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Diagnostic accuracy of a validated screening tool for monitoring nutritional status in patients with colorectal cancer: a systematic review protocol

Håkonsen, Sasja Jul RN, MScN, Deputy Director; Pedersen, Preben Ulrich Associate Professor, PhD, Director; Thomsen, Thordis Associate Professor, PhD, core staff member; Bath-Hextall, Fiona Associate Professor and Reader in Evidence-Based Health Care; Kirkpatrick, Pamela Lead Academic and Director; Christensen, Birgit Nørgaard Subject Specialist (Health Science)

JBI Database of Systematic Reviews and Implementation Reports: August 2013 - Volume 11 - Issue 8 - p 186–198
doi: 10.11124/jbisrir-2013-951

Review question/objective The aim of this systematic review is to comprehensively search the available literature and to synthesize the best available evidence to determine the diagnostic accuracy of currently available and published nutritional screening tools used to screen or assess the nutritional status of patients with colorectal cancer compared to Subjective Global Assessment (SGA) or Patient Generated Subjective Global Assessment (PG-SGA).

The objective of this review is therefore to determine:

How sensitive and specific are the screening tools used to assess malnutrition in patients with colorectal cancer?

Review question: How sensitive and specific are screening tools compared to the scored Patient Generated-Subjective Global Assessment (PG-SGA) or the Subjective Global Assessment (SGA) when used to assess malnutrition in patients with colorectal cancer?

Background Colorectal cancer

Colorectal cancer (CRC) is the third leading cause of cancer-related death worldwide. An estimated 1.24 million people worldwide were diagnosed with colorectal cancer in 2008.1

In the USA the incidence of CRC in 2011 was 57.2 per 100.000 in men and 42.5 per 100.000 in women and the mortality rate was 21.2 per 100.000 in men and 14.9 per 100.000 in women.2

CRC patients presenting with many of the symptoms of cachexia (weight loss, muscle atrophy, fatigue, weakness, and significant appetite loss) thus require an evaluation of their nutritional status.1

A study aiming to determine the extent of malnutrition in preoperative colorectal cancer patients in a British hospital concluded that over half of the patients included in the study had lost weight prior to surgery and one in five were malnourished. The author of the study concluded that nutritional screening would be beneficial among these patients to identify weight-losing patients at an early stage in the care pathway.3


Malnutrition is a common problem in hospitalized cancer patients worldwide, especially those with postoperative weakness caused by metabolic abnormalities that result in weight loss, anorexia and other conditions. Malnutrition has a high clinical and economic impact.1,4

The prevalence of malnutrition in hospitalized patients undergoing treatment for CRC in the United Kingdom is estimated to be between 41%-60%.3

Minor, conservative abdominal surgery can cause a short-term increase in metabolic rate. In contrast, major surgery involving tumor resection may lead to a 20-50% increase in metabolism lasting for a week or more postoperatively. If the patient develops a bacterial infection or sepsis, the increase in metabolism may exceed 50%.3,4

In general, postoperative nutritional status will deteriorate because the amount of muscle protein breakdown is primarily dependent on the metabolic rate. Protein wasting also increases more rapidly than the metabolic rate. About 50% of patients with increased metabolism will develop a breakdown rate of protein that more than twice exceeds the normal rate, resulting in a negative nitrogen balance.5,6

Consequences of malnutrition

The consequences of malnutrition can be fatal. Malnutrition leads to weight loss, muscle weakness, apathy, immune deficiency, frequent infections and higher mortality. It can prolong illness and convalescence, hospitalization and treatment.4

A retrospective analysis conducted in the USA of the association between malnutrition and quality of life in patients with colorectal cancer, concluded that well-nourished patients had statistically significantly better quality of life scores on global, physical and role functions compared to malnourished patients.7

Similarly, quality of life scores on multiple symptom scales were significantly better among well-nourished patients.7 This is not only of great importance for patients. It is equally relevant for hospital staff, resource allocation and socioeconomically.

