A WHO study showing that long working hours kill three quarters of a million people each year used innovative two-stage peer-review and research quality control approaches championed by experts at Lancaster University.

The ground-breaking research, which revealed for the first time that long working hours is the single biggest cause of work-related illness, used a systematic review (SR) of previous research to come up with its conclusions.

The study, run jointly by the World Health Organisation (WHO) and the International Labour Organisation (ILO), found that working 55 hours or more a week was associated with a 35% higher risk of stroke and a 17% higher risk of dying from heart disease, compared with a working week of 35 to 40 hours. Middle aged and older men are particularly at risk.

Dr Paul Whaley, an honorary researcher at Lancaster Environment Centre, is an expert in systematic reviews. These aim to provide authoritative summaries of what existing evidence says in answer to research questions, by minimising bias in the processes of finding, analysing and aggregating scientific studies.

As well as editing the WHO/ILO study for the journal Environmental Impact, Paul had a crucial input into the way it was carried out.

Dr Whaley, who runs his own consultancy, did his PhD at Lancaster exploring how systematic reviews, which are commonly used in the medical field, could be applied to environmental risks and their impact on health. Since then, working with his former PhD supervisor Professor Crispin Halsall and others, Dr Whaley has developed COSTER, which sets out a series of recommendations of how environmental health systematic reviews should be carried out.

One of the key recommendations is that the methodology being used for a systematic review should be peer-reviewed before data is collected – the usual process is for peer review to occur only after the research has been completed. The two-stage peer review process involves publishing the proposed methodology and inviting comments from experts in the field: the methodology is then adapted in response and protocols agreed, which all those involved in the research will follow.

“What can happen otherwise is that researchers make ad-hoc decisions about the methodology as they analyse the evidence, which might lead them to unconsciously massage the data to make it fit a predetermined conclusion,” Dr Whaley said.

“Systematic reviews are also very complex projects and benefit from their methods being reviewed before they are carried out, as this can solve a lot of issues that are hard to fix after the work has been done. “The two-stage peer-review approach makes the whole review process much more robust and gives a higher degree of certainty about the results.”

Dr Whaley first got involved in the ground-breaking study in 2016, when he was contacted by WHO researchers, and then the WHO itself, as it started work on a series of 14 systematic reviews into how the work environment impacts on workers’ health. The reviews covered five types of exposure, which had not been quantified for impact before: dust and fibres, workplace ergonomics (such as repetitive motion and posture), sunlight, noise, and long working hours.

“I was asked to do some training in systematic reviews for one of the WHO-commissioned research teams. I based the training on the COSTER recommendations which I was developing at the time,” he said.

Following the training, Dr Whaley got into discussions with Dr Frank Pega, technical officer at the Department of Environment, Climate Change and Health at the WHO, who was leading the project. He decided to adopt the two-stage peer review process on all the 14 systematic reviews, the first time this approach had been used for environmental health research at the WHO.

“The two-stage peer review approach worked well for the systematic reviews, which formed a key evidence base for our official burden of disease estimation,” Dr Pega said.

“Through the first stage of developing and publishing a protocol, we in the World Health Organization and the International Labour Organization ensured that the same understanding of our standard systematic review methods was developed by all participating individual experts, of which there were 220 based in 35 countries.

“This made the second stage – conducting the systematic reviews – more efficient, because everybody understood the approach and agreed peer-reviewed methods could be followed and implemented. The two-stage process helped us to coordinate effective collaboration of a large group of diverse experts across many different disciplines.”

Dr Whaley then played a further role: as associate editor for systematic reviews at the Environmental International journal, he edited all 14 reviews and the paper on long working hours, which has been picked up by the media worldwide.

“Working with Paul meant that our protocols and systematic reviews were rigorously peer-reviewed and edited, by a handling editor who is an expert in systematic review methods in occupational and environmental health. This is still a rarity in occupational and environmental health journals,” said Dr Pega.

Dr Whaley is excited that the approach paid off and has revealed the damage done to health by long working hours, which he hopes will lead to a change in working culture.

“Historically the role of long working hours has been suspected but not clear. By using the most up-to-date systematic review methods it was possible for the first time to characterise the level of certainty in the evidence with enough clarity to justify its use in global policy and WHO and ILO recommendations.”