UWL: Screening and Assessment Methods (2009)
Kruizenga HM, Seidell JC, de Vet HC, Wierdsma NJ, van Bokhorst-de van der Schueren MA. Development and validation of a hospital screening tool for malnutrition: The short nutritional assessment questionnaire (SNAQ). Clin Nutr. 2005 Feb; 24(1): 75-82. PMID: 15681104PubMed ID: 15681104
Development, diagnostic value and reproducibility of the short nutritional assessment questionnaire (SNAQ).
Development (Population A)
Admitted to mixed internal ward (internal medicine, gastroenterology, dermatology, nephrology) and mixed surgical ward (general surgery and surgical oncology) of the VU University medical center between April 2002 and October 2002.
Validation (Population B)
Admitted to same wards between February 2003 and June 2003.
Same for development (population A) and validation (population B) phases:
- Patients who were not able to give informed consent
- Patients who could not be weighed
- Patients who were younger than 18 years of age.
- On the day of admission to the hospital:
- Weight was obtained (SECA 880 calibrated scale); height was asked for and measured if not known using a SECA 220
- Asked whether they had lost weight unintentionally over the last six months
- Completed a detailed questionnaire on symptoms and risk factors of malnutrition (26 nutrition-related questions adopted from the quality of life questionnaires EORTC-C30 and EORTC H&N 35, and from complex screening instruments (Nutricia Nutritional Screening List, Mini Nutritional Assessment, Subjective Global Assessment)
- Severely malnourished; had one or more of the following conditions: a BMI less than 18.5, unintentional weight loss of more than 5% in the last month or more than 10% in the last six months
- Moderately malnourished patients had lost 5% to 10% of their weight unintentionally in the last six months
- On the day of admission to the hospital:
- Statistical Analysis:
- Selection of questions to make up the SNAQ was conducted in three phases:
- First, the odds ratio was calculated for each question of the questionnaire with the presence or absence of malnutrition as dependent variable. All questions with a statistically significant odds ratio (P<0.05) were included in the next phase.
- Second, the logistic regression was carried out with the presence or absence of malnutrition as dependent variable and with questions with a significant odds ratio as independent variables. The questions associated with malnutrition at a significance level of P<0.05 in a backward stepwise procedure were selected for the next phase of the analysis.
- Third, multinomial logistic regression was carried out with severe malnutrition, moderate malnutrition and no malnutrition as the dependent variable and the questions from phase two as the independent variables using P<0.05 as selection criterion. This model contained all the final selected items together.
- Selection of questions to make up the SNAQ was conducted in three phases:
- Upon admission to the hospital, the nurse filled out the SNAQ for every patient
- Patients who were classified as moderately or severely malnourished following the SNAQ score (two points or more) received energy- and protein-enriched meals and a nutritious snack
- Patients who were classified as severely malnourished (three points or more) received, besides the energy- and protein-enriched meals and snacks, treatment by a dietitian (who was not involved in the study)
- The dietitian scored the referrals based on the SNAQ score as "very necessary," "moderately necessary" or "not necessary"
- The measurement and the definition of nutritional status were identical to the procedure during the design phase of the study
- Statistical Analysis:
- The validity of the SNAQ in population B is expressed in the sensitivity, specificity and the negative and positive predictive value
- To measure the cross-validity of the SNAQ, a receiver-operator characteristic (ROC) curve was constructed to present the relationship of the SNAQ score with the definition of malnutrition. ROC curves characterize the relationship between the true positive rate (sensitivity) and the false positive rate (one-specificity)
- The specificity of a test is the probability (zero percent to 100%) that the SNAQ score is less than two points for well-nourished patients
- The sensitivity is the probability (zero percent to 100%) that the SNAQ score is two points or more for moderately malnourished patients and three points or more points for severely malnourished patients
- The area under the curve (AUC) quantifies the validity of the SNAQ; the greater the AUC, the better the performance of the SNAQ. It varies between 0.5, when the SNAQ is no better than the chance in correctly categorizing the two groups, and 1.0 when its sensitivity and specificity are perfect.
