Joint symmetry in early and late rheumatoid and psoriatic arthritis: Comparison with a mathematical model

摘要: Objective To establish a mathematical model to predict the probability of symmetry joint involvement as function number joints involved and compare expected with actual probabilities in psoriatic arthritis (PsA) rheumatoid (RA) early late disease. Methods Random was assumed, binomial theorem used give frequency distribution each count. Ten pairs were included: shoulder, elbow, wrist, metacarpophalangeal joints, proximal interphalangeal (PIP) hands, hip, knee, ankle, metatarsophalangeal PIP feet. Observed obtained from subjects (duration ≤12 months) PsA RA. Results The disease subgroups follows: n = 33, 77, RA 61, 93. exceeded predicted for all subgroups. The median group 4, 8, 15 (χ2 95.3, 3 degrees freedom, P 0.0001, by Kruskal-Wallis test). After correcting discrepancy no difference found between groups 1.77, 0.62 Friedman two-way analysis variance). Similar results when individual hand foot analyzed separately. Conclusion The pattern is often distinguish arthritis. This study confirms that largely total that, terms pattern, differences these disorders are more quantitative than qualitative. Both have high absolute values symmetry, particularly wrist hand.