Fig. 1.

Flow of participant recruitment in the Taiwan National Health Insurance. Systemic sclerosis patients in Catastrophic Illness Database during 1998–2007; first systemic sclerosis diagnosis date was the index date (n = 4378). Nonsystemic sclerosis patients were enrolled from the Longitudinal Health Insurance Database (LHID) 2005, which excluded all systemic sclerosis diagnoses (ICD-9 CM 710.1). LHID is a representative database comprising 1,000,000 subjects from the entire National Health Insurance enrollees randomly sampled by the National Health Research Institute of Taiwan