ICD-10 Diagnostic Coding Patterns and Clinical Correlates in Refractory Chronic Cough: Analysis from the Korean Chronic Cough Registry

The International Classification of Diseases (ICD) system plays a key role in health data classification but currently lacks a specific code for refractory chronic cough (RCC). This study analyzed ICD-10 coding patterns among 331 RCC patients enrolled in the Korean Chronic Cough Registry. Each patient had a median of 3 [IQR: 2–4] ICD-10 codes at their most recent outpatient visit. The most frequently assigned primary code was R05 (Cough), recorded in 80.4% of cases. Patients with R05 as their primary code tended to have fewer identifiable etiologies but reported more cough hypersensitivity symptoms. Additionally, the number of ICD-10 codes correlated with both cough severity and cough-specific quality-of-life impairment. In a pooled analysis including RCC and non-RCC cases, the R05 code showed high specificity (80.5%) but low sensitivity (25.8%) for RCC. These findings support the need for a dedicated ICD code to accurately capture RCC in clinical and epidemiological contexts.