Ambulatory pulse oximetry monitoring in Japanese COPD outpatients not receiving oxygen therapy

Table 5 Multivariate Cox proportional hazards analysis of relationships between variables and exacerbation in ex-/non-smokers (n = 39)

Variable	Risk ratio	95% CI	p
Age-adjusted Charlson Comorbidity Index	0.96	0.67 – 1.37	0.82
Body mass index	0.88	0.72 – 1.06	0.18
CAT score	1.08	0.99 – 1.18	0.10
%FEV₁	0.99	0.95 – 1.02	0.45
Daytime proportion of SpO₂ values < 90%	1.00	0.84 – 1.18	0.97
Nighttime proportion of SpO₂ values < 90%	0.99	0.92 – 1.05	0.68

CAT, Chronic obstructive pulmonary disease assessment test; CI, confidence interval; FEV₁, forced expiratory volume in one second; SpO₂, Oxygen saturation by pulse oximetry.

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