Risk of deep vein thrombosis and pulmonary embolism in asthma

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Figure 1–
Flow diagram of study patients.
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Figure 2–
Cumulative hazards for a) venous thromboembolism, b) pulmonary embolism, and c) deep vein thrombosis in asthma of different severities and the general population. Data for the general population was obtained from Naess et al. [12].

Table 1– Baseline characteristics

	Mild-to-moderate asthma	Severe asthma
Patients n	365	283
Age years	50 (18–88)	51 (17–77)
Female sex	58	61
BMI kg·m⁻²	28 (17–45)	27 (18–59)
Age of asthma onset years^#	39 (0–78)	27 (0–70)
Duration of asthma years^#	5.0 (0.1–78)	20 (0.1–76)
Atopy	42	49
Smoking history^#
Never-smoker	52	64
Ex-smoker	40	33
Current smoker	8	3
Severe exacerbations in previous year
<1 per year	73	28
1–2 per year	19	31
>2 per year	8	41
FEV₁ post-bronchodilator % pred	97.0 (22–146)	84.9 (23.1–133)
ICS dose ≥1000 μg·day⁻¹	0	85
Chronic oral corticosteroid	0	38
Omalizumab	0	7

Data are presented as median (range) or %, unless otherwise stated. BMI: body mass index; FEV₁: forced expiratory volume in 1 s; % pred: % predicted; ICS: inhaled corticosteroid. ^#: data derived from questionnaires; not objectively confirmed in 26 patients.

Table 2– Venous thromboembolic events (VTEs) in study population

	Mild-to-moderate asthma	Severe asthma
Patients	365	283
Total number of person-years	17 914	13 975
Before and after asthma onset
All VTEs	17	18
Only DVT	11	5
PE ± DVT	6	13
Before asthma onset
All VTEs	10	2
Only DVT	8	1
PE ± DVT	2	1
After onset of asthma
All VTEs	7	16
Only DVT	3	4
PE ± DVT	4	12

Table 3– Rate ratios for first pulmonary embolism (PE) and deep vein thrombosis (DVT) events in our asthma population versus the general population

	Mild-to-moderate asthma	Severe asthma
Patients n	365	283
All VTEs (definite and probable)
DVT	1.45 (0.30–4.23)	1.62 (0.44–4.14)
PE	3.56 (0.97–9.12)	8.93 (4.62–15.63)
All definite VTEs
DVT	1.45 (0.30–4.23)	1.21 (0.25–3.55)
PE	2.67 (0.55–7.80)	8.93 (4.62–15.63)

Data are presented as rate ratio (95% CI), unless otherwise stated. VTE: venous thromboembolic event.