Table 3

Results of factor analyses on all sociodemographic, clinical and self-reported health status variables using varimax rotation

FactorsFactor loading
Factor 1: medication use
    Ever used methotrexate0.98
    Ever used immunosuppressive drugs0.95
Factor 2: disability and impairments
    SF-36 pain−0.85
    HAQ0.62
    Morning stiffness0.46
Factor 3: laboratory parameters of disease activity
    Male sex0.48
    Haemoglobin (g/l)0.95
    ESR (mm/h)−0.62
Factor 4: illness duration
    Duration of arthritis0.96
    Duration of psoriasis0.58
Factor 5: disease activity
    No of actively inflamed joints0.81
    No of swollen joints0.71
Factor 6: history of hypertension
    Age0.50
    History of hypertension0.74
Factor 7: joint damage
    Average grip strength in both hands (mm Hg)−0.59
    No of clinically deformed joints0.49
Factor 8: fibromyalgia status
    Male sex0.43
    No of fibromyalgia tender points−0.54
Factor 9: medication use
    Ever used oral steroids0.35
    Ever used DMARD0.41

  • DMARD, disease-modifying antirheumatic drugs; ESR, erythrocyte sedimentation rate; HAQ, health assessment questionnaire; SF-36, medical outcome survey short form 36.