Materials and methods

Study design

This longitudinal, observational, single-center study was conducted at a tertiary rheumatology department in Morocco. Medical records of patients with RA who initiated biologic therapy between June 2025 and December 2025 were reviewed. Eligible patients had persistent active RA despite treatment with csDMARDs and initiated biologic therapy according to EULAR recommendations and the treating rheumatologist's clinical judgment, regardless of the treatment line. Patients were followed for six months after biologic initiation.

Inclusion and exclusion criteria

Eligible patients were adults aged ≥18 years fulfilling the 2010 ACR/EULAR classification criteria for RA and initiating treatment with a bDMARD, namely either a tumor necrosis factor inhibitor (anti-TNF) or rituximab. Only patients receiving long-term GC therapy for more than three months, with a daily prednisone-equivalent dose >5 mg at the time of biologic initiation, were included.

Patients were excluded in cases of refusal to participate, irregular follow-up during the six-month study period, cognitive impairment, age <18 years, or absence of GC therapy at baseline.

Ethical approval

The study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Ethics Committee for Biomedical Research of Mohammed V University (approval number: 66-26).

Data collection

The following data were collected for all participants: socio-demographic characteristics, including age and sex; medical history, including hypertension, diabetes mellitus, dyslipidemia, cardiovascular disease, osteoporosis, fibromyalgia, and other comorbidities; and disease-related characteristics, including diagnostic delay, disease duration, rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody status, erosive disease, extra-articular manifestations, and disease activity, which was assessed using the DAS28 based on CRP (DAS28-CRP) and erythrocyte sedimentation rate (DAS28-ESR).

Therapeutic characteristics: previous or concomitant use of csDMARDs, analgesics, prior exposure to biologic therapies, type of biologic therapy initiated, baseline GC dose, and GC exposure, assessed by recording the daily prednisone-equivalent dose (mg/day) at each assessment time point. Disease activity and GC exposure were assessed at current biologic initiation (M0) and at four months (M4) and six months (M6) after treatment initiation.

Outcomes

The primary outcome was the proportion of patients achieving a daily GC dose ≤5 mg at six months after biologic therapy initiation. Secondary outcomes included the mean daily GC dose at M4 and M6, the proportion of patients who completely discontinued GC therapy during the six-month follow-up, and the comparison of GC-sparing effects between patients treated with rituximab and those treated with anti-TNF agents.

Statistical analysis

Statistical analyses included descriptive and comparative analyses and were performed using Jamovi software version 2.4.14 (The Jamovi Project Pty Ltd., Australia). Quantitative variables were expressed as mean ± standard deviation or median (interquartiles), according to data distribution assessed using the Shapiro-Wilk test. Categorical variables were expressed as frequencies and percentages.

Comparisons were performed using Student's t-test or the Mann-Whitney U test for continuous variables, and the chi-square test or Fisher's exact test for categorical variables, as appropriate. Changes in GC doses over time (M0, M4, and M6) were analyzed using repeated-measures analysis of variance (ANOVA). Test statistics (t, U, χ², or F, as applicable) were reported alongside p-values. A two-sided p-value < 0.05 was considered statistically significant.