Maddrey's Discriminant Function Calculator
Maddrey's Discriminant Function (mDF) is the standard scoring tool for estimating 30-day mortality in patients with alcoholic hepatitis and for identifying who may benefit from corticosteroid therapy. Enter the patient prothrombin time, a control prothrombin time, and the serum bilirubin level. The score and its clinical interpretation update instantly. Switch bilirubin units between mg/dL and umol/L using the selector below.
Formula
Worked example
A patient has PT of 18 s, control PT of 12 s, and bilirubin of 6 mg/dL. PT prolongation = 18 - 12 = 6 s. 4.6 x 6 = 27.6. mDF = 27.6 + 6 = 33.6. Because 33.6 >= 32, this is severe alcoholic hepatitis with an estimated 30-day mortality of 35-45% and the patient should be evaluated for corticosteroid therapy.
What is Maddrey's Discriminant Function?
Maddrey's Discriminant Function (mDF) was developed in 1978 by Willis Maddrey and Jack Boitnott during a randomized controlled trial comparing prednisolone with placebo in 55 patients with biopsy-proven alcoholic hepatitis. The formula quantifies the two laboratory hallmarks of severe disease: prolonged clotting time (reflecting hepatic synthetic failure) and elevated bilirubin (reflecting cholestasis and hepatocellular injury). Together they generate a single score that stratifies patients by short-term mortality risk. A threshold of 32 emerged from that original study as the cutoff above which steroid therapy appeared to reduce 30-day mortality, and it has remained the standard in clinical practice for over four decades.
How to use this calculator
Enter the patient's prothrombin time (PT) in seconds, the laboratory control PT (the reference value run on the same analyzer), and the serum total bilirubin. If your laboratory reports bilirubin in umol/L, select that unit with the toggle and the calculator converts it automatically (1 mg/dL = 17.1 umol/L). The mDF score, PT prolongation, converted bilirubin, estimated 30-day mortality, and a plain-language steroid guidance statement all update instantly. The show-your-work panel traces every arithmetic step with the actual values entered.
Clinical interpretation and steroid therapy
A score below 32 corresponds to mild-to-moderate alcoholic hepatitis. Short-term mortality in this group is below 10% at 90 days, and corticosteroids are not routinely recommended because the risk-benefit ratio does not favor treatment. Management centers on strict alcohol abstinence, nutritional support (targeting 35 kcal/kg/day and at least 1.5 g protein/kg/day), and monitoring for complications. A score at or above 32 defines severe disease. In these patients, prednisolone 40 mg/day for 28 days is the most extensively studied intervention. Before starting steroids, active infection and gastrointestinal bleeding must be excluded because they are relative contraindications. Response to steroids is assessed with the Lille Model at day 7: a Lille score above 0.45 predicts non-response and guides early discontinuation to avoid prolonged immunosuppression without benefit.
Limitations and complementary scores
The mDF was derived from a small trial and several subsequent meta-analyses have shown more modest survival benefits from steroids than the original study suggested. The score captures only two variables and does not account for renal function, which is a powerful predictor of outcome in alcoholic hepatitis. The MELD (Model for End-Stage Liver Disease) score incorporates creatinine and INR and has been shown to predict 30-day mortality with comparable or superior accuracy. The Glasgow Alcoholic Hepatitis Score adds age, white cell count, and blood urea to prognosis and can help when mDF is borderline. Clinicians typically use mDF as the initial screen and confirm severity with one or more complementary scores before committing to steroid therapy.
Maddrey mDF thresholds and clinical implications
| mDF score | Severity | Estimated 30-day mortality | Steroid indication |
|---|---|---|---|
| < 32 | Mild-to-moderate | < 10% | Not routinely indicated |
| >= 32 | Severe | 35-45% | Evaluate for prednisolone 40 mg/day x 28 days |
Based on Maddrey et al. (1978) and subsequent validation studies. 30-day mortality estimates refer to historical controlled trials.
Frequently asked questions
What is the mDF threshold for corticosteroid therapy?
A score of 32 or above is the standard threshold. Patients with mDF >= 32 have an estimated 30-day mortality of 35-45% in the historical trials and are the group in whom corticosteroid therapy (prednisolone 40 mg/day for 28 days) has shown a survival benefit. Scores below 32 are associated with much lower short-term mortality and steroids are not routinely indicated.
What is the difference between PT and the control PT?
Prothrombin time (PT) measures how quickly blood clots by the extrinsic pathway. Because reagents vary between laboratories and instruments, every coagulation analyzer runs a concurrent control (reference) sample. The mDF formula uses the difference between the patient's PT and that lab-specific control, not absolute PT values. This makes the score comparable across institutions regardless of which reagent is used.
Can I use INR instead of PT for the mDF score?
No. The original Maddrey formula specifically uses the PT difference in seconds, not the International Normalized Ratio (INR). The INR was developed to standardize anticoagulation monitoring, not to assess acute liver failure, and substituting INR for (PT - control) gives a different and unvalidated result. Always use the raw PT in seconds alongside the laboratory control value.
What unit of bilirubin does the formula require?
The formula requires bilirubin in mg/dL. If your laboratory reports in umol/L, divide by 17.1 to convert. For example, 102 umol/L / 17.1 = 5.96 mg/dL. This calculator handles the conversion automatically when you select the umol/L option.
Are corticosteroids safe for all patients with mDF >= 32?
No. Active bacterial infection, active gastrointestinal bleeding, uncontrolled diabetes, and pancreatitis are important contraindications or relative contraindications to corticosteroid therapy in this setting. Renal failure (creatinine > 2.5 mg/dL at baseline) is also associated with markedly worse outcomes even with steroids. A thorough clinical assessment is required before starting treatment.
What is the Lille score and why does it matter?
The Lille Model is a formula calculated on day 7 of corticosteroid therapy using the change in bilirubin. A Lille score above 0.45 predicts non-response, and stopping steroids early in those patients avoids the risks of prolonged immunosuppression without benefit. Many centres now use the Lille score as an integral part of the steroid treatment protocol for severe alcoholic hepatitis.
What other scores are used alongside the mDF?
The MELD score is widely used and incorporates creatinine, which the mDF ignores. The Glasgow Alcoholic Hepatitis Score adds age, white cell count, and blood urea. ABIC (Age, Bilirubin, INR, Creatinine) is another validated alternative. Many hepatologists use at least two of these tools together before deciding on treatment strategy.
Sources
- Maddrey WC, Boitnott JK, Bedine MS, Weber FL Jr, Mezey E, White RI Jr. Corticosteroid therapy of alcoholic hepatitis. Gastroenterology. 1978;75(2):193-199.
- Thursz MR, Richardson P, Allison M, et al. Prednisolone or pentoxifylline for alcoholic hepatitis (STOPAH trial). N Engl J Med. 2015;372(17):1619-1628.