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Systemic Immune-Inflammation Index Associated With Increased Risk of Depressive Symptoms
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Key Takeaways
- SII is associated with increased depressive symptoms risk, particularly in individuals without CVD, suggesting a need for further research.
- Depression is prevalent in CVD patients, with inflammation as a potential link between the two conditions.
Depression and cardiovascular disease are often linked, with research showing inflammation is common for the 2 disease states.
Investigators find that the systemic immune-inflammation index was associated with an increased risk of depressive symptoms, particularly for those without cardiovascular disease (CVD). The results indicate that the association should be further researched; particularly exploration of the social isolation index (SII) in depressive symptoms assessment, especially for cardiovascular health, is needed.1
Cardiovascular, Depression, Inflammation | Image Credit: Maridav | stock.adobe.com
According to a study published in Frontiers in Cardiovascular Medicine, individuals who have depression are susceptible to developing CVD compared with individuals who are in good health. Further, patients with CVD and depression have a heightened risk of mortality within a 5-year period. Psychological interventions in conjunction with medication is common; however, it has limited effectiveness and unfavorable prognosis, according to the study authors. They also state that inflammation is thought to play a large role in CVD and depression. The current pharmacological treatments typically include antidepressants in addition to cardiovascular treatment. They note that statins have shown to reduce the risk of depression.2
According to the current study, it has been estimated that 20% to 40% of those with CVD experience depressive symptoms, suggesting that depression and CVD may be related. Chronic inflammation has been studied as a pathway linking the 2 diseases, with C-reactive protein, interleukin-6, and tumor necrosis factor-alpha being associated with depression and CVD. SII has been used as a novel marker of systemic inflation, holding promise in predicting diseases such as cancer, nonalcoholic fatty liver, and CVD. Investigators of the study aimed to determine the predictive value of SII for depression, particularly in the context of CVD.1
Data from the National Health and Nutrition Examination Survey between 2005 and 2016 were used, with analyses assessing the association between SII and depressive symptoms for individuals at a single time point. Investigators evaluated depressive symptoms with the Patient Health Questionnaire-9 (PHQ-9), consisting of 9 items that assess the frequency of depressive symptoms over the past 2 weeks. For the SII, investigators used the formula: platelet count × neutrophil count / lymphocyte count. Sociodemographic factors, medication use, physical examinations, and laboratory tests were also assessed in the analysis.1
A total of 29,479 individuals were included and stratified by those with CVD and those without CVD. Compared with those without CVD, patients with CVD were older, had a higher BMI, and lower family poverty income ratio, according to the investigators. Further, the mean PHQ-9 score was significantly higher in the CVD group at 4.29 compared with 2.88 for those without CVD, indicating a higher prevalence of depressive symptoms in the CVD group.1
Investigators found a positive association between SII and depressive symptoms for both groups, but the relationship was stronger and more linear for those without CVD. For these patients, the probability of depression steadily increased with SII values. For CVD, the curve for individuals was more complex, beginning with a higher baseline probability of depression compared with those without CVD, even at low SII values. The curve slightly increases in depression probability as SII increases, but the slope is less compared to those in the non-CVD group.1
Furthermore, investigators found that the positive association between SII and depressive symptoms were generally consistent across subgroups, but the association was stronger with males, those less than age 60, and those with less than a high school education. The association also remained consistent with a stronger association for those without CVD than those with CVD.1
