Currently, high-resolution CT is the gold standard for diagnosing ILD, but its high cost and radiation exposure hinders its routine use in clinical practice; the researchers noted. As a more accessible alternative, they designed an algorithm (VECTOR) designed to detect Velcro crackles; which occur early in the development of ILD, in pulmonary sounds recorded via electronic stethoscope. An algorithm designed to detect Velcro crackles in the lungs demonstrated diagnostic accuracy; for detecting interstitial lung disease in patients with rheumatoid arthritis.
Rheumatoid arthritis who have undergone high-resolution CT
In a recent study, the delay between first symptoms and referral to an IPF centre was 2.2 yrs; similar to other rare (orphan) lung diseases. Reasons for such delay may include patient-dependent factors (e.g.reluctance to acknowledge symptoms that may herald health problems and a sedentary lifestyle masking dyspnoea at exercise); disease-dependent factors (e.g. progressive onset and slow progression of IPF allows the disease to go undetected unless exacerbations occur); and physician-dependent factors (e.g. lack of awareness of rare diseases by general practitioners and even by lung specialists).
The study enrolled patients with rheumatoid arthritis who had undergone high-resolution CT within 12 months of showing signs; or symptoms of lung disease at seven centers in Italy.Of 137 patients included in the final analysis, 59 had ILD. In 83.9% of cases; VECTOR correctly classified patients, translating to a sensitivity of 93.2% and a specificity of 76.9%. VECTOR missed ILD in four patients and resulted in false positives in 18 of 78 patients, according to the data.
The researchers also found that VECTOR’s diagnostic accuracy for detecting ILD was higher than for detecting dyspnea (64.6%); cough (58.3%), diffusion capacity of the lungs for carbon monoxide (54.9%), FVC (52.8%) and chest X-ray (71.3%). Results showed that the rheumatologist correctly identified Velcro crackles in 69.1% of patients with ILD; however; they also detected crackles in 34.2% of patients without ILD, as compared with 23.1% of patients identified with the algorithm.
Correctly detected ILD in patients
VECTOR also correctly detected ILD in patients regardless of radiological pattern. In the four patients with false negatives, the patterns showed organizing pneumonia in two patients and usual interstitial pneumonia in two patients. Of 18 false positives, 12 patients had an airway disease, most often bronchiectasis chronic bronchitis and obliterative bronchiolitis. Despite the positive results, the study had limitations; including its retrospective design and the fact that the study population was not completely comparable to the general patient population with rheumatoid arthritis, the researchers noted.
Overall, they concluded that VECTOR with an electronic stethoscope “could allow a real-time screening of patients with ILD at rheumatologists” and could help inform the design of prospective studies in which patients with rheumatoid arthritis and ILD are identified using a noninvasive method and followed throughout the course of disease. – by Melissa Foster