DiagnosisBMJ 2006; 332 doi: https://doi.org/10.1136/bmj.332.7552.1261 (Published 25 May 2006) Cite this as: BMJ 2006;332:1261
- Graeme P Currie, specialist registrar,
- Joe S Legge, consultant
- Respiratory Unit, Aberdeen Royal Infirmary, Aberdeen.
As with most other common medical conditions, the diagnosis of chronic obstructive pulmonary disease (COPD) depends on a consistent history and appropriate examination findings. Confirmatory objective evidence is provided by spirometry. Doctors should consider the possibility of COPD in any patient aged 35 years or older with any relevant respiratory symptom and a history of smoking.
Consider COPD in any current or former smoker age > 35 years who complains of any combination of breathlessness, chest tightness, wheeze, sputum production, cough, frequent chest infections, and impaired exercise tolerance.
COPD may also be present in the absence of noticeable symptoms, so look for it in individuals who are current or former smokers. Pay particular attention to features in the history or examination that may suggest an alternative or concomitant diagnosis. Since asthma tends to be the main condition in the differential diagnosis of COPD, a careful history should be taken in order to help distinguish between the disorders. Ask about previous and present occupations, particularly with regard to exposure to dusts and chemicals.
Record the patient's current smoking status and calculate the number of smoking pack years.
Number of pack years = (number of cigarettes smoked/day x number of years smoked)/20
For example: a patient who has smoked 15 cigarettes a day for 40 years has a (15x40)/20 = 30 pack year smoking history.
Calculating the number of smoking pack years overcomes the problems of differences in duration and intensity of cigarette smoking. The decline in forced expiratory volume in 1 second (FEV1) is generally related to the extent of cumulative exposure, although there is wide variability between individuals.