Hemosiderin in sputum macrophages may predict infective exacerbations of chronic obstructive pulmonary disease: a retrospective observational study

Table 3 Negative binomial regression model

Coefficients	Estimate	z	P-value	95% CI	Rate ratio	95% CI
Intercept	−0.65	−1.53	0.13	−1.54–0.13	0.52	0.21–1.14
% Hemosiderin +	0.04	5.26	<0.0001	0.02–0.05	1.04	1.02–1.05
Absolute Neutrophils (×10⁶/g)	0.04	1.31	0.19	−0.02–0.09	1.04	0.98–1.09
Smoking Moderate	0.09	0.28	0.78	−0.59–0.76	1.10	0.56–2.13
Smoking Many	−0.95	−1.84	0.07	−1.99–0.02	0.39	0.14–1.02
FEV₁ %Predicted	−0.01	−0.96	0.34	−0.03–0.01	0.99	0.97–1.01

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