Table 2

 Comparison of patients with psoriatic arthritis with type I and type II psoriasis

PsA subgroups
Type I psoriasis, n = 354Type II psoriasis, n = 123Comparison (p value)
DMARD, disease-modifying antirheumatic drug; HAQ, Health Assessment Questionnaire; IQR, interquartile range; PsA, psoriatic arthritis.
*Involved joints refer to tender, swollen or damaged joints.
Median (IQR) age at onset of psoriasis (years)20 (12–29)52 (47–59)<0.001 (Mann–Whitney U test)
Median (IQR) age at onset of arthritis (years)31(24–41)51 (45–59)<0.001 (Mann–Whitney U test)
Median (IQR) duration of psoriasis (years)25(15–39)8 (4–14)<0.001 (Mann–Whitney U test)
Median (IQR) duration of arthritis (years)11(5–20)9 (4–14)0.03 (Mann–Whitney U test)
PASI score median (IQR)6.3 (3.1–11.5)4.85 (1.6–9)0.003 (Mann–Whitney U test)
Family history of
    Psoriasis, n (%)196 (55)37 (30)<0.001
    PsA, n (%)32 (9)2 (2)0.007
Joints
    Involved*, median (IQR)9 (4–21)13 (8–22)0.03 (Mann–Whitney U test)
    Damaged, median (IQR)5 (1–15)8 (4–17)0.006 (Mann—Whitney U test)
    Tender, median (IQR)2 (0–6)2 (0–5)0.81 (Mann—Whitney U test)
    Swollen, median (IQR)2 (0–4)1 (0–3)0.20 (Mann—Whitney U test)
    Nail involvement, n (%)299 (85)91 (75)0.02
Onset, n (%)
    Psoriasis before arthritis268 (76)36 (29)Global
    Arthritis before psoriasis28 (8)41 (33)<0.001
    Same time (±1 year)58 (16)46 (38)
    Median (IQR) HAQ1.13 (0.38–1.75)1.38 (0.63–2)0.03 (Mann–Whitney U test)
    Ever used DMARD, n (%)287 (81)99 (80)0.89