Both observational as well as experimental studies clearly shows that if nutritional needs are ignored health outcomes are worse.8-10 Meta-analysis of such trials suggest that provision of nutritional supplements to malnourished men and women aged 50+ with colon cancer stage 0 - IV undergoing surgery, reduces complications such as infection and wound dehiscence by 70% and mortality by 40%.11 These are studies undertaken in the United Kingdom.11

Early diagnosis of malnutrition in CRC patients

Effective nutritional screening, nutritional care planning and nutritional support are essential in all settings, and there is no doubt that a health service seeking to increase safety and clinical effectiveness must take nutritional care seriously. Screening and early detection of malnutrition is crucial in identifying patients at nutritional risk.11

To meet the goal of offering a relevant nutritional plan that minimizes the risk of complications related to malnutrition, an appropriate method for evaluating nutritional status is needed for identifying patients at high-risk.3

Among the plethora of nutritional assessment methods available, the Subjective Global Assessment (SGA), the Patient Generated Subjective Global Assessment (PG-SGA)11 and the Malnutrition Universal Screening Tool (MUST)12,13,14 are commonly used in clinical settings.3

The Subjective Global Assessment is a proven nutritional assessment tool that has been found to be highly predictive of nutrition-associated complications based on features of the patient's history and physical examination.18

The SGA assesses nutritional status based on features of the patient's medical history (weight change, dietary intake, gastrointestinal symptoms that have persisted for more than two weeks and changes in functional capacity) and physical examination (loss of subcutaneous fat, muscle wasting, ankle/sacral edema and ascites). The SGA has been applied successfully as a method of assessing nutritional status and predicting complications in a number of different patient groups, including cancer patients. The SGA has been correlated with a number of objective parameters (anthropometric, biochemical and immunological) and three measures of morbidity (incidence of infection, use of antibiotics, length of stay) and has a high degree of inter-rater reproducibility.18

Although complex, the SGA is a well-validated existing method of nutritional assessment and, thus, provides an appropriate gold standard (reference standard) against which other nutritional screening tools specific to CRC patients can be compared.

The PG-SGA is an adaptation of the SGA and a validated tool for assessing nutritional status in patients with cancer. It is based on a combination of known prognostic indicators of weight loss, performance status as well as clinical aspects of dietary intake and its impediment, allowing identification and prioritization of malnutrition. The scored PG-SGA can be used as a nutrition screening, assessment and outcome measure and has been validated against SGA, and is also a gold standard (reference standard) along with SGA in this systematic review.19 The reason for using two reference standards in this systematic review is that they are both well validated and usable as reference standards in this patient population. In the studies investigating the validity of screening tools specific to colorectal cancer patients, both the SGA and the PG-SGA have been used as golden standards.

Several diagnosis-specific screening instruments have been developed in order to provide tools that are simpler and quicker for clinical practice to use than SGA and PG-SGA.

These diagnosis-specific tools include; the Malnutrition Screening Tool (MST), Short Screening Sheet (SSH) and the Nutritional Risk Index (NRI). The validity of such screening instruments against the SGA/PG-SG will be examined in this systematic review.13,14

Many non-validated or unpublished screening tools are routinely used in clinical practice to assess nutritional status in patients with colorectal cancer. This may potentially lead to misclassification or non-classification of patients at nutritional risk and pack a standardized approach.

No other systematic review of research has been published within this area, therefore the aim of this systematic review is to synthesize existing literature on the diagnostic accuracy (sensitivity and specificity) of nutritional screening tools used to identify the nutritional status in patients with colorectal cancer compared to SGA, in order to provide practice with best available evidence regarding nutritional screening instruments.



