased exercise capacity, impaired quality of life) and mortality.2,4,6 As there is no gold standard for the assessment of nutritional status in patients with COPD, a variety of objective nutrition parameters (anthropometric, biochemical and immunological) have been used in the literature either alone or in combination to diagnose malnutrition. The use of single objective nutrition parameters to assess nutritional status has been questioned due to
* Corresponding author. Tel.: þ61 7 334 67703; fax: þ61 7 3365 6877. E-mail address: [email protected] (J. Bauer).
lack of sensitivity and specificity as many non-nutritional factors affect the results.7 The scored patient-generated subjective global assessment (PG-SGA) is a method of nutrition assessment developed by Ottery.8 In common with subjective global assessment,9 nutritional status is determined on the basis of a combination of a medical history (weight loss, oral intake, nutrition impact symptoms, functional capacity) and physical examination (loss of subcutaneous fat, muscle wasting, oedema), which are combined subjectively into the global categories of well nourished, moderately or suspected of being malnourished or severely malnourished. The scored PG-SGA provides additional information regarding shortterm weight loss, more extensive nutrition impact symptoms and a numerical score. It has been demonstrated to be a valid method of nutrition assessment in oncology, renal and stroke specialties as well as general patients in the acute care setting.10e15 The PG-SGA score correlates with objective nutrition parameters (% weight loss, BMI), quality of life, morbidity (survival, length of stay), has a high degree of inter-rater reproducibility and a high sensitivity and
1751-4991/$36.00 Ó 2010 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.eclnm.2010.10.003
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J. Bauer et al. / e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism 6 (2011) e27ee30
specificity when compared with other validated nutrition assessment tools.10e15 The aim of this study was to assess the validity of the scored PG-SGA as a nutrition assessment tool in participants attending a pulmonary rehabilitation program.
Table 1 Participant characteristics (n ¼ 72).
2. Materials and methods Subjects with COPD were recruited at the first session of a sixweek pulmonary rehabilitation program over an 18-month period. The inclusion criteria for this group were as follows: age > 18 years, moderate to severe COPD based on Forced Expiratory Volume (FEV1) < 60%, cognitive function and ability to communicate adequately to provide informed consent and understand and respond to questions. Seventy-seven subjects enrolled in the pulmonary rehabilitation program and seventy-two participants participated in this study. Nutritional status was assessed by a dietitian experienced at using the scored PG-SGA. A global rating of nutritional status (well nourished, suspected or moderately malnourished or severely malnourished) and an overall PG-SGA score was calculated. Body weight and resistance were measured in light clothing using a footto-foot single frequency bioelectrical impedance analyser (Tanita Inc, Tokyo, Japan, Model 300GS). Fat free mass (FFM) was estimated using a BIA prediction formula developed by Shols in patients with COPD using the deuterium oxide dilution technique as the reference method.5 FFM index (FFMI) was calculated as FFM/height2 and classified as low (15 females or 16 males) based on the standard criteria developed by VanItallie et al.17 Exercise capacity was measured by a physiotherapist using a standard 6-min walk protocol which assesses the individual’s capacity to cover as much distance as they can in 6-min.18 The multidisciplinary ethics committee of the hospital approved the conduct of this study. Voluntary signed informed consent was obtained from each subject prior to commencement of the study. 3. Statistical analysis Statistical analysis was carried out using SPSS for Windows (Version 11.0.1, 2001, SPSS Inc., Chicago, USA) statistical software package. Continuous variables were normally distributed except % oxygen saturation, which was transformed (natural log) to improve distribution. Characteristics of well-nourished and malnourished participants were compared by independent sample t-tests for continuous variables and Fisher’s Exact test for categorical variables. Correlation analysis was used to examine the association between PG-SGA score and % oxygen saturation and 6-min walking distance. A contingency table was used to determine the sensitivity, specificity and predictive value of the PG-SGA score compared to the global categorisation of nutritional status (well-nourished or malnourished). Statistical significance was set at the conventional p < 0.05 level (two-tailed), however results were also interpreted for clinical significance. 4. Results The characteristics of participants are shown in Table 1. According to the global categorisation, 61 of 72 participants were well nourished, 11 were moderately malnourished and none were severely malnourished. The PG-SGA score, BMI, FFM, FFMI, measurement of respiratory function and exercise capacity of wellnourished and malnourished participants are shown in Table 2. Well-nourished participants had a significantly lower mean PGSGA score and higher BMI than malnourished participants, and a trend towards lower FFMI in the malnourished group, although
Variable
Mean standard deviation
Gender Male: Female Age (years) Height (cm) Weight (kg) BMI (kg/m2) FEV1 (%) FFM (kg)* Male Female FFMI (kg/m2)* Male Female
22:50 66.4 166.5 73.3 26.5 47.8
*
8.7 8.0 17.4 6.5 19.7
59.1 8.5 45.2 6.8 19.4 2.6 16.9 2.6
n ¼ 63.
