Overweight and Obesity, Inflammation, Metabolic Syndrome
Conditions
Keywords
obesity, overweight, Systemic Immune Inflammatory Index (SII), Systemic Inflammation Response Index (SIRI), inflammation
Brief summary
This observational study aims to evaluate the diagnostic and prognostic value of the systemic immune-inflammatory index (SII) and the systemic inflammation response index (SIRI) in individuals with overweight or obesity. The study will assess their association with obesity status, metabolic complications, lifestyle patterns, dietary indices, and established inflammatory biomarkers. Participants will undergo anthropometric assessment, laboratory testing, dietary evaluation, and follow-up for response to different obesity treatment modalities over 3 years. The study intends to determine whether SII and SIRI can serve as clinically useful predictors of metabolic risk and treatment outcomes of obesity.
Detailed description
Obesity is a complex chronic disease associated with systemic low-grade inflammation, metabolic dysfunction, and increased risk of comorbidities such as type 2 diabetes, dyslipidemia, nonalcoholic fatty liver disease, and cardiovascular disease. Adipose tissue acts as an active endocrine organ, influencing immune regulation and inflammatory signalling. Although numerous inflammatory biomarkers have been evaluated in obesity, the diagnostic performance of novel composite systemic immune-inflammatory indices, particularly the systemic immune-inflammation index (SII) and the systemic inflammation response index (SIRI), remains inadequately characterised. SII and SIRI, derived from peripheral blood counts, have shown prognostic potential in various clinical settings but have not been systematically evaluated in predicting metabolic complications or treatment response in obesity. This study seeks to expand their application in patients with overweight and obesity by 1) evaluating the cross-sectional associations between SII/SIRI and obesity severity, inflammatory biomarkers, metabolic disorders, and dietary patterns; and 2) determining the prognostic value of SII/SIRI for predicting metabolic complications and clinical response to behavopural and lifestyle modification, pharmacotherapy, and bariatric surgery over a 1-year follow-up. Participants will complete anthropometric measurements, comprehensive biochemical profiling, inflammatory cytokine assessment, dietary evaluation, and structured follow-up at 12 and 24 weeks, with continued monitoring of treatment response and metabolic outcomes over 1 year. STUDY PROCEDURES (Structured per visit) Visit 1 - Baseline (Week 1) * Informed consent * Anthropometrics (height, weight, waist circumference, hip circumference, BIA) * Venous blood sampling: complete blood count (CBC) and differential blood count (DBC), fasting glucose, HbA1c, lipid profile (cholesterol, LDL, HDL, triglycerides), thyroid panel (TSH, FT4, FT3), liver panel, renal panel, CRP, cortisol, bilirubin, iron status parameters, vitamins/minerals (Ca, P, Mg, vitamin D) * Biobanking: 3 frozen aliquots for hs-CRP, adiponectin, IL-6, TNF-α * Lifestyle and dietary questionnaires (socio-demographics, physical activity, smoking, sleep, stress, medication use; 24 h dietary recall + FFQ) * Motivational and educational counselling (diet, activity, pharmacotherapy options) Visit 2 - Week 12 * Anthropometrics + BIA * Laboratory testing (repeated, as above) * Assessment of dietary and lifestyle adherence * Motivational counselling (in person or telephone) Visit 3 - Week 24 * Anthropometrics + BIA * Full biochemical panel * Dietary questionnaires (24 h recall+MEDAS+Short Diet Screener) * Evaluation of treatment response to lifestyle intervention, pharmacotherapy, or bariatric surgery * Motivational counselling LONG-TERM FOLLOW-UP (Year 1) * Monitoring metabolic outcomes * Evaluation of obesity treatment response * Prognostic assessment of SII/SIRI
Interventions
BEHAVIORALNutritional counselling
Participants will receive interventions that are part of routine medical care, i.e. structured personalised nutritional intervention aligned with the Croatian Guidelines for the Treatment of Adults with Obesity. It emphasises lifestyle modification, energy-reduced dietary patterns, and the adoption of healthy eating habits as the first-line approach to weight management. The intervention consists of a 30-minute individualised counselling session delivered by a licensed nutrition professional. During the session, participants are guided to adopt a Mediterranean diet, with goal-setting, portion guidance, and strategies to increase adherence. The routine medical intervention aligned with the guidelines' recommendation for a nutritionally balanced diet combined with a modest daily energy deficit (\~500 kcal) to support gradual, sustainable weight loss and long-term weight maintenance.
