TABLE 2.

Multivariate, multilevel analysis of factors associated with length of stay longer than the median

Variable	Category		OR (95% CI)
Patient-related variables
Age years			1.01 (1.01–1.02)
Smoking status	Ex-smoker		1
	Active		0.85 (0.78–0.93)
	Never-smoker		0.94 (0.80–1.12)
	Missing		1.08 (0.92–1.28)
Charlson Comorbidity Index score			1.04 (1.01–1.06)
Body mass index kg·m−2	<19.5		1.13 (0.97–1.33)
	19.5–24.99		1
	25–29.99		0.89 (0.79–1.00)
	>29.99		0.88 (0.78–1.00)
	Missing		0.83 (0.74–0.93)
Disease-related variables
Previous admissions	No		1
	Yes		1.15 (1.07–1.24)
	Missing		1.11 (0.96–1.28)
GOLD stage	1		1
	2		1.10 (0.79–1.55)
	3		1.20 (0.86–1.67)
	4		1.77 (1.25–2.49)
	Missing		1.36 (0.97–1.90)
Exacerbation severity-related variables
pH	<7.35		1.25 (1.12–1.40)
	≥7.35		1
	Missing		1.04 (0.93–1.16)
Purulent sputum	No		1
	Yes		1.11 (1.03–1.20)
	Missing		1.05 (0.91–1.20)
Consolidation	No		1
	Yes		1.27 (1.16–1.40)
Treatment-related variables
Invasive mechanical ventilation	No		1
	Yes		2.15 (1.25–3.72)
In-hospital antibiotics	No		1
	Yes		1.46 (1.30–1.64)
In-hospital methylxanthines	No		1
	Yes		1.22 (1.07–1.40)
In-hospital inhaled corticosteroids	No		1
	Yes		1.10 (1.01–1.20)
In-hospital diuretics	No		1
	Yes		1.36 (1.25–1.49)
Radiography performed	No		1
	Yes		1.42 (1.03–1.95)
Resources-related variables
Respiratory ward	Yes		1
	No		1.33 (1.22–1.45)
	Missing		0.38 (0.11–1.32)
Number of respiratory specialists in unit	<6		1
	≥6		1.19 (1.00–1.40)
	Missing		0.68 (0.38–1.24)
Level	Empty model		Final model
	Country	Hospital	Country	Hospital
Intra-class correlation coefficient	0.11	0.19	0.12	0.21
Median odds ratio	0.19	2.31	1.94	2.42

GOLD: Global Initiative for Chronic Obstructive Lung Disease. Wald χ² (35) 1006.00; log likelihood −9562.0768; probability that χ²>0.0000.