Researchers reported that delayed diagnosis of fibrotic interstitial lung disease (ILD) was common and was associated with gastroesophageal reflux disease and repeated complaints of cough and shortness of breath. More than half of patients were diagnosed more than 6 months after the first documented symptom considered potentially attributable to fibrotic ILD, with an average time to diagnosis of nearly 17 months.
Researchers conducted a retrospective cohort study using electronic health records, claims data, and medical chart review from a large integrated tertiary-care health system in the US Midwest to identify adults with chart-confirmed fibrotic ILD between 2011 and 2019. The final analysis included 239 patients with at least 5 years of continuous enrollment before diagnosis and a symptom onset date that could be ascertained. Patients were categorized as having a timely diagnosis (within 6 months of symptom onset) or a delayed diagnosis (more than 6 months following symptom onset). The primary outcome was time from symptom onset to diagnosis, and secondary analyses evaluated demographic and clinical characteristics, symptoms, health care use, and costs associated with delayed diagnosis using multivariable logistic regression and machine learning.
Overall, 138 of the 239 patients (58%) experienced a delayed diagnosis. Mean time from symptom onset to diagnosis was 17 months overall, compared with 28 months among patients with delayed diagnosis and 2 months among those diagnosed within 6 months.
Compared with patients who received a timely diagnosis, those with delayed diagnosis were more often women and more frequently had gastroesophageal reflux disease or rheumatic disease. They also had more repeated complaints of cough and shortness of breath before diagnosis. In multivariable analyses, gastroesophageal reflux disease was associated with approximately 2.6 times the odds of delayed diagnosis, while repeated complaints of cough and shortness of breath also remained independently associated with diagnostic delay.
Machine-learning analyses identified similar patterns. The characteristics associated with a higher predicted probability of delayed diagnosis included repeated complaints of cough and shortness of breath, gastroesophageal reflux disease, depression, family history of ILD, and age between 65 and 70 years. A patient cluster characterized by obesity, female sex, gastroesophageal reflux disease, and frequent respiratory complaints had a positive predictive value of 91% for delayed diagnosis; 20 of 22 patients in that cluster had delayed diagnosis.
The researchers noted several limitations. The study was retrospective and conducted within a single US integrated health system, which may limit generalizability. The threshold used to define delayed diagnosis was based on clinical judgment rather than an established standard, symptom onset dates were determined retrospectively from medical records, and the prediction models were not externally validated. The investigators also were unable to assess factors such as referral delays, appointment availability, or insurance coverage that may influence time to diagnosis.
Overall, the findings suggest that repeated respiratory complaints, particularly among patients with gastroesophageal reflux disease, may help physicians identify patients who warrant earlier evaluation for fibrotic ILD. Additional research is needed to determine how diagnostic delay affects clinical outcomes.
“Delays in diagnosing fibrotic ILD are common, with the average time between presumed symptom onset and clinical identification estimated to be about 17 months. Key factors associated with delayed diagnosis include GERD and repeated complaints of cough or shortness of breath,” wrote first author Hyun J. Kim, of the University of Minnesota, and colleagues.
Disclosures: The study was funded by Boehringer Ingelheim Pharmaceuticals. Several authors reported employment with Boehringer Ingelheim, Thermo Fisher Scientific/PPD, or Henry Ford Health, and Hyun J. Kim reported research-related relationships.
Source: BMC Pulmonary Medicine
