In rheumatoid arthritis (RA), the patient global assessment (PGA) has been strongly associated with pain severity, but less often with other measures, including disease activity measures. We tested whether RA activity and psychological measures had direct associations with the PGA or indirect associations that were mediated by pain. We also tested whether the correlates of the PGA differed with the degree of RA activity.
We studied 260 patients with active RA on 2 visits in a prospective longitudinal study. We used path analysis to test direct and indirect associations of Disease Activity Score in 28 joints (DAS28), morning stiffness, Health Assessment Questionnaire (HAQ), fatigue, physical role limitations, social functioning, depressive symptoms, and health distress with the PGA.
Among the 509 visits, the median PGA score was 50 (25th-75th percentile: 24-66). Pain severity had the strongest association with the PGA, but direct associations were also found for morning stiffness severity, health distress, fatigue, and DAS28. Morning stiffness severity, DAS28, health distress, and HAQ were also indirectly associated with the PGA through pain. Among visits with DAS28 ≥5.4, pain, morning stiffness severity, and HAQ were the only determinants of the PGA. Among visits with DAS28 <4.2, health distress and age were additional determinants, and fatigue was marginally associated with the PGA.
Although pain was the strongest determinant of the PGA in RA, morning stiffness severity, health distress, fatigue, and DAS28 were also important. Determinants of the PGA differed with RA activity, with health distress, age, and to a lesser degree, fatigue, contributing only in patients with less active RA.