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. Author manuscript; available in PMC: 2023 Feb 2.
Published in final edited form as: Br J Nutr. 2021 Sep 16;128(4):721–732. doi: 10.1017/S000711452100372X

Table 4.

Risk of COPD According to Glucosamine Use Within Each Smoking Category

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.

a

Incidence rates are provided per 1000 person-years;

b

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.