COPD is a disease with an indeterminate course and variable prognosis. Its prognosis depends on several factors including genetic predisposition, environmental exposures, comorbidities, and, to a lesser degree, acute exacerbations.
Although short-term survival for patients with COPD and respiratory failure depends on the overall severity of acute illness, long-term survival is primarily influenced by the severity of COPD and the presence of comorbid conditions. Traditionally, prognosis has been reported based on the FEV1, which is a part of pulmonary function testing. A meta-regression analysis showed a significant correlation between increased FEV1 and lower risk of COPD exacerbation.
In addition to the FEV1, other factors that predict prognosis are weight (very low weight is a negative prognostic factor, with one meta-analysis identifying a significant association between low body mass index and accelerated FEV1 decline), distance walked in 6 minutes, and degree of shortness of breath with activities. These factors, known as the Body mass index, airflow Obstruction, Dyspnoea, and Exercise (BODE) index, can be used to provide information on prognosis for 1-year, 2-year, and 4-year survival. One study revealed that plasma pro-adrenomedullin concentration plus BODE index is a better prognostic tool than BODE index alone. Elevation of adrenomedullin, arginine vasopressin, atrial natriuretic peptide, and C-reactive protein is associated with increased risk of death in patients with stable COPD. UK guidelines do not recommend using the BODE index to assess prognosis.
Recently, more interest has been put on comorbidities and prior exacerbations as the predictor of COPD course. CODEX index (comorbidities, obstruction, dyspnoea, and previous severe exacerbations) is proved to be superior to BODE index in predicting prognosis for patients with COPD. Frequent COPD exacerbations and requirement for multiple intubation and invasive mechanical ventilation for acute respiratory failure in patients with COPD are markers of poor prognosis.
Among different therapeutic modalities in COPD, the only two factors that improve survival are smoking cessation and oxygen supplementation.
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