Idiopathic interstitial pneumonia diagnostic criteria
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Zaghw, M.D. [2]; Chetan Lokhande, M.B.B.S [3]
Overview
Repeated measurements of different clinical and physiological parameters are believed to be useful in assessing the clinical course of IPF. Assessment of dyspnea and using an established clinical scale for rating the impact of dyspnea on activities are standard for IIPs evaluation. [1] Lung volumes, DLCO, resting arterial blood gases, cardiopulmonary exercise testing with measurement of gas exchange, HRCT lung scans are our current tools for diagnosing and monitoring idiopathic interstitial pneumonia. Physiologic testings have been used to determine the current functional lung capacity. Studies have shown that conventional lung function tests by spirometry have more precision in prognosis of patients with IPF, while extensive tests like gas exchange measurements at rest and exercise do not add additional information to make the prognostic or treatment evaluation more precise. [2].
Diagnosis
The diagnosis of IIPs is dynamic as it depends on multidisciplinary approach among different specialists. The histological patterns identified by the pathologists give better distinguishing patterns than imaging patterns identified by radiologists. Clinical-radiological-pathological diagnosis (CRP diagnosis) is rely on histopathological findings as a very informative tool to reach the definitive diagnosis. Also the practice of delaying the biopsy till the patient starts to deteriorate clinically and radiologically is not helpful as it delays the diagnosis and reduce the likelihood of the disease to be accurately identified. [3]
| Histological patterns | Clinical-Radiological-Pathological diagnosis |
| Usual interstitial pneumonia | Idiopathic pulmonary fibrosis/ cryptogenic fibrosing alveolitis |
| Nonspecific interstitial pneumonia | Nonspecific interstitial pneumonia |
| Organizing pneumonia | Cryptogenic organizing pneumonia |
| Diffuse alveolar damage | Acute interstitial pneumonia |
| Respiratory bronchiolitis | Respiratory bronchiolitis interstitial lung disease |
| Desquamative interstitial pneumonia | Desquamative interstitial pneumonia |
| Lymphoid interstitial pneumonia | Lymphoid interstitial pneumonia |
However the surgical biopsy is important for classification and confident CRP diagnosis, it is not always necessary to reach diagnosis, especially in the cases where there is a typical clinical-radiological picture of UIP/IPF. The diagnostic criteria for idiopathic pulmonary fibrosis without a surgical biopsy adopted by AT/ERS.[3]
| AMERICAN THORACIC SOCIETY / EUROPEAN RESPIRATORY SOCIETY CRITERIA for diagnosing of IDIOPATHIC PULMONARY FIBROSIS in absence of surgical lung biopsy |
Major criteria:(must have all)
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Minor criteria:
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Adopted from the joint statement of American Thoracic Society.
In the immunocompetent adult, the presence of all of the major diagnostic criteria + at least three of the four minor criteria increases the likelihood of a correct clinical diagnosis of IPF.[3]
Assessment of Severity
Disease severity is assessed on the basis of symptoms, HRCT, and pulmonary function testing.
Mild or early disease:
- Asymptomatic or with a mild, nonproductive cough and dyspnea with substantial exertion.
- Radiographic changes of reticular opacities and areas of honeycombing are limited to subpleural and basilar areas, < 10% of the lung parenchyma.
- Pulmonary function tests is normal or may show mild reductions in forced vital capacity (FVC), diffusing capacity (DLCO), and/or distance walked on the six-minute walk test. Alveolar to arterial oxygen gradient (P[A-a]O2) is normal or mildly elevated (<20 mmHg).
- Supplemental oxygen is not needed.
Moderate disease:
- Dyspnea on moderate exertion, nonproductive cough
- Radiographic changes of more extensive with reticular opacities involving >20-30% of the lung parenchyma and honeycombing of <5% of the lung parenchyma[4] Quantitative assessment of these radiographic abnormalities on HRCT slices taken at three levels (eg, tracheal carina, inferior pulmonary veins, and 1 cm above the dome of the diaphragm).[5]
- Mild to moderate pulmonary function abnormalities. reduced FVC (50-70% of predicted), a reduced DLCO (45-65% of predicted) and/or P(A-a)O2 (>21-30 mmHg).Discrepancy in the degree of impairment of FVC and DLCO may be noted.
- Supplemental oxygen may be needed with exertion.
Advanced disease
- Dyspnea at rest/on mild exertion (walking <300 feet/climbing <1 flight of stairs).
- Extensive honeycombing is noted on HRCT (>5% of the lung parenchyma in three or more zones).[4]
- Pulmonary function testing typically reveals moderate to severe reductions in the FVC (<50% of predicted), DLCO (<50% of predicted), and oxygen desaturation (≥4 percent) during a six-minute walk test.[6] Gas exchange is also impaired with room air oxygen saturation <88% and P(A-a)O2 difference elevated (>30 mmHg).
- Supplemental oxygen is required at rest and/or with exertion.
References
- ↑ McSweeny, AJ.; Creer, TL. (1995). "Health-related quality-of-life assessment in medical care". Dis Mon. 41 (1): 1–71. PMID 7805548. Unknown parameter
|month=ignored (help) - ↑ Erbes, R.; Schaberg, T.; Loddenkemper, R. (1997). "Lung function tests in patients with idiopathic pulmonary fibrosis. Are they helpful for predicting outcome?". Chest. 111 (1): 51–7. PMID 8995992. Unknown parameter
|month=ignored (help) - ↑ 3.0 3.1 3.2 "American Thoracic Society. Idiopathic pulmonary fibrosis: diagnosis and treatment. International consensus statement. American Thoracic Society (ATS), and the European Respiratory Society (ERS)". Am J Respir Crit Care Med. 161 (2 Pt 1): 646–64. 2000. doi:10.1164/ajrccm.161.2.ats3-00. PMID 10673212. Unknown parameter
|month=ignored (help) - ↑ 4.0 4.1 Arakawa, H.; Honma, K. (2011). "Honeycomb lung: history and current concepts". AJR Am J Roentgenol. 196 (4): 773–82. doi:10.2214/AJR.10.4873. PMID 21427324. Unknown parameter
|month=ignored (help) - ↑ Lynch, DA.; Godwin, JD.; Safrin, S.; Starko, KM.; Hormel, P.; Brown, KK.; Raghu, G.; King, TE.; Bradford, WZ. (2005). "High-resolution computed tomography in idiopathic pulmonary fibrosis: diagnosis and prognosis". Am J Respir Crit Care Med. 172 (4): 488–93. doi:10.1164/rccm.200412-1756OC. PMID 15894598. Unknown parameter
|month=ignored (help) - ↑ Lama, VN.; Flaherty, KR.; Toews, GB.; Colby, TV.; Travis, WD.; Long, Q.; Murray, S.; Kazerooni, EA.; Gross, BH. (2003). "Prognostic value of desaturation during a 6-minute walk test in idiopathic interstitial pneumonia". Am J Respir Crit Care Med. 168 (9): 1084–90. doi:10.1164/rccm.200302-219OC. PMID 12917227. Unknown parameter
|month=ignored (help)