The burden of adult asthma in Finland: impact of disease severity and eosinophil count on health care resource utilization

Figures & data

Table 1. Baseline characteristics by asthma severity and eosinophil status.

	Asthma severity^a			Blood eosinophil count^b
	Non-severe asthma	Transitioning asthma	Severe asthma	≥300 cells/μL	<300 cells/μL	Unknown
	N = 13,157	N = 853	N = 388	N = 1434	N = 2347	N = 10,617
Age, years, mean (SD)	49 (23)	55 (18)	60 (18)	55 (19)	55 (20)	48 (23)
Male, n (%)	4937 (38)	248 (29)	119 (31)	523 (36)	655 (28)	4126 (39)
BMI, kg/m^2
n (%)	4627 (38)	413 (48)	159 (41)	586 (41)	925 (39)	3688 (35)
Mean (SD)	27.8 (5.9)	27.6 (5.7)	28.3 (5.9)	27.4 (5.6)	28.1 (5.9)	27.8 (5.9)
Lung function, mean (SD)
Pre-bronchodilator FEV1 (relation to reference)
n (%)	4622 (35)	413 (48)	159 (41)	586 (41)	923 (39)	3685 (35)
Mean (SD)	0.8 (0.2)	0.8 (0.2)	0.8 (0.2)	0.8 (0.2)	0.8 (0.2)	0.8 (0.2)
Post-bronchodilator FEV1 (relation to reference)
n (%)	2726 (21)	216 (25)	92 (24)	319 (22)	526 (22)	2189 (21)
Mean (SD)	0.9 (0.2)	0.8 (0.2)	0.8 (0.2)	0.8 (0.2)	0.8 (0.2)	0.9 (0.2)
Charlson comorbidity index, mean (SD)	1.5 (1.0)	1.3 (0.8)	1.7 (1.3)	1.6 (1.2)	1.6 (1.2)	1.4 (1.0)
Follow-up years, mean (SD)	5.2 (3.5)	7.2 (3.3)	4.7 (3.4)	6.8 (3.4)	6.2 (3.4)	4.9 (3.5)

^a Baseline characteristics are presented for three groups: non-severe (patients who had non-severe asthma at index and throughout follow-up); transitioning (patients who had non-severe asthma at index but presented with severe asthma during follow‐up); severe (patients who had severe asthma at index and throughout follow-up). Baseline characteristics were recorded at index date for all patients.

^b Blood eosinophil count categories: <300 cells/μL (throughout the follow-up period); ≥300 cells/μL (at any time during the follow-up period); unknown (no blood eosinophil count available).

BMI: body mass index; FEV₁: forced expiratory volume in 1 s; SD: standard deviation.

Figure 1. HCRU per patient year by (A) asthma severity* and (B) blood eosinophil count^†. *Patients were divided into two groups according to time spent in the non-severe and severe categories. ^†Blood eosinophil count categories: <300 cells/μL (throughout the follow-up period); ≥300 cells/μL (at any time during the follow-up period); unknown (no blood eosinophil count available). Severe eosinophilic asthma was defined as severe asthma with a blood eosinophil count of ≥300 cells/μL. ^‡Outpatient visits include scheduled and ER outpatient visits and scheduled telephone calls from which data were recorded in the patient files. BEC: blood eosinophil count; HCRU: health care resource utilization; ER: emergency room.

Figure 2. Annual HCRU from index date to Year 5 of follow-up in patients according to asthma severity. *Patients were divided into two groups according to time spent in the non-severe and severe categories. HCRU: health care resource utilization.

Table 2. HCRU-Associated total and asthma-related costs by asthma severity and blood eosinophil count.

	Asthma severity^a		Blood eosinophil count^b			Asthma severity and eosinophil status
	Non-severe asthma N = 14,010	Severe asthma N = 1241	≥300 cells/μL N = 1434	<300 cells/μL N = 2347	Unknown N = 10,617	Severe eosinophilic asthma^c N = 270
Costs per patient, €
Total	9515	13,761	24,147	18,228	6841	27,142
Asthma-related	387	998	1026	823	306	1870
Costs per patient year, €
Total	1878	3147	3527	2952	1392	5143
Asthma-related	76	228	150	133	62	354
Total cost, €
Total	133,300,673	17,077,985	34,626,470	42,782,262	72,635,326	7,328,323
Asthma-related	5,422,075	1,237,920	1,471,365	1,930,660	3,251,360	504,890

^a Patients were divided into two groups according to time spent in the non-severe and severe categories.

^b Blood eosinophil count categories: <300 cells/μL (throughout the follow-up period); ≥300 cells/μL (at any time during the follow-up period); unknown (no blood eosinophil count available).

^c Severe eosinophilic asthma was defined as severe asthma with a blood eosinophil count of ≥300 cells/μL.

Total costs were based on visits, outpatient/ER visits, inpatient days, procedures, laboratory measures and surgeries; asthma-related costs were based on visits, outpatient/ER visits and inpatient days.

ER: emergency room; HCRU: health care resource utilization.

Figure 3. Overall survival by (A) asthma severity* and (B) blood eosinophil count^† and competing risk models for non-asthma and asthma-related mortality by (C) asthma severity* and (D) blood eosinophil count^†. *Patients were divided into two groups by baseline disease severity status: non-severe and severe. ^†Blood eosinophil count categories: <300 cells/μL (throughout the follow-up period); ≥300 cells/μL (at any time during the follow-up period); unknown (no blood eosinophil count available). BEC: blood eosinophil count.

Figure 4. Cox regression models of all-cause mortality by disease severity* and patient characteristics. *To account for patients with transitioning asthma (non-severe asthma at index but presented with severe asthma during follow‐up), severity was modeled as a time-varying covariate. CI: confidence interval; BEC: blood eosinophil count; FEV_1: forced expiratory volume in 1 s; PEF: peak expiratory flow.

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