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August 29, 2024
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Systemic immune-inflammation index predicts mortality in rheumatoid arthritis

Fact checked byShenaz Bagha
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Key takeaways:

  • The systemic immune-inflammation index showed a nonlinear positive correlation with all-cause and cardiovascular mortality in RA.
  • A score of 529.7 or greater indicated high mortality risk.

Systemic immune-inflammation index levels may be used to predict all-cause and cardiovascular mortality among patients with rheumatoid arthritis, according to data published in Scientific Reports.

“The SII has been extensively investigated as an indicator that reflects the level of systemic inflammation and immune response,” Wei Wang, of Dandong Central Hospital and China Medical University, and colleagues wrote. “The SII is determined through the formula: (platelet count×neutrophil count)/lymphocyte count.

Patients with RA who have an SII score above 529.7 are at increased risk for all-cause and cardiovascular mortality.
Data derived from Wang W, et al. Sci Rep. 2024;doi:10.1038/s41598-024-67750-y.

“Therefore, utilizing the biomarker SII, which represents the level of systemic immune-inflammation, to assess the risk of all-cause or cardiovascular mortality in RA patients has become a feasible approach,” they added. “This inflammation biomarker SII offers the advantages of being easy to collect, providing rapid results, low cost, and high efficiency, obtainable through routine blood tests.”

To investigate the relationship between the SII and RA prognosis, particularly all-cause and cardiovascular mortality, Wang and colleagues conducted a retrospective analysis of National Health and Nutrition Examination Survey data from 1999 to March 2020. The analysis included 2,247 adults with RA (mean age, 61 years) and 29,177 control individuals from the general population during 20 years of follow-up. Associations between SII and prognosis were determined using multivariable Cox proportional hazards regression and receiver operating characteristic curves.

According to the researchers, the Cox regression indicated a nonlinear positive correlation between SII score and mortality, which was consistent in models adjusting for either demographic characteristics or all other covariates. For every 100-unit increase in SII level, the researchers observed 6% increases in both all-cause mortality risk (95% CI, 1.04-1.07) and cardiovascular mortality risk (95% CI, 1.04-1.09).

“Notably, at an SII level of 529.7, the HR for all-cause and cardiovascular mortality reaches 1, indicating a critical threshold beyond which the prognosis for RA patients deteriorates,” Wang and colleagues wrote. “Consequently, this threshold serves as a pivotal determinant for distinguishing between high and low mortality risk among RA patients.”

Meanwhile, the receiver operating characteristic curve analysis indicated SII had “better predictive capacity” than the neutrophil-to-lymphocyte ratio biomarker, according to the researchers.

“In essence, SII not only demonstrates elevated specificity in predicting mortality risk among RA patients, but also surpasses the discernible prognostic value offered by other known markers,” Wang and colleagues wrote.

“This finding equips clinicians with a novel approach to promptly identify RA patients at heightened risk of mortality,” they added. “Our research underscores the clinical utility of the novel inflammatory biomarker SII in prognosticating outcomes for RA patients.”