Independent effect of prior exacerbation frequency and disease severity on the risk of future exacerbations of COPD: a retrospective cohort study.
Few studies have researched the independent effect of COPD severity on the risk of future exacerbations adjusted by previous exacerbation frequency. We aimed to analyse the independent effect of COPD severity on the risk of exacerbations in the following year, and whether this effect was stronger or not than the effect of a previous history of exacerbations. We conducted a retrospective population-based cohort study including 900 patients with confirmed COPD. Exacerbation frequency was observed for the previous year and for the following year. Patients were defined as 'Frequent Exacerbator' (FE) phenotype if they suffered ⩾2 exacerbations in a year, and were categorised according to the severity of COPD (GOLD Grades 1-4). Odds ratios (ORs) were estimated by logistic regression adjusting for age, gender, smoking status, severity of COPD and being FE in the previous year. The main predictor of being FE among all grades of COPD severity was a history of frequent exacerbations in the previous year: adjusted OR 4.97; 95% confidence interval (CI) (3.54-6.97). COPD severity was associated with a higher risk of being FE: Crude OR GOLD Grade 4 3.86; 95% CI (1.50-9.93). However, this association diminished after adjusting for being FE in the previous year: adjusted OR 2.08; 95% CI (0.75-5.82). Our results support that a history of frequent exacerbations in the previous year is the most important independent predictor of exacerbations in the following year, also among the most severe COPD patients. Severity of COPD would be associated with a higher risk of exacerbations, but this effect would be partly determined by the exacerbations suffered in the previous year.
Preventive Medicine and Public Health Area, Universidad de Cantabria, IDIVAL, Santander, Spain.
Miguel Santibañez
MS
Margüello
Centro de Salud de Gama, Servicio Cántabro de Salud, Bárcena de Cicero, Spain.
Roberto
R
Garrastazu
Centro de Salud de Liérganes, Servicio Cántabro de Salud, Miera, Spain.
Mario
M
Ruiz-Nuñez
Centro de Salud Bajo Asón, Servicio Cántabro de Salud, Ampuero, Spain.
Jose Manuel
JM
Helguera
Centro de Salud de Suances, Servicio Cántabro de Salud, Suances, Spain.
Sandra
S
Arenal
Centro de Salud Campoo-Los Valles, Servicio Cántabro de Salud, Mataporquera, Spain.
Cristina
C
Bonnardeux
Centro de Salud de Suances, Servicio Cántabro de Salud, Suances, Spain.
Carlos
C
León
Pneumology Department, Hospital Universitari Vall d'Hebron; CIBER of respiratory diseases (CIBERESP), Barcelona, Spain.
Marc
M
Miravitlles
Pneumology Department, Hospital de Laredo, Servicio Cántabro de Salud, Laredo, Spain.
Juan Luis
JL
García-Rivero
D000368:Aged; D018450:Disease Progression; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects