Anti-carbamylated protein antibodies in premenopausal rheumatoid arthritis women: relation to disease activity and bone loss

Objectives. Anti-carbamylated protein antibodies (anti-CarP Abs) are present in patients with RA, however, their association with bone loss is not confirmed. The purpose of this study was to determine the relation between the serum level of anti-CarP Abs in premenopausal RA women and disease activity and bone loss. Methods. This case-control study was conducted on 48 premenopausal women with RA and 48 matched healthy premenopausal women. All RA women were subjected to clinical examination, disease activity assessment using the 28-joint DAS (DAS28) and Clinical Disease Activity Index (CDAI), functional assessment using the HAQ, physical activity assessment using the International Physical Activity Questionnaire (IPAQ), fatigue assessment using the Modified Fatigue Impact Scale (MFIS), serological tests as well as anti-CarP Abs using ELISA. Moreover, the BMD was measured by DXA and plain X-ray of both hands was done to assess juxta-articular osteopenia and erosions. Results. The anti-CarP Abs level was significantly higher in RA patients than in healthy controls. The serum level of anti-CarP Abs had a significant positive correlation with the RA DAS28, CDAI, HAQ, MFIS and original Sharp score, while a significant negative correlation was present with the IPAQ. Anti-CarP Abs were negatively correlated with either spine BMD or Z-score and positively correlated with the original Sharp score. Conclusion. Anti-CarP Abs were higher in premenopausal RA women compared with older and BMI matched healthy women. Anti-CarP Abs are associated with higher RA disease activity, increased disability and fatigability and decreased physical activity. Moreover, anti-CarP Abs are associated with systemic trabecular bone loss as well as local bone loss.