# data[].attributes.body
i would use a plastic bag and punch 4 holes and put strings through them

# data[].attributes.attachment_link.readable_text
Objective To determine if using a parachute prevents death or major traumatic injury when jumping from an aircraft.

Design Randomized controlled trial.

Setting Private or commercial aircraft between September 2017 and August 2018.

Participants 92 aircraft passengers aged 18 and over were screened for participation. 23 agreed to be enrolled and were randomized.

Intervention Jumping from an aircraft (airplane or helicopter) with a parachute versus an empty backpack (unblinded).

Main outcome measures Composite of death or major traumatic injury (defined by an Injury Severity Score over 15) upon impact with the ground measured immediately after landing.

Results Parachute use did not significantly reduce death or major injury (0% for parachute v 0% for control; P>0.9). This finding was consistent across multiple subgroups. Compared with individuals screened but not enrolled, participants included in the study were on aircraft at significantly lower altitude (mean of 0.6 m for participants v mean of 9146 m for non-participants; P<0.001) and lower velocity (mean of 0 km/h v mean of 800 km/h; P<0.001).

Conclusions Parachute use did not reduce death or major traumatic injury when jumping from aircraft in the first randomized evaluation of this intervention. However, the trial was only able to enroll participants on small stationary aircraft on the ground, suggesting cautious extrapolation to high altitude jumps. When beliefs regarding the effectiveness of an intervention exist in the community, randomized trials might selectively enroll individuals with a lower perceived likelihood of benefit, thus diminishing the applicability of the results to clinical practice.

Study protocol

Between September 2017 and August 2018, individuals were screened for inclusion in the PArticipation in RAndomized trials Compromised by widely Held beliefs aboUt lack of Treatment Equipoise (PARACHUTE) trial. Prospective participants were approached and screened by study investigators on commercial or private aircraft.

For the commercial aircraft, travel was related to trips the investigators were scheduled to take for business or personal reasons unrelated to the present study. Typically, passengers seated close to the study investigator (typically not known acquaintances) would be approached mid-flight, between the time of initial seating and time of exiting the aircraft. The purpose and design of the study were explained. Owing to difficulty in enrolling patients at several thousand meters above the ground, we expanded our approach to include screening members of the investigative team, friends, and family. For the private aircraft, the boarding of aircraft was done for the explicit purpose of participating in the trial.

All participants were asked whether they would be willing to be randomized to jump from the aircraft at its current altitude and velocity. Potential study participants completed an anonymous survey using a survey app on the screening investigator's phone or tablet. Responses were transmitted to an online database upon landing for later analysis.

We enrolled individuals willing to participate in the trial and meeting inclusion criteria in the study. We randomized patients (1:1) to the intervention or the control. We obtained written informed consent. Participants were then instructed to jump from the aircraft after being provided their assigned device. Jumps were conducted at two sites in the US: Katama Airfield in Martha's Vineyard, MA (conducted by investigators from the Beth Israel Deaconess Medical Center), and the Yankee Air Museum in Belleville, MI (conducted by investigators from the University of Michigan). The same protocol was followed at each site, but the type of aircraft (airplane v helicopter) differed between the two sites.

Study population

Participants aged 18 and over, seated on an aircraft, and deemed to be rational decision makers by the enrolling investigator were eligible. Only participants who were willing to be randomized in the study were ultimately enrolled and randomized. Most of the participants who were randomized were study investigators.

Interventions

Participants were randomized to wear either a parachute (National 360, National Parachute Industries, Inc, Palenville, NY; or Javelin Odyssey, Sun Path Products, Inc, Raeford, NC; supplementary materials fig 1) or an empty backpack (The North Face, Inc, Alameda, CA; or Javelin Odyssey Gearbag, Sun Path Products, Inc). The interventions were not blinded to either participants or study investigators.

Randomization

We used block randomization, stratified by site and sex with a block size of two. The trial statistician created the randomization sequence by using the R package blockrand. The research team had previously assigned unique numeric identifiers to each participant. At both sites, only one team member had access to the list of numeric identifiers. Participants were verbally assigned their treatment, which was done by order of enrolment. Allocation was not concealed to the investigator who assigned the treatment.

Data collection

We collected data on basic demographic characteristics during screening by using paper forms or the survey app. 8 Characteristics included age, sex, ethnic group, height, and weight. We also collected information on participants' medical history including a history of broken bones, acrophobia (fear of heights), previous parachute use, family history of parachute use, and frequent flier status. Flight characteristics included carrier, velocity, altitude, make and model of the aircraft, the individual's seating section, and whether the flight was international or domestic. Velocity and altitude were captured by using flight information provided by aircraft on individual television screens when available, as well as through pilot announcements. When neither was directly available, visual estimations were made by the study investigators.

