Objective:

To investigate the prevalence and factors associated with delayed diagnosis of fibrotic interstitial lung disease (ILD).

Approach:

• Study Design: 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.
• Patient Selection: Included 239 adults with chart-confirmed fibrotic ILD diagnosed between 2011 and 2019, with at least 5 years of continuous enrollment before diagnosis.
• Diagnosis Timing: Patients were categorized as having timely diagnosis (within 6 months of symptom onset) or delayed diagnosis (more than 6 months following symptom onset).
• Data Analysis: Primary outcome was time from symptom onset to diagnosis; secondary analyses evaluated demographic and clinical characteristics, symptoms, healthcare use, and costs using multivariable logistic regression and machine learning.

Key Findings:

• 58% of patients experienced a delayed diagnosis, with an average time to diagnosis of 17 months.
• Patients with delayed diagnosis had a mean time of 28 months from symptom onset compared to 2 months for timely diagnoses.
• Factors associated with delayed diagnosis included being female, having gastroesophageal reflux disease (GERD), repeated complaints of cough and shortness of breath, depression, family history of ILD, and being aged 65 to 70 years.
• Machine-learning analyses identified obesity, female sex, GERD, and frequent respiratory complaints as predictors of delayed diagnosis.

Interpretation:

Limitations:

• The study was retrospective and conducted within a single health system, limiting generalizability.
• The definition of delayed diagnosis was based on clinical judgment rather than an established standard.
• Symptom onset dates were determined retrospectively from medical records.
• Prediction models were not externally validated.
• Factors such as referral delays, appointment availability, or insurance coverage were not assessed.

Conclusion:

Delays in diagnosing fibrotic ILD are common, with key factors including GERD, repeated respiratory complaints, depression, family history of ILD, and age.

Sources:

• BMC Pulmonary Medicine