Review of NASA's Evidence Reports on Human Health Risks 2013 Letter Report (2014) / Chapter Skim
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Review of NASA's evidence reports on human health risks: 2013 letter report.
Review of NASA's evidence reports on human health risks: 2013 letter report.
Pages 1-34
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The committee will provide an independent review of the more than 30 evidence reports that NASA has compiled on human health risks for long-duration and exploration spaceflights. In 2008, NASA asked the IOM to assess the process for developing the evidence reports.1 The resulting report, Review of NASA's Human Research Program Evidence Books: A Letter Report, provided an initial and brief review of the evidence reports.
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BOX 1 Review of NASA's Evidence Reports on Human Health Risks Statement of Task NASA has requested a study from the Institute of Medicine (IOM) to pro vide an independent review of more than 30 evidence reports on human health risks for long-duration and exploration spaceflight.
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The committee approached its task by analyzing each evidence report's overall quality, which included readability; internal consistency; the source and breadth of cited evidence; identification of existing knowledge and research gaps; authorship expertise; and, if applicable, response to recommendations from the 2008 IOM letter report, described above. In the 2008 letter report, the IOM urged NASA to "require authors to use categories of evidence in future versions of the evidence books, while recognizing that experience with the explicit categorization of evidence may be refined over time, particularly regarding the categories used" (IOM, 2008, p.
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Such an analysis could be used by NASA to bolster discussions of risk interactions in updated evidence reports or to trigger further literature searches. During the course of this effort, however, substantial variability in the formatting, internal consistency, and completeness of the references contained in many of the individual evidence reports became apparent, making the exercise arduous and results difficult to confirm.
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Does the Evidence Report Provide Sufficient Evidence, as Well as Sufficient Risk Context, That the Risk Is of Concern for Long-Term Space Missions? The Injury Report provides the context for many of the risks associated with dynamic loading during launch, abort, landing, and anomalous events.
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Does the Evidence Report Make the Case for the Research Gaps Presented? The Injury Report clearly states the case for each of the research gaps presented in the report.
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. Extraterrestrial and Extravehicular Activity The Injury Report provides appropriate consideration to dynamic loading during launch and landing and the extent to which launch/entry suits may affect the load experienced by crew members.
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plays in preventing injury or mitigating the effects of injury on opera tional requirements Effect of individual crew variation on protection and restraint systems (e.g., NASCAR) and on rover/EVA suit design for use during surface exploration Application of known principles of injury prevention into an in tegrated system of occupant protection (e.g., NASCAR)
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may be harder to treat or more susceptible to infection during spaceflight. The Injury Report should include cross-referencing and information on interactions between the risk of injury due to dynamic loads and the evidence reports on inflight medical capabilities (Archibald and Kelleher, 2013)
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Expanding the discussion to include external factors associated with each crew vehicle and launch system, utilizing a systems engineering approach, would be a significant addition to the Injury Report. One approach suggested in NASA's Risk Master Logic Diagram for the Injury
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Has the Evidence Report Addressed Previous Recommendations Made by the IOM in the 2008 Letter Report? The Injury Report was developed after the 2008 IOM letter report.
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12 Injury Due to Dynamic Environments Requirements, Testing, and Protection of Suit/Vehicle Suit Design Vehicle Design Verification Controls for Crewmember Interface Dynamic Environments Volume Certification requirements Energy attenuation Rigid suit Control of spinal Restraint of for complex combinations system may stroke elements alignment movement in seat of X, Y, and Z accelerations crewmember into vehicle surface Control of head Body movement Fit for specific Certification requirements and neck Stowage of within the suit body type for dynamic loads movement hardware Positioning of Position Testing and verification Head movement Vehicle structural restraints on and/or analysis and tools to predict within the helmet integrity body/suit surfaces posture injuries Energy attenuation FIGURE 1 Risk master logic diagram.
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NASA should continue to seek input from other disciplines in which occupants are exposed to dynamic loads. RISK OF CLINICALLY RELEVANT UNPREDICTED EFFECTS OF MEDICATION3 The evidence report titled Risk of Clinically Relevant Unpredicted Effects of Medication ("Medication Report")
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NASA's decision to include the risk of clinically relevant unpredicted effects of medication as an evidence report is valid, however, if the a priori assumption is made that exposure to microgravity alters total body/organism physiology, this will impact medication PK/PD. Does the Evidence Report Provide Sufficient Evidence, as Well as Sufficient Risk Context, That the Risk Is of Concern for Long-Term Space Missions?
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In general, the Medication Report provides good context and support for the research gaps identified. Research gaps are spread across the report by section and are collapsed into five broad categories on NASA's Human Research Roadmap summary website (NASA, 2013b)
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In addition, the Medication Report should emphasize the need for more information on what drug residues (e.g., parent drug and metabolites) appear in astronauts' urine after medication use and in what concentrations.
