Table 4.
Subgroup | Total No. of participants | No. of COPD cases (%) | Person-years | IRa | HR (95% CI) b | P value | P for interaction |
---|---|---|---|---|---|---|---|
Smoking status and glucosamine | 0.078 | ||||||
Never smoking | |||||||
Non-user | 216 421 | 1275 (0.59) | 1 920 589 | 0.66 | 1.00 (reference) | - | |
User | 51 434 | 311 (0.60) | 456 567 | 0.68 | 0.84 (0.73 to 0.96) | 0.009 | |
Former smoking | |||||||
Non-user | 131 021 | 3258 (2.49) | 1 144 262 | 2.85 | 1.00 (reference) | - | |
User | 35 250 | 742 (2.10) | 309 753 | 2.40 | 0.84 (0.77 to 0.92) | <0.001 | |
Current smoking | |||||||
Non-user | 43 668 | 3105 (7.11) | 372 512 | 8.34 | 1.00 (reference) | - | |
User | 5909 | 325 (5.50) | 51 008 | 6.37 | 0.71 (0.63 to 0.80) | <0.001 | |
Smoking pack-years and glucosamine | 0.019 | ||||||
None smoking (0) | |||||||
Non-user | 217 369 | 1343 (0.62) | 1 928 471 | 0.70 | 1.00 (reference) | - | |
User | 51 620 | 319 (0.62) | 458 184 | 0.70 | 0.82 (0.72 to 0.94) | 0.003 | |
Hardly ever smoking (0.1–10.0) | |||||||
Non-user | 29 610 | 335 (1.13) | 261 763 | 1.28 | 1.00 (reference) | - | |
User | 7719 | 80 (1.04) | 68 446 | 1.17 | 0.78 (0.68 to 1.02) | 0.065 | |
Light smoking (10.1–20.0) | |||||||
Non-user | 31 668 | 727 (2.30) | 277 697 | 2.62 | 1.00 (reference) | - | |
User | 7473 | 128 (1.71) | 65 765 | 1.95 | 0.70 (0.57 to 0.85) | <0.001 | |
Moderate smoking (20.1–30.0) | |||||||
Non-user | 23 367 | 1059 (4.53) | 202 325 | 5.23 | 1.00 (reference) | - | |
User | 4901 | 154 (3.14) | 42 912 | 3.59 | 0.66 (0.55 to 0.79) | <0.001 | |
Heavy smoking (>30.0) | |||||||
Non-user | 32 130 | 3315 (10.32) | 266 394 | 12.44 | 1.00 (reference) | - | |
User | 5712 | 496 (8.68) | 47 966 | 10.34 | 0.85 (0.77 to 0.94) | 0.002 |
Abbreviations: CI, confidence interval; COPD, Chronic Obstructive Pulmonary Disease; HR, hazard ratio; IR, incidence rate.
Incidence rates are provided per 1000 person-years;
Cox proportional hazards regression adjusted for age, sex, ethnicity, education, household income, body mass index, physical activity, alcohol consumption, fruit consumption, vegetable consumption, passive smoking, occupational exposure, CVD, hypertension, diabetes, cancer, chronic pulmonary infections, rheumatoid arthritis, osteoarthritis, joint pain, asthma, arthritis, cholesterol lowering medication use, anti-hypertensive drug use, insulin use, aspirin use, Non-aspirin NSAIDs use, vitamin use, minerals and other dietary supplements use, chondroitin use, and cortisone use.