Malnutrition is a condition that develops when the body does not get the required amount of vitamins, minerals, and other nutrients that are essential for maintaining healthy tissues and organ function.3

Malnutrition occurs in people who are either undernourished or over-nourished.3

Undernutrition is a result of insufficient intake of essential nutrients and/or of metabolizing or excreting them more rapidly than they can be replaced.3

Overnutrition is a result of excessive eating, eating too many of the wrong things, not exercising enough, or intake of too many vitamins or other dietary replacements.3

Although the term malnutrition can encompass both overnutrition and undernutrition, this systematic review will use term to refer solely to under-nutrition.

Diagnostic tests

Diagnostic tests aid clinicians in diagnosing and treating patients based on the available test results.15 Diagnostic test interpretation involves comparing features of the patient against known features of the suspected condition and generating a likelihood of the presence or absence of the condition. In order to determine how accurate a diagnostic test is, the test should be compared to a reference test/standard that has been proven reliable for the particular condition of interest and patient population. Systematic reviews of diagnostic tests are a recent development and aim to inform clinicians by critically appraising and synthesizing the best available evidence concerning the accuracy of diagnostic tests, ideally in comparison with alternate techniques.16 However, this type of review can be challenging because determining what accuracy means in this context is more complex than in for example studies of therapeutic interventions.17

The accuracy of a test is determined by posing two questions:

• How often does the test give positive results for patients that have the condition? (sensitivity)


• How often does the test give negative results for patients that do not have the condition? (specificity)

As with any procedure, there are benefits and limitations. One of the major benefits is that (generally) diagnostic tests are relatively straightforward to conduct and provide clinicians with evidence on which to base a diagnosis within a useful timeframe. When conducting a diagnostic test, a patient sample (e.g. blood, urine, scan etc.) is compared against a reference or test standard. Therefore test accuracy can be compromised if the wrong type of patient sample or reference test/material is used.

1. Danish Centre of Systematic Reviews in Nursing: an Affiliate Centre of The Joanna Briggs Institute, The Centre of Clinical Guidelines - Danish National Clearing House for Nursing.

2. Director of the Nottingham Centre of Evidence Based Health Care: a Collaborating Centre of the Joanna Briggs Institute

3. Enterprise in Health and Social Care.

4. The Scottish Centre for Evidence-based Multi-professional Practice: an Affiliate Centre of the Joanna Briggs Institute

5. Library of Health Sciences, University of Aarhus, Denmark

Corresponding author:

Sasja Jul Håkonsen

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Inclusion criteria

Types of participants

This review will consider studies that include adult participants with colorectal cancer requiring either (or all) surgery, chemotherapy and/or radiotherapy in secondary care.

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Focus of the review

The following index tests for assessing nutritional status will be addressed:

Assessment of nutritional status using a published and validated screening/assessment tool /instrument

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Reference test

The diagnostic accuracy of the index tests will be compared against either PG-SGA or SGA.

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Types of outcomes

This review will consider studies that include the following outcome measures:

Diagnostic accuracy defined as how well the index test correctly gives positive results (sensitivity and specificity) in regard to identifying malnutrition in patients with colorectal cancer using the reference test.

Where available, Positive Predictive Values (PPV), Negative Predictive Values (NPV) and likelihood ratios will also be included.

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Types of studies

This review will consider any quantitative studies that examine the diagnostic accuracy of a screening tool used to assess the nutritional status of patients with colorectal cancer.

Cohort studies or cross-sectional studies addressing the diagnostic accuracy of the diagnostic tools specified for nutritional screening among patients with colorectal cancer and where the participants are given one or more index tests and the reference standard.

Randomized studies of test accuracy where participants are randomized to different index tests and all participants are verified by the same gold standard.

Case-control studies where participants have been selected by outcomes.

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Search strategy

The search strategy aims to find both published and unpublished studies. A three-step search strategy will be utilised in this review.

Initial search terms were chosen in discussion with a research librarian with the aim of identifying the maximum number of articles.

An initial limited search of MEDLINE and CINAHL will be undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe the article.

A second search using all identified keywords and index terms will then be undertaken across all included databases as well as citation searches will be applied.

Thirdly, the reference list of all identified reports and articles will be searched for additional studies. Studies published in English, German, Danish, Swedish and Norwegian will be considered for inclusion in this review.

