Effectiveness and Safety of Pamidronate in Refractory Axial Spondyloarthritis: A Prospective Observational Study from a Tertiary Care Hospital in Bangladesh

Pamidronate has been evaluated in several clinical studies involving patients with active or refractory ankylosing spondylitis. Although biologic disease-modifying antirheumatic drugs are effective for refractory disease like spondyloarthritis (axSpA), their high cost and limited availability restrict their use in many low-resource settings. Intravenous pamidronate has emerged as a potential alternative because of its anti-inflammatory and immunomodulatory properties. This study evaluates the effectiveness and safety of intravenous pamidronate in patients with refractory radiographic axSpA (RR axSpA) treated at a tertiary care hospital in Bangladesh. This prospective observational study was conducted among 17 patients with RR axSpA, who received intravenous pamidronate and were followed for six months in the Department of Rheumatology, Bangladesh Medical University (BMU), Dhaka, from March 2022 to September 2024. Clinical outcomes were assessed using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), and Bath Ankylosing Spondylitis Global Score (BAS-G). Inflammatory activity was evaluated using erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Changes over time were analyzed using the Friedman test with Wilcoxon signed-rank post hoc comparisons, while correlations between clinical measures and inflammatory markers were assessed using Spearman's rank correlation. The mean age was 28.0 ± 6.09 years, with a male predominance (94.1%). Mean disease duration was 4.5±1.17 years, and peripheral joint involvement was present in 11.8%. The mean age of the participants was 28.0±6.09 years, and 94.1% were male. Significant improvements were observed in all clinical outcome measures over six months. Mean BASDAI decreased from 6.87±1.38 at baseline to 3.16±1.27 at six months (Friedman χ²= 27.4, p<0.001), BASFI from 6.31±1.77 to 3.45 ± 1.41 (χ²= 24.8, p<0.001), BASMI from 0.87±0.60 to 0.58±0.50 (χ²= 8.9, p=0.012), and BAS-G from 8.03±1.50 to 4.21±1.63 (χ²= 26.1, p<0.001). ESR declined from 60.5±34.2 to 28.5±22.4 mm/hour, while CRP decreased from 23.9±25.0 to 10.6±12.3 mg/L (both p<0.001). Pamidronate therapy was significantly associated with clinical outcome and inflammatory markers, i.e., progressive improvement in disease activity, function, spinal mobility, and patient global assessment. By six months, 94.0% of patients achieved at least a 20% reduction in BASDAI, 52.9% achieved a 50% reduction, and 29.4% achieved a 70% reduction. Baseline correlation analysis demonstrated strong positive associations between BASFI and BASMI (rₛ = 0.64), BASFI and BAS-G (rₛ = 0.60), and BASMI and BAS-G (rₛ = 0.63), indicating close relationships among functional impairment, spinal mobility, and patient-reported disease status. Pamidronate was well tolerated, with only mild transient infusion-related adverse events and no serious treatment-related complications. Bangladesh Med J. 2026 Jan; 55(1): 30-38