Maddrey's Discriminant Function Calculator
Calculate Maddrey's Discriminant Function to help assess the severity of alcoholic hepatitis using bilirubin and prothrombin time values.
What Is Maddrey's Discriminant Function?
Maddrey's Discriminant Function (MDF) is a clinical scoring system used to assess the severity of alcoholic hepatitis. It calculates a numerical value based on two laboratory values: serum bilirubin and prothrombin time. The result helps clinicians determine which patients have a poor prognosis and may benefit from specific medical interventions, such as corticosteroid therapy.
The formula was developed to identify patients with severe alcoholic hepatitis who are at high risk of short-term mortality. A score above 32 is generally considered indicative of severe disease and a poor prognosis without treatment.
How the Score Is Calculated
The Maddrey's Discriminant Function uses the following formula:
MDF = 4.6 × (PT − control PT) + (Total Bilirubin / 17.1)
Where:
- PT = patient's prothrombin time in seconds
- Control PT = the laboratory's reference prothrombin time in seconds
- Total Bilirubin = serum total bilirubin in µmol/L
The formula accounts for the difference between the patient's prothrombin time and the laboratory control value, then adds a bilirubin component. The constant 4.6 and the division by 17.1 are derived from the original statistical model that established the scoring system.
Interpreting the Results
The calculated MDF value guides clinical decision-making:
- MDF < 32: Indicates less severe alcoholic hepatitis. Patients in this range generally have a better short-term prognosis and may not require corticosteroid therapy.
- MDF ≥ 32: Indicates severe alcoholic hepatitis with a high risk of 30-day mortality. This threshold is commonly used to identify patients who may benefit from corticosteroid treatment, though clinical judgment and other factors should always be considered.
The score is a prognostic indicator, not a diagnostic tool. It should be used alongside other clinical assessments, including liver function tests, MELD score, and the patient's overall clinical presentation.
Clinical Use Cases
Maddrey's Discriminant Function is primarily used in hospital settings for patients with suspected alcoholic hepatitis. Common applications include:
- Risk stratification at the time of admission to identify patients who need intensive monitoring
- Treatment guidance for determining candidacy for corticosteroid therapy
- Prognostic assessment to estimate short-term mortality risk
- Clinical research for patient selection and outcome measurement in studies on alcoholic hepatitis
Important Limitations
While Maddrey's Discriminant Function is a validated clinical tool, it has several limitations that should be understood:
- The score was derived from a specific patient population and may not generalize perfectly to all demographics
- It does not account for other factors that influence prognosis, such as renal function, infection, or gastrointestinal bleeding
- The prothrombin time control value varies between laboratories, which can affect the calculated score
- The score is most reliable when calculated within the first few days of hospitalization
- It should not be used as the sole criterion for treatment decisions
Frequently Asked Questions
What is the normal range for Maddrey's Discriminant Function?
There is no "normal" range because the score is designed for patients with alcoholic hepatitis. A score below 32 is considered less severe, while a score of 32 or higher indicates severe disease. Healthy individuals without liver disease would not typically have this score calculated.
Can Maddrey's score be used for other types of hepatitis?
Maddrey's Discriminant Function was specifically developed and validated for alcoholic hepatitis. It is not intended for use in viral hepatitis, autoimmune hepatitis, or other forms of liver disease. Different scoring systems, such as the MELD score, are more appropriate for those conditions.
How often should Maddrey's score be recalculated?
In clinical practice, the score is typically calculated at the time of admission and may be repeated periodically to assess response to treatment. The frequency depends on the patient's clinical course and the treating physician's judgment. Some protocols recalculate the score after 7 days of corticosteroid therapy to evaluate treatment response.
What does a Maddrey's score of 40 mean?
A score of 40 is well above the 32 threshold and indicates severe alcoholic hepatitis with a high risk of short-term mortality. Patients with scores in this range are typically considered candidates for corticosteroid therapy, provided there are no contraindications. The treating physician will also consider other factors such as renal function, infection status, and the presence of gastrointestinal bleeding before making treatment decisions.
Is Maddrey's score still used in modern practice?
Yes, Maddrey's Discriminant Function remains a widely used clinical tool for assessing alcoholic hepatitis severity. However, it is often used alongside other scoring systems such as the MELD score, Glasgow Alcoholic Hepatitis Score, and ABIC score to provide a more comprehensive prognostic assessment. Many clinicians consider it a standard part of the initial evaluation for suspected alcoholic hepatitis.