- To measure the inter-observer agreement of the SNAQ, it was filled out for 47 patients by two nurses and for another 47 patients by a nurse and a dietitian. The inter-observer agreement was tested with the kappa (K) and the 95% confidence interval (CI) (K±1.96 SE).
Timing of Measurements
Measurements occurred on the day of admission for both phases.
- Variable One: Presence of malnutrition (measured using SNAQ)
- Variable Two: Sensitivity (ROC curve)
- Variable Three: Specificity (ROC curve)
- Variable Four: Positive predictive value
- Variable Five: Negative predictive value.
Questions with a significant odds ratio (final questions selected for the SNAQ):
- Did you lose weight unintentionally?
- More than 6.0kg in the last six months?
- More than 3.0kg in the last month?
- Did you experience a decreased appetite over the last month?
- Did you use supplemental drinks or tube feeding over the last month?
Development study, N=291; Validation study, N=297
oncological ward (N) (% internal)
VU University Medical Center, Amsterdam, The Netherlands,
Selection of questions for SNAQ:
- 17 questions showed statistically significant odds ratios
- From these, seven remained in the binary logistic regression analyses of the second phase
- Third and last phase of multinomial logistic regression, based on a significant Wald-test, resulted in the final selection of the four questions for the SNAQ
- These were "Did you lose weight unintentionally? More than 6.0kg in the in the last six months (three points) or more than 3.0kg in the last month" (two points), "Did you experience a decreased appetite over the last month?" (one point), "Did you use supplemental drinks or tube feeding over the last month?" (one point)
- Patients with less than 2 points were classified as well nourished. Patients with two points were classified as moderately malnourished and patients with three points or more were classified as severely malnourished.
Questionnaire validation study:
In population B, both sensitivity and specificity proved to be more than 75% for both cut-off points. The ROC curve of the moderately and severely malnourished patients (cut-off point, two or more) shows an area under the curve of 0.85 (95% CI 0.79 to 0.90; P<0.0001). The area under the curve for the severely malnourished patients (cut-off point, three or more) was similar (AUC=0.85; 95% CI=0.79 to 0.90; P<0.0001).
Dietary intervention based on the SNAQ score:
- 89 patients were treated by a dietitian based on the SNAQ score
- In 89% of the cases (79 patients), the dietitian scored the consultation as very necessary, in 7% (six patients) as moderately necessary and in 4% (four patients) as not necessary
- All patients scored by the dietitian as 'not necessary' were indeed well nourished following the objective criteria.
Reproducibility of SNAQ:
- The kappa (K) of the SNAQ score, an indicator for the nurse-nurse reproducibility in 47 patients, was 0.69 (95% CI: 0.45 to 0.94) (seven patients were classified in different categories)
- The K of the SNAQ score in 47 patients by a nurse and a dietitian was 0.91 (95% CI, 0.80 to 1.03). (Three patients were classified differently.)
The SNAQ proves to be a valid and reproducible instrument to detect and treat malnourished hospital patients in an early stage of hospitalization without the need to calculate percentage weight loss or BMI. The SNAQ and its linked treatment plan is, therefore, a very practical instrument that can easily be used in all Dutch hospitals and on all medical wards with adult patients, even if nurses are not focused on inquiring specific details of nutritional status.
|Other:||the Society of University Hospitals of the Netherlands|
Regarding clinical significance, it is important to note that patients who scored two points still received intervention (enriched meals and snacks and extra attention of the nutritional assistant on the ward). Not all hospitals have this automatic system in place nor do they have a nutrition assistant or equivalent covering a single ward. In some hospitals, dietitians fill some of the roles of a "nutrition assistant" in addition to the traditional role of the dietitian.
Would the system of automatic intervention without an RD assessment be supported by JCAHO?
The impact on clinical outcomes were published in a later study.
