Clinical trials have an impact on the environment, and novel approaches may help researchers reshape their activities toward a greater sustainability
Based on the estimations of The Sustainable Healthcare Coalition, clinical trials would be responsible for 100 megatonnes of CO2 emission annually. It is almost the equivalent of the yearly emission of Belgium, with a population of 11.5 million people. But what is the environmental impact of a single clinical trial?
For an individual clinical researcher it would be useful to know what the environmental impact of a single clinical trial is to reduce carbon footprint coming from research activities. An analysis of 12 pragmatic randomised trials involving more than 4,800 participants in total, showed that the average carbon emissions generated by the trials were 78.4 tonnes (BMJ. 2009 Oct 30:339:b4187). More recently, an estimate of 1632 tonnes of CO2 were calculated for the first three years of the ADRIATIC trial investigating immunotherapy in patients with limited-stage small-cell lung (BMJ Open. 2023 Aug 21;13(8):e072491). This important trial, that could lead to practice-changing results in terms of survival for a disease with very poor prognosis is still ongoing: patients will be enrolled in 261 investigational sites in 19 countries, and it is expected to be completed in a few years. By then, the total carbon footprint would exceed 3000 tonnes of CO2, with an average emission of 5 tonnes of CO2 per participant, which is similar to the yearly emission of a citizen in Spain or Denmark. In the analysis, it was calculated that more than 50% of carbon emissions of the trial came from clinical trial units and their operations, while nearly 15% from global trial management, including global monitor or investigators meetings, Institutional Review Boards, and data monitoring committee meetings.
Despite these data giving an idea of the possible impact of single trials on the environment, it is hard to make realistic predictions as many more aspects related to trial design should be considered. For instance, in studies evaluating screening or observation/follow-up schemes, a significant proportion of carbon emissions may come from patient travels and travels for site monitoring visits, while in trials that include extensive sampling for additional translational research, a greater environmental impact may be due to sample collection using single-use kits, shipment to central laboratories, storage in ultra-low temperature freezers for many years, and secondary shipment to analytical laboratories. Interestingly, drug manufacturing is often not included in the analyses, although it may be responsible for a large part of the emissions (J Cleaner Prod. 2019 Mar. Vol 214;185-194).
While clinical research is crucial to develop new treatments or investigate and optimise the current possibilities, the environmental impact of clinical research cannot be neglected. It is time for action. As part of the Sustainable Healthcare Coalition, a partnership group of healthcare companies and national health systems in England and Scotland, the Low Carbon Clinical Trials (LCCT) Working Group set out a strategy to reduce emissions of clinical trials. Their guidelines on quantification of carbon emission are currently available and can be easily applied to any trial. Several improvements in trial design are suggested to reduce carbon emissions, including a decentralisation of clinical trials, with trial units located closer to patients, thus allowing for a reduction of travel-related emissions, and the involvement of local laboratories, biobanks, and Contract Research Organisations to limit monitoring visits or shipment of samples.
Technology should also be helpful to make clinical trials “greener”. Video consultations, e-diaries, or applications to collect patient-reported outcomes, sensors, and wearables for remote data collection are potential approaches to ease the patient journey while reducing the total carbon footprint of healthcare. Also, artificial intelligence is already being used to optimise trial management and the selection of study sites, and novel designs with the use of synthetic control arms (use of previously collected data as per control arm) can be a promising strategy from both an environmental (reducing number of participants, sites and study duration) and patient’s (receiving active treatment) perspectives (Nat Med. 2023 Nov;29(11):2689-2692)
There is much to do to make the future of clinical research more sustainable and environmentally friendly. As changes aimed at conducting “greener” trials should not make them less inclusive, patient-centeredness will remain the inspiring principle of our actions while trying to protect the environment. However, a change of mindset is urgent, and as researchers we should reflect on how the success of a trial is measured, today mainly in median survival, objective response rate, hazard ratio value, or its impact on clinical practice guidelines. But can we consider research successful if it contributes to climate change, which ultimately affects the health of all human beings including our patients? Should carbon footprint be selected as an endpoint in clinical trials?
