The path to a diagnosis of interstitial lung disease (ILD) is often long and tortuous. On average, ILD is diagnosed nearly 12 months after symptom onset 1. Patients frequently present with non-specific symptoms such as exertional dyspnoea or chronic cough, which they may attribute to ageing and thus fail to seek medical attention promptly 1. Even when care is sought, the symptoms of ILD are easily confused with more common disorders such as chronic obstructive pulmonary disease (COPD), and can be challenging to diagnose for primary care physicians who rarely encounter these conditions 2. The care provider may prescribe empirical trials of inhalers, proton pump inhibitors, or cough suppressants before pursuing more definitive evaluation 3. In a multinational survey, almost half of ILD patients were initially misclassified or investigated for alternative diagnoses, enduring 7 to 10 investigations prior to a diagnosis of ILD 4. Such diagnostic delay carries clinically important consequences. In idiopathic pulmonary fibrosis (IPF), diagnostic delays exceeding 1 year are associated with poorer progression-free survival, reduced quality of life, and higher rates of hospitalisation 5. It also carries substantial socioeconomic costs, with detrimental effects on the ability to work 4. Therefore, identifying the earliest clinical signals of ILD represents an important step toward improving patient outcomes, as highlighted in a recent publication in Respirology by Fermoyle et al. 6 Using the UK Optimum Patient Care Research Database, a large longitudinal healthcare dataset comprising more than 25 million patients from over 1000 primary care practices across the United Kingdom, the authors examined the prevalence of symptoms and clinical findings up to 10 years preceding the diagnosis of ILD. Their analysis encompassed a heterogeneous cohort of ILD patients including IPF, hypersensitivity pneumonitis, and connective tissue disease-related ILD. Each case was matched with up to four controls without ILD from the same primary care practice. The study compared 18,914 ILD cases against 60,156 matched controls. Symptoms such as dyspnoea, cough, fatigue, weight loss, and loss of appetite were more prevalent among ILD patients than controls, with their frequency increasing significantly closer to the index diagnosis date, a finding that underscores the progressive nature of these diseases. Crackles on lung auscultation were also more commonly recorded. Despite these signals, patients with ILD frequently accumulated multiple primary care encounters and underwent investigations such as spirometry and chest radiography. Yet, misdiagnosis remained common, with the most frequent alternative diagnoses being asthma, COPD, and heart failure. This study addresses an important knowledge gap regarding the clinical features and presentation of ILD prior to diagnosis. By analysing longitudinal electronic health records, it overcomes the limitation of recall bias. Nonetheless, some caution is warranted. Clinical details recorded in the free-text fields were not accessible, which may partly explain why close to a quarter of ILD patients had no cough or dyspnoea documented in primary care. Notably, the frequency of crackles on lung auscultation was very low in this cohort. Depending on the ILD subtype, crackles were recorded in only 1.2% to 3.1% of patients, although this remained higher than in controls (0.2% to 0.6%). Bilateral ‘Velcro-type’ crackles strongly predict fibrotic ILD on high-resolution computed tomography (HRCT) and correlate with the extent of radiologic features of pulmonary fibrosis such as honeycombing and traction bronchiectasis 7. Importantly, fine crackles are also more common than symptoms and lung function abnormalities, and have been proposed as a potential screening tool for ILD 8. Diagnostic tools commonly used in primary care also have important limitations. In this study, though more patients in the ILD group had spirometry and X-rays performed, chest radiographs can miss up to 30% of ILD cases 9 and spirometry can remain normal in early ILD. Together, these factors may have resulted in missed opportunities where early ILD was present but not recognised. Reducing diagnostic delays will require a multipronged approach that acknowledges the complexity of the problem. Patients should be encouraged to report persistent respiratory symptoms rather than downplaying them. Earlier use of chest CT imaging by primary care physicians has been proposed to accelerate ILD diagnosis 1. Health-system interventions may also play an important role. In Spain, a rapid diagnostic pathway, incorporating training of primary care physicians for ILD identification and direct referral to a specialised ILD unit, reduced the time from symptom onset to ILD diagnosis from 22 months to 6 months. This translated to meaningful clinical gains, including diagnosis of ILD at earlier clinical stages, with a higher likelihood of lung transplantation and better post-transplant survival 10. The study by Fermoyle et al. provides valuable insights into the years preceding an ILD diagnosis. Their findings reinforce a recurring message: the clues to ILD are frequently present but insufficiently recognised within routine clinical practice. Improving awareness among patients and primary care physicians, encouraging careful attention to auscultatory findings such as fine ‘Velcro-type’ crackles, and streamlining referral pathways may help shorten the diagnostic journey. The greatest crime is to miss an opportunity for earlier recognition, and the work by Fermoyle et al. paves the way to create opportunities for earlier intervention in the disease course, preserve lung function, and improve the lives of patients living with ILD. The author has nothing to report. The author declares no conflicts of interest.
Gin Tsen Chai (Tue,) studied this question.