FLIPI Calculator for Follicular Lymphoma

Q: What are the five FLIPI factors?

Age over 60 years, Ann Arbor stage III or IV, haemoglobin under 12 g/dL (pre-transfusion), serum LDH above the reporting laboratory's upper limit of normal, and more than four involved nodal areas. Each scores one point, giving a total of 0 to 5: low risk 0 to 1, intermediate 2, high 3 or more.

Q: Is the FLIPI still valid now that everyone gets rituximab?

Its discrimination has held up better than its absolute figures. The index still separates groups with different outcomes in chemoimmunotherapy-era cohorts, but the survival percentages published with it come from patients diagnosed between 1985 and 1992 and are not what a patient treated today should expect. FLIPI-2 was developed from prospectively collected data for exactly this reason.

Q: What is the difference between FLIPI and FLIPI-2?

Different factors and a different cohort. FLIPI-2 keeps haemoglobin and age, replaces LDH with beta-2 microglobulin, replaces the nodal-area count with the diameter of the largest involved node, and adds bone marrow involvement. It was developed on prospectively collected data and predicts progression-free survival, where FLIPI was fitted to overall survival in retrospective archive data.

Q: Does a high FLIPI mean the patient needs treatment?

No. The index predicts outcome; it does not define an indication. Whether treatment is indicated in follicular lymphoma is assessed against tumour burden criteria such as GELF — nodal mass size, splenomegaly, effusions, cytopenias, symptoms — which are a different instrument with different items. Patients with a high FLIPI and low tumour burden exist, and so do the reverse.

Q: Do I count nodes or nodal areas?

Areas, on the published diagram of nodal regions. A single region containing six enlarged nodes counts once. This is the item two assessors most often score differently on the same patient, and because the intermediate stratum is only one point wide, that one disagreement moves the group.

Five adverse factors, one point each. FLIPI was built on patients diagnosed between 1985 and 1992 — before rituximab existed — which is the entire reason FLIPI-2 was later developed, and the reason its survival figures are a historical measurement rather than a forecast.

Last updated 8 Oct 2026

FLIPI (Solal-Céligny 2004)

5 factors → 0–5

Age over 60 yearsThe published factor is age above 60. Some later renderings write it as 60 or over, which moves only patients aged exactly 60; the original index and the trial-protocol reproduction read for this page both say over 60.

Ann Arbor stage III or IVAdvanced stage by Ann Arbor — nodal disease on both sides of the diaphragm, or disseminated extralymphatic involvement. Most follicular lymphoma presents at stage III or IV, so this item is positive in the large majority and contributes less discrimination than its weight suggests.

Haemoglobin under 12 g/dL12 g/dL is 120 g/L. The original index specifies a PRE-TRANSFUSION haemoglobin, which the trial-protocol reproduction read for this page states explicitly — scoring a post-transfusion value loses the factor in exactly the patients in whom it matters most.

Serum LDH above the laboratory upper limit of normalA RATIO question, not an absolute one: the factor is LDH above the reporting laboratory’s own upper limit of normal. LDH activity is method- and temperature-dependent and upper limits in routine use span roughly 190 to 280 U/L, so an absolute threshold carried from one laboratory to another scores some patients wrongly in both directions. Read the flag off the report.

More than 4 nodal sites involvedNodal AREAS, counted on the published diagram of nodal regions rather than as individual enlarged nodes, and the commonest source of disagreement between two assessors scoring the same patient. Later renderings write the factor as 4 or more areas rather than more than 4; both appear in print and they differ for a patient with exactly four.

1pointsExample

Age 67 (1); Ann Arbor stage II (0); haemoglobin 13.4 g/dL (0); LDH 210 U/L with a laboratory upper limit of 250 U/L (0); three nodal areas (0)

The five factors and the three strata

FLIPI = age >60 + Ann Arbor stage III–IV + haemoglobin <12 g/dL + LDH above the laboratory ULN + more than 4 nodal areas
One point each; range 0 to 5

