title: Seasonality and determinants of moderate and severe COPD exacerbations in the TORCH study.
abstract: We investigated the impact of season relative to other determinants of chronic obstructive pulmonary disease (COPD) exacerbation frequency in a long-term international study of patients with forced expiratory volume in 1 s (FEV(1)) <60% predicted. COPD exacerbations were defined by worsening symptoms requiring systemic corticosteroids and/or antibiotics (moderate) or hospital admission (severe). Seasonality effect was calculated as the proportion of patients experiencing an exacerbation each month. Exacerbations in the northern and southern regions showed an almost two-fold increase in the winter months. No seasonal pattern occurred in the tropics. Overall, 38% of exacerbations were treated with antibiotics only, 19% with systemic corticosteroids only and 43% with both, while 20% required hospital admission irrespective of the season. Exacerbation frequency was associated with older age, lower body mass index, lower FEV(1) % pred and history of prior exacerbations. Females and patients with worse baseline breathlessness, assessed using the Medical Research Council (MRC) dyspnoea scale, exacerbated more often (rate ratio (RR) for male versus female 0.7, 95% CI 0.7-0.8 (p<0.001); RR for MRC dyspnoea score 3 versus 1 and 2 combined 1.1, 95% CI 1.1-1.2 (p<0.001)). The effect of season was independent of these risk factors. COPD exacerbations and hospitalisations were more frequent in winter.
authors: Woolcock Institute of Medical Research, PO Box M77, Missenden Road, Camperdown, Sydney NSW 2050, Australia. crj@med.usyd.edu.au
authors: C R
authors: CR
authors: Jenkins
authors: B
authors: B
authors: Celli
authors: J A
authors: JA
authors: Anderson
authors: G T
authors: GT
authors: Ferguson
authors: P W
authors: PW
authors: Jones
authors: J
authors: J
authors: Vestbo
authors: J C
authors: JC
authors: Yates
authors: P M A
authors: PM
authors: Calverley
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy; D015272:Pulmonary Medicine / Q000379:methods*; D012306:Risk; D012621:Seasons; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones; D000900:Anti-Bacterial Agents