COPD is an underdiagnosed condition and is often mistaken for asthma. Although, spirometry is needed to confirm a COPD diagnosis, it is not commonly available in most physicians’ offices.
COPD is diagnosed based on the patient’s history, physical exam and lung function tests. COPD may be suspected in patients who exhibit any of the following:(5)
Currently smoke or are past smokers with a 20-pack-year history, whether they complain of respiratory symptoms or not
Have recurrent or chronic respiratory symptoms including cough and breathlessness on exertion
Have significant occupational exposure to respiratory irritants
Have a family history of pulmonary disease
Have increased responsiveness to provocative agents
Have a history of childhood factors that may predispose them to COPD such as low birth weight, frequent respiratory infections or second hand tobacco smoke
>> Calculating Smoking Pack Years
Spirometry is typically used to measure lung function and can be done in the physician’s office, especially given the availability of portable spirometers (Figure 6).
The main lung function measurements to be assessed are the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC).
In order to diagnose COPD, physicians must examine the % predicted FEV1 and the FEV1/FVC ratio.
The % predicted FEV1= [the patient’s FEV1/the patient’s predicted FEV1] x 100. The predicted FEV1 depends on the patient’s height, age and gender(12) and therefore varies between individuals.
The FEV1/FVC ratio is calculated by dividing the patient's FEV1 by the patient's FVC.
