New IPF staging and prognosis model announced - PulmCCM
Dec 262012

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Access the online GAP Score Calculator for IPF

Although idiopathic pulmonary fibrosis (IPF) has a poor prognosis -- a median survival of only 3 years -- there is wide heterogeneity among individual patients. Some have a precipitous decline and die within months of diagnosis; others live for a decade or longer, with little apparent progression of IPF. This inherent uncertainty in prognosis provokes anxiety among patients and frustration among physicians trying to provide appropriate counseling, support, and timely referral to lung transplant centers. Previous outcome prediction models have been proposed, but so far none has been validated prospectively or entered wide use.

Brett Ley, Christopher Ryerson, Talmadge King, Harold Collard et al hope to change that. They have developed a new staging and outcome prediction system for IPF which they call the "GAP model" (for the Gender, Age, and Physiology variables it uses). After it showed good integrity in both its derivation and validation cohorts, they published their new GAP model, combined with a simple scoring system (the GAP index) in the May 15 Annals of Internal Medicine. (See also: Idiopathic Pulmonary Fibrosis Review - PulmCCM Central Topic Update.)

What They Did

Authors used the records of 228 patients with IPF at University of California-San Francisco as a derivation cohort, and 330 IPF patients from Morgagni-Pierantoni Hospital (Forli, Italy) and the Mayo Clinic as a validation cohort. Logistic regression was used to identify variables predictive of outcome, and a weighted point system was created to fit the data.

What They Found

The authors' GAP model / GAP index can be summarized as follows:

GAP Index for IPF*
Factor  Points 
 Gender:  Male 1
 Age:  61-65 1
>65 2
 Physiology:  FVC 50-75% pred. 1
 < 50% pred. 2
 DLCO 36-55% pred. 1
 < 36% pred. 2
 Pt. cannot perform 3

* Patient characteristics not fitting the described criteria are scored as zero.

 GAP Staging for IPF
  Mortality (%)
 Points  Stage  1-yr  2-yr  3-yr
0-3 I 5.6 11 16
4-5 II 16 30 42
6-8 III 39 62 77
What It Means

Physicians may now have an effective tool to help predict the outcome of idiopathic pulmonary fibrosis; further validation in other cohorts could result in the GAP model entering wider use. Most physicians probably already had a sense that among patients with IPF, older patients with more severe impairments in lung function (forced vital capacity and diffusing capacity, or transfer factor) had a poorer prognosis than younger patients with less severe lung disease. Still, the data and the stratification of outcomes presented here could help doctors counsel patients more effectively, guide referral to lung transplant centers, and provide some low-risk patients with anxiety-reducing peace of mind.

Access the online GAP Score Calculator for IPF

Ley B et al. A Multidimensional Index and Staging System for Idiopathic Pulmonary Fibrosis. Ann Intern Med 2012;156:684-691. 

See also:  Idiopathic Pulmonary Fibrosis Review (PulmCCM Central Topic Update)

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  5 Responses to “New IPF staging and prognosis model announced”

  1. Myself, 73 yrs of age, suffering from ILD– sensitive to Pigeon (guessed) feather/ droppings since January 2012. Under treatment at Hinduja Hospital Mumbai, India — Physician : Dr. Zarir Udwadia.Treatment began with 20 mg Prednisolone first month, for 2 months 10 mg, 3rd month 7.5 mg and now till Dec 2012 5 mg daily dose. Symptoms have greatly reduced, breathing easiernad much less cough except mornings. Currently visiting at Pleasanton, CA.

    • Thanks for the note Krishna. I’m glad you’re feeling better and enjoying your visit to California. Be well … -Matt

  2. hi, my father is 60 yr old. he was diagnosed with ILD 20 yrs back along with dermatomyositis n polymyositis plus h/o working in chemical factory. since then he has been on steroids. he had 3-4 exacerbations since then.. but since last 6-8 mths his symptoms (dyspnea) have increased. he is requiring >18-20 hr oxygen with sometimes DOE grade 4. Recent CT shows UIP pattern. we have told its IPF progression n we have started pirfenidone. are there any currents trials of stem cell research which can benefit us? is lung transplant an option for him?

  3. The above grading criteria is flawed. It does not extend mortality calculations beyond 3 yrs. Also it is easier for patient to know survival in years rather than % mortality. Biggest challenge is which should be starting point? I had mild CT scan abnormality and FVC of 70% in 2007 which was not diagnosed as ILD at that time and not followed up by primary physician. But after worsening of dyspnea and chronic cough finally I went to pulmonologist in Oct 2012 and was diagnosed as ILD. Still exact cause is not known. In Oct 2012 my FVC went down to 46% and DLCO less 35 % which went further down I Dec 2012. Drs. have been advising to go for transplant but before I decide I wanted to know my GAP index but now I don’t know which one should be my starting point and also mortality percentage beyond 3 yrs are not listed if I want to use year 2007 to compute GAP index.

  4. Hello Gentlemen,
    My father is around 65 years of age, who diagnosed IPF recently. According to medical report, 30% of of the lung has affected the illness and the doctor precribed Pirfinex tabs. Anyhow, I have seen a research report from a US university shows that Fisudil intake is an effective treatment for IPF.
    It will be highly appreciated if you could share us your valuable opinion in this regard.