An intervention has been developed and will be evaluated by means of a two-armed randomised controlled trial (RCT). The intervention, named MORE Energy, will have a follow-up period of six months. The recruitment of the participants will start in autumn 2012. The study design and procedures have been assessed by the Medical Ethics Committee of the VU University Medical Center, Amsterdam, the Netherlands (#2011/065).
Study population
The study population will consist of pilots of all aircraft types of a large internationally operating airline company.
Study procedures
The study design is presented in Figure 1. First, potential participants will be made aware of the project by means of a publicity campaign, using intranet, internet and news bulletins. In addition, meetings with supervisors will be held to make sure they can propagate the study to their employees, and motivate them to participate.
After the publicity campaign, all pilots will receive a postal information brochure. In this brochure, the pilots will be made aware of the participation mail, which they will receive in their company e-mail inbox. In this e-mail, all potential participants will be asked to fill in the baseline questionnaire, by using the included unique internet link. By filling in the questionnaire the pilots agree to participate in the study, no additional written informed consent will be obtained. After the researchers receive the filled in questionnaire, participants will be allocated to either the control or intervention group.
Inclusion and exclusion criteria
The pilots can participate in the study if they:
Randomisation
Study group allocation will be conducted at individual level, using the minimisation technique. After the baseline measurement the participants will be assigned to one of the two study groups. A minimisation procedure will make sure that the group allocation of the next participant enrolled in the trial takes into account the characteristics of those participants already enrolled. The aim is that each allocation should minimise the imbalance across multiple factors [29]. The factors that are considered for minimisation are aircraft type (five different types of aircraft units), and job title (captain, first officer, and second officer).
Development of the intervention
To optimize the content of the advices, a literature study was performed in order to gain insight in the latest scientific knowledge regarding work-related fatigue in flight crew. Based on this literature study, the following intervention objectives were defined (Figure 2).
It is hypothesized that tailoring the relevant fatigue-related information, and making it easy accessible to the flight crew, will lead to improvement of their knowledge about the different aspects. This will be measured using knowledge tests before and during the intervention. Improved knowledge will enlarge the possibility that the participant will use this knowledge to improve their behaviour regarding exposure to daylight, sleep, physical activity and nutrition, before, during, and after flight schedules. Accordingly, it is hypothesized that if their behaviour is altered, participants’ circadian disruption and fatigue will reduce, leading to an improvement of general health.
To find out what implementation strategy and what medium should be used to optimise compliance to the intervention, focus groups with the target population were held. For each aircraft type, two focus groups were organised. Considering five different types of aircrafts, ten focus groups were held. A total of 30 pilots attended the focus groups, heterogeneous regarding age, gender and job title. The discussions were recorded and field notes were written. The focus groups made clear that the intervention should be easy available, appealing, and to be used by pilots of all ages and ranks. Further, it was made clear that the intervention should be evaluated by means of a test phase first, and that it should be evident that the advice given is evidence based. The advices should be made flight schedule specific; short haul pilots have a different need for information and advice than long haul pilots have.
The input from these meetings was used to elaborate the intervention strategy and to take into account the raised facilitators and barriers for implementation. Finally, interviews with key management stakeholders were held, aiming to match the intervention to the present laws and legislation, collective labour agreement, and the policy of the airline company.
After the development of the intervention, it was pre-tested by pilots and researchers. The group of test pilots was heterogeneous with respect to both aircraft units and job type. In total, 34 pilots were invited to take part in this test phase, which lasted eight weeks in total. At the end of this period, the pilots who had actually participated were asked to fill in a digital evaluation form. Further, they were asked if they were available for a telephone consultation, in case the researchers needed additional information from them. Based on the results of the test phase evaluation, the intervention was reconsidered and optimised where necessary. An important result of the test phase was the report of the short-haul pilots that their advice was not substantive enough. This issue was addressed by adding more extensive advices with regard to short-haul flight schedules.
Description of the intervention
As a result of the focus groups, a tailoring strategy was constructed. It was decided that the best tool to transfer the knowledge would be using a smartphone application. This ensures that the advice can be supplied tailored to flight characteristics (e.g. flight direction, departure and return time, number of time zones crossed) and to personal characteristics (morning vs. evening types).
For each destination with its specific schedule, the participants are provided with specific advices on optimal sleep, nutrition, and physical activity, in order to reduce fatigue. The user can fill in his flight and location, after which he will receive the advices. Subsequently, the user can choose himself to read extensive information about either exposure to daylight, sleep, nutrition, or physical activity in the glossary menu. For each screen of the application, a help menu is available.
A website containing more background information was developed alongside the smartphone app. In the app, the user is guided to the website to read, listen to and see more detailed information. See Additional file 1 for examples of the application and website.
Participants in the intervention group will be stimulated to consider the advice on the application and the website by means of reminders. The first form of reminding occurs through timed alerts; the user receives an alert once he has not opened the app for longer than three weeks. Another reminder strategy that will be used is called geofencing; the user is given an alert each time he is outside the Netherlands, with a maximum of one alert per four days.
Control intervention
The participants allocated to the control group will receive a minimal intervention consisting of the available fatigue-related information of the airline company. This information is normally scattered throughout the company and by putting it to the study website it is made sure that the information is available for each participant. Minimal intervention strategies are commonly used for control groups in order to compare them to an intervention group [30].
Consequently, the researchers will send an e-mail to the participants with instructions how to obtain and use the advices. The members of the intervention group will receive a link to download the smartphone application and a link to access the intervention website. The participants of the control group will be invited to log in to the study website, after which they will be directed to the standard available information. During the intervention period, all participants will be kept involved by sending a regular newsletter with information about the study in general, and upcoming questionnaires. Reminders will be sent to increase compliance among all participants, and communication throughout the airline company will be used to raise awareness.
Outcomes
Measurements will take place at three moments; participants will be asked to fill in questionnaires at baseline (T0), and at three (T1), and six months after baseline (T2). Before each follow-up measurement, subjects from both groups will receive an e-mail in which they are asked to fill out the online questionnaires. Reminders will be sent to increase the response rate. All questionnaires are in Dutch.
Primary outcome
The primary outcome variable is fatigue. Fatigue will be measured using the 20-item Checklist Individual Strength (CIS) [31]. The questionnaire consists of four dimensions; the subjective experience of fatigue, reduction in motivation, reduction in activity, and reduction in concentration. It has been found that the questionnaire has a good internal consistency: the Cronbach’s α for the total CIS was 0.90 and for the scales the α ranged from 0.83 to 0.92 [31].
The questions have seven answer options, ranging from “yes that is correct” to “no that is not correct”.
Secondary outcomes
Sleep quantity and quality as well as timing of sleep will be measured using the Jenkins Sleep Scale [32] and the subscales subjective sleep quality, sleep latency, sleep duration, and use of sleeping medication of the Pittsburgh Sleep Quality Index [33].
The Jenkins sleep scale is a short, 4-item, multiple choice questionnaire, which is regularly used in flight personnel [34]. The internal consistency has been found to be reasonable, with a Cronbach’s α of 0.79. The used subscales from the Pittsburgh Sleep Quality Index comprise 5 multiple choice items. The