National Health and Safety Network case definitions and determination of imputability
| Case definition |
| Definitive |
| A clinical syndrome occurring from 2 days to 6 weeks after cessation of transfusion characterized by characteristic rash: erythematous, maculopapular eruption centrally that spreads to extremities and may, in severe cases, progress to generalized erythroderma and hemorrhagic bullous formation; diarrhea; fever; hepatomegaly; liver dysfunction (elevated liver enzymes); marrow aplasia; and pancytopenia AND characteristic histological appearance of skin or liver biopsy |
| Probable |
| Meets definitive criteria EXCEPT biopsy negative or not done |
| Imputability |
| Definite |
| WBC chimerism present in the absence of alternative diagnoses |
| Probable |
| WBC chimerism present BUT other potential causes are present (eg, stem cell transplantation) |
| Possible |
| WBC chimerism not present or not done OR alternative explanations are more likely (eg, solid organ transplantation) |
| Doubtful |
| Evidence is clearly in favor of a cause other than the transfusion, but transfusion cannot be excluded |
| Ruled out |
| There is conclusive evidence beyond reasonable doubt of a cause other than the transfusion |
| Not determined |
| The relationship between the adverse reaction and the transfusion is unknown or not stated |
| Case definition |
| Definitive |
| A clinical syndrome occurring from 2 days to 6 weeks after cessation of transfusion characterized by characteristic rash: erythematous, maculopapular eruption centrally that spreads to extremities and may, in severe cases, progress to generalized erythroderma and hemorrhagic bullous formation; diarrhea; fever; hepatomegaly; liver dysfunction (elevated liver enzymes); marrow aplasia; and pancytopenia AND characteristic histological appearance of skin or liver biopsy |
| Probable |
| Meets definitive criteria EXCEPT biopsy negative or not done |
| Imputability |
| Definite |
| WBC chimerism present in the absence of alternative diagnoses |
| Probable |
| WBC chimerism present BUT other potential causes are present (eg, stem cell transplantation) |
| Possible |
| WBC chimerism not present or not done OR alternative explanations are more likely (eg, solid organ transplantation) |
| Doubtful |
| Evidence is clearly in favor of a cause other than the transfusion, but transfusion cannot be excluded |
| Ruled out |
| There is conclusive evidence beyond reasonable doubt of a cause other than the transfusion |
| Not determined |
| The relationship between the adverse reaction and the transfusion is unknown or not stated |