Table 3

Age and multivariate-adjusted RR for the association between smoking and the risk of PsA with different severity scores*

Person-yearsScores 47–57Multivariate-adjusted RR (95% CI)Scores ≥57Multivariate-adjusted RR (95% CI)
Reference: never smokers865 189541.00221.00
Smoking status
Past smokers309 749351.61 (1.04 to 2.48)111.34 (0.64 to 2.79)
Current smokers129 032192.30 (1.35 to 3.91)165.34 (2.78 to 10.28)
 1–14 cigarettes/day62 47971.88 (0.85 to 4.16)53.62 (1.36 to 9.65)
 ≥15 cigarettes/day66 553122.64 (1.40 to 4.98)116.81 (3.27 to 14.16)
 p for trend0.002<0.0001
Duration, years
 <25366 471421.80 (1.19 to 2.72)131.43 (0.71 to 2.86)
 ≥2572 310121.80 (0.95 to 3.43)147.89 (3.81 to 16.35)
 p for trend0.002<0.0001
Pack-years
 <20342 974331.54 (0.99 to 2.40)111.32 (0.64 to 2.75)
 ≥2095 807212.47 (1.47 to 4.17)166.05 (3.08 to 11.89)
 p for trend0.001<0.0001
  • * Psoriasis cases with only skin phenotypes were excluded during the follow-up. PsA cases were classified into two groups by the cutoff of scores at 57, picked to include those with the top third of the scores into one category.

  • Adjusted for age (continuous variable), body mass index (<18.5, 18.5–24.9, 25–29.9, 30–34.9 or ≥35 kg/m2), alcohol drinking (no, <4.9, 5.0–9.9, 10–14.9, 15–29.9 or ≥30.0 g/day), vigorous physical activity (metabolic equivalent h/week, in quintiles).

  • PsA, psoriatic arthritis.