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.[citation needed]
In 1984, the first prognostic indicator for advanced non-Hodkin's lymphoma was developed. 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. The authors concluded that trials using a patient mix weighted toward good prognosis will not find such a difference.
In 1993, a retrospective analysis was performed on 2031 patients with aggressive non-Hodgkin's lymphoma, of all ages, treated with a doxorubicin-based chemotherapy regimen such as CHOP between 1982 and 1987.[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.
One point is assigned for each of the following risk factors:[citation needed]
The sum of the points allotted correlates with the following risk groups:
A simplified index can be used when comparing patients within an age group (i.e. 60 or younger, or over 60) and includes only 3 of the above factors:[citation needed]
The sum of the points allotted correlates with the following risk groups:
Although the IPI has shown itself to be a useful clinical tool, widely used by oncologists and a mainstay of risk stratification in clinical trials for lymphoma, it should be kept in mind that it was developed prior to the use of rituximab, which is now included with anthracycline-based combination chemotherapy as of the standard of care in B-cell lymphomas (the majority of non-Hodgkin's lymphomas). Rituximab has significantly improved the outcomes of lymphoma patients; and its effect on the prognostic value of the IPI is uncertain. Future development of a more rigorous prognostic index may thus be useful.
Given the success of the IPI for intermediate grade lymphomas, an effort was undertaken to develop a similar prognostic index for the most common low-grade lymphoma, follicular lymphoma. The prognostic factors that emerged from this were: age, stage, number of lymph node areas involved, serum hemoglobin level, and serum LDH.[3]
One point is assigned for each of the following adverse prognostic factors:[citation needed]
The sum of the points allotted correlates with the following risk groups:
An effort was more recently undertaken to identify a similar prognostic index predictive of outcome in advanced mantle cell lymphoma. There were four factors found to have independent prognostic relevance: age, performance status, LDH, and white blood cell count (WBC).[4]
The point values are assigned as follows:
The sum of the allotted points correlates with the following risk groups: