Tumour Necrosis Factor Inhibitor Treatment Normalises Hand Bone Loss in a Minority of Rheumatoid Arthritis Patients Treated in Clinical Practice. Results from the Copenhagen Osteoarthritis Study and the Danbio Registry

Background Rheumatoid arthritis (RA) is characterised by progressive joint destruction and loss of periarticular bone mass. Hand bone loss (HBL) is measured by Digital X-ray Radiogrammetry (DXR) which has been proposed as an outcome measure for treatment effect in RA. A definition of increased HBL adjusted for age- and gender-related bone loss is lacking. Furthermore, it is unknown to which extent HBL is normalised in RA patients during treatment with tumour necrosis factor alpha inhibitors (TNF-I).Objectives To establish a reference material for HBL and to investigate whether HBL normalises in RA patients during TNF-I treatment in clinical practice.Methods Hand bone mass (DXR-BMD) was measured with DXR, a computerised method of estimating cortical bone mineral density in the diaphysis of the 2nd – 4th metacarpal bone in a reference population and a patient cohort. The reference population consisted of 1,533 men and 2618 women randomly selected from the urban county of Osterbro in Denmark who had hand x-rays performed in the cross-sectional Copenhagen Osteoarthritis Study. Linear regression analyses were used to calculate normal HBL (defined as the 95% Confidence Interval (95%CI) for the age-related mean changes in DXR-BMD between subsequent age-groups).The patient cohort was 135 patients from the DANBIO registry with hand x-rays obtained ∼2 years before start of TNF-I (pre-baseline, all patients treated with conventional synthethic Disease-Modifying Anti-Rheumatic Drugs (csDMARD)), at start of TNF-I (baseline) and ∼ 2 years after start of TNF-I (follow-up). Annual HBL during csDMARD and TNF-I treatment were calculated in individual patients and compared with the lower 95%CI of mean DXR-BMD change in the gender- and age-matched reference group to assess if increased HBL was present.Results [Table 1][1] presents the HBL reference material. The 135 RA patients (85% women, 71% IgM-RF positive, median age 55 (range 23-84) years; median disease duration 5 (range 1-53) years) had a pre-baseline median DAS28 of 4.3 (range 1.6-6.9) and a baseline DAS28 of 5.3 (1.4-8.2). TNF-I treatment was infliximab (74%), etanercept (13%) or adalimumab (13%). At follow-up (DAS28 3.1 (1.4-7.7) 59% received the initial TNF-I, 27% had switched to another biological drug and 14% had withdrawn.Compared to the reference population, 84 (62%) patients had increased HBL during csDMARD treatment and 60 (44%) had during TNF-I treatment (p=0.10,Chi-Sq). In 42 patients who had elevated HBL during csDMARD treatment HBL was normalised during TNF-I. Eighteen patients had normal HBL during csDMARD treatment but increased HBL during treatment with TNF-I.![Figure][2] Conclusions We have established a reference material for HBL in the general population and found significant age-related decreases in DXR-BMD in both men and women. Increased HBL was present in the majority of RA patients initiating TNF-I treatment in clinical practice and was normalised in only a minority of patients during treatment.Disclosure of Interest None declared [1]: #F1 [2]: pending:yes