Correlation of systemic immune-inflammation index and functional status of living score with disease activity in patients with rheumatoid arthritis.

OBJECTIVE: This study aims to investigate the correlation between Systemic Immune-Inflammation (SII) index and Health Assessment Questionnaire (HAQ) scores and disease activity in patients with Rheumatoid Arthritis (RA). METHODS: Clinical and laboratory data of 132 RA patients, including SII index, disease activity scores, and HAQ scores were collected. The patients were categorized as moderate disease activity and High Disease Activity (HAD). Univariate and multivariate linear analyses were performed to find correlations between the SII index and HAQ with DAS28-CRP and DAS-ESR. RESULTS: The HAD-RA cohort had a higher SII index (1.28 [IQR: 0.97, 2.10] vs. 0.89 [IQR: 0.66, 1.27], p < 0.001) and HAQ (1.80 [1.40, 2.10] vs. 1.05 [IQR: 0.71, 1.40], p < 0.001). A relationship was found between the SII index, HAQ scores, and disease activity, where individuals with worse functional status had higher disease activity. Multifactor linear analysis further validated the independent correlation between the SII index and HAQ scores with RA disease activity. Decreased hemoglobin was a relevant factor affecting DAS28-CRP and DAS-ESR. The AUC of the SII index was 73.69 with a cutoff value of 0.93, and the AUC of HAQ was 84.41 with a cutoff value of 1.45. The combination of the two resulted in an AUC of 85.76, which increased the sensitivity and specificity to 83.99 % and 94.00 %, respectively. CONCLUSION: Both the SII index and the HAQ scores are significantly associated with disease activity in RA patients. These insights support the accurate assessment of the disease, the design of personalized treatment plans, and the evaluation of treatment efficacy.