A One Year Case Control Study in Rheumatoid Arthritis Patients Indicates a Prevention of Bone Mineral Density Loss in Both Responders and Non Responders to Infliximab

Hubert Marotte; Beatrice Pallot-Prades; Laurent Grange; Philippe Gaudin; Christian Alexandre; Pierre Miossec

Disclosures

Arthritis Res Ther. 2007;9(3) 

In This Article

Materials and Methods

All patients fulfilled the American College of Rheumatology criteria for RA[11] and gave informed consent to participate in this study, which was approved by the ethics committee. This study was performed by the investigators, independent of and unsupported by Centocor or Schering-Plough.

The control group included 99 patients (21 men and 78 women) who were consecutively enrolled before the advent of anti-TNF-α treatment, from 1996 to 2000. All of them were receiving methotrexate. The infliximab-treated group included 90 patients (16 men and 74 women) requiring anti-TNF-α therapy for treatment of persistent active disease, despite treatment with methotrexate. Patients were enrolled, starting from when infliximab entered the market, from January 2001 to October 2003. Infliximab was administrated at 3 mg/kg on weeks 0, 2 and 6, and then every 8 weeks combined with methotrexate (in accordance with the ATTRACT [Anti-TNF Therapy in RA with Concomitant Therapy] protocol[7]). All of these patients were included in the study and followed over 1 year.

RA activity was evaluated using the Disease Activity Score (DAS)28,[12] and a good clinical response was defined as an improvement of at least 1.2 in DAS28 score at 1 year.

At baseline and 1 year later, BMD (g/cm2) was determined at the lumbar spine (first to fourth vertebrae, antero-posterior view) and at the right femoral neck, by dual-energy X ray absorptiometry using a QDR 4500 device (Hologic, Waltham, MA, USA). Quality control for the device was performed by daily assessment of a spine phantom. The in vivo precision error for dual-energy X ray absorptiometry, expressed as a coefficient of variation, was 0.9% at the lumbar spine and 1% at the femoral neck.

T scores (number of standard deviations [SDs]) from control individuals were calculated, in accordance with published reference values obtained in sex-matched control individuals studied using the same equipment at the same institution.[13] Osteopenia was defined as a T score between -1 and -2.5 SD and osteoporosis as a T score of -2.5 SD or less.

All bone markers were measured using commercial assays, in accordance with instructions of the manufacturers. Osteocalcin (normal values 15 to 46 ng/ml), C-terminal cross-linking telopeptide of type I collagen (CTX-I; 330 to 782 pg/ml) and parathyroid hormone (PTH; 15 to 65 pg/ml) were measured using an Elecsys 2010 (Roche Diagnostics, Mannheim, Germany), and 25-hydroxycholecalciferol (25-OHD; 12 to 40 ng/ml) was measured using a radioimmunoassay (Incstar, Stillwater, MN, USA).

Changes were compared between values at entry and at 1 year for BMD, DAS28, osteocalcin, CTX-I, PTH, 25-OHD, erythrocyte sedimentation rate and C-reactive protein. Data for both groups were compared using the unpaired Student's t-test for continuous variables. In each group, data were compared using the Student's paired t-test for continuous variables, between baseline and 1 year later. Absolute changes were measured and presented as variation, defined as the final values minus the initial values. BMD variation was also represented as relative (%) changes. Correlations between changes in BMD and in biochemical parameters were tested using the Pearson correlation coefficient. Several analysis of covariance models for BMD variations (final values minus initial values) were built to analyze the effect of cofactors (continuous variables and discrete variables) on that of infliximab. All analyses were performed with SPSS (SPSS Institute, Cary, NC, USA) software.

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