Sponsors
University of Rijeka
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Age ≥ 18 years * BMI 25.0-29.9 kg/m² (overweight) or BMI ≥ 30 kg/m² (obesity) * Ability to attend scheduled clinical visits * Willingness to provide informed consent
Exclusion criteria
* Pregnancy or breastfeeding * Use of immunosuppressive therapy * Active infection * Inflammatory disease * Malignancy * Acute illness affecting immune parameters * Conditions interfering with study participation (as assessed by the investigator) * Known hematologic disorders affecting leukocyte or platelet counts * Chronic inflammatory diseases requiring systemic therapy * Recent major surgery (within the last 3 months) * Any condition that could confound the relationship between SII/SIRI and obesity-driven inflammation, such as immune disorders
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Diagnostic and prognostic value of SII and SIRI | baseline, 24 weeks and at study completion, an average of 1 year | The diagnostic and prognostic value of systemic inflammation indices (SII and SIRI) will be assessed using ROC curve analysis, including sensitivity, specificity, and AUC calculations. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Association of SII and SIRI with Metabolic Complications | baseline, 24 weeks and at study completion, an average of 1 year | The association of SII and SIRI with metabolic complications (insulin resistance, dyslipidemia, NAFLD) and their ability to predict response to obesity treatment (behavioural and pharmacologic) will be evaluated. |
| Association of SII and SIRI with Dietary Patterns | baseline, 24 weeks and at study completion, an average of 1 year | The relationship between SII/SIRI and adherence to anti-inflammatory and pro-inflammatory dietary patterns will be examined using indices such as the Mediterranean Diet Index and the Dietary Inflammatory Index. The analysis will provide insight into the impact of diet quality on systemic inflammation over time. |
| Identification of Prognostic Markers of Metabolic Comorbidities | baseline, 12 weeks, 24 weeks, and at study completion, an average of 1 year | Inflammatory indices (SII, SIRI) and monitored biomarkers will be analysed to determine their ability to predict the development or progression of obesity-related metabolic complications. The aim is to identify early indicators of increased risk for adverse metabolic outcomes and help in providing timely and appropriate obesity management. |
| Changes in SII and SIRI During Treatment | baseline, 12 weeks, 24 weeks, and at study completion, an average of 1 year | Longitudinal changes in SII and SIRI will be monitored throughout the treatment period to assess the degree and sustainability of systemic inflammation reduction. Results will be associated with clinical outcomes and treatment effectiveness. |
| Relationship Between SII/SIRI and Inflammatory Biomarkers | baseline, 12 weeks, 24 weeks, and at study completion, an average of 1 year | The associations between SII and SIRI and inflammatory biomarkers will be examined to confirm their biological significance and diagnostic value. This analysis will contribute to understanding the mechanisms of systemic inflammation in the context of obesity and metabolic disorders. |
Contacts
CONTACTGordana Kenđel Jovanović, Asst.Prof.
CONTACTJelena Vresk Špiranec, MD, spec. endocrinology
PRINCIPAL_INVESTIGATORGordana Kenđel Jovanović, Asst. Prof.
Faculty of Medicine, University of Rijeka
STUDY_DIRECTORSanja Klobučar, Assoc.Prof.
Faculty of Medicine, University of Rijeka; Clinical Hospital Rijeka
Outcome results
None listed