Immunogenicity of subcutaneous TNF inhibitors and its clinical significance in real-life setting in patients with spondyloarthritis.

KEY MESSAGES: Considerable proportion of patients with SpA have been immunized to the subcutaneous anti-TNF drug they are using. Concomitant use of MTX protects from immunization, whereas SASP does not. Patients with SpA using subcutaneous anti-TNF drugs can benefit from monitoring of the drug trough levels. Immunization to biological drugs can lead to decreased efficacy and increased risk of adverse effects. The objective of this cross-sectional study was to assess the extent and significance of immunization to subcutaneous tumor necrosis factor (TNF) inhibitors in axial spondyloarthritis (axSpA) patients in real-life setting. A serum sample was taken 1-2 days before the next drug injection. Drug trough concentrations, anti-drug antibodies (ADAb) and TNF-blocking capacity were measured in 273 patients with axSpA using subcutaneous anti-TNF drugs. The clinical activity of SpA was assessed using the Bath AS Disease Activity Index (BASDAI) and the Maastricht AS Entheses Score (MASES). ADAb were found in 11% of the 273 patients: in 21/99 (21%) of patients who used adalimumab, in 0/83 (0%) of those who used etanercept, in 2/79 (3%) of those who used golimumab and in 6/12 (50%) of those who used certolizumab pegol. Use of methotrexate reduced the risk of formation of ADAb, whereas sulfasalazine did not. Presence of ADAb resulted in decreased drug concentration and reduced TNF-blocking capacity. However, low levels of ADAb had no effect on TNF-blocking capacity and did not correlate with disease activity. The drug trough levels were below the consensus target level in 36% of the patients. High BMI correlated with low drug trough concentration. Patients with low drug trough levels had higher disease activity. The presence of anti-drug antibodies was associated with reduced drug trough levels, and the patients with low drug trough levels had higher disease activity. The drug trough levels were below target level in significant proportion of patients and, thus, measuring the drug concentration and ADAb could help to optimize the treatment in SpA patients.

Reactive arthritis following Salmonella infection: a population-based study.

OBJECTIVES: To study the incidence and clinical picture of Salmonella-associated reactive arthritis (ReA), as well as other reactive musculoskeletal symptoms and the arthritogenicity of various Salmonella enterica ssp. enterica serotypes in the population. METHOD: We sent a questionnaire on enteric and extraintestinal (especially musculoskeletal) symptoms to 999 consecutive subjects with a Salmonella-positive stool culture. Analysis of self-reported musculoskeletal symptoms was supplemented with a clinical examination of subjects with recent symptoms. RESULTS: Of the 999 Salmonella-positive subjects, 496 (50%) returned the questionnaire. Of these, 4.4% (22/496) had ReA and 13.7% (68/496) had other reactive musculoskeletal symptoms [tendinitis, enthesopathy, or bursitis (ReTe)]. Among the ReA patients, all adults, Salmonella Enteritidis was the most common causative serotype. The clinical picture of patients with ReA was mostly monoarticular or oligoarticular. Human leucocyte antigen (HLA)-B27 was positive in 42% of patients with ReA. The Salmonella O antigens of the 496 subjects belonged to eight groups (B, C, D1, E, G, I, L, and O), all with different major O antigenic determinants. All 22 patients with ReA and all 68 patients with ReTe were in O antigen groups B, C, D1, or E. However, the occurrence of musculoskeletal complications showed no statistically significant difference in relation to different O antigen groups (p = 0.69). CONCLUSIONS: ReA occurred in 4.4% of patients after Salmonella infection, with an annual incidence of 1.8/100,000 in Finland. We found no differences in arthritogenicity between different Salmonella serotypes that trigger musculoskeletal complications.