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.
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
The diagnostic accuracy of the index tests will be compared against either PG-SGA or SGA.
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.
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.
The search strategy aims to find both published and unpublished studies.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:
Diagnostic test accuracy
Positive predictive value
Negative predictive value
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.
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.
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.
Conflicts of interest
We express our appreciation to the late Dr. Yash Kumarasamy, whose contribution to this work was of great significance.
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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?
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?