Table 4

Causal relationship between surgery and adverse events

	Certainly relevant	Probably relevant	Likely relevant	Unlikely relevant	Irrelevant
Adverse events are obviously caused by external factors	-	-	-	-	+
Adverse events are correlated with surgical treatment at rational time	+	+	+	-	-
Adverse events are correlated with patient diseases	-	-	+	+	+
Adverse events are correlated with suspected postoperative response patterns	+	+/-	+	-	-
After relief of related surgical factors, adverse events alleviate or disappear	+	+	-	-	-
After surgery-related factors worsen, adverse events recur	+	+	-	-	-

To minimise the surgical risk and meet the requirements of laws and regulations, the sponsor will manage the correlations as follows: ‘Irrelevant’ belongs to the irrelevant category, and ‘certainly relevant’, ‘probably relevant’, ‘likely relevant’ and ‘unlikely relevant’ belong to the relevant category.