Background Chronic respiratory diseases are risk factors for severe disease in coronavirus disease 2019 (COVID-19). Respiratory tract infection is one of the commonest causes of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). There has not been evidence suggesting the link between COVID-19 and AECOPD, especially in places with dramatic responses in infection control with universal masking and aggressive social distancing. Methods This is a retrospective study to assess the number of admissions of AECOPD in the first three months of 2020 in Queen Mary Hospital with reference to the admissions in past five years. Log-linear model was used for statistical inference of covariates, including percentage of masking, air quality health index and air temperature. Results The number of admissions for AECOPD significantly decreased by 44.0% (95% CI 36.4%–52.8%, p < 0.001) in the first three months of 2020 compared with the monthly average admission in 2015–2019. Compare to same period of previous years, AECOPD decreased by 1.0% with each percent of increased masking (p < 0.001) and decreased by 3.0% with increase in 1 °C in temperature (p = 0.045). The numbers of admissions for control diagnoses (heart failure, intestinal obstruction and iron deficiency anaemia) in the same period in 2020 were not reduced. Conclusions The number of admissions for AECOPD decreased in first three months of 2020, compared with previous years. This was observed with increased masking percentage and social distancing in Hong Kong. We postulated universal masking and social distancing during COVID-19 pandemics both contributed in preventing respiratory tract infections hence AECOPD.

Background and objective: Bronchiolitis obliterans syndrome (BOS) after haematopoietic stem cell transplantation (HSCT) presents with lung function decline. The pattern of lung function decline after BOS diagnosis could impact prognostication of BOS as a complication after HSCT. The aim of this study was to assess the impact of lung function decline on overall survival (OS) in BOS subjects. Methods: Subjects with BOS were compared to those without BOS and matched for age, gender, primary diagnoses, conditioning regimes and chronic graft versus host disease. Lung function tests at baseline, at BOS diagnosis and every 3 months after HSCT were evaluated. Results: Of the 1461 subjects undergoing allogeneic HSCT (allo-HSCT) between 1998 and 2015, 95 (6.5%) were diagnosed with BOS. A total of 159 matched HSCT recipients without BOS were identified. A 25% decline in FEV 1 within the first 3 months after BOS diagnosis would separate BOS subjects into a subgroup with initial rapid decline and another subgroup with initial gradual decline in lung function. The rapid decline group showed lower subsequent lung function parameters and significantly worse OS compared to the gradual decline group (P = 0.013). Conclusion: Post-HSCT BOS subjects with initial rapid lung function decline within 3 months after BOS diagnosis will have significantly poorer lung function and worse OS compared to those with initial gradual decline in lung function after BOS diagnosis. HSCT BOS patients with rapid initial decline in lung function warrant closer monitoring for the development of other post-HSCT complications that could affect their survival.

In patients with type 2 DM and moderate to severe OSA, 3 months of CPAP therapy did not decrease HbA1c but lowered systolic and diastolic blood pressures. In view of a potentially limited effect size of CPAP treatment on glycemic control, sample size estimation for future randomized controlled studies must make adequate allowance for influence from external factors of medications/diet and CPAP use.