New Zealand Autism Spectrum Disorder Guideline - Ministry of Health

Appendices
The NZGG grading system (information on this system can be found on www.nzgg.org.nz) was used
for developing these ‘strength of evidence’ grades. Prior to this decision being made, Workstream 1
had used the grades applied by the NAPC UK Guideline. These grades were analysed and converted
to NZGG grades, where possible.
The NZGG grading system is a two-tier system with the following steps:
1. Critical appraisal of individual studies
Each relevant study was critically appraised using a checklist and was assigned an overall level of
evidence, indicating whether the study had met most or all of the criteria in the checklist (+), some
of the criteria (~) or very few or none of the criteria (-).
2. Weighing the body of evidence and development of graded recommendations
For each clinical question, the relevant body of evidence summarised in evidence tables was
considered. Decisions were made on the quality (level of evidence), quantity, consistency,
applicability and clinical impact of all the studies forming the body of evidence that were relevant
to each question. Recommendations were developed based on the evidence by the guideline
writers. The recommendations were graded by the following system:
Recommendations:
The recommendation is supported by GOOD evidence (where there are a number of
studies that are valid, applicable and clinically relevant).
The recommendation is supported by FAIR evidence (based on studies that are mostly
valid, but there are some concerns about the volume, consistency, applicability and/or
clinical relevance of the evidence that may cause some uncertainty, but are not likely to
be overturned by other evidence).
The recommendation is supported by EXPERT OPINION only (from external opinion,
published or unpublished, eg, consensus guidelines).
No recommendation can be made. The evidence is insufficient (either lacking, of poor
quality or conflicting, and the balance of benefits and harms cannot be determined).
Grade
A
B
C
I
Appendices
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New Zealand Autism Spectrum Disorder Guideline