DIAGNOSIS

A MULTIDISCIPLINARY DIAGNOSTIC APPROACH IS RECOMMENDED

The current recommended approach to diagnosing IPF is multidisciplinary and collaborative, involving the pulmonologist, pathologist, and radiologist in the review of clinical, radiologic, and pathologic assessments. ¹

A confident diagnosis of IPF can be made without a surgical lung biopsy in patients with consistent clinical and high-resolution computed tomography (HRCT) radiographic findings. ^1,2 HRCT scans are an important part of diagnosing IPF because they clarify the pattern, distribution, and extent of parenchymal disease. According to a study by Hunninghake et al, the HRCT features that are most strongly correlated with a pathologic diagnosis of IPF are upper lobe irregular lines (P = 0.007) and lower lobe honeycombing (P = 0.004). ²

EARLY DIAGNOSIS MAY HELP OPTIMIZE MANAGEMENT OF PATIENTS WITH IPF ¹

Early diagnosis allows for earlier referral to a clinical trial, which is important to consider in the initial stages of IPF because trials are generally limited to patients with mild to moderate disease. ³ Similarly, the sooner a patient is diagnosed, the sooner she or he can be considered for other therapeutic options including pulmonary rehabilitation (often combined with oxygen therapy) and lung transplantation. ¹ In addition, evidence showing that even patients with mild to moderate disease can experience rapid fatal deterioration underscores the need for early diagnosis and frequent evaluation. ^1,4

The American Thoracic Society and the European Respiratory Society (ATS/ERS) have devised a set of criteria that increases the likelihood of a correct diagnosis of IPF in the absence of surgical lung biopsy. The ATS/ERS recommend that all major criteria listed as well as at least 3 minor criteria be met to increase the likelihood of a correct diagnosis of IPF. ¹

ATS/ERS DIAGNOSTIC CRITERIA

Major Criteria

• Exclusion of other known causes of interstitial lung disease, such as certain drug toxicities, environmental exposures, and connective tissue diseases.
• Abnormal pulmonary function studies that include evidence of restriction (reduced VC often with an increased FEV1/FVC ratio) and impaired gas exchange (increased A-aPO2 with rest or exercise or decreased DLCO).
• Bibasilar reticular abnormalities with minimal ground-glass opacities on HRCT scans.
• Transbronchial lung biopsy or bronchoalveolar lavage (BAL) showing no features to support an alternative diagnosis.

Minor Criteria

• Age >50 years.
• Insidious onset of otherwise unexplained dyspnea on exertion.
• Duration of illness >3 months.
• Bibasilar inspiratory crackles (dry or "Velcro" type in quality).

References:

1. American Thoracic Society/European Respiratory Society. Idiopathic pulmonary fibrosis: diagnosis and treatment. International consensus statement. Am J Respir Crit Care Med. 2000;161:646-664.
2. Hunninghake GW, Lynch DA, Galvin JR, et al. Radiologic findings are strongly associated with a pathologic diagnosis of usual interstitial pneumonia. Chest. 2003;124:1215-1223
3. du Bois RM. Evolving Concepts in the early and accurate diagnosis of idiopathic pulmonary fibrosis. Clin Chest Med. 2006; 27(suppl); S17-S25.
4. Martinez FJ, Safrin S, Weycker D, et al. The clinical course of patients with idiopathic pulmonary fibrosis. Ann Intern Med. 2005;142:963-967.

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