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Table 2 Smoking amounts of COPDs and controls in the included studies.

From: Nicotinic acetylcholine receptor variants associated with susceptibility to chronic obstructive pulmonary disease: a meta-analysis

Study and reference

Pack-years of smoking

 

Controls (N)

COPDs (N)

Bergen cohort from Pillai et al [26]

19 ± 13*(810)

32 ± 19*(823)

Copenhagen City Heart Study from Kaur-Knudsen et al [25]

NR

NR

COPDGene study from Kim et al [24]

52 ± 29*(335)

37 ± 19*(507)

COPACETIC cohort from Lambrechts et al [23]

38.0 (28.0-46.2) (295)

38.7 (29.7-49.5)(161)

LEUVEN cohort from Lambrechts et al [25]

42.3 (30.0-50.5) (184)

40.0 (30.0-57.0) (475)

NETT/NAS cohorts from Pillai et al [26]

40 ± 28*(472)

66 ± 30*(389)

New Zealand study from Young et al [27]

40 ± 19*(488)

47 ± 20*(458)

  1. Abbreviations: Data were presented as median (25th - 75th percentiles) for COPACETIC and LEUVEN cohorts, and as mean ± SD for other studies. NR, not reported; COPD, chronic obstructive pulmonary disease, defined by spirometric results; * p < 0.05