Low 0–1 · intermediate 2 · high 3–5

all five weights are 1: the index is a count of adverse factors and not a weighted sum, even though the factors were not equally prognostic in the derivation data. The per-factor relative risks of death reported alongside it were 2.38 for age over 60, 2.00 for stage III–IV, 1.55 for haemoglobin under 12, 1.50 for a raised LDH and 1.39 for more than four nodal areas, so age carries nearly twice the hazard of the nodal count and the same single point
the LDH factor is a ratio: above the REPORTING LABORATORY’s upper limit of normal, not above a fixed number of units per litre. That is the same construct the IPI family and MIPI use, for the same reason
nodal AREAS, not nodes: counted on a published diagram of nodal regions. The threshold is printed as more than four in the original and as four or more in several later renderings, and the two differ for any patient with exactly four
what it predicts, and what it does not: overall survival in the cohort it was derived in. It was not built to decide who needs treatment — that question belongs to tumour burden criteria such as the GELF or BNLI criteria, which are a different instrument entirely and are not computed here
the era: derived on retrospectively collected archive data from patients diagnosed between 1985 and 1992, with 90 months’ median follow-up. Rituximab was not licensed until 1997. FLIPI therefore describes the natural history of follicular lymphoma under alkylator and anthracycline-based chemotherapy, which is why FLIPI-2 and the m7-FLIPI exist and why its own survival percentages are the floor rather than the expectation now

Worked example

Age 67 (1); Ann Arbor stage II (0); haemoglobin 13.4 g/dL (0); LDH 210 U/L with a laboratory upper limit of 250 U/L (0); three nodal areas (0)
1 + 0 + 0 + 0 + 0 = 1 adverse factor
1 sits in the 0–1 low-risk band, about 36% of the derivation cohort, with five-year overall survival of 91% and ten-year of 71% in patients diagnosed between 1985 and 1992
Note the LDH. 210 U/L looks raised against the 190 U/L upper limit some laboratories use, and is normal against this laboratory's 250 — the factor is the flag on the report, not the number
Add advanced stage and a raised LDH and the total becomes 3: high risk, with ten-year overall survival of 36% in the same cohort. Two items, two strata, and a 35-point difference in a figure measured thirty years ago
A patient with four nodal areas scores 0 on that item under the original wording (more than four) and 1 under the commoner later wording (four or more). At a total of 2 that single reading decides between intermediate and high risk

The five factors, their published relative risks and the strata

The weights are all 1 and the hazards are not: age carries 2.38 and the nodal count 1.39, and both score a single point. That is a deliberate simplification — the index was built to be computable at the bedside from five yes/no answers — but it means two patients with the same FLIPI are not interchangeable.
Adverse factor	Points	Relative risk of death in the derivation data
Age over 60 years	1	2.38
Ann Arbor stage III or IV	1	2.00
Haemoglobin under 12 g/dL (pre-transfusion)	1	1.55
LDH above the laboratory upper limit of normal	1	1.50
More than 4 nodal areas involved	1	1.39

The three strata and what they predicted, 1985 to 1992

From the FLIPI training series: 1,795 patients analysed out of a retrospectively collected international archive, diagnosed between 1985 and 1992, median follow-up 90 months. The two sources read for this page disagree on the size of the collected database — one says 4,167 patients and one says 5,120 — and agree on the 1,795-patient training series and on every survival figure above. NONE of these patients received rituximab. Every outcome figure here describes the cohort the index was derived in and not the patient in front of you; the spread within one stratum is wider than the gap between strata.
Risk group	Adverse factors	Share of cohort	5-year overall survival	10-year overall survival
Low	0 – 1	36%	91%	71%
Intermediate	2	37%	78%	51%
High	3 – 5	27%	53%	36%

An index from before rituximab, and why that matters more than the arithmetic

The Follicular Lymphoma International Prognostic Index counts five adverse features present at diagnosis — age over 60, advanced Ann Arbor stage, haemoglobin under 12 g/dL, an LDH above the laboratory’s upper limit of normal, and more than four involved nodal areas — and separates three groups of roughly equal size with very different survival. It replaced an earlier index built for aggressive lymphoma that discriminated poorly in follicular disease, and it is still the stratification most trials of follicular lymphoma report and balance their arms on.

The arithmetic is the least interesting thing about it. What a working reader needs to know is when the numbers were measured. The index was fitted to retrospectively collected archive data from patients diagnosed between 1985 and 1992, with 90 months of median follow-up. Rituximab was not licensed anywhere until 1997. So the index’s own ten-year overall survival figures — 71% in the low-risk group, 51% intermediate, 36% high — describe follicular lymphoma treated with alkylators and anthracyclines and nothing else. Chemoimmunotherapy changed those numbers substantially, and the index’s discrimination survived the change better than its absolute percentages did. That is precisely why FLIPI-2 was developed in a prospectively collected, rituximab-era cohort, and why the clinicogenetic m7-FLIPI was built on top of it later.

