Interstitial lung diseases: never forget to think about it in primary care

Figures & data

Figure 1. Fibrotic ILDs at risk of progression. IPF is the paradigm of fibrotic progression, sooner or later these patients progress. Non-IPF fibrotic ILD involves many ILDs with variable fibrotic component that are at risk of progression depending on different factors, including the type of ILD.

Table 1. Diagnostic criteria for identifying progressive pulmonary fibrosis (PPF) in non-IPF fibrotic ILDs.

In a patient with ILD of known or unknown etiology other than IPF who has radiological evidence of pulmonary fibrosis, PPF is defined as at least of the following three criteria occurring within the past year with no alternative explanation:

1. Worsening respiratory symptoms. 2. Physiological evidence of disease progression (either of the following)

a. Absolute decline in FVC ≥ 5% predicted within 1 year of following. b. Absolute decline in DLCO (corrected for Hb) ≥10% predicted within 1 year or follow-up.

3. Radiological evidence of disease progression (one or more of the following): a. Increased extent of severity of traction bronchiectasis and bronchiolectasis. b. New ground-glass opacity with traction bronchiectasis. c. New fine reticulation. d. Increased extent or increased coarseness of reticular abnormality. e. New or increased honeycombing. f. Increased lobar volume loss.

ILD: interstitial lung disease; IPF: idiopathic pulmonary fibrosis; PPF: progressive pulmonary fibrosis; FVC: forced vital capacity; DLCO: diffusion capacity for carbon monoxide; Hb: hemoglobine.

Figure 2. Proposed patient referral circuit for rapid diagnosis and continuum care.

There are four types of patients with a suspected diagnosis of ILD in Primary Care. Subclinical cases are patients with no respiratory symptoms, patients at risk of developing ILD (due to family history or environmental or occupational exposures, for example) and incidental cases (diagnosis of ILD by chance, such as through and abdominal CT scan performed for other reasons). However, most patients are referred with clinical symptoms (dry cough and/or dyspnea). All these patients should undergo an appropriate physical examination to find finger clubbing, inspiratory crackles on auscultation, and risk-factors at the medical history. Chest X-ray and/or CT scan, and spirometry help to suspect ILD in primary care centers. The relationship with primary care centers may also help to improve the communication and information about follow-up and consequent needs over time, including end-of-life approach.

Table 2. Clinical features that help to suspect fibrotic ILDs.

Patient clinical features	Complementary tests	Possible ILD diagnosis
Progressive dyspnea and/or cough that worsen or appears with exercise or laughing	Chest X-ray or computed tomography (CT)Scan	Idiopathic Pulmonary Fibrosis. Familial Pulmonary Fibrosis. Fibrotic Hypersensitivity Pneumonitis. Smoking-related interstitial fibrosis. Connective tissue disease associated ILD. ILD with autoimmune features (IPAF). Unclassifiable ILD. Fibrotic nonspecific interstitial pneumonia. Drug-induced ILD. Pneumoconiosis. Fibrotic sarcoidosis. Post-SDRA ILD (including severe covid).
No improvement after the use of bronchodilators, antibiotics, or antitussives	Spirometry: FVC and FEV1/FVC
Presence of risk factors: Family history of ILD Use of pneumotoxic drugs Organic or inorganic exposures (working, daily habits, home) Smoking history Gastroesophageal reflux History of relevant viral infection Telomere dysfunction Known gene mutations
Velcro crackles (auscultation)
Clubbing