Table 1. Interaction between sleep apnoea and heart failure (HF): arbitrary score weighting the evidence for possible cause–effect relationships in different directions^#

Suggested direction of causal relationship	Pathophysiological evidence	Epidemiological evidence	Clinical evidence	Cumulative score^¶
OSA to HF	2	1	1	4
HF to OSA	3	3	1	7
CSA to HF	2	0	0	2
HF to CSA	3	3	0	6

OSA: obstructive sleep apnoea; CSA: central sleep apnoea. ^#: there are no evidence-based data supporting this arbitrary score, which corresponds to expert opinions as summarised by the authors; ^¶: the individual total of each row.