Table 3– Hazard ratio (HR) of pulmonary thromboembolism risk associated with the number of emergency room visits and admissions due to asthma exacerbation

	Pulmonary embolism	Crude HR	p-value for trend	Adjusted^# HR	p-value for trend
Nonasthma	23	1 (Reference)		1 (Reference)
Emergency room visits per year			<0.0001		<0.0001
1–2	5	1.17 (0.45–3.08)		1.23 (0.46–3.25)
3–4	4	7.36 (2.55–21.3)***		7.28 (2.50–21.3)***
≥4	10	10.7 (5.08–22.5)***		8.39 (3.92–18.0)***
Admissions per year			<0.0001		0.0002
0	15	2.89 (1.51–5.54)**		3.08 (1.59–5.95)**
1–2	4	7.06 (2.44–20.4)***		4.16 (1.39–12.4)*
Admissions and emergency room visits per year			<0.0001		<0.0001
1–2	4	0.94 (0.33–2.72)		0.99 (0.34–2.88)
3–4	4	7.25 (2.51–21.0)***		7.15 (2.45–20.8)***
≥4	11	11.6 (5.64–23.8)***		9.04 (4.31–18.9)***

Data are presented as n or HR (95% CI), unless otherwise stated. ^#: multivariable analysis including age, sex and comorbidities. *: p<0.05; **: p<0.01; ***: p<0.001.