Criteria for IPF Diagnosis

Early Consideration of IPF Is Essential to Make a Timely Diagnosis1,2

  • There is often at least a 1-year delay between symptom onset and diagnosis; meanwhile, disease may be progressing3
    • Signs and symptoms are nonspecific, including cough and dyspnea on exertion4-6
    • ≈50% of patients with IPF receive an incorrect initial diagnosis3
      • These include heart disease and obstructive lung disease (eg, chronic obstructive pulmonary disease)
    • ≈38% of patients with IPF see 3 or more physicians before diagnosis3

IPF Should Be Considered Early in the Diagnostic Algorithm, as Signs and Symptoms Are Nonspecific4,6,7

  • Suspect IPF in a patient who is >50 years of age4 and has any of the following:
    • Inspiratory, bibasilar "Velcro®-like" crackles8
    • A chronic cough4,8
    • Dyspnea on exertion4,8
    • Fatigue9
    • Digital clubbing8
  • When you suspect IPF, make a timely diagnosis by conducting a clinical (eg, patient history and physical exam), physiologic, and radiologic evaluation4,7
    • Refer to the 2011 ATS Guideline for recommendations on a diagnostic algorithm for IPF4

Timely diagnosis of IPF is the first step to early management: initiating a management plan for patients with IPF is important because loss of lung function is irreversible10

Patient History and Physical Exam

Conduct a Comprehensive Clinical Evaluation

  • A comprehensive clinical evaluation includes patient history and physical exam1
    • Results may help provide a diagnosis suggestive of IPF
*
Listed in alphabetical order
Metabolic disorders include diabetes, hypercholesterolemia/hyperlipidemia, and weight disorders.
  • Consider IPF as a possible diagnosis if your patient is aged >50 years, has a chronic cough and/or dyspnea upon exertion, or has a history of smoking4

It Is Important to Listen to the Bases of the Lungs for Inspiratory Crackles

Click on the image to hear inspiratory bibasilar "Velcro®-like" crackles at the bases of the lung, a hallmark feature of IPF14

  • Note that there is subjectivity in the interpretation of lung sounds by the human ear15
    • For example, "Velcro®-like" crackles associated with IPF are commonly mistaken for the crackles of chronic heart failure16
  • A normal lung exam does not rule out IPF; the totality of data should be considered when evaluating a patient for IPF14

Physiologic Testing

Pulmonary Function Tests and Oxygen Saturation Are Important Components of an IPF Diagnosis

  • Conduct pulmonary function tests (PFTs) and assess oxygen saturation
  • Consider IPF as a diagnosis if a patient shows a reduced total lung capacity (TLC) and/or forced vital capacity (FVC), a forced expiratory volume in one second (FEV1)/FVC ratio consistent with a restrictive pattern, reduced diffusing capacity of the lungs for carbon monoxide (DLCO), and low oxygen saturation with exertion or at rest17,18
  • In certain situations, patients with IPF may exhibit normal or obstructive patterns if concomitant obstructive disease exists; therefore, while a restrictive pattern is indicative of IPF, lacking a restrictive pattern does not preclude an IPF diagnosis19,20
    • For example, up to 50% of patients with IPF may have concomitant chronic COPD19
    • In these cases, careful clinical and radiologic assessment is recommended19

Comparing Restrictive, Obstructive, and Mixed Lung Disease Patterns20-22

Using HRCT to Diagnose IPF

A Pattern of Usual Interstitial Pneumonia (UIP) on HRCT Is Indicative of IPF4,23

  • UIP is the radiologic pattern seen on HRCT in IPF4
  • The HRCT criteria for UIP pattern are listed below4
Definitive UIP4:
  • Subpleural, basal predominance
  • Reticular abnormality
  • Honeycombing with or without traction bronchiectasis
  • Absence of features listed as inconsistent with UIP pattern
Possible UIP4*:
  • Subpleural, basal predominance
  • Reticular abnormality
  • Absence of features listed as inconsistent with UIP pattern
Inconsistent UIP4:
  • Upper or mid-lung predominance
  • Peribronchovascular predominance
  • Extensive ground-glass abnormality (extent > reticular abnormality)
  • Profuse micronodules (bilateral, predominantly upper lobes)
  • Discrete cysts (multiple, bilateral, away from areas of honeycombing)
  • Diffuse mosaic attenuation/air-trapping (bilateral, in 3 or more lobes)
  • Consolidation in bronchopulmonary segment(s)/lobe(s)

Criteria for Definitive UIP Pattern4,23

Image adapted from Mueller-Mang, et al. RadioGraphics. 2007;27:595-615.

