CHSJ

Curr Health Sci J, vol. 52, no. 3, 2026

The Systemic Immune-Inflammation Index Reflects Disease Activity and Functional Limitation in Spondyloarthritis: A Single-Center Cross-Sectional Analysis

[Original Paper]

R.D. UNGUREANU(1), C.E. BITA(2), M.N. VOICU(3), A. TURCU-STIOLICA(4,5), S.C. FIRULESCU(2), M. TURCU-STIOLICA(6), A.L. BARBULESCU(7), S.C. DINESCU(2), A. TCACIUC(8), F.A. VREJU(2)


(1)Doctoral School, University of Medicine and Pharmacy of Craiova, Romania;
(2)Department of Rheumatology, Faculty of Medicine, University of Medicine and Pharmacy of Craiova, Romania;
(3)Discipline of Clinical Pharmacology, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy Bucharest, Romania;
(4)Biostatistics Department, Faculty of Pharmacy, University of Medicine and Pharmacy of Craiova, Romania;
(5)Health Economics and Outcomes Research Department, Faculty of Medicine, “Iuliu Ha?ieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania;
(6)Rheumatology Department, Emergency County Clinical Hospital of Craiova, Romania;
(7)Department of Pharmacology, Faculty of Medicine, University of Medicine and Pharmacy of Craiova, Romania;
(8)Department of Internal Medicine, Nicolae Testemitanu State University of Medicine and Pharmacy, Republic of Moldavia


Abstract:

Objectives: The Systemic Immune-Inflammation Index (SII) has emerged as a promising biomarker in inflammatory rheumatic diseases, yet its behavior across spondyloarthritis (SpA) subtypes remains poorly characterized. This study aimed to evaluate SII and its associations with disease activity (BASDAI), functional impairment (BASFI), and clinical subgroups in SpA patients. Material and Methods: This cross-sectional study included 64 patients with SpA classified according to ASAS criteria: 32 with axial SpA, 8 with peripheral SpA, and 24 with psoriatic SpA. SII was calculated as (Platelets × Neutrophils)/Lymphocytes. Between-group comparisons were performed using Kruskal-Wallis, Chi-square/Fisher’s exact, and Mann-Whitney U tests. Spearman correlations were computed between SII, BASDAI, BASFI, age, and BMI. The study adhered to STROBE guidelines for cross-sectional studies. Results: The mean SII was 834±505, with no significant differences across SpA subtypes (?²(2)=0.44, p=0.80, ?²=7.05×10?³). SII correlated significantly with BASDAI (?=0.350, p<0.01) and BASFI (?=0.316, p<0.05), and inversely with BMI (?=?0.250, p<0.05). ROC analysis for discriminating active disease (BASDAI?4) yielded an AUC of 0.612 (95% CI 0.421-0.803), with an optimal SII cutoff of 565 (sensitivity 63.5%, specificity 58.3%, PPV 86.8%, NPV 26.9%). SII did not differ significantly by diabetes (p=0.73), though hypertension showed a borderline trend (p=0.09). Conclusions: SII correlates significantly with disease activity and functional impairment across the SpA spectrum, supporting its potential as a readily accessible, subtype-agnostic inflammatory biomarker. The proposed cutoff of 565 for active disease requires validation in larger cohorts. Longitudinal studies are needed to establish SII’s utility in treatment monitoring.


Keywords: Systemic immune-inflammation index, spondyloarthritis, psoriatic arthritis, BASDAI, BASFI, biomarker



Corresponding: Cristina Elena Bita, Department of Rheumatology, Faculty of Medicine, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania, e-mail: cristina.gofita@umfcv.ro


DOI 10.12865/CHSJ.52.03.13 - Download PDF
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