Underlying causes of death among US decedents with systemic sclerosis, 2003−2016. Systemic sclerosis ICD-10 (International Classification of Diseases, 10th edition): M34.0, M34.1, M34.8, M34.9; circulatory system diseases ICD-10: I00-I99; malignancies ICD-10: C00-C96; digestive system diseases ICD-10: K00-K95; respiratory system diseases ICD-10: J00-J99; infectious diseases ICD-10: A00-A99, B00-B99; metabolic diseases ICD-10: E00-E89; genitourinary system diseases ICD-10: N00-N99; nervous system diseases ICD-10: G00-G99.