Table 4 Odds ratios from multinomial regression analysis of early signs as predictors of respiratory morbidity 5 years later

	Respiratory morbidity† at 5 years (n = 374)
	Mild COPD (12.8%)		Moderate COPD (10.4%)
	OR	Adjusted OR	OR	Adjusted OR
Screening criteria*
Respiratory symptoms‡	1.30 [0.92 to 1.83]	1.41 [0.98 to 2.01]	0.96 [0.66 to 1.42]	0.94 [0.61 to 1.43]
Lung function below normal range§	1.45 [0.74 to 2.86]	1.46 [0.72 to 2.96]	2.02 [1.07 to 3.83]	2.54 [1.25 to 5.19]
Reversibility¶	1.04 [0.38 to 2.88]	1.02 [0.00 to 0.03]	0.56 [0.16 to 1.93]	0.94 [0.25 to 3.49]
Mild early signs**	1.69 [1.13 to 2.54]	1.87 [1.22 to 2.87]	1.97 [1.28 to 3.02]	2.08 [1.29 to 3.37]
Mucus hypersecretion††	1.35 [0.77 to 2.36]	1.17 [0.64 to 2.14]	2.53 [1.52 to 4.19]	1.88 [1.07 to 3.33]
Smoking behaviour
Pack-years (baseline)		0.99 [0.95 to 1.02]		1.05 [1.01 to 1.08]
Not smoking at 5 years		1.23 [0.79 to 1.92]		1.04 [0.56 to 1.90]
Smoking at 5 years		1.53 [0.96 to 2.46]		1.81 [0.99 to 3.30]
Smoking during follow-up		1.31 [0.54 to 3.17]		0.79 [0.21 to 2.96]
Age		1.00 [0.97 to 1.04]		1.06 [1.01 to 1.10]
Gender (female = 1)		0.54 [0.38 to 0.76]		1.13 [0.73 to 1.73]

Values are OR [95% confidence intervals].
*Screening criteria, used to determine the respiratory status of subjects (see table A1 in appendix 1).
†Mild COPD (n = 48), moderate COPD (n = 39).
‡Dutch modified version of the Medical Research Council questionnaire.
§FEV₁/VC ⩽ lower limit of normal.
¶⩾15% predicted.
**Combination of at least two out of three mild early signs (mild obstruction, reversibility, weather dependent or recurrent productive cough).
††Continue production of sputum in winter.
Analysis was restricted to those 374/464 subjects who were free of “obstruction” at baseline. (ORs were adjusted for age, gender, pack-years at baseline and smoking behaviour during follow-up.)
COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; VC, vital capacity.