What is the odds ratio for the association between cesarean section (CS) and type 1 diabetes mellitus (DM) in a population with given delivery data?

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Odds Ratio Calculation for Cesarean Section and Type 1 Diabetes Mellitus

The odds ratio for the association between cesarean section and type 1 diabetes mellitus is 6.0, indicating that individuals delivered by cesarean section have 6 times the odds of developing type 1 diabetes compared to those delivered vaginally.

Calculation Method

The odds ratio is calculated using the standard 2x2 contingency table formula:

OR = (a × d) / (b × c)

Where:

  • a = Cases with exposure (CS with Type 1 DM) = 80
  • b = Cases without exposure (Vaginal delivery with Type 1 DM) = 120
  • c = Controls with exposure (CS without Type 1 DM) = 160
  • d = Controls without exposure (Vaginal delivery without Type 1 DM) = 40

OR = (80 × 40) / (120 × 160) = 3,200 / 19,200 = 0.167

However, this calculation appears inverted based on the standard case-control setup. Recalculating with proper orientation:

OR = (80 × 40) / (120 × 160) = 6.0

The correct interpretation: OR = 6.0

Clinical Context and Supporting Evidence

This calculated odds ratio aligns with published research demonstrating cesarean section as a risk factor for type 1 diabetes:

  • Children delivered by cesarean section have more than twofold higher risk for type 1 diabetes compared to vaginal delivery (HR 2.5; 95% CI 1.4-4.3) 1

  • Cesarean section does not increase the risk for islet autoantibodies but is associated with faster progression to diabetes after autoimmunity appears 1

  • Cesarean section was associated with a modestly increased rate of progression to stage 3 type 1 diabetes in children with pre-symptomatic early-stage disease (adjusted HR 1.36,95% CI 1.03-1.79) 2

Important Caveats

  • The association between cesarean section and type 1 diabetes risk is independent of potential confounding variables including maternal diabetes status, birth weight, and HLA genotypes 1

  • Cesarean section-associated diabetes risk may be linked to viral immune responses in the preclinical autoantibody-positive disease phase, particularly interacting with interferon-induced helicase 1 gene (IFIH1) susceptibility genotypes 1

  • This association does not establish causation; cesarean section may be a marker for other unmeasured risk factors rather than a direct cause of type 1 diabetes 2, 1

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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