Table 3.

Overall Adjusted Odds Ratio (aOR) for the Risk Factors for COPD of Different Severity: Mild (GOLD Grade 1) and Moderate-Severe (GOLD Grade 2–4)

	Mild COPD (GOLD Grade 1) aOR	Moderate-to-Severe COPD (GOLD Grade 2–4) aOR
Age, years	1.99 (1.80, 2.20)	2.22 (1.87, 2.63)*
Asthma (Y vs N)	2.69 (2.01, 3.59)	5.22 (3.54, 7.70)*
Childhood hospitalization (Y vs N)	1.89 (1.21, 2.94)	3.07 (2.02, 4.66)
Ever-smoker status (Y vs N)	1.65 (1.33, 2.05)	3.05 (2.24, 4.16)
Lifetime tobacco exposure, pack-years#	1.18 (1.10, 1.28)	1.36 (1.25, 1.48)*
Smoking status (current vs former)	2.34 (1.67, 3.29)	4.09 (2.78, 6.01)

Notes: GOLD Grades are defined as GOLD 1 = FEV1/FVC < 0.7 and FEV1% predicted ≥80%; GOLD 2 = FEV1/FVC < 0.7 and FEV1% predicted ≥50% and <80%; GOLD 3 = FEV1/FVC < 0.7 and FEV1% predicted ≥30% and <50%; GOLD 4 = FEV1/FVC < 0.7 and FEV1% predicted <30%. *Indicates presence of significant site heterogeneity. ^#Pack years = (number of cigarettes per day/20) × number of years smoked. Separate models were constructed for each risk factor. Age adjusted for school years and ever-smoking history. Asthma adjusted for age, school years, and ever-smoking history. Childhood hospitalization adjusted for age, school years, and ever-smoking history. Ever-smoker status adjusted for age and school years. Lifetime tobacco exposure adjusted for age and school years. Smoking status adjusted for age and school years.

Abbreviation: aOR, overall adjusted odds ratio for men and women.