Databases will be searched from their inception to April 2013.

The databases and resources to be searched include:

PubMed, CINAHL, Embase, Scopus, Swemed+, MedNar, CDC, MEDION, Health technology assessment database, Turning research into practice, NTIS, ProQuest dissertations and theses, ASPEN, ESPEN

Additional searching for published literature will include:

Hand searching reference lists and bibliographies of included articles.

Initial keywords/search terms to be used will be:

Colorectal cancer





Nutritional screening


Nutritional assessment





Diagnostic test

Diagnostic test accuracy






Positive predictive value

Negative predictive value

Likelihood ratio

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Assessment of methodological quality

The methodological quality of each paper will be critically appraised and assessed by two reviewers independently, in order to limit potential reviewer bias. Several quality criteria need to be considered when evaluating studies for potential inclusion. These include:

• The clinical spectrum of included patients

• Blinded interpretation of test and reference standard results

• Potential for verification bias

• Patient sampling, prospective design is preferred

• Adequate description of the index test, reference standard, and study population.

In order to assess the methodological quality of papers included in the review, the checklist developed by the QUADAS initiative checklist. 20,21 will be used as a critical appraisal instrument. Studies will not be excluded on the basis of quality and issues relating to study quality will be explored. The checklist is presented in Appendix I. In situations where study features may not be reported in the primary studies, the reviewers might need to contact authors or seek additional information for clarification.

In situations when primary and secondary reviewers disagree upon the methodological quality of the paper, a third reviewer will be consulted to resolve disagreements.

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Data collection

Data will be extracted from included studies using the STARD checklist for the reporting of studies of diagnostic accuracy22 (Appendix II) and will include details pertinent to: population, setting, test details and the sensitivity and specificity for the index test.

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Data synthesis

Sensitivity, specificity, true positives (TP), false positives (FP), true negatives (TN) and false negatives (FN) are taken directly from the source papers. If this is not possible, values are calculated from the data that was provided. Positive and negative likelihood ratios, diagnostic odds ratios, and 95% confidence intervals are calculated. The data will be displayed on forest and ROC plots.

Heterogeneity will be assessed statistically using the standard Chi-square and also explored using subgroup analyses based on the different study designs included in this review.

When synthesizing diagnostic outcomes, it is essential to plot sensitivity-specificity pairs for each included study. The relationship between the sensitivity-specificity pair depicts how significant heterogeneity differences exist and helps define the appropriate approach to synthesizing outcomes.

Where statistical pooling is not possible the findings will be presented in narrative form including tables and figures to aid in data presentation where appropriate. If meta-analysis is possible, sensitivity and specificity scores will as a minimum be pooled in a meta-analysis.

Rev Man (Cochrane Collaboration) will be used as an appropriate software to generate outcome measures and ROC plots.

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Conflicts of interest

None identified.

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We express our appreciation to the late Dr. Yash Kumarasamy, whose contribution to this work was of great significance.