this did not reach statistical significance. Well-nourished participants had significantly higher % oxygen saturation but there was no difference in FEV1 or 6 min walking distance between the groups. There were significant negative correlations between nutritional status (PG-SGA score) and both % oxygen saturation (r ¼ 0.275, p ¼ 0.026) and 6-min walking distance (r ¼ 0.245, p ¼ 0.044). In this study, six participants were underweight (BMI < 18.5), 31 within the acceptable range (BMI 18.5e24.9), 16 were overweight (BMI 25.0e29.9 kg/m2) and 19 were obese (BMI 30 kg/m2). There was a significant difference in FEV1% between participants with BMI < 18.5 (30.0 6.6), BMI 18.5e24.9 (46.4 19.1) and BMI 25 (51.4 19.9) (p ¼ 0.041). There was no significant difference between 6-min walking distances based on BMI categorisation. A low FFMI was found in 16 participants (15 female and 1 male), four participants with low FFMI were underweight (BMI <18.5) and 12 participants within the acceptable range (BMI 18.5e24.9), whereas 11 participants with low FFMI were classified as malnourished and 5 classified as well-nourished. There was no significant difference between FEVI, % oxygen saturation or 6-min walking distances based on FFMI categorisation. Based on triage recommendations of Ottery8 that a PG-SGA score 9 requires critical nutrition intervention, the ability of the PG-SGA score to predict the global classifications of well-nourished or malnourished was determined. Forty-eight of 72 participants were correctly classified by the PG-SGA as being well-nourished (true negatives) and 9 participants were correctly classified as being malnourished (true positives). Two participants were misclassified as being well nourished (false negatives) and 13 participants were misclassified as being malnourished (false positives). The scored PG-SGA had a sensitivity of 82% and a specificity of 79%. Concurrent validity was determined from a Receiver Operating Characteristic (ROC) curve plotting the sensitivity and 1-specificity of the PG-SGA score against identification of malnutrition by low FFMI. The area under the curve of 63.8% (95% CI 49.1e78.4%) indicated the PG-SGA score estimates low FFMI with fair accuracy.
Table 2 Difference in measures of nutritional status and respiratory function in COPD participants (n ¼ 72). Well-nourished (n ¼ 61) PG-SGA score BMI (kg/m2) Oxygen saturation (%) FEV1 (%) FFM (kg)* FFMI (kg/m2)* Six minute walk distance (m) *
n ¼ 63.
5.3 27.1 95.4 51.1 48.8 17.7 349.2
3.0 5.1 2.3 19.3 9.8 2.8 122.6
Malnourished (n ¼ 11) 12.3 20.4 93.8 43.2 47.3 15.9 346.3
6.0 3.5 2.9 28.6 7.9 2.2 100.3
p value 0.003 0.000 0.039 0.078 0.655 0.066 0.943
J. Bauer et al. / e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism 6 (2011) e27ee30
5. Discussion This study showed that the scored PG-SGA is a suitable method for assessing the nutritional status of subjects with COPD and there were significant associations between nutritional status and measures of respiratory function and exercise capacity. According to the global categorisation of nutritional status, 11 patients were moderately malnourished. In addition to factors such as different methods and criteria used to diagnose malnutrition, the relative low prevalence of malnutrition found in this study may be reflective of the higher socioeconomic status of the participants as all were attending a private physician and had private health insurance. Well-nourished participants had significantly lower PG-SGA scores (5.9 3.0) compared to malnourished participants (12.1 5.4). These findings are in agreement with studies using this assessment tool in patients with cancer,11e13,20 chronic kidney disease,14 stroke15 and general medical patients.14 An advantage of the scored PG-SGA as a nutrition assessment tool is that it yields both a global categorisation (well nourished, moderately or suspected of being malnourished and severely malnourished) and a numerical score. The global categorisation can be used to determine the nutritional status of the individual or group. The score can be used to triage nutrition intervention,19 as an outcome measure to demonstrate change in nutritional status12,20 or as a surrogate measure of change in quality of life.16 The score is more sensitive to smaller changes in nutritional status than the global categorisation.20 Construct validity of the PG-SGA score has been measured from several perspectives. Firstly based on triage recommendations,8 a PG-SGA score of 9 had a sensitivity of 82% and a specificity of 79% at predicting nutritional status (well-nourished or malnourished). Although a lower sensitivity, these findings are consistent with the sensitivity and specificity of the tool in oncology.11,13 Secondly, based on the ROC of PG-SGA score against low FFMI, the PG-SGA score estimates low FFMI with fair accuracy. Thirdly, there was a significant negative correlation between PG-SGA score and % oxygen saturation and 6-min walking distance. These findings are in agreement with other studies, which have demonstrated that malnourished subjects have decreased muscle mass, which has a negative influence on oxygen saturation and walking distance.3,21 There was no difference in 6-min walk between the global categorisation of well nourished and malnourished, yet significant but weak correlation was observed with 6-min walk and the PG-SGA score. This highlights the advantage of using a