For Quality Imaging, Ensure HRCT Is Conducted Using Proper Technique

  • The following criteria are supported by the 2011 ATS Guideline24:
    • Slice thickness ≤2 mm
    • Noncontrast conditions
    • Full inspiration and without respiratory motion
    • Field of view to include lungs only
    • Prone positioning
    • High-resolution reconstruction algorithm
List not exhaustive. Please see Reference 24.

Sample HRCT Protocol Appropriate for Interstitial Lung Disease (ILD) Assessment25

Figure 9. Suggested technique for HRCT using multidetector CT scanners. Ensuring proper slice thickness is most critical. Table adapted from Mayo. J Thorac Imaging. 2009;24:252-259.
  • Ensure slice thickness is appropriate, as it may limit the detection of lung abnormalities, as seen in the example below

Impact of Slice Thickness on Detection of Lung Abnormalities

Figure 10. Lung abnormalities, highlighted in the red box, are obscured because of a thick slice reconstruction (A), which is clearly evident in (B). Images courtesy of Jonathan Chung, MD.
* The ATS diagnostic guidelines are based on categorization of HRCT patterns such as UIP, possible UIP, and inconsistent with UIP. The Fleischner Society has since released a white paper with revised categories: typical UIP, probable UIP, and indeterminate for UIP. The white paper states that a confident diagnosis of IPF can be made in the correct clinical context with a radiographic pattern of typical or probable UIP. The ATS guidelines may be updated to reflect the revised categories.26

Multidisciplinary Approaches

Multidisciplinary Approaches May Be Useful in Diagnosing Cases of IPF

  • Talking with the radiologist may facilitate a timely diagnosis4
  • Multidisciplinary approaches can be as simple as a quick phone call or email

Drs Steele and Loyd Discuss the Utility of Multidisciplinary Approaches (00:43)

Mark Steele, MD

Professor of Medicine
Vanderbilt University Medical Center

Jim Loyd, MD

Director, Familial Idiopathic Pulmonary Fibrosis Registry
Vanderbilt University Medical Center

References

1. Lamas, et al. Am J Respir Crit Care Med. 2011;184:842-847. 2. Kreuter, et al. BioMed Res Int. 2015;2015:1-10. 3. Collard, et al. Respir Med. 2007;101:1350-1354. 4. Raghu, et al. Am J Respir Crit Care Med. 2011;183:788-824.
5. Meyer. Transl Respir Med. 2014;2:4-17. 6. Spagnolo, et al. Multi Respir Med. 2012;7:1-10. 7. du Bois. Eur Respir Rev. 2012;21:141-146. 8. ATS/ERS Joint Statement. Am J Respir Crit Care Med. 2002;165:277-304. 9. Duck A, et al. J Adv Nurs. 2015;71:1055-1065. 10. Cottin and Maher. Eur Respir Rev. 2015;24:58-64. 11. Raghu, et al. Eur Respir J. 2015;46:1113-1130. 12. National Jewish Health website https://www.nationaljewish.org/healthinfo/conditions/ild/causes. Accessed June 2016. 13. Mayo Clinic website. http://www.mayoclinic.org/diseases-conditions/interstitial-lung-disease/basics/causes/con-20024481. Accessed June 2016. 14. Cottin and Cordier. Eur Respir J. 2012;40:519-521. 15. Gurung, et al. Respir Med. 2011;105:1396-1403. 16. Vyshedskiy, et al. Chest. 2005;128:1468-1474. 17. Meyer. Transl Respir Med. 2014;2:4-17. 18. ATS International Consensus Statement. Am J Respir Crit Care Med. 2000;161(2 Pt 1):646-664. 19. Lin and Jiang. J Thorac Dis. 2015;7:767-779. 20. Ryerson, et al. Chest. 2013;144:234-240. 21. Al-Ashkar, et al. Cleve Clin J Med. 2003;70:868-881. 22. Pellegrino, et al. Respir J. 2005;26:948-968. 23. Mueller-Mang, et al. RadioGraphics. 2007;27:595-615. 24. Raghu, et al. Am J Respir Crit Care Med. 2011;183:788-824 (online supplement). 25. Mayo. J Thorac Imaging. 2009;24:252-259. 26. Lynch, et al. Published online ahead of print November 15, 2017. Lancet Respir Med. doi: 10.1016/S2213- 2600(17)30433-2. Accessed December 4, 2017.

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