Follow-up

• on > 2.5 g of paracetamol a week 
• recently started warfarin-potentiating medication 
• taking more warfarin than prescribed 
• advanced cancer 
• decreased oral intake in the last week 
• acute diarrhoeal illness in the last week 

Why?

Cancer and paracetamol use increase the risk of an INR > 6.0

Outcome b	Risk Factor	PEER	OR (95% CI)	NNH (95% CI)
INR > 6.0	advanced malignancy independent	6%	16.4 (2.4 to 111)	2 (1 to 15)
	newly-started potentiating medication independent	4%	8.5 (2.9 to 24.7)	4 (2 to 11)
	warfarin dose > prescribed independent	3%	8.1 (2.2 to 30)	4 (2 to 17)
	decreased oral intake independent	6%	3.6 (1.3 to 9.7)	8 (3 to 64)
	acute diarrhoeal illness independent	8%	3.5 (1.4 to 8.6)	9 (4 to 48)
	paracetamol dose > 9.1 g per week independent	3%	10.0 (2.6 to 37.9)	3 (2 to 13)
	paracetamol dose 4.6 to 9.0 g per week independent	5%	6.9 (2.2 to 21.9)	4 (2 to 17)
	paracetamol dose 2.2 to 4.5 g per week independent	5%	3.5 (1.2 to 10.0)	9 (3 to 96)