Two items account for most of the disagreement between assessors. The nodal count is of nodal AREAS read off a published regional diagram, not of individual enlarged nodes, and the published threshold appears both as more than four and as four or more — a difference that decides a whole stratum for a patient with exactly four. The haemoglobin is specified as pre-transfusion, which is easy to lose in a patient who arrived anaemic and was transfused before the staging bloods were drawn. The LDH item is a ratio question in disguise: it asks whether the value exceeds the reporting laboratory’s own upper limit, and those limits differ enough between methods that an absolute cut-off carried from one hospital to another misscores patients in both directions.

The index also says nothing about whether to treat. Follicular lymphoma is frequently managed without immediate therapy, and the decision rests on tumour burden criteria — the GELF criteria and their relatives — which are a separate instrument with separate items and are not computed here. A high FLIPI does not satisfy those criteria and a low FLIPI does not fail them. Every laboratory threshold here is method- and laboratory-dependent, so the reader’s own laboratory’s reference interval takes precedence. A risk stratum is not a diagnosis and not a plan. This page computes the index, names the stratum and reports what it predicted in the derivation cohort; what follows is a decision for the treating team with the patient.

Frequently asked questions

What are the five FLIPI factors?

Age over 60 years, Ann Arbor stage III or IV, haemoglobin under 12 g/dL (pre-transfusion), serum LDH above the reporting laboratory’s upper limit of normal, and more than four involved nodal areas. Each scores one point, giving a total of 0 to 5: low risk 0 to 1, intermediate 2, high 3 or more.

Is the FLIPI still valid now that everyone gets rituximab?

Its discrimination has held up better than its absolute figures. The index still separates groups with different outcomes in chemoimmunotherapy-era cohorts, but the survival percentages published with it come from patients diagnosed between 1985 and 1992 and are not what a patient treated today should expect. FLIPI-2 was developed from prospectively collected data for exactly this reason.

What is the difference between FLIPI and FLIPI-2?

Different factors and a different cohort. FLIPI-2 keeps haemoglobin and age, replaces LDH with beta-2 microglobulin, replaces the nodal-area count with the diameter of the largest involved node, and adds bone marrow involvement. It was developed on prospectively collected data and predicts progression-free survival, where FLIPI was fitted to overall survival in retrospective archive data.

Does a high FLIPI mean the patient needs treatment?

No. The index predicts outcome; it does not define an indication. Whether treatment is indicated in follicular lymphoma is assessed against tumour burden criteria such as GELF — nodal mass size, splenomegaly, effusions, cytopenias, symptoms — which are a different instrument with different items. Patients with a high FLIPI and low tumour burden exist, and so do the reverse.

Do I count nodes or nodal areas?

Areas, on the published diagram of nodal regions. A single region containing six enlarged nodes counts once. This is the item two assessors most often score differently on the same patient, and because the intermediate stratum is only one point wide, that one disagreement moves the group.

Related calculators

References

Solal-Céligny P, et al. Follicular Lymphoma International Prognostic Index (FLIPI). Blood. 2004. The derivation paper: a training series of 1,795 patients diagnosed 1985–1992 from retrospective archive data.
Protocol for NCT01234766, Appendix B: FLIPI and FLIPI-2 — both instruments’ items, risk groups and outcome figures. clinicaltrials.gov.
University of Florida Division of Hematology & Oncology. Lymphoma prognostic indices and outcome tables: IPI, R-IPI and FLIPI.
Prognostic indices in follicular lymphoma: the IPI, the Italian Lymphoma Intergroup index and the FLIPI. Hematology Reviews — the training series (1,795 of 5,120 collected, diagnosed 1985–1992), the 36/37/27% distribution and survival by group.
Prognostic models in follicular lymphoma. Diagnostics (MDPI), 2025 — FLIPI as a pre-rituximab instrument, this review’s own internal disagreement about the FLIPI-2 factor set, and the Arcaini FLIPI-2 validation in 498 patients diagnosed 1980–2008.
Federico M, et al. Follicular Lymphoma International Prognostic Index 2 (FLIPI-2), from the International Follicular Lymphoma Prognostic Factor Project. J Clin Oncol. 2009. The derivation paper; PROSPECTIVELY collected data, unlike FLIPI’s retrospective archive series.

Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/