Understanding diagnostic pathways in systemic sclerosis and systemic sclerosis-associated interstitial lung disease: A retrospective cohort study

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is usually detected in a patient known to have SSc but may be diagnosed prior to SSc. We probed an insurance database to investigate documentation of ILD prior to SSc. Using Optum's Clinformatics (R) Data Mart Database, we identified patients with an SSc index date between January 1, 2010, and September 30, 2015, based on International Classification of Diseases (ICD)-9-Clinical Modification (CM) codes, >= 2 medical claims associated with SSc on different dates within 1 year, and >= 3 years of continuous enrollment prior to SSc index date (ICD-9-CM cohort). We identified an ICD-10-CM cohort comprising patients with an SSc index date between October 1, 2017, and June 30, 2019, based on ICD-10-CM codes, >= 2 medical claims associated with SSc on different dates within 1 year, and >= 2 years of continuous enrollment prior to SSc index date. ILD was defined as >= 2 medical claims associated with ILD on different dates. The ICD-9-CM and ICD-10-CM cohorts comprised 1779 and 1032 patients, respectively. In these cohorts, respectively, 7.6% and 9.3% of patients had their second medical claim associated with ILD prior to their SSc index date, and 4.3% and 5.6% of patients had their second medical claim associated with ILD >1 year prior to the SSc index date. In this analysis, 4% to 6% of patients with SSc had claims for ILD >1 year prior to a claim for SSc. These data show that SSc can affect the lung early and demonstrate the importance of screening patients with SSc for ILD and patients with ILD for SSc.