Prognosis

• three or more emergency department visits within the last 6 months ^a
• difficulty performing work or other activities due to physical health within last 4 weeks ^a
• left hospital within 24 hours without achieving 50% predicted PEFR ^a
• hospital admission within 12 months ^b

Why?

Frequent emergency department visits, leaving hospital before full recovery and symptoms on exertion increase the risk of relapse

Patient	Prognostic Factor	Outcome	CER	OR (95% CI)	NNF+ (95% CI)
severe asthma exacerbation a    b	more than 3 emergency department visits within last 6 months independent	relapse at 8 weeks	45% (39% to 51%)	2.3 (1.6 to 3.4)	5 (4 to 9)
severe asthma exacerbation a	left before 24 hours without achieving 50% predicted PEFR independent	relapse at 8 weeks	45% (39% to 51%)	2.6 (1.6 to 4.1)	4 (3 to 9)
	difficulty performing work or other activities due to physical health within last 4 weeks independent		45% (39% to 51%)	2.7 (1.6 to 4.3)	4 (3 to 9)

The high the number of risk factors, the greater the risk of relapse

number of risk factors b	% relapse  (95% CI)
3	100%  (79% to 100%)
2	63%  (53% to 73%)
1	32%  (24% to 39%)
0	14%  (3.8% to 26%)