In patients with rheumatoid arthritis (RA) who were treated with tocilizumab (TCZ), baseline C-reactive protein (CRP) levels were closely associated with long disease control time (DCT). A retrospective study was conducted of patients with RA who received treatment with TCZ from April 2008 to August 2018 at Kansai Medical University in Moriguchi-City, Osaka, Japan. Results of the analysis were published in the Journal of Inflammation Research.

Complete blood cell counts, various platelet volume indices, and CRP values were measured. In the study, the DCT was defined as the time from the date patients initially received TCZ to the time that the treating physician decided to discontinue the treatment because of inadequate efficacy. The endpoint event was divided into 3 different categories: TCZ treatment was discontinued because of inadequate efficacy; death of a patient for any reason; and TCZ therapy was discontinued because of an unacceptable adverse effect.

A total of 144 patients with RA treated with TCZ were enrolled in the study. Participants’ median age was 66 years (range, 34 to 85 years). Overall, 114 patients were women and 30 were men. The median duration of RA was 73.9 months.  All of the patients were Asian (Japanese, Korean, or Chinese).


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Per univariate analysis, the DCT was significantly increased among patients who had never received prior biologic disease-modifying antirheumatic drug (bDMARD) therapy (P =.0064). The variables of age, sex, disease duration, concomitant use of glucocorticoids, and concomitant use of methotrexate, however, were not statistically significant.

When the contribution of baseline CRP level to DCT was analyzed, the participants were divided into 2 groups based on a cutoff value of 1000 mg/dL for CRP. For patients with high and low CRP levels, the median control times were 77.5% (95% CI, 44.8 to median not reached) and 34.5 months (95% CI, 17.0 to 79.3), respectively. Per univariate analysis, in participants with a high CRP value, the DCT was increased significantly (P =.0283).

A history of treatment with bDMARDs was a significant predictive factor for a shorter DCT, investigators noted, but no significant differences were reported between the groups with high and low CRP levels. According to an analysis of various hematologic indices in the 2 groups, erythrocyte sedimentation rates, white blood cell counts, and platelet counts were all significantly increased in participants with RA who had high baseline CRP values compared with those with low baseline CRP values (P <.0001, P =.0011, and P <.0001, respectively). Hematocrit, hemoglobin, red blood cell distribution width, mean platelet volume, platelet distribution width, and platelet-large cell ratio, however, were all significantly decreased in patients with RA and low baseline CRP values (P =.0139,  P =.0217, P =.0353, P =.0009, P =.0017, and P =.0010, respectively).

Multivariate analysis demonstrated that a high baseline CRP value was an independent and favorable predictive factor for a longer DCT (hazard ratio [HR], 0.608; 95% CI, 0.378 to 0.981; P =.0416). Further, no history of bDMARD use was also an independent favorable predictive factor for longer DCT (HR, 0.470; 95% CI, 0.275 to 0.780; P =.0031).

Study limitations cited by the study authors were its retrospective design and small study sample.

The investigators concluded that the results of the study demonstrate that a high baseline CRP value might be indicative of a dominant inflammatory pathogenic process in patients with RA in whom TCZ therapy might attain longer DCT. The researchers suggest that additional research might lead to an improved understanding of the therapeutic selection of appropriate patients with RA for treatment with TCZ.

Reference

Ishii N, Shimizu T, Ishiura Y, et al. A single-center retrospective observational study evaluating the favorable predictive factors for the disease control time of treatment with tocilizumab in patients with rheumatoid arthritis. J Inflamm Res. 2021;14:3721-3728. doi:10.2147/JIR.S323577