ATLAS Score for Clostridium Difficile Infection

ATLAS Score Calculator

Age

Treatment with Systemic Antibiotics

Leukocyte Count

Albumin

Serum Creatinine

ATLAS Score: 0

Likely Response to Therapy

Score 0: Likely to respond to initial C. difficile therapy. Low risk of treatment failure.

Predicts response to therapy in patients with C. diff.

Why Use

Useful for identifying patients with CDI who are at high risk for severe outcomes or mortality. Determining disease severity can aid in clinical decision-making for treatment intensity and level of care (e.g., outpatient versus inpatient management). Results can assist in discussions with patients and families about prognosis and treatment options.

When to Use

Use in patients diagnosed with C. difficile infection (CDI) at the time of diagnosis to stratify disease severity.

Formula

Addition of the selected points: Variable Points A ge, years <60 0 60-79 1 ≥80 2 T reatment with systemic antibiotics during C. diff infection therapy (≥1 day duration) No 0 Yes 2 L eukocyte count, cells/µL <16,000 0 16,000-25,000 1 >25,000 2 Serum a lbumin >3.5 g/dL (>35 g/L) 0 2.6-3.5 g/dL (26-35 g/L) 1 <2.6 g/dL (<26 g/L) 2 S erum creatinine (as a measure of renal function) ≤1.3 mg/dL (≤120 μmol/L) 0 1.4-2.0 mg/dL (121-179 μmol/L) 1 ≥2.1 mg/dL (≥180 μmol/L) 2 *Note: the original validation ( Miller 2013 ) examined 6 parameters: age, temperature, leukocyte count, albumin, serum creatinine, and systemic antibiotics. The combination of parameters which led to the greatest discrimination among risk groups and correlation with cure was the five excluding temperature, and MDCalc uses this version for that reason.

Pearls / Pitfalls

Scores correlate with cure rates; however, the correlation with recurrence was not statistically significant. Does not account for all markers of disease severity—for example, strain type was excluded since this information is not always readily available at diagnosis. Patients with life-threatening or fulminant disease were excluded from the derivation study, potentially leading to under-representation of patients at the upper extreme of score values. Note: Clostridium difficile is now referred to as Clostridioides difficile .

Management

For detailed treatment recommendations, please refer to clinical guidelines from the American College of Gastroenterology , the American Society of Colon and Rectal Surgeons , and the Infectious Disease Society of America/Society for Healthcare Epidemiology of America .

Advice

No definitive management recommendations have been made based on ATLAS score results. For lower scores: Consider less intensive treatment and possible outpatient management, if the patient is clinically stable. For higher scores: Escalate care, potentially involving infectious disease consultation, hospitalization, or ICU care if warranted. Use alongside clinical judgment; the score complements, but does not replace, bedside evaluation.

More Information

Interpretation: ATLAS Score Cure rate Mortality 0 95.7% 0.0% 1 93.3% 0.0% 2 92.7% 0.0% 3 89.5% 3.6% 4 81.1% 4.2% 5 76.1% 8.7% 6 85.7% 10.9% 7 50.0% 14.3% 8 55.6% 56.0% 9 33.0% >56.0% 10 <33.0% Cure rate from Miller 2013 and mortality from Miller 2010 .