de Vries et al reported teh Amsterdam-Oxford Model (AOM) to predict transplant-free survival for a patient with primary sclerosing cholangitis. The authors are from Academic Medical Center Amsterdam, University of Amsterdam, University of Oxford, University Medical Center Groningen and the Oxford University Research Unit in Vietnam.
Patient selection: primary sclerosing cholangitis (PSC)
Parameters:
(1) PSC subtype
(2) serum AST
(3) upper limit of normal range for serum AST
(4) serum alkaline phosphatase
(5) upper limit of normal range for serum alkaline phosphatase
(6) serum total bilirubin
(7) upper limit of normal range for serum total bilirubin
(8) serum albumin
(9) platelet count
(10) lower limit of normal for platelets (LLN)
(11) age at diagnosis
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Parameters
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Findings
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Points
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PSC subtype
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small duct
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0
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large duct
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0.323
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Parameter
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serum AST
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0.347 * LOG10((AST) / (AST ULN))
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serum alkaline phosphatase
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0.393 * LOG10((ALP) / (ALP ULN))
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serum total bilirubin
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0.337 * LOG10((total bilirubin) / (bilirubin ULN))
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serum albumin
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-2.485 * LOG10((albumin) / (albumin LLN))
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platelet count
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2.5451*ABS(LOG10(((platelet count) /(platelet LLN)) - 0.5))
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age at diagnosis
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0.018 * (age)
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where:
• LOG10 is used rather than LN since de Vries et al refer to (10-log).Also in Goet et al log is used on page 993 and ln for another equation on page 994.
• The handling of the platelet count is a bit uncertain but this is the best guess.
total score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: slightly below 0
• maximum score: slightly above 4
• Transplant-free survival for 5, 10 and 15 years can be estimated from Figure 2 in de Vries et al.
• A score < 2 is associated with a higher transplant-free survival (Goet et al, Figure 4).
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Score
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10-Year Transplant-Free Survival
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< 0
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> 96%
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0 to 2
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((-4.8162 * ((score)^2)) - (2.1483 * (score)) + 95.55) / 100
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2 to 4
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((1.0823 * ((score)^2)) - (39.071 * (score)) + 146.51) / 100
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> 4
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< 8%
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Performance:
• The area under the ROC curve is 0.68.
