Background: Aerospace medicine focuses on the health of pilots, aircrews, astronauts and passengers. There are a few systematic reviews conducted in aviation medicine but none in space medicine. Therefore, we started to conduct two systematic reviews in space medicine: a) rehabilitation of astronauts after space travel; and, b) the impact of partial gravity on physiological outcomes.
In conducting clinical trials on astronauts, terrestrial simulation studies are used to inform decision making.

Objectives: This abstract outlines the work on a methodological tool to evaluate simulation studies in these types of reviews.

Methods: The most valid simulation of human space studies are bed-rest studies. However, these studies can be designed with potentially variable elements which may affect their quality as a simulation. We decided to develop a tool to judge the indirectness of bed-rest studies – compare the Bed-rest studies to an 'ideal design' study simulating the space environment. We tested the tool in the two mentioned systematic reviews. We identified the key features of an ideal 'bed-rest' study based on a review of the literature, consultation with experts and the aspects of European Space Agency (ESA) bed-rest protocols provided by the German Aerospace Centre.

Results: The tool also includes 8 items including head tilt, control on diet and daily routine, standardisation of phases, uninterrupted bed-rest, sunlight exposure, time of data collection and, finally, duration of bed rest. None of the studies in these reviews met all the criteria. Most studies do not manage sunlight exposure although it’s a major issue for astronauts. The tool also records the duration of bed-rest, as simulation studies can only relate to spaceflight of similar duration and shorter bed-rest studies are unlikely to model longer-term space missions.

Conclusions: The tool is very useful to deal with systematic reviews in space medicine and is a fundamental tool for future systematic reviews in aerospace medicine. The first review is used as ESA topic team report to inform operational guidance.