NICE process and methods

11 Reviewing the evidence

11 Reviewing the evidence

The quality of individual pieces of evidence or studies can be assessed using checklists. Appendix 2 gives examples of checklists for assessing the quality of different types of non‑randomised and economic studies.

The criteria that are likely to be the most important indicators of quality should be agreed in advance and be tailored to the question being addressed. These criteria will be useful in guiding decisions about the overall quality of individual studies, and when summarising and presenting the body of evidence. Expert input may be needed to identify the most appropriate quality criteria.

When assessing the quality of evidence being used within effectiveness and economic analyses, the evidence should be assessed for potential bias (size and direction), and by conducting a sensitivity analysis to explore the impact of this where possible. Any analysis should be conducted in accordance with chapter 7 of 'The guidelines manual'.

The assessment of quality of evidence should be presented clearly in the full guidance. Assessment of quality will require input from experts to ensure that the study is assessed properly; these could include statisticians, epidemiologists and clinicians.

Appropriate methods should be used to present evidence. A GRADE-like approach (see appendix K of 'The guidelines manual') can be used if it is considered to add value to the presentation of the evidence.

Along with the presentation of the evidence, there should be an accompanying evidence statement to summarise the findings from the key features of the evidence on clinical and cost effectiveness.