Quality Criteria Checklist: Primary Research
|1.||Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)||Yes|
|2.||Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?||Yes|
|3.||Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?||Yes|
|4.||Is the intervention or procedure feasible? (NA for some epidemiological studies)||Yes|
|1.||Was the research question clearly stated?||Yes|
|1.1.||Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?||Yes|
|1.2.||Was (were) the outcome(s) [dependent variable(s)] clearly indicated?||Yes|
|1.3.||Were the target population and setting specified?||Yes|
|2.||Was the selection of study subjects/patients free from bias?||Yes|
|2.1.||Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?||Yes|
|2.2.||Were criteria applied equally to all study groups?||Yes|
|2.3.||Were health, demographics, and other characteristics of subjects described?||Yes|
|2.4.||Were the subjects/patients a representative sample of the relevant population?||Yes|
|3.||Were study groups comparable?||Yes|
|3.1.||Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)||N/A|
|3.2.||Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?||Yes|
|3.3.||Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)||N/A|
|3.4.||If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?||Yes|
|3.5.||If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)||N/A|
|3.6.||If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?||N/A|
|4.||Was method of handling withdrawals described?||N/A|
|4.1.||Were follow-up methods described and the same for all groups?||N/A|
|4.2.||Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)||N/A|
|4.3.||Were all enrolled subjects/patients (in the original sample) accounted for?||N/A|
|4.4.||Were reasons for withdrawals similar across groups?||N/A|
|4.5.||If diagnostic test, was decision to perform reference test not dependent on results of test under study?||N/A|
|5.||Was blinding used to prevent introduction of bias?||Yes|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||N/A|
|5.2.||Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)||Yes|
|5.3.||In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?||Yes|
|5.4.||In case control study, was case definition explicit and case ascertainment not influenced by exposure status?||N/A|
|5.5.||In diagnostic study, were test results blinded to patient history and other test results?||N/A|
|6.||Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?||Yes|
|6.1.||In RCT or other intervention trial, were protocols described for all regimens studied?||N/A|
|6.2.||In observational study, were interventions, study settings, and clinicians/provider described?||N/A|
|6.3.||Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?||Yes|
|6.4.||Was the amount of exposure and, if relevant, subject/patient compliance measured?||N/A|
|6.5.||Were co-interventions (e.g., ancillary treatments, other therapies) described?||N/A|
|6.6.||Were extra or unplanned treatments described?||N/A|
|6.7.||Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?||N/A|
|6.8.||In diagnostic study, were details of test administration and replication sufficient?||N/A|
|7.||Were outcomes clearly defined and the measurements valid and reliable?||Yes|
|7.1.||Were primary and secondary endpoints described and relevant to the question?||Yes|
|7.2.||Were nutrition measures appropriate to question and outcomes of concern?||Yes|
|7.3.||Was the period of follow-up long enough for important outcome(s) to occur?||Yes|
|7.4.||Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?||Yes|
|7.5.||Was the measurement of effect at an appropriate level of precision?||Yes|
|7.6.||Were other factors accounted for (measured) that could affect outcomes?||Yes|
|7.7.||Were the measurements conducted consistently across groups?||Yes|
|8.||Was the statistical analysis appropriate for the study design and type of outcome indicators?||Yes|
|8.1.||Were statistical analyses adequately described and the results reported appropriately?||Yes|
|8.2.||Were correct statistical tests used and assumptions of test not violated?||Yes|
|8.3.||Were statistics reported with levels of significance and/or confidence intervals?||Yes|
|8.4.||Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?||N/A|
|8.5.||Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?||Yes|
|8.6.||Was clinical significance as well as statistical significance reported?||Yes|
|8.7.||If negative findings, was a power calculation reported to address type 2 error?||N/A|
|9.||Are conclusions supported by results with biases and limitations taken into consideration?||Yes|
|9.1.||Is there a discussion of findings?||Yes|
|9.2.||Are biases and study limitations identified and discussed?||Yes|
|10.||Is bias due to study's funding or sponsorship unlikely?||Yes|
|10.1.||Were sources of funding and investigators' affiliations described?||Yes|
|10.2.||Was the study free from apparent conflict of interest?||Yes|