Table 5.

Linear mixed effect models of sputum cells

Independent variable	Time interval	B	95% CI	P value
Log (total cells, 106/ml)	0–3 hours	0.075	-0.15–0.30	0.52
Log (neutrophils, % and 106/ml)
%	0–3 hours	-0.17	-0.34 – -0.00	0.07
number	0–3 hours	-0.22	-0.49–0.30	0.11
%	3–12 hours	0.03	-0.02–0.07	0.27
number	3–12 hours	0.13	0.04–0.22	0.007
Log (macrophages, % and 106/ml)
%	0–3 hours	0.12	-0.01–0.25	0.08
number	0–3 hours	0.13	-0.11–0.36	0.31
Log (eosinophils, % and 106/ml)
%	0–6 hours	-0.22	-0.71–028	0.39
number	0–6 hours	-0.12	-0.30–0.06	0.20
%	3–6 hours	-0.84	-3.63–1.96	0.57
number	3–6 hours	-0.31	-1.35–0.73	0.57
Log (lymphocytes, % and 106/ml)
%	0–3 hours	-0.28	-0.59–0.02	0.08
number	0–3 hours	-0.26	-0.42–-0.11	0.004
%	3–12 hours	0.19	0.06–0.31	0.006
number	3–12 hours	0.23	0.09–0.36	0.002

The time intervals of the above parameters were selected based on visual inspection of the plots. The slopes of the parameters were estimated using linear mixed effect models [11] by including the variables time (hours), smoking (yes or no) and their interaction. B: regression coefficient for the variable time (for further information see the method section).