Inserm UMR1246 SPHERE

Universities of Nantes and Tours


SPHERE is a multidisciplinary unit that seeks to develop and validate methods that can be used in clinical or epidemiological studies.

The philosophy that drives the SPHERE unit is that the patient must be considered as a whole, i.e. taking into account his/her environment, and integrating his/her perceptions, experience, and wishes.

Photo sphere u1246

4 axes of research

Axis 1

Cluster Randomized Trials and Complex Interventions

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Axis 2

Definition, selection, validation, and assessment of outcomes

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Axis 3

Methods for the measurement and interpretation of Self-Reported Outcomes

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Axis 4

Prediction and Causality

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Our latest news


Restricted mean survival time to estimate an intervention effect in a cluster randomized trial

Author(s) of the publication: Floriane Le Vilain–Abraham, Elsa Tavernier, Etienne Dantan, Solène Desmée and Agnès Caille

For time-to-event outcomes, the difference in restricted mean survival time is a measure of the intervention effect, an alternative to the hazard ratio, corresponding to the expected survival duration gain due to the intervention up to a predefined time t*. We extended two existing approaches of restricted mean survival time estimation for independent data to clustered data in the framework of cluster randomized trials: one based on the direct integration of Kaplan-Meier curves and the other based on pseudo-values regression. Then, we conducted a simulation study to assess and compare the statistical performance of the proposed methods, varying the number and size of clusters, the degree of clustering, and the magnitude of the intervention effect under proportional and non-proportional hazards assumption.

Members of SPHERE summer 2023

SPHERE Summer Science Day in Tours

On Thursday 29 June, all SPHERE members met in Tours!

The programme included a workshop on the CARER systematic review project and a workshop on the ecological and social transition.

After a convivial lunch that was the occasion of a few photos and a meeting of young researchers, the unit exchanged on how to evaluate the future of patients after reanimation and how to involve patients and caregivers in conducting research.


SPHERE young researchers' days - March 2023

On March 27, 2023, the young researchers of SPHERE met in Nantes for their first scientific day!

On the agenda: presentation of software for the writing of the thesis manuscript and thoughts concerning the group's identity.

We started by a presentation of the LaTeX language and a feedback from former SPHERE PhD students: how did they write their manuscript? What challenges did they face ? etc.

After a convivial moment during lunch, everyone got to work:

- The first group made its first steps with Overleaf, an online Latex editor. This workshop was organized by Floriane and Yseulys.

- The second group worked on the identity of the "young researchers of SPHERE" group, which brings together a wide variety of profiles: interns, residents, PhD students, young doctors, junior engineers, postdoctoral researchers and graduate assistants. They also brainstormed on the actions we could take to stimulate scientific life, cohesion and mutual aid between young researchers.

It is already time to leave, but everyone leaves full of ideas! We will meet again in June at the SPHERE scientific day !