continuous measure such as the PG-SGA score, which may be more sensitive to changes than a categorical variable such as SGA. In this study 16 participants were classified as overweight (BMI 25e<30 kg/m2) and 19 were classified as obese (BMI 30 kg/ m2). These results are not surprising as in Australia over 50% of adults are classified as overweight or obese.22 Other studies have shown that a low BMI increases mortality and morbidity in this patient group.1,4,23,25 In patients with COPD receiving long-term oxygen therapy, nutritional depletion (BMI<20) was an independent risk factor for mortality and hospitalisation and the best prognosis was observed in the overweight and obese patients.4 Shols et al.24 showed that low BMI had a negative effect on survival in COPD patients admitted to a rehabilitation centre. In this study, there was a significant difference between FEV1 based on BMI categorisation, which is consistent with previous findings.1 Several studies in patients with COPD have recommended measurement of FFMI as BMI alone underestimates depletion of FFM.23,26 Our results are in agreement with these findings, as 12 of the 16 participants with low FFMI were within the healthy BMI range. There are several potential limitations of this study. Selection bias that may have been introduced by the convenience sample of patients attending a rehabilitation program and the exclusion of
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participants with cognitive or communication problems. A further limitation was that FFMI could not be calculated for all participants due to the presence of oedema or a pacemaker. Body composition was determined using foot-to foot BIA. This may underestimate fat mass compared to other BIA devices such as hand-to-foot and bioimpedance spectroscopy and these differences may increase with higher BMI.26 The high false positive rate raises the question as to whether the moderately malnourished patients are indeed malnourished. Detsky9originally termed SGA B as suspected or moderately malnourished; therefore there may be some patients in this category who are well nourished. This is consistent with the concept of nutritional status as a continuum from well nourished to severely malnourished. In summary, the scored PG-SGA is a valid tool for the assessment of nutritional status in an ambulatory COPD population. It enables nutritional status to be quickly determined for appropriate medical nutrition therapy to be commenced. Authors contribution JDB participated in the study design, performed data collection, performed the statistical analysis and drafted the manuscript. EE assisted with data collection, supervision of the study and assisted with the manuscript draft. AC devised the study protocol, assisted with the statistical analysis and the interpretation and the writing of the manuscript. Source of funding The authors would like to thank The Wesley Research Institute for sponsorship of the study. Conflict of interest The authors have no conflict of interest to declare. References 1. Sahebjami H, Doers JT, Render ML, Bond TL. Anthropometric and pulmonary function test profiles of outpatients with stable chronic obstructive pulmonary disease. Am J Med 1993;94(5):469e74. 2. Landbo C, Prescott E, Lange P, Vestbo J, Almdal TP. Prognostic value of nutritional status in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1999;160(6):1856e61. 3. Schols AM, Soeters PB, Dingemans AM, Mostert R, Frantzen PJ, Wouters EF. Prevalence and characteristics of nutritional depletion in patients with stable COPD eligible for pulmonary rehabilitation. Am Rev Respir Dis 1993;147 (5):1151e6. 4. Chailleux E, Laaban JP, Veale D. Prognostic value of nutritional depletion in patients with COPD treated by long-term oxygen therapy: data from the ANTADIR observatory. Chest 2003;123(5):1460e6. 5. Steiner MC, Barton RL, Singh SJ, Morgan MD. Bedside methods versus dual energy X-ray absorptiometry for body composition measurement in COPD. Eur Respir J 2002;19(4):626e31. 6. Foley RJ, ZuWallack R. The impact of nutritional depletion in chronic obstructive pulmonary disease. J Cardiopulm Rehabil 2001;21(5):288e95. 7. Gibson R. Principles of nutrition assessment. New York: Oxford University Press; 1990. 8. Ottery F. Patient-Generated subjective global assessment. In: McCallum P, Polisena C, editors. The clinical Guide to oncology nutrition. Chicago: American Dietetic Association; 2000. p. 11e23. 9. Detsky AS, McLaughlin JR, Baker JP, Johnston N, Whittaker S, Mendelson RA, et al. What is subjective global assessment of nutritional status? J Parenteral Enteral Nutr 1987;11(1):8e13. 10. Janda M, Obermair A, Laky B, Cleghorn G. Comparison of different nutritional assessments and body-composition measurements in detecting malnutrition among gynecologic cancer patients. Am J Clin Nutr 2008;87(6):1678e88. 11. Chasen MR, Bhargava R. A rehabilitation program for patients with gastroesophageal cancerda pilot study. Support Care Cancer 2010;18(2):35e6. 12. Bauer J, Capra S, Ferguson M. Use of the scored Patient-Generated Subjective Global Assessment (PG-SGA) as a nutrition assessment tool in patients with cancer. Eur J Clin Nutr 2002;56(8):779e85. 13. Isenring E, Thomas JM, Kellett E. Nutritional status and length of stay in patients admitted to an acute assessment unit. J Hum Nutr Dietetics 2007;20 (4):320e9.
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