Risk Factors Associated with Irreversible Airway Obstruction in Asthma: A Systematic Review and Meta-Analysis

Table 2

Pooled odds risks (OR) and 95% confidence intervals (CIs) of irreversible airway obstruction asthma and risk factor in cohort or case control study.

Type	Number of studies	OR (95% CI); Fixed effects	OR (95% CI); Random effects
Age	5 (cohort)	1.037 (1.012, 1.062)	1.023 (0.878, 1.192)	92.4% (R)
Male	10 (case control)	2.222 (1.821, 2.731)		53.3% (F)
Age at onset	4 (cohort)	0.971 (0.937, 1.006)	1.166 (0.646, 2.103)	47.2% (R)
Disease duration	5 (cohort)	1.062 (1.038, 1.086)	1.158 (1.026, 1.308)	91.6% (R)
Rhinitis	3 (case control)	0.31 (0.24, 0.40)		0.0% (F)
Atopic dermatitis	2 (cohort)	0.599 (0.424, 0.848)		2.1% (F)
Aspirin sensitivity	2 (cohort)	2.053 (1.417, 2.689)	1.826 (0.263, 12.693)	92.4% (R)
Smoking	9 (case control)	1.79 (1.46, 2.19)	—	38.2% (F)
Sputum eosinophils	2 (cohort)	0.979 (0.937, 1.022)	2.514 (0.334, 18.893)	91.6% (R)
Blood eosinophils	2 (cohort)	2.031 (0.958, 4.304)		32.4% (F)
FENO	2 (cohort)	2.156 (1.050, 4.425)		0.0% (F)
Atopy	8 (case control)	0.584 (0.466, 0.732)	—	22.2 (F)

R: randomised effects; F: fixed effects.