COPD, ozone pollution and talc for malignant pleural effusion: the standout respiratory papers of 2019

Studies into the diagnostic accuracy of spirometry thresholds in COPD, how ozone pollution might promote tumour metastasis in the lungs, and the best way of managing malignant pleural effusion have been highlighted as the three stand-out respiratory papers this year by UK respiratory specialists.

Summing up the respiratory research articles of the year at the 2019 British Thoracic Society Winter Conference, one delegate said his paper aimed to answer the long-standing debate and inconsistent evidence about how best to manage patients with malignant pleural effusion.

Study leader Dr Rahul Bhatnagar, consultant respiratory physician at North Bristol NHS Trust said his just-published study found no difference in outcome or cost effectiveness between talc poudrage and talc slurry in patients. This meant that decisions should largely be about patient choice but as both procedures were equally effective and pretty well tolerated, he told the conference.

Many factors would come into play but personally he would choose a talc slurry and that the study suggested while there were many reasons to do thoracoscopy, local anaesthetic thoracoscopy services should not be expanded just for doing talc poudrage.

The randomised trial of 330 patients at 17 centres showed that at 90 days, the pleurodesis failure rate was 36 of 161 patients (22%) in the talc poudrage group and 38 of 159 (24%) in the talc slurry group with no significant difference in any other outcomes. Cost-effectiveness data will be published at a later date but also shows no difference, the conference heard.

“This is the largest RCT ever looking at this,” said Dr Bhatnagar. “We found that poudrage was not superior to slurry with success rates of about 75% at three months.

“The idea of patient choice is increasingly key in how we manage these patients.”

Cancer patients should avoid air pollution

Delegates also heard from Professor Didier Cataldo from the University of Liege, Belgium about his work in mice showing that neutrophils in the lungs are induced by ozone and promote metastatic dissemination to lungs by producing neutrophil extracellular traps also known as NETS.

The paper which was published in Thorax in July opens up new avenues for treatment prevention in patients affected by metastatic disease he said.

“It does suggest that patients with cancer should avoid being exposed to air pollution where possible.

“There is a huge amount to explore in the relationship between the neutrophils and metastasis,” he said.

FEV1:FVC ratio identifies individuals at risk of COPD 

In another JAMA paper set out to answer a key clinician dilemma, Professor George T O’Connor from Boston University School of Medicine presented results supporting the use of FEV1:FVC less than 0.70 to identify individuals at risk of clinically significant COPD.

The study of data from more than 24,000 patients looked at fixed thresholds ranging from 0.75 to 0.65 as well as comparing with lower level of normal (LLN) thresholds.

Professor O’Connor pointed out that the 0.70 threshold had historically been set as a pragmatic cut off based on expert opinion rather than any clear evidence.

The results showed that the discriminative accuracy of the 0.71 threshold was not significantly different than that of the 0.70 threshold but it was more accurate than a lower-limit-of-normal threshold derived from population-based reference equations

Overall, the 0.70 threshold provided the best discrimination in a subgroup analysis of ever smokers and in adjusted models.

“We believe these results support the use of a FEV1:FVC ratio to identify individuals at risk of clinically significant COPD,” he said.

“But you’re not going to do a diagnosis just based on that, you’re always going to work the patient up clinically,” he added. “You have to use your clinical judgement and look at various aspects.”

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