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Table 2 Best Practice Guidelines for dietary assessment in health research

From: DIET@NET: Best Practice Guidelines for dietary assessment in health research

E/Da Stage I. Define what you want to measure in terms of dietary intake: the key a priori considerations to guide your choice of the appropriate type of dietary assessment tool (DAT)
  1 What? — Characteristics of the main dietary component of interest
E 1.1 Clearly define what needs to be measured (e.g. intake of energy, food groups, specific or a range of macro- or micro-nutrients)
E 1.2 Determine how the dietary data will be analysed and presented (e.g. total daily or meal level intakes, food groups or nutrients)
  2 Who? — Considerations around the characteristics of study participants
E 2.1 Define the target sample in terms of characteristics (e.g. life stage, ethnicity, health status, body mass index (BMI), socio-economic level, country/region and setting — home, school, hospital)
E 2.2 Identify other issues that could affect the choice of DAT (e.g. literacy, numeracy, language, cultural, disability, time or familiarity with technology)
E 2.3 Consider the study sample size required in relation to the level of variation of your dietary component of interest and study power
  3 When? — Time frame considerations
E 3.1 Are you interested in ‘actual’/short-term (hours or several days, up to one week) or ‘usual’/long-term intake (e.g. months or years)? Consider what reference period (e.g. daily, weekly, monthly, yearly) would be best suited to your dietary component of interest
E 3.2 Will data collection in your study be retrospective or prospective?
  Stage II. Investigate the different types of DATs and their suitability for your research question
  4 Consider and appraise the different DAT types
E 4.1 In relation to your research question, consider the suitability, strengths and weaknesses of different DAT typesb
E 4.2 Think about participant burden (e.g. study participants’ potential willingness, time, ability, ethical considerations, interest in using different tools and access issues associated with different DATs)
E 4.3 Identify the availability of resources (e.g. staff skill, time, finances)
  Stage III. Evaluate existing tools to select the most appropriate DAT
  5 Research and evaluate available tools of interest
E 5.1 Read any available published validation studies:
   • Has the DAT been evaluated to measure the dietary component you are interested in?
   • Has the DAT been evaluated in a population similar to your population of interest?
   • Is the nutrient database used appropriate?
   • Are the portion sizes used relevant?
D 5.2 Assess the quality of validation in terms of:
   • Has the DAT been compared to an objective method (e.g. biomarkers)?
   • Has the DAT been compared to a subjective method (e.g. a different self-reported diet assessment)?
   • What were the limitations of the validation study?
D 5.3 The strength of agreement between the two methods:
   • Is there any evidence of bias; do the methods agree on average?
   • Is there any evidence of imprecision; how closely do the methods agree for an individual?
  6 If, based on the validation studies, none of the existing DATs is entirely or wholly suitable, consider the need to modify or update an existing DAT, or create a new DAT and evaluate it
E 6.1 Decide whether an existing tool can be improved. Investigate whether:
   • Foods and portion sizes included are characteristic of your target population, and frequency categories are appropriate
   • The time period that the questionnaire refers to could be modified to better suit your needs
D 6.2 Consider the face validity of existing tools. Is there evidence the tool has been used to measure dietary intake in your population of interest?
D 6.3 Updated or modified tools may require re-evaluation. Consider if validation can be integrated into your study
  Select your DAT
  Stage IV. Think through the implementation of your chosen DATs
  7 Consider issues relating to the chosen DAT and the measurement of your dietary component of interest
E 7.1 Obtain information regarding DAT logistics (e.g. tool manual, relevant documents and other requirements from the DAT developer)
E 7.2 Check that the chosen DAT has the most appropriate food/nutrient database and software
E 7.3 Check the requirements for dietary data collection (e.g. entry, coding and software)
D 7.4 Consider collecting additional related data (e.g. was intake typical, supplement use)
  8 Prepare an implementation plan to reduce potential biases when using your chosen DAT
E 8.1 Consider potential sampling/selection bias and track non-participation/dropout/withdrawal at different stages
E 8.2 Minimise interviewer bias (e.g. ensure staff qualifications and training are appropriate, develop standardised training protocols and monitoring procedures)
E 8.3 Minimise respondent biases (e.g. use prompts, clear instructions)
E 8.4 Quantify misreporting
  1. aGuidelines which achieved > 70% as essential were defined as Essential guidelines (E), whilst those achieving lower scores were defined as Desirable guidelines (D)
  2. bSee Additional file 1: Table S1 for DATs’ strengths and weaknesses