The International Prognostic Index (IPI) is a clinical tool developed by oncologists to aid in predicting the prognosis of patients with aggressive non-Hodgkin's lymphoma.
Previous to IPI's development, the primary consideration in assessing prognosis was the Ann Arbor stage alone, but this was increasingly found to be an inadequate means of predicting survival outcomes, and so other factors were studied.
An information theory guided, computer search and evaluation procedure entropy minimax was employed to discover the largest sub-groupings for which survival is as extreme as possible[1] In the clinical trials analyzed retrospectively and containing a large fraction of patients not matching the 'good' - of 'good' (Karnofsky status >80 and 'A" Symptoms and SGOT <36 U/L), 'poor' (Karnofsky status <70 or Night sweats) and 'intermediate' (All Remaining) prognosis patterns identified, a significant difference was found between the survival of patients with and those without a complete response to therapy.
[2] Several patient characteristics were analyzed to determine whether they were associated with differences in survival, and the factors that emerged as significant were, in addition to the Ann Arbor stage: age, elevated serum lactate dehydrogenase (LDH), performance status, and number of extranodal sites of disease.
There were four factors found to have independent prognostic relevance: age, performance status, LDH, and white blood cell count (WBC).