Increased Risk of Anemia in Patients with Asthma

Figures & data

Figure 1 Flow diagram for study subject inclusion.

Table 1 Characteristics of Study Subjects

Characteristics	Healthy Adults (n = 1731)	Asthma Patients (n = 1354)
Age group
Adult (≥ 18 and < 65 y)	1657 (95.7)	1009 (74.52)
Elderly (≥ 65 y)	74 (4.3)	345 (25.48)
Sex
Male	634 (36.6)	926 (68.39)
Female	1097 (63.4)	428 (31.61)
Obesity
Non-obese (BMI < 25.0 kg/m^2)	1246 (72.0)	855 (63.15)
Obese (BMI ≥ 25.0 kg/m^2)	485 (28.0)	499 (36.85)

Note: Data are presented as numbers (%).

Abbreviation: BMI, body mass index.

Table 2 The Risk of Anemia According to the Presence of Asthma and Other Potential Risk Factors

Characteristics	Hazard Ratio	95% Confidence Interval	P value
Asthma
Healthy adults	Reference	–
Asthma patients	4.056	2.703–6.087	< 0.001
Age	1.015	1.006–1.026	0.003
Sex
Male	Reference	–
Female	1.028	0.744–1.420	0.877
Obesity
Non-obese (BMI < 25.0 kg/m^2)	Reference	–
Obese (BMI ≥ 25.0 kg/m^2)	0.835	0.604–1.155	0.279

Abbreviation: BMI, body mass index.

Table 3 Age-Stratified Risk of Anemia According to the Presence of Asthma

Groups	Total Number	Number of Anemia Cases	Person-Time, y	Incidence per 1000 Person-Years	Rate Ratio	Unadjusted HR (95% CI)	P value	Adjusted HR^† (95% CI)	P value
Adults (≥ 18 and < 65 y)
Healthy adults	1657	76	4941	15.38	-	Reference		Reference
Asthma patients	1009	122	4359	27.98	1.82	3.71 (2.45–5.60)	<0.001	3.27 (2.12–5.04)	<0.001
Elderly (≥ 65 y)
Healthy adults	74	3	224	13.39	-	Reference		Reference
Asthma patients	345	81	1292	62.69	4.68	4.72 (1.15–19.39)	0.031	5.56 (1.31–23.67)	0.020

Note: ^†Adjusted for age, sex, and obesity.

Abbreviations: CI, confidence interval; HR, hazard ratio.

Table 4 Sensitivity Analysis for the Risk of Persistent Anemia^† According to the Presence of Asthma

Group	Total Number	Number of Persistent Anemia Cases	Unadjusted HR (95% CI)	P value	Adjusted HR ^‡ (95% CI)	P value
Healthy adults	1731	7	Reference		Reference
Asthma patients	1354	67	9.33 (4.28–20.34)	<0.001	9.32 (4.16–20.89)	<0.001

Notes: ^†Two consecutive anemia diagnoses ≥ 3 months apart. ^‡Adjusted for age, sex, and obesity.

Abbreviations: CI, confidence interval; HR, hazard ratio.