Tocilizumab Effectiveness in RA Does Not Differ by Comorbidity Burden

Per study data published in the Journal of Rheumatology, tocilizumab (TCZ) effectiveness was not affected by comorbidity burden or obesity status in patients with rheumatoid arthritis (RA).

Investigators extracted data from the Corrona RA registry, a prospective observational cohort of patients with RA recruited from 174 sites in the United States (ClinicalTrials.gov Identifier: NCT01402661). Data were included from patients who initiated TCZ between January 2010 and October 2017, with at least 12 months of follow-up. Variables of interest included number of physician-reported comorbid conditions, modified Charlson Comorbidity Index (mCCI), and body mass index (BMI). The primary outcome was change in Clinical Disease Activity Index (CDAI) at 6 and 12 months. Using mCCI score, patients were classified as having high (mCCI ≥2) or low (mCCI <2) comorbidity burdens. Logistic regression analyses were performed to assess the impact of baseline BMI and mCCI on 6- and 12-month disease activity outcomes. The proportion of patients achieving low disease activity (CDAI ≤10) was also evaluated.

Of 805 patients in the Corrona registry who initiated TCZ, 575 (74.7%) had a low mCCI and 195 (25.3%) had a high mCCI. Overall, 356 (44.2%) were classified as obese (mean [SD] BMI, 36.7 [6.2] kg/m²). The majority (93.8%) of patients received intravenous TCZ; a small proportion (6.1%) received subcutaneous TCZ.

Compared with patients with low mCCI, patients with high mCCI were older (mean [SD] age, 56.9 [13.1] vs 61.5 [12.3] years), more likely to be obese (41.7% vs 52.8%), had longer mean (SD) disease duration (11.6 [8.9] vs 12.8 [9.9] years), and had higher mean (SD) CDAI scores at baseline (23.9 [13.9] vs 25.7 [13.4]).

The most common comorbidities among patients with high mCCI were diabetes (42.6%), solid-tumor cancer (21.0%), liver disease (20.5%), and chronic obstructive pulmonary disease (10.3%). At 6 months, the mean change in CDAI was -7.57 for patients with low mCCI and -7.72 for patients with high mCCI (P >.05). At 12 months, CDAI improvements continued, with no significant difference observed between patients with low and high mCCI (P <.05). Similarly, obesity status had no significant effect on CDAI outcomes at 6 and 12 months (P >.05).

Although high comorbidity burden was associated with greater RA activity at baseline, mCCI had no significant effect on long-term TCZ outcomes. Similarly, patients with and without obesity had comparable TCZ response at follow-up.

As study limitations, investigators cited the lack of TCZ dosing data; higher TCZ dosing among patients with greater comorbidity burden may have informed greater response at 6 and 12 months. Even so, these results support the real-world effectiveness for TCZ in patients with RA, regardless of comorbidity and obesity status.  

Disclosure: This study was sponsored by Corrona, LLC. Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Pappas DA, Etzel CJ, Crabtree M, et al. Effectiveness of tocilizumab in patients with rheumatoid arthritis is unaffected by comorbidity burden or obesity: data from a US registry [published online January 15, 2020]. J Rheumatol. doi: 10.3899/jrheum.190282