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Underreporting Exacerbation of Chronic Obstructive Pulmonary Disease in a Longitudinal Cohort

¹ Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, and ² Department of Epidemiology, Biostatistics, and Occupational Health, McGill University; and ³ Department of Medicine, McGill University Health Center, Montreal, Quebec, Canada

Correspondence and requests for reprints should be addressed to Jean Bourbeau, M.D., Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, 3650 St. Urbain, Montreal, PQ, Canada H2X 2P4. E-mail: jean.bourbeau{at}mcgill.ca

Rationale: Unreported exacerbations and failure to seek medical attention may have consequences on the health of patients with chronic obstructive pulmonary disease.

Objectives: This study aims to determine the incidence of reported and unreported exacerbations, to identify predictors of reporting, and to compare the impact of reported and unreported exacerbations on health status.

Methods: The study is based on a multicenter Canadian cohort of patients with chronic obstructive pulmonary disease.

Measurements and Main Results: Patients completed a daily diary from which exacerbations were defined as a worsening of at least one key symptom (dyspnea, sputum amount, sputum color) recorded on at least 2 consecutive days. Patients were asked to contact the study center if there was a sustained worsening of symptom. Reported exacerbations were events that led to contacting study center or health care visit. The study enrolled 421 patients. The overall incidence of diary exacerbations was 2.7 per person per year, but only 0.8 per person per year was reported. Predictors of reporting included age (HR [hazard ratio], 0.90; 95% confidence interval [CI], 0.81–0.98 per 5-yr increase), FEV₁% predicted (HR, 0.84; 95% CI, 0.70–0.99 per 10% increase), number of symptoms at onset (HR, 1.59; 95% CI, 1.37–1.84 per additional symptom), and time of the week (HR, 0.35; 95% CI, 0.22–0.56 weekend vs. weekday). There was a clinically important decline in health status for 52% of patients with reported exacerbation and 43% with unreported exacerbations.

Conclusions: This study has shown that less than one-third of the exacerbations were reported. The number of symptoms at onset was the most important predictor of reporting an exacerbation, and both reported and unreported exacerbations had an impact on health status.

Key Words: chronic obstructive pulmonary disease • exacerbation • health status • predictor

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject The determinants and consequences of underreporting exacerbations of chronic obstructive pulmonary disease (COPD) are not well known. Failure to seek medical attention may have consequences. What This Study Adds to the Field Event-based definitions of COPD exacerbation fail to capture all exacerbations. Unreported exacerbations may not be serious enough to warrant an emergency room visit or hospitalization, but they can have impact on health status for a given patient.