Overview

Sepsis commonly disturbs hemostasis: endothelial activation, consumption of platelets and clotting factors, and organ injury can coexist in ways that older disseminated intravascular coagulation (DIC) scores did not fully capture once sepsis was redefined around life-threatening organ dysfunction and infection. The sepsis-induced coagulopathy (SIC) score addresses that gap by integrating three domains that are usually available at the bedside: prothrombin time expressed as INR, platelet count, and organ dysfunction measured with selected SOFA components.

The score is not a substitute for diagnosing infection or sepsis; it assumes the patient is already being evaluated in that framework. Its purpose is to summarize how abnormal coagulation tests are in relation to non-neurologic, non–platelet-based organ failure—using a SOFA construction specified in the primary derivation so that the same inputs can be reproduced across hospitals.

What the score measures

Each of the three domains contributes between 0 and 2 points. The maximum total is 6. Points are assigned from contemporaneous values (ideally from the same blood draw and clinical snapshot used for severity assessment).

Prothrombin time (PT-INR)

INR reflects extrinsic pathway and common pathway factor consumption or dilution, liver synthetic dysfunction, vitamin K deficiency, and the effect of anticoagulants. In the SIC framework, progressively higher INR receives more points, reflecting worse coagulopathy in the setting of sepsis.

• 0 points: INR ≤ 1.2
• 1 point: INR > 1.2 and ≤ 1.4
• 2 points: INR > 1.4

Use the INR reported by your laboratory for the same specimen. If only PT ratio versus control is available instead of INR, local validation or conversion policies may apply; the published SIC criteria were described in INR terms.

Platelet count

Thrombocytopenia in sepsis may reflect consumption, marrow suppression, dilution, or immune-mediated destruction. The SIC score assigns higher points when counts fall below standard thresholds expressed in ×10⁹/L (the units typically printed on a complete blood count).

• 0 points: platelets ≥ 150 ×10⁹/L
• 1 point: platelets < 150 but ≥ 100 ×10⁹/L
• 2 points: platelets < 100 ×10⁹/L

Total SOFA from four organ systems

This component is not the full six-component SOFA used in every ICU display. For SIC, you sum only the SOFA subscores for:

1. Respiratory (oxygenation / ventilation as defined by SOFA)
2. Cardiovascular (vasopressor or inotrope requirement and mean arterial pressure)
3. Hepatic (bilirubin)
4. Renal (creatinine and/or urine output criteria)

Exclude the SOFA coagulation (platelet) subscore and the central nervous system (Glasgow Coma Scale) subscore from this sum—platelets are already counted in the platelet domain, and neurology is intentionally left out of the organ-failure sum in the SIC definition to match the derivation analysis.

Map the resulting four-organ total to SIC points as follows:

• 0 points: four-organ SOFA sum = 0
• 1 point: four-organ SOFA sum = 1
• 2 points: four-organ SOFA sum ≥ 2

In practice, compute respiratory, cardiovascular, hepatic, and renal SOFA strictly per the Sepsis-3 SOFA definitions, add them, then apply the mapping above. The theoretical maximum of this four-organ sum is lower than a full SOFA that includes all six systems; enter the integer sum your team calculated (this calculator accepts 0–16 for data entry consistency with four subscores each capped in standard SOFA tables).

Defining “SIC-positive” status

A total score of 4 or higher is necessary but not sufficient. The original definition also requires that the combined contribution from PT-INR and platelets exceeds 2 points—that is, the two coagulation-related domains together must sum to at least 3 (strictly greater than 2). This rule reduces the chance that organ dysfunction alone, with relatively preserved coagulation tests, triggers a positive label.

Examples of the logic (illustrative, not exhaustive):

• If PT-INR and platelet points together are only 2 (for example, mild prolongation and mild thrombocytopenia), then even a maximal organ-failure contribution may not meet the formal SIC criteria—because the coagulation pair does not exceed the required threshold.
• Conversely, if coagulation tests are substantially abnormal (so that PT + platelet points reach 3 or 4), a lower four-organ SOFA sum may still fail to reach a total of 4—SIC would not be met by the published rule despite obvious laboratory derangement in isolation.

Clinical use and limitations

The SIC score is used in research and clinical pathways that emphasize early recognition of sepsis-related coagulopathy and risk stratification. Mortality and treatment-effect relationships reported in the literature are cohort-specific; transportability depends on case mix, timing of labs, and baseline anticoagulant or antiplatelet use.

Abnormal INR and platelets have broad differentials (liver disease, nutritional deficiency, drugs, hematologic disorders, sampling issues). Similarly, SOFA subscores require accurate FiO₂, ventilator settings, vasopressor doses, creatinine, urine output, and bilirubin—any of which can be missing or misleading during transport or early resuscitation.

The score should be interpreted as one structured summary alongside infection source control, hemodynamic support, antimicrobial therapy, and bleeding risk assessment. It does not by itself indicate anticoagulant, antifibrinolytic, or procoagulant therapy; those decisions depend on trial evidence, regulatory status, institutional policy, and individual patient context.

Using this calculator

Enter platelets in ×10⁹/L, INR from the same time point, and the integer sum of the four SOFA organ subscores described above. The tool reports component points, the PT + platelet subtotal, the total (0–6), and whether the formal SIC criteria are met. Always verify inputs against the raw laboratory values and the SOFA charting used in your unit.