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1 Kudsk KA, Tolley EA, DeWitt RC, Janu PG, Blackwell AP, et al.: Preoperative albumin and surgical site identify surgical risk for major postoperative complications. JPEN J Parenter Enteral Nutr27, 1-9, 2003.
    2 American Cancer Society. Colorectal Cancer - Facts & Figures 2011-2013. National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention
      3 Tu M, Chein T, Chou M. (2012). Using a nutritional screening tool to evaluate the nutritional status of patients with colorectal cancer. Nutrition and Cancer. 64:2, p.p.323-330.
        4 Maxfield D, Geehan D, and Van Way CW, III: Perioperative nutritional support. Nutr Clin Pract16, 69-73, 2001.
          5 Leon-Carlyle M, Spiegle G, Schmoker S, Gagliardi A, Urbach D, et al.: Using patient and physician perspectives to develop a shared decision-making framework for colorectal cancer. Implement Sci4, 81, 2009.
            6 Burden ST, Hill J, Schaffer JL, Todd C. Nutritional status of preoperative colorectal cancer patients. J Jum Nutr Diet.23 (4), 402-407, 2010
              7 Gupta D, Lis CG, Granich J, Grutsch JF, Vashi PG, Lammersfield CA. Malnutrition was associated with poor quality of life in colorectal cancer: a retrospective analysis. Journal of Clinical Epidemiology.59, 704-709. 2006
                8 Kondrup J, Johansen N, Plum LM, Bak L, Larsen IH, et al.: Incidence of nutritional risk and causes of inadequate nutritional care in hospitals. Clin Nutr21, 461-468, 2002.
                  9 Shil ME: Principles of nutrition therapy. Cancer43(5 Suppl), 2093-2102, 1979.
                    10 Rasmussen HH, Kondrup J, Ladefoged K, and Staun M: Clinical nutrition in Danish hospitals: a questionnaire-based investigation among doctors and nurses. Clin Nutr18, 153-158, 1999.
                      11 Detsky AS, McLaughlin JR, Baker JP, Johnston N, Whittaker S, et al.: What is subjective global assessment of nutritional status? JPEN J Parenter Enteral Nutr11, 8-13, 1987.
                        12 Stratton RJ, Hackston A, LongmoreD,Dixon R, Price S, et al.:Malnutrition in hospital outpatients and inpatients: prevalence, concurrent validity and ease of use of the malnutrition universal screening tool (MUST) for adults. Br J Nutr92, 799-808, 2004.
                          13 Corish CA, Flood P, and Kennedy NP: Comparison of nutritional risk screening tool in patients on admission to hospital. J Hum Nutr Diet17, 133-139, 2004.
                            14 Buzby GP,WillifordWO, Peterson OL, Crosby LO, Page CP, et al.: A randomized clinical trial on total parenteral nutrition in malnourished surgical patients: the rationale and impact of previous clinical trials and pilot study on protocol design. Am J Clin Nutr47, 357-365, 1988.
                              15 Zhuo X, Obuchowski N, McClish D. Statistical methods in diagnostic medicine. New York: Wiley; 2002.
                                16 Deeks J. Systematic reviews of evaluations of diagnostic and screening tests. In: Egger M, Davey Smith G, Altman D, editors. Systematic reviews in healthcare: Meta-analysis in context: BMJ publishing group; 2001. p. 248-81.
                                  17 Gatsonis C, Paliwal P. Meta-analysis of diagnostic and screening test accuracy evaluations: Methodologic primer. American Journal of Roentgenology. 2006;187:271-81.
                                  18 Detsky AS, McLaughlin JR, Baker JP, Johnson N, Whittaker S, Mendelson RA; Jeejeebhoy KN. What is the subjective global assessment of nutritional status? JPEN J Parenter Enteral Nutr. 1987: 11, 8-13
                                    19 Ottery FD. Patient generated subjective global assessment. In: McCallum P, Polisena C (eds). The clinical guide to oncology nutrition.The American Dietetic Association. Chicago IL, USA: 2000, 11-23
                                      20 Whiting P, Rutjes A, Reitsma J, Bossuyt P, Kleijnen J. The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews. BMC Medical Research Methodology. 2003;3(25):1-13.
                                      21 Whiting P, Weswood M, Rutjes A, Reitsma J, Bossuyt P, Kleijnen J. Evaluation of QUADAS, a tool for the quality assessment of diagnostic accuracy studies. BMC Medical Research
                                      22 Meyer G. Guidelines for reporting information in studies of diagnostic accuracy: The STARD initiative. Journal of Personality Assessment. 2003;81(3):191-3.
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                                      Appendix I Critical appraisal tool - the QUADAS checklist20

                                      1. Was the spectrum of patients representative of the patients who will receive the test in practice?

                                      2. Were selection criteria clearly described?

                                      3. Is the reference standard likely to correctly classify the target condition?

                                      4. Is the time period between reference standard and index test short enough to be reasonably sure that the target condition did not change between the two tests?

