The committee was consulted about any uncertainty regarding inclusion or exclusion. The key population inclusion criterion was: Adults (18 and older) with symptoms or a diagnosis of chronic heart failure (including heart failure with reduced ejection fraction and heart failure with preserved ejection fraction) The key population exclusion criterion was: Diagnostic screening for heart failure in people who are asymptomatic. People with isolated right heart failure. Heart failure in people having chemotherapy. Heart failure in people having treatment for HIV. Heart failure in women who are pregnant. Chronic Heart Failure Methods NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 Conference abstracts were not included in any of the reviews. Literature reviews, posters, letters, editorials, comment articles, unpublished studies and studies not in English were excluded. 4.3.1.1 Saturation of qualitative studies Data extraction in qualitative reviews is a thorough process and may require more time compared to intervention reviews. It is common practice to stop extracting data once saturation has been reached. This is the point when no new information emerges from studies that match the review protocol. The remaining identified studies are, however, not directly excluded from the review as they nevertheless fit the criteria defined in the review protocol. Any studies for which data were not extracted due to saturation having been reached, but that fit the inclusion criteria of the protocol, were listed in the table for studies identified but not included due to saturation in the appendix for the qualitative evidence review. 4.3.2 Type of studies Randomised trials, non-randomised intervention studies, and other observational studies (including diagnostic or prognostic studies) were included in the evidence reviews as appropriate. 