About the International Prognostic Index for Lymphoma (IPI)

Until the creation of the Follicular Lymphoma International Prognostic Index (FLIPI), the standard prognostic tool for assessing all lymphomas was the International Prognostic Index (IPI). This is a points-based system that allows doctors to guess how a given person's disease is likely to progress, based on a handful of particularly significant common risk factors.


How IPI Works
The IPI was the product of a research project in the 1990s, meaning essentially that it was based on the standard regimens of the 1980s and early 1990s (alkalating agent-based regimens like CHOP). The report of the International Non-Hodgkin's Lymphoma Prognostic Factors Project, published in the New England Journal of Medicine in 1993, formed the basis for the IPI model. They evaluated data from over 3000 patients in all stages of lymphoma.

IPI established five basic factors known to equate with a worse prognosis (less response to therapy, and shorter overall survival expectancy):

1. Age (60+ years old)
2. Advanced Disease (Stage III or Stage IV)
3. Elevated LDH levels
4. ECOG performance status greater than 1 (meaning unable to work, bedridden, and/or fully disabled)
5. More than one affected site outside of the lymph nodes

Each factor is worth one "point." People with zero or one points are considered low-risk and have the best survival rate, about 75% over 5 years. People with two points are low-intermediate risk and have a 5-year survival rate of 50%. Three points is categorized as high-intermediate risk (with 43% survival after 5 years), and four or five points is considered high risk, with a five-year survival rate of only 25%.

After IPI

There are two important caveats with respect to IPI. First, it is a general index which is most effective in evaluating intermediate and aggressive lymphomas, such as Diffuse Large B-Cell Lymphoma (DLBCL). More focused indices now exist for follicular lymphoma (the FLIPI) and mantle cell lymphoma (the Mantle Cell Lymphoma International Prognostic Index, or MIPI).

In addition, although the prognostic factors behind the IPI are still relevant, the survival rates originally associated with these factors have changed significantly in the era of advanced targeted therapies, such as the anti-CD20 monoclonal antibody rituximab. Changes are particularly apparent for slow-growing lymphomas like follicular lymphoma, where, although the disease was considered incurable, life expectancies were still comparatively long. Oncologists currently differ in their opinions of just how relevant the IPI and FLIPI models still are in an era of new targeted therapies. Very likely, the IPI/FLIPI are still generally good guidelines for assessing the severity of disease, but the original statistics regarding survival rates have improved dramatically.