Nocturnal emergency department visits, duration of symptoms and risk of hospitalisation among adults with asthma exacerbations: a multicentre observational study

Objectives: We sought to compare the characteristics of patients with asthma presenting to the emergency department (ED) during the night-time with those of patients presenting at other times of the day, and to determine whether the time of ED presentation is associated with the risk of hospitalisation. Design and setting: A multicentre chart review study of 23 EDs across Japan. Participants: Patients aged 18-54 years with a history of physician-diagnosed asthma, presented to the ED between January 2009 and December 2011 Outcome measures: The outcome of interest was hospitalisation, including admissions to an observation unit, inpatient unit and intensive care unit. Results: Among the 1354 patients (30.1% in the night-time group vs 69.9% in the other time group) included in this study, the median age was 34 years and ∼40% were male. Overall 145 patients (10.7%) were hospitalised. Patients in the night-time group were more likely to have a shorter duration of symptoms (≤3 hours) before ED presentation than those in the other time group (25.9% in night-time vs 13.4% in other times; p<0.001). In contrast, there were no significant differences in respiratory rate, initial peak expiratory flow or ED asthma treatment between the two groups (p>0.05). Similarly, the risk of hospitalisation did not differ between the two groups (11.3% in nighttime vs 10.5% in other times; p=0.65). In a multivariable model adjusting for potential confounders, the risk of hospitalisation in the night-time group was not statistically different from the other time group (OR, 1.10; 95% CI 0.74 to 1.61; p=0.63). Conclusions: This multicentre study in Japan demonstrated no significant difference in the risk of hospitalisations according to the time of ED presentation.