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The Medication Report should underscore the benefit of increased data collection and transparency on both NASA's research and operations. Pharm02: We Do Not Know How Long Medications May Be Safe and Effective Beyond Their Expiration Dates The committee agrees that this is an important research gap that has clear operational relevance, as outlined in the risk report.
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. A number of research teams, in publications spanning 2000 to 2007, demonstrated that Salmonella typhimurium grown on the space 6 The committee will review NASA's evidence reports Risk of Adverse Health Effects Due to Alterations in Host Microorganism Interactions and Risk of Crew Adverse Health Event Due to Altered Immune Response in subsequent letter reports.
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The committee believes that the following topics, some of which are noted in the narrative of the Medication Report, could be elevated to the status of "research gap":
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and alter drug PK/PD 7 The committee will review NASA's evidence report Risk Factor of Inadequate Nutrition in a subsequent letter report.
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The Medication Report enumerates general PK/PD issues that have relevance to other risks and body system–specific PD that are relevant to central nervous system, cardiovascular, gastrointestinal, skeletal, muscular, and immunologic systems, as well as multisystem radiation effects. The previously mentioned co-citation analysis revealed that many cited articles discuss medication use in the context of other human health risks.
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The IOM's 2008 letter report, Review of NASA's Human Research Program Evidence Books: A Letter Report, included recommendations relevant to this Medication Report. First, the 2008 letter report suggested changing the report title to Risk of Therapeutic Failure or Adverse Effect 8 This rating is included on NASA's website, which provides the report overview and direct link to the evidence report (NASA, 2013b)
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A methodology for decision making should be included. Gaps 4 and 5 point to the intersection of two reports, Risk of Clinically Relevant Unpredicted Effects of Medication and Risk of Unacceptable Health and Mission Outcomes Due to Limitations of Inflight Medical Capabilities.
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As described in NASA's evidence report Risk of Spaceflight-Induced Intracranial Hypertension and Vision Alterations ("Vision Report") , 15 crew members on long-duration spaceflights have experienced optic and visual changes (some of which have been short-lived and others that have persisted after the flight)
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Does the Evidence Report Make the Case for the Research Gaps Presented? As visual impairment and intracranial pressure (VIIP)
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The methods being proposed to study the eye findings include spectral domain optical coherence tomography, which has the potential to identify important changes in the retinal, optic nerve, and choroidal anatomy. The committee is concerned that the Vision Report makes a strong assumption that high ICP is the cause of ocular disc swelling and urges that alternate mechanisms be explored thoroughly.
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For example, comparing inflight noninvasive ICP monitoring with pre- and postflight lumbar puncture is unlikely to provide useful data. Lumbar puncture generates data for a single moment and is subject to numerous variables; in terrestrial medicine, lumbar puncture is not considered equivalent to ICP monitoring data, which provides a more realistic and relevant view of ICP for making clinical decisions.
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The Vision Report could include more information on the challenges of ICP measurement. If the ICP elevation is not the cause of the optic disc swelling, then the risk that increased ICP poses may be less than originally postulated (Williams, 2013)
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The Vision Report could explore the benefits and risks of other preventive and treatment scenarios, such as consideration to forego additional testing and start empirical treatment with an ICP-lowering agent such as acetazolamide and assessment of ocular and ICP changes. However, the committee cautions that empiric treatment with typical terrestrial agents such as acetazolamide or topiramate does carry significant risks, such as renal calculi, dehydration, and impaired cognition.
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(Countermeasures) The Vision Report correctly notes that it is difficult to judge the safety and efficacy of countermeasures because the actual causes of the optic disc swelling, vision impairment (when present)
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The committee identified several additional research gaps that could be explored in the evidence report: sex and age differences; potential for a biologic toxin to accumulate at the optic nerve head or within the nerve sheath; systematic approach to assessment of long-term impacts of VIIP on terrestrial visual function; time course of VIIP development and potential stabilization; and need for collection of baseline data from all incoming astronauts to determine if there are anatomic or genetic factors that may predispose to VIIP and to detect any preexisting changes to the
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Does the Evidence Report Address Relevant Interactions Among Risks? The Vision Report identifies the possible contributions of radiation exposure, environmental hazards (increased CO2 levels)
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As with any feedback of this nature, however, the input will have to be carefully verified. Has the Evidence Report Addressed Previous Recommendations Made by the IOM in the 2008 Letter Report?
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Although the evidence reports would benefit generally from more diverse authorship across various disciplines, the committee is encouraged by NASA's commitment to improving the quality of its evidence reports, seeking input from numerous internal and external reviewers, such as this committee and NASA's Standing Review Panels. NASA's dedication to more in-depth understanding of health risks associated with spaceflight will contribute to improved risk mitigation strategies and enhanced performance capabilities for future human spaceflight endeavors.
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