Chronic obstructive pulmonary disease (COPD) can be diagnosed when the FEV₁/FVC ratio is below 70%, according to global initiative for chronic obstructive lung disease (GOLD). COPD is known as a disease which is frequently under-diagnosed. However, there is a risk of over diagnosis when this diagnostic threshold is applied among the elderly.

To contribute to the discussion about the criteria for diagnosing COPD, by describing lung function and pulmonary symptoms in a population aged 60 years or more, and in particular the changes in the mean and 5% percentile of the FEV₁/FVC ratio by increasing age.

A cross sectional population-based study was performed in the city of Tromsø, Norway, in 2001–2002. Spirometry was performed in 4102 people 60 years and older (54.6% women), who also filled in a questionnaire.

Decreased FEV₁% predicted and FEV₁/FVC ratio were associated with smoking, increasing age, and reported pulmonary and cardiovascular diseases. Dyspnoea and coughing were also strongly associated with smoking and reported pulmonary and cardiovascular diseases, but coughing did not become more frequent by increasing age. In never smokers aged 60–69 years the frequency of FEV₁/FVC ratio<70% was approximately 7% compared to 16–18% in those 70 years or more (p<0.001). FEV₁/FVC ratio<70% among never smokers aged 60–69 years was just as frequent as FEV₁/FVC ratio <65% in never smokers older than 70 years.

Adjustments of the GOLD criteria for diagnosing COPD are needed, and FEV₁/FVC ratios down to 65% should be regarded as normal when aged 70 years and older.