As a guide to treatment of rheumatoid arthritis (RA), physicians use measurement tools to quantify disease activity. The Patient Global Assessment (PGA) asks a patient to rate on a scale how they feel overall. The Physician Global Assessment (MDGA) is a similar item completed by the assessing physician. Both these measures are frequently incorporated into other indices. We studied reliability characteristics for global assessments and compared test-retest reliability of both the PGA and the MDGA, as well as other commonly used measures in RA.
We studied 122 patients with RA age 17 years or older. Patients who received steroid injection or change in steroid dose at the visit were excluded. Patients completed the HAQ, PGA, visual analog scale for pain (VAS Pain), VAS Fatigue, and VAS Sleep. After seeing their physician, they received another questionnaire to complete within 2 days at the same time of day as clinic visit. Physicians completed the MDGA at the time of the patient's appointment and at the end of their clinic day. Test-retest results were assessed using intraclass correlations (ICC). "Substantial" reliability is between 0.61-0.80 and "almost perfect" > 0.80.
Four rheumatologists and 146 patients participated, with 122 questionnaires returned (response rate 83.6%). Test-retest reliability was 0.702 for PGA, 0.961 for MDGA, and 0.897 for HAQ; VAS results were 0.742 for Pain, 0.741 for Fatigue, and 0.800 for Sleep. The correlation between PGA and MDGA was -0.172.
PGA, MDGA, HAQ, and VAS Pain, VAS Fatigue, and VAS Sleep all showed good to excellent test-retest reliability in RA. MDGA was more reliable than PGA. The correlation between PGA and MDGA was poor.