Definition

Adult bronchiectasis was defined using the following criteria: (1) age ≥ 20 years and (2) at least one claim under ICD-10 code J47⁶. Bronchiectasis-associated comorbidities were defined using the following ICD-10 codes: angina pectoris (I20), myocardial infarction (I21, I22, or I25.2), asthma (J45–J46), chronic obstructive pulmonary disease (COPD) (J42–J44, except J43.0 [unilateral emphysema]), cerebrovascular disease (G45–G46, I60–I69, or H34.0), depression (F32–F34), diabetes mellitus (E10–E14), high cholesterol level (E78), gastroesophageal reflux disease (K21), hypertension (I10–I15), heart failure (I43, I50, I09.9, I11.0, I25.5, I13.0, I13.2, I42.0, I42.5–I42.9, or P29.0), inflammatory bowel disease (K50–K51), non-tuberculous mycobacteria (NTM) infection (A31), osteoporosis (M80–M81), and rheumatological disease (M05, M06, M31.5, M32, M33, M34, M35.1, M35.3, or M36.0)¹⁵. Baseline comorbidities were assessed at the time of study enrolment; those were used to calculate CCI (see Table ​Table11 and Supplementary Table ^S1). Comorbidities over the study period were assessed at the time of study enrolment as well as during follow-up period. As we excluded patients with malignancies diagnosed during the washout period, lung cancer (C34) plus other malignancies (C00–C97, except C34) were only assessed during the follow-up period.

Baseline patient characteristics.

Data are presented as number (%) or mean with standard deviation.

^aComorbidities at the time of enrolment were used.

All-cause mortality was defined as all deaths during follow-up for up to 10 years after enrolment (January 2005–December 2015) irrespective of the cause of death. Causes of mortality were determined using data provided by Statistics Korea, an initiative of the Ministry of Strategy and Finance of South Korea. Causes of death were classified as one of the followings: (1) respiratory diseases (J00–J99); (2) cardiovascular diseases (I00–I99); (3) malignant neoplasms including lung cancer (C00–C97); (4) injury, poisoning, and external causes (S00–S99 and T00–T98); (5) endocrine diseases (E00–E90); (6) gastrointestinal diseases (K00–K93); (7) neurological diseases (G00–G99); (8) mental and behavioural disorders (F00–F99); (9) musculoskeletal and connective tissue diseases (M00–M99); and (10) miscellaneous.