                                      5. Did the whole sample or a random selection of the sample, receive verification using a reference standard of diagnosis?

                                      6. Did patients receive the same reference standard regardless of the index test result?

                                      7. Was the reference standard independent of the index test (i.e. the index test did not form part of the reference standard)?

                                      8. Was the execution of the index test described in sufficient detail to permit replication of the test?

                                      9. Was the execution of the reference standard described in sufficient detail to permit its replication?

                                      10. Were the index test results interpreted without knowledge of the results of the reference standard?

                                      11. Were the reference standard results interpreted without knowledge of the results of the index test?

                                      12. Were the same clinical data available when test results were interpreted as would be available when the test is used in practice?

                                      13. Were uninterpretable/ intermediate test results reported?

                                      14. Were withdrawals from the study explained?

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                                      Appendix II Data extraction tool - the STARD checklist22

                                      1 Was the study identified as being a diagnostic accuracy study?

                                      2 Were research questions or study aims, such as estimating diagnostic accuracy or comparing accuracy between tests or across participant groups, detailed?

                                      3 Does the study describe the study population, inclusion and exclusion criteria, setting and locations where the data were collected?

                                      4 Does the study describe participant recruitment? Was recruitment based on presenting symptoms, results from previous tests, or the fact that the participants had received the index tests or the reference standard?

                                      5 Describe participant sampling: Was the study population a consecutive series of participants defined by the selection criteria in items 3 and 4? If not, specify how participants were further selected

                                      6 Describe data collection: Was data collection planned before the index test and reference standard were performed (prospective study) or after (retrospective study)?

                                      7 Did the study describe the reference standard and its rationale?

                                      8 Describe technical specifications of material and methods involved including how and when measurements were taken, and/or cite references for index tests and reference standard.

                                      9 Describe definition of and rationale for the units, cut-offs and/or categories of the results of the index tests and the reference standard.

                                      10 Describe the number, training and expertise of the persons executing and reading the index tests and the reference standard

                                      11 Describe whether or not the readers of the index tests and reference standard were blind (masked) to the results of the other test and describe any other clinical information available to the readers.

                                      12 Describe methods for calculating or comparing measures of diagnostic accuracy, and the statistical methods used to quantify uncertainty (e.g. 95% confidence intervals)

                                      13 Describe methods for calculating test reproducibility, if done

                                      14 Report when study was done, including beginning and ending dates of recruitment

                                      15 Does the study report clinical and demographic characteristics of the study population (e.g. age, sex, spectrum of presenting symptoms, comorbidity, current treatments, recruitment centres?

                                      16 Does the study report the number of participants satisfying the criteria for inclusion that did or did not undergo the index tests and/or the reference standard; describe why participants failed to receive either test (a flow diagram is strongly recommended)

                                      17 Does the study report time interval from the index tests to the reference standard, and any treatment administered between?

                                      18 Does the study report distribution of severity of disease (define criteria) in those with the target condition; other diagnoses in participants without the target condition?

                                      19 Does the study report a cross tabulation of the results of the index tests (including indeterminate and missing results) by the results of the reference standard; for continuous results, the distribution of the test results by the results of the reference standard?

                                      20 Does the study report any adverse events from performing the index tests or the reference standard?

                                      21 Does the study report estimates of diagnostic accuracy and measures of statistical uncertainty (e.g. 95% confidence intervals)?

                                      22 Does the study report how indeterminate results, missing responses and outliers of the index tests were handled?

                                      23 Does the study report estimates of variability of diagnostic accuracy between subgroups of participants, readers or centres?

                                      24 Does the study report estimates of test reproducibility?

                                      25 Does the study discuss the clinical applicability of the study findings?


                                      Diagnostic accuracy; nutritional status; colorectal cancer; nutritional assessment tools

                                      © 2013 by Lippincott williams & Wilkins, Inc.