Measuring disease activity and functionality during pregnancy in patients with rheumatoid arthritis.

OBJECTIVE: Pregnancy has a favorable effect on the course of rheumatoid arthritis (RA), although the magnitude of this effect is equivocal because RA assessment tools have never been validated in pregnancy. The goal of this study was to assess how pregnancy influences the scoring of the Disease Activity Score in 28 joints (DAS28) and the Health Assessment Questionnaire (HAQ), and how both scores perform in pregnant patients with RA.
METHODS: Thirty-two healthy women and 30 pregnant patients with RA were prospectively studied during pregnancy and at postpartum. At each trimester and postpartum the components of the DAS28 (global health [GH], erythrocyte sedimentation rate [ESR], and C-reactive protein level [CRP]) and HAQ scores were determined. Maximal influences of healthy pregnancy on each component of the DAS28 were calculated. The performances of different DAS28 scores and the HAQ were also determined in RA patients. Furthermore, variants of the HAQ were developed within the HAQ scoring rules.
RESULTS: The components of the DAS28 were influenced by healthy pregnancy, with average increases in DAS28 score of 0.22 (GH), 1.1 (ESR), and 0.25 (CRP). The DAS28 calculated with CRP (DAS28-CRP) and without GH performed the best in pregnant RA patients. In healthy pregnancy, the median HAQ increased to 0.50 in the third trimester and was reduced by the HAQ variants to 0.25.
CONCLUSION: Pregnancy considerably influences the scoring of the DAS28 and HAQ. RA disease activity in pregnant patients should preferably be calculated with DAS28-CRP without GH. Even with HAQ variants, influences of pregnancy on the assessment of functionality cannot be precluded.