Clinicians should ditch GOLD and instead adopt lower limits of normal (LLN) criteria for defining airflow when assessing patients for COPD, experts have argued in a Too Much Medicine paper in the BMJ.

Retired respiratory physician Professor Martin Miller and General Practitioner Dr Mark Levy claim the GOLD diagnostic criteria are leading to over-diagnosis in elderly people and missed diagnosis in younger people.

For example in the UK up to 13% of people who are thought to have COPD under the GOLD criteria have been misdiagnosed, they argue.

Misdiagnosing patients may lead to poorer outcomes “because of adverse effects of inappropriate medication or incorrect treatment,” they warn.

GOLD also misses one in eight cases of airflow obstruction identified by the LLN, particularly among younger women.

“Clinicians should use the LLN instead when assessing patients for COPD,” they wrote.

Christine Jenkins a Senior Staff Specialist in Thoracic Medicine at the Concord Hospital said that although the authors had some valid concerns around overdiagnosis, they were incorrect to attribute the problem solely to spirometry and the use of a fixed ratio.

“In clinical practice we see underdiagnosis and overdiagnosis through a lack of spirometry,” she told the limbic.

For instance in Australia data from BOLD showed that about 30% of patients who were told they had COPD by their GP did not have the disease.

Conversely the exact same data showed that 30 percent of people with airflow limitation had never been diagnosed with lung disease.

“We need to perform spirometry to make the diagnosis of airways disease both to prevent under diagnosis as well as over diagnosis,” she said.

Not doing so was akin to diagnosing ischaemic heart disease without an ECG, she said.

“The challenge is in doing the test, doing it well, and interpreting it appropriately and not just making a diagnosis based on the fact that a patient gets better with a combination of an inhaled steroid and a LABA,” she said.

But it was important to note that COPD was never simply a diagnosis made on spirometry alone, she said.

“Whether you used a fixed ratio or a lower limit of normal criterion you need to assess the patient’s history and clinical presentation before you make a final diagnosis,” she said.

“We don’t diagnose in a vacuum,” she added.