At the time of each jump, researchers recorded the altitude and velocity of the aircraft, and conducted a follow-up interview with each participant to ascertain vital status and to record any injuries sustained from the free fall within five minutes of impact with the ground, and again at 30 days after impact. We collected data electronically or with paper forms and uploaded the data to an online deidentified, password protected database.

Outcomes

The primary outcome was the composite of death and major traumatic injury, defined by an Injury Severity Score greater than 15, within five minutes of impact. The Injury Severity Score is a commonly used anatomical scoring system to grade the severity of traumatic injuries. 9 Separate scores are assigned to each of six anatomical regions, and the three most highly injured regions contribute to a final score ranging from 0 to 75. Higher scores indicate a more severe injury. Secondary outcomes included death and major traumatic injury assessed at 30 days after impact using the Injury Severity Score, as well as 30 day quality of life assessed by the Short Form Health Survey. The Short Form Health Survey is a multipurpose questionnaire that measures a patient's overall health-related quality of life based on mental and physical functioning. 10

Statistical analysis

The primary efficacy analysis tested the hypothesis that parachute use is superior to the control in preventing death and major traumatic injury. Based on an assumption of an average jump altitude of 4000 meters (typical of skydiving) and the anticipated effect of impact with the Earth at terminal velocity on human tissue, we projected that 99% of the control arm would experience the primary outcome at ground impact with a relative risk reduction of 95% in the intervention arm. A sample size of 14 (7 in each arm) would yield 99% power to detect this difference at a two sided α of 0.05. In anticipation of potential withdrawal after enrolment owing to last minute anxieties, a total sample size of 20 participants was targeted. Analysis was performed on an intention-to-treat basis. We performed secondary subgroup analyses stratified by aircraft type (airplane v helicopter) and previous parachute use through formal tests of statistical interaction.

We summarized continuous variables by mean (standard deviation) and categorical variables by frequency and percentage. We tabulated baseline characteristics of the two trial arms to examine for potential imbalance in variables. We tested for differences between the outcomes of the two trial arms by using Student's t test (continuous variables) and Fisher's exact test (categorical variables). To better understand what drove the willingness to participate in the trial, we also compared characteristics of individuals who were screened but chose not to enroll with individuals who enrolled. Baseline characteristics between those enrolled and not enrolled were compared using the same statistical tests. Confidence intervals for the difference in continuous outcomes between the two arms were constructed using T distributions. We could not calculate confidence intervals for the difference between arms (eg, risk difference, odds ratio, or relative risk) because no events were observed for any of the binary outcomes in either arm.

We performed all analyses by using SAS version 9.4 (SAS Institute Inc, Cary, NC). A P value less than 0.05 was considered statistically significant.

Study population

A total of 92 individuals were screened and surveyed regarding their interest in participating in the PARACHUTE trial. Among those screened, 69 (75%) were unwilling to be randomized or found to be otherwise ineligible by investigators. Figure 1 shows that a total of 23 individuals were deemed eligible for randomization.

Table 1 shows that the baseline characteristics of enrolled participants were generally similar between the intervention and control arms. The median age of randomized participants was 38 years and 13 (57%) were male. Three (13%) of the randomized participants had previous parachute use and nine (39%) had a history of acrophobia. Table 2 shows that participants in the study were similar to those screened but not enrolled with regard to most demographic and clinical characteristics. However, participants were less likely to be on a jetliner, and instead were on a biplane or helicopter (0% v 100%; P<0.001), were at a lower mean altitude (0.6 m, SD 0.1 v 9146 m, SD 2164; P<0.001), and were traveling at a slower velocity (0 km/h, SD 0 v 800 km/h, SD 124; P<0.001) ( table 2).

Among the 12 participants randomized to the intervention arm, the parachute did not deploy in all 12 (100%) owing to the short duration and altitude of falls. Among the 11 participants randomized to receive an empty backpack, none crossed over to the intervention arm. Figure 2 shows a representative jump (additional jumps are shown in supplementary materials fig 2).

Outcomes

Table 3 shows the results for the primary and secondary outcomes. There was no significant difference in the rate of death or major traumatic injury between the treatment and control arms within five minutes of ground impact (0% for parachute v 0% for control; P>0.9) or at 30 days after impact (0% for parachute v 0% for control; P>0.9). Health status as measured by the Short Form Health Survey was similar between groups (43.9, SD 1.8 for parachute v 44.0, SD 2.4 for control; P=0.9; mean difference of 0.1, 95% confidence interval −2.0 to 2.2). In subgroup analyses, there were no significant differences in the effect of parachute use on outcomes when stratified by type of aircraft or previous parachute use (P>0.9 for interaction for both comparisons).

Strengths and weaknesses of this study

A key strength of the PARACHUTE trial was that it was designed and initially powered to detect differences in the combination of death and major traumatic injury. Although the use of softer endpoints, such as levels of fear before and after jumping, or its surrogates, such as loss of urinary continence, could have yielded more power to detect an effect of parachutes, we believe that that our selection of bias-resistant endpoints that are meaningful to all patients increases the clinical relevance of the trial.

The study also has several limitations. First and most importantly, our findings might not be generalizable to the use of parachutes in aircraft traveling at a higher altitude or velocity. Consideration could be made to conduct additional randomized clinical trials in these higher risk settings. However, previous theoretical work supporting the use of parachutes could reduce the feasibility of enrolling participants in such studies. 16

Second, our study was not blinded to treatment assignment. We did not anticipate a strong placebo effect for our primary endpoint, but it is possible that other subjective endpoints would have necessitated the use of a blinded sham parachute as a control.

Third, the individuals screened but not enrolled in the study were limited to passengers unfortunate enough to be seated near study investigators during commercial flights, and might not be representative of all aircraft passengers. The participants who did ultimately enroll, agreed with the knowledge that the aircraft were stationary and on the ground.

Finally, although all endpoints in the study were prespecified, we were unable to register the PARACHUTE trial prospectively. We attempted to register this study with the Sri Lanka Clinical Trials Registry (application number APPL/2018/040), a member of the World Health Organization's Registry Network of the International Clinical Trials Registry Platform. After several rounds of discussion, the Registry declined to register the trial because they thought that "the research question lacks scientific validity" and "the trial data cannot be meaningful." We appreciated their thorough review (and actually agree with their decision).

The PARACHUTE trial satirically highlights some of the limitations of randomized controlled trials. Nevertheless, we believe that such trials remain the gold standard for the evaluation of most new treatments. The PARACHUTE trial does suggest, however, that their accurate interpretation requires more than a cursory reading of the abstract. Rather, interpretation requires a complete and critical appraisal of the study. In addition, our study highlights that studies evaluating devices that are already entrenched in clinical practice face the particularly difficult task of ensuring that patients with the greatest expected benefit from treatment are included during enrolment.

To safeguard this last issue, we see several solutions. First, overcoming such a hurdle requires extreme commitment on the part of the investigators, clinicians, and patients; thankfully, recent examples of such efforts do exist. 17 Second, stronger efforts could be made to ensure that definitive trials are conducted before new treatments become inculcated into routine practice, when greater equipoise is likely to exist. Third, the comparison of baseline characteristics and outcomes of study participants and non-participants should be utilized more frequently and reported consistently to facilitate the interpretation of results and the assessment of study generalizability. 14 Finally, there could be instances where clinical beliefs justifiably prevent a true randomized evaluation of a treatment from being conducted.

Conclusion

Parachute use compared with a backpack control did not reduce death or major traumatic injury when used by participants jumping from aircraft in this first randomized evaluation of the intervention. This largely resulted from our ability to only recruit participants jumping from stationary aircraft on the ground. When beliefs regarding the effectiveness of an intervention exist in the community, randomized trials evaluating their effectiveness could selectively enroll individuals with a lower likelihood of benefit, thereby diminishing the applicability of trial results to routine practice. Therefore, although we can confidently recommend that individuals jumping from small stationary aircraft on the ground do not require parachutes, individual judgment should be exercised when applying these findings at higher altitudes.

View Abstract

# data[].attributes.attachment_link.title
Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial

# data[].attributes.attachment_link.description
Objective To determine if using a parachute prevents death or major traumatic injury when jumping from an aircraft. Design Randomized controlled trial. Setting Private or commercial aircraft between September 2017 and August 2018. Participants 92 aircraft passengers aged 18 and over were screened for participation. 23 agreed to be enrolled and were randomized.

# data[].attributes.body
he imagined and sketched the frst ever parachute

# data[].attributes.body
it makes air resistance so you slowly glide to the ground

# data[].attributes.body
except I do know that it has something to do with air resistance