October 25, 2018

expert reaction to study looking at blood pressure drugs and lung cancer risk

Research published in the BMJ  shows the use of angiotensin converting enzyme inhibitors (ACEIs) which are used to treat high blood pressure, was associated with an increased risk of lung cancer.

Prof Stephen Evans, Professor of Pharmacoepidemiology, London School of Hygiene & Tropical Medicine, said:pre

“This study has several strengths.  Basically a fairly rigorous statistical analysis and the use of a large database derived from electronic health records, with some lifestyle factors recorded and long follow-up.

“It has a number of weaknesses, which make it quite likely that the observed association is not a causal one.  This is mainly because of inadequacies in the underlying data, and a possible weakness in the analysis.

“Firstly, the authors did not utilise the possibility of linking the cancer diagnoses with cancer registries though this would have reduced the sample size.  Secondly smoking in CPRD (the UK Clinical Practice Research Datalink, the database used), is not well recorded and does not distinguish heavy from light smoking.  Heavy smoking can lead to a 20 fold increase in lung cancer risk (and this study finds a tiny risk in comparison).  Not all those recorded as non-smokers are actually non-smokers, so small errors in smoking status could have large effects on the estimates of risk.

“ACEI (angiotensin converting enzyme inhibitor drugs) almost certainly prevent deaths from heart disease (and evidence for ARBs (angiotensin receptor blockers) is less) and that means that especially after long follow-up, the cohort of ACEI users may contain those at higher risk of lung cancer.

“Drawing strong conclusions and talking about public health impact in this situation seems premature.”

‘Angiotensin converting enzyme inhibitors and risk of lung cancer: population based cohort study’ by Blánaid M Hicks et al. was published in the BMJ at 23:30 UK time on Wednesday 24 October 2018.

Declared interests

Prof Stephen Evans: “I have the CofI of having published on the topic but no other interests.”