Effects of seasonal variation on hospitalisations for acute exacerbations of chronic obstructive pulmonary disease.

ABSTRACT

Objective. To identify seasonal differences in the frequency and outcome of hospital admissions due to acute exacerbation of chronic obstructive pulmonary disease (AE-COPD). Method. A cohort study with data from 94 admissions due to AE-COPD at a tertiary care hospital in New Delhi, during the period 1995-1997. Results. The sample consisted of 94 patients (21.3% females) with a mean age of 61.2 years. There were an average of 7.8 admissions per month during the year. After a trough in November (two admissions/month), there was a sharp rise in admissions which peaked in February (15 admissions/month). Overall, there was no statistically significant difference in admissions per month in winter season (November-February) versus summer season (March-October) (p=0.251.) We did not identify significant seasonal differences in patients' demographics, laboratory results including arterial blood gases, mortality, duration of stay, requirement of invasive mechanical ventilation, or intensive care unit (ICU). Conclusions. There was no association between the season of the year and the frequency of hospitalisation or outcome due to AE-COPD. However, there are dramatic increases in the frequency of admissions starting in November and peaking in February of the following year.