Table 3.
Five-year cumulative incidence of moderate chronic obstructive pulmonary disease (COPD: GOLD II) in middle-aged smokers.
| Characteristic | (Participants/n)a | GOLD II (%) | P-valueb |
|---|---|---|---|
| Overall incidence | Total (33/399) | 8.3 | |
| Baseline spirometry | Normal (12/292) | 4.1 | <0.001 |
| GOLD I (21/107) | 19.6 | ||
| Age (years) | 40–44 (3/99) | 3.0 | 0.011 |
| 45–49 (6/97) | 6.2 | ||
| 50–54 (9/108) | 8.3 | ||
| 55–65 (15/95) | 15.8 | ||
| Pack years | <20 (4/109) | 3.7 | 0.011 |
| 20–29 (15/198) | 7.6 | ||
| ≥30 (14/92) | 15.2 | ||
| Family history of obstructive lung disease | Absent (20/238) | 8.4 | 0.9 |
| Present (12/149) | 8.1 | ||
| Parental smoking | Absent (2/40) | 5.0 | 0.4 |
| Present (27/292) | 9.2 | ||
| Childhood smoking | Absent (11/245) | 4.5 | 0.002 |
| Present (22/154) | 14.3 | ||
| Cough | Absent (19/315) | 6.0 | 0.002 |
| Present (14/84) | 16.7 | ||
| ≥1 GP contact for LRT | Absent (21/329) | 6.4 | 0.003 |
| Present (12/70) | 17.1 | ||
a
Participants/n = number of participants with GOLD II/number of participants positive for the characteristic.
b
χ2 test for association or trend. GOLD II = chronic obstructive pulmonary disease stage II according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Pack years = number of packs smoked per day times number of years smoked. LRT = lower respiratory tract problems in the previous 12 months.