Table 1

Characteristics of studies on rheumatoid arthritis and pack-years
Authors, year Study population, country, follow-up period/study period Cases/cohort size or controls Range of exposure pack-years Highest category RR/OR* Highest vs. lowest category§ (95% CI) Controlled variables NOQAS*
Cohort
Criswell et al., 2002 [20] Iowa Women’s Health Study, USA, 1986 to 1997 Women 158/31,336 0 to 50a ≥40 Total 1.7 (1.0 to 3.0) Age, body mass index, alcohol use, coffee consumption, marital status, occupation, age at menopause, use of oral contraceptives and hormone replacement therapy. 8
Costenbader et al., 2006 [4] Nurses’ Health Study, USA, 1976 to 2002 Women 680/103,818 0 to 45a >40 Total 1.86 (1.46 to 2.38) RF +* 2.22 (1.63 to 3.02) RF-* 1.43 (0.96 to 2.12) Age, body mass index, alcohol intake, father’s occupation, age at menarche, menstrual regularity, duration of breastfeeding, postmenopausal hormone use. 8
Di Giuseppe et al., 2013 [5] Swedish mammography cohort, 2003 to 2010 Women 219/34,101 0 to 28b >22 Total 1.82 (1.19 to 2.79) Age, menopause status, parity, alcohol use, educational level, and body mass index. 8
Case-control
Voigt et al., 1994 [16] Population-based controls, USA, 1986 to 1991 Women 349/1,457 0-27a >20 Total 1.49 (1.06 to 2.10) Age, body mass index. 7
Hutchinson et al., 2001 [24] Hospital-based controls, UK Men + Women 239/239 0 to 55a >50 Total 8.41 (2.45 to 28.84) Matched for age, gender and social class. 7
Olsson et al., 2001 [21] Population-based controls, Sweden, 1980 to 1995 Men 91/203 Women 154/222 0 to 27a ≥20 Total men 2.7 (1.2 to 5.8) Total Women 1.8 (0.7 to 4.6) RF + Men 3.4 (1.5 to 8.4) RF + Women 2.5 (0.9 to 6.7) Age, economic status. 7
Stolt et al., 2003 [2] Population-based controls, Sweden, 1996 to 2000 Men + Women 486/724 0 to 25a ≥20 RF + 2.7 (1.8 to 3..9) Age, residential area and gender. 7
Pedersen et al., 2006 [22] Population-based controls, Denmark, 1988 to 2003 Men 149/291 Women 366/478 0 to 25a >20 Total men 2.00 (1.12 to 3.58) Total Women 2.07 (1.35 to 3.16) Birth year, year of RA diagnosis, gender. 7
Mikuls et al., 2010 [14] Population-based controls, US (African Americans) Men + Women 605/255 0 to 15a ≥10 Total 2.37 (1.56 to 3.60) RF + 2.51 (1.63 to 3.87) RF- 1.93 (1.11 to 3.35) Age, gender. 7
Yahya et al., 2012 [23] Population-based controls, Malaysia, 2005 to 2009 Men + Women 1056/1416 0 to 25a ≥20 Total 2.3 (1.0 to 5.5) Matched for age, gender and residential area. Additionally adjusted for formal education and ethnicity. 6

aMidpoint in the lowest-highest category bMedian of the highest category.

§The lowest category corresponded to never smokers in all study except the study of Navarro-Compàn et al., that used <20 pack/years as reference level.

*CI, confidence interval; NOQAS, Newcastle-Ottawa Quality Assessment Scale (score from 0 as poor to 9 as excellent); OR, odds ratio; RF+, rheumatoid factor positive; RF-, rheumatoid factor negative; RR, relative risk.

Di Giuseppe et al.

Di Giuseppe et al. Arthritis Research & Therapy 2014 16:R61   doi:10.1186/ar4498

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