Table 5

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

Person-yearsScores 47–57Multivariate-adjusted RR (95% CI)Scores ≥57Multivariate-adjusted RR (95% CI)
Reference: never smokers2356541.00221.00
Smoking status
Past smokers1191351.35 (0.78 to 2.35)111.21 (0.51 to 2.87)
Current smokers805191.27 (0.68 to 2.39)162.72 (1.15 to 6.42)
 1–14 cigarettes/day32870.93 (0.35 to 2.47)51.95 (0.57 to 6.69)
 ≥15 cigarettes/day477121.55 (0.73 to 3.28)113.48 (1.24 to 9.77)
 p for trend0.1460.017
Duration, years
 <251680421.32 (0.80 to 2.19)131.15 (0.50 to 2.62)
 ≥25316121.30 (0.61 to 2.79)144.29 (1.65 to 11.18)
 p for trend0.2590.005
Pack-years
 <201453331.19 (0.69 to 2.03)110.94 (0.38 to 2.30)
 ≥20543211.61 (0.85 to 3.06)163.86 (1.62 to 9.19)
 p for trend0.5920.030
  • * 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.