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143 Hospital mortality in patients with rare diseases during the COVID-19 and SARS pandemics: results from a 7.5 million population
  1. Claudia Ching Yan Chung,
  2. Wilfred Hing Sang Wong,
  3. Brian Hon Yin Chung
  1. Hong Kong


Background The threat of pandemics occur differently for different groups. The rare disease population is at particular risk of being further marginalised during pandemics.

Objectives To assess hospital mortality in the rare disease and general populations during the coronavirus disease of 2019 (COVID-19) and severe acute respiratory syndrome (SARS) pandemics in the 7.5 million population in Hong Kong.

Methods Using the Clinical Data Analysis and Reporting System (CDARS), a population-level database that records all public healthcare records in Hong Kong, all admission records during the COVID-19 (January 23 – August 23, 2020) and SARS (March 11 – June 30, 2003) pandemics were extracted. Patients with rare diseases were identified using one or more of the 1,084 10th version International Classification of Diseases and Related Health Problems (ICD-10) codes cross-referenced with 467 ORPHAcodes. Admission records during the same period in 2019 and 2002 were retrieved for comparison. Primary outcomes were COVID-19/SARS mortality in hospital. Secondary outcomes were overall hospital mortality during the COVID-19 and SARS pandemic periods. Subgroup analysis by age-group (≤18, >18 to <60, ≥60) was performed to understand the mortality patterns. Logistic regression was used to estimate the odds ratios with 95% confidence intervals (CIs).

Results During the COVID-19 pandemic, 407,219 patients were admitted to one or more of the 43 public hospitals in Hong Kong, of which, 39,576 (9.7%) were paediatric patients ≤18 years old, and 13,894 (3.4%) were rare disease patients. Of the 4,381 patients admitted with COVID-19, 81 (1.8%) died during the same admission, of which, 5 (6.2%) were patients with rare diseases. COVID-19-related mortality was almost exclusively seen in patients ≥60 years in both rare disease and general populations, with mortality being 21.7% and 7.4%, respectively. None of the COVID-19 patients ≤18 years died by the time of data extraction. Patients with rare diseases had an adjusted 3.4 times odds of COVID-19-related hospital mortality compared with that of the general population (95% CI 1.24–9.41). In contrast, 158,930 patients were admitted during the SARS pandemic, with 24,045 (15.1%) being ≤18 years and 5,249 (3.3%) being rare disease patients. Of the 1,449 patients admitted with SARS, 234 (16.1%) died during the same admission, of which, 1 (0.4%) was ≤18 years, and 6 (2.6%) were patients with rare diseases. While age-related increase in mortality was observed for the general population during the SARS pandemic, this pattern was not observed in the rare disease population. Rare disease patients ≤18 years had a 12.5 times higher SARS-related mortality than those in the general population (12.5% vs 1.0%). Patients admitted during the same pandemic periods without coronavirus infection had a significantly higher hospital mortality compared with those admitted one year before the pandemics (p<0.001).

Conclusions This population-based study demonstrated the differential impacts of COVID-19 and SARS on rare disease patients in Hong Kong, a group that is currently not strategically protected. Real-time data analysis by age group within different populations could be of consideration when developing prioritisation guidelines in the future. Taken together, this study warrants cautious healthcare planning, with consideration of prioritising patients with rare diseases.

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