Horn et al developed a Patient Severity Index (PSI) that can be used for preparing case mix groups of hospitalized patients. The authors are from the Johns Hopkins University in Baltimore.
(1) stage of principal diagnosis (chief complaint)
(2) interactions (concurrent or comorbid conditions)
(3) response to therapy, rate of
(4) response to therapy, residual findings after therapy
(6) dependence on hospital facilities and staff (disability, requirements for equipment, etc.)
(7) extent of procedures not performed in the operating room
rate of response to therapy
residual findings after therapy
none or very minor
extent of non-OR procedures
therapeutic or invasive diagnostic
emergency life-sustaining (critical care)
• A major complications is one that is as important or more important than the principal diagnosis.
• The appendix to the paper provides definitions for all of the parameters.
severity index =
= SUM(points for all 7 parameters)
• minimum score: 7
• maximum score: 28
• The higher the score the more severe the patient's condition.
percent of maximal score =
= (((patient severity index) – 7) / 21) * 100%
• This would probably work fairly well for many simple situations but might start to decompensate with really complex clinical problems with many principal diagnoses.
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Purpose: To evaluate the severity of a patient's illness using the Patient Severity Index of Horn et al.
Objective: severity, prognosis, stage, disease progression, economic cost