DRAFT Australian Dietary Guidelines - Eat For Health

Level III-2 - A comparative study with concurrent controls:
Non-randomised experimental trial
Cohort study
Case-control study
Interrupted time series with a control group
Level III-3 - A comparative study without concurrent controls:
Historical control study
Two or more single arm study
Interrupted time series without a parallel control group
Level IV - Case series with either post-test or pre-test/post-test outcomes
Data was extracted from included studies and assessed for strength of evidence, size of
effect and relevance of evidence according to standardised NHMRC processes [34, 39-41]. The
components of the body of evidence - evidence base (quantity, level and quality of evidence);
consistency of the study results; clinical impact; generalisability; and applicability to the Australian
context) - were rated as excellent, good, satisfactory or poor according to standard NHMRC
protocols [41]. The reviewers then translated the evidence into a draft body of evidence
statement. The draft Evidence Statements were graded A to D according to standard NHMRC
protocols [41] where:
Grade A indicates that the body of evidence can be trusted to guide practice
Grade B indicates that the body of evidence can be trusted to guide practice in most
situations
Grade C indicates that the body of evidence provides some support for the
recommendations but care should be taken in its application
Grade D indicates that the body of evidence is weak and any recommendation must be
applied with caution.
In order to reduce potential risks associated with advice being based on findings of single or only a
few studies, the Working Committee and DAA Contractors advised that a minimum of five quality
studies were required before a graded draft evidence statement could be made. The individual
studies in included meta-analysis studies were considered as separate studies.
Once the Evidence Statements and Grades had been drafted the NHMRC commissioned a
methodologist through the NHMRC methodologist panel, Ms Phillippa Middleton from the
University of Adelaide, to assist the Working Committee to ensure that the review activities had
been undertaken in a transparent, accurate and unbiased manner. The methodologist and the
Working Committee scrutinised each step of the review process by accessing the original papers
and reviewing the rating of evidence components, and the wording and grading of each draft
Evidence Statement. As a result, some Evidence Statements and Grades were amended using a
Working Committee consensus approach, and the final Evidence Statements and Grades were
agreed.
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