Effect of season on clinical outcomes of Thai systemic sclerosis: Analysis of the Thai national healthcare database

Abstract

Objectives: We aimed to determine rate of admission, mortality rate, and causes of death in systemic sclerosis (SSc) patients after stratifying by season.Method: A cross-sectional analysis was performed of patients over 15 in the national database with a primary diagnosis of SSc (ICD-10:M34) covered by the National Health Security Office hospitalized between 2014 and 2018. The seasons were stratified into hot, rainy, and Cool dry seasons.Results: Included were 2480 SSc patients with 3684 admissions: most (64.3%) were female. The respective mean age and median length of stay was 56.9 ± 12.3 years and 3 days (IQR 2–6). The admission rate was highest during the rainy season (1574 visits, 42.7%), followed by the cool dry season (1183 visits, 32.1%) then the hot season (927 visits, 25.2%). During the 13,180 person-days, 1660 SSc patients died resulting in a mortality rate of 12.1 per 100 person-days. The proportion of SSc patients who died in the Cool dry season was significantly higher than in the hot or rainy season (p = .04). Pulmonary involvement in SSc was the most common cause of death in the hot season, which is greater than in the other seasons (p = .004). By comparison, death due to cardiac involvement in SSc was common during the rainy season and cool dry seasons (p = .04).Conclusion: The admission rate among Thai SSc patients was greatest during the rainy season, while mortality was highest during the cool dry season. The most common causes of death were SSc-related irrespective of season, particularly cardiopulmonary involvement.