Table 3 Single factor analysis.

Description		OR	p Value (Z)
Age at first clinic visit (y)		1.00	0.64
Duration of psoriasis at clinic entry (y)		0.99	0.14
Duration of psoriatic arthritis at clinic entry (years)		0.98	0.035
Family history of psoriasis (yes/no)		0.82	0.25
Family history of psoriatic arthritis (yes/no)		1.30	0.39
ESR at clinic entry (abnormal/normal)		0.80	0.27
Rheumatoid factor at clinic entry (present/absent)		1.12	0.66
Drug treatment
NSAIDs		1	0.66*
DMARDs		0.90
IAS		0.67
None		0.84
Antinuclear antibody (present/absent)		0.85	0.41
Age at onset of psoriasis (y)		1.00	0.43
Age at onset of arthritis (y)		1.01	0.34
History of activity before damage (present/absent)		0.92	0.50
History of effusion before damage (present/absent)		1.12	0.43
Recent history of effusion (present/absent)		1.73	0.002
Current effused joint (yes/no)		1.24	0.16
Duration of psoriasis at time of damage (y)		0.99	0.03
Duration of psoriatic arthritis at time of damage (y)		0.98	0.01
ESR at time of damage (abnormal/normal)		0.88	0.55

*Likelihood ratio test.

ESR, erythrocyte sedimentation rate; IAS, intra‐articular steroids; DMARD, disease modifying antirheumatic drug; NSAID, non‐steroidal anti‐inflammatory drug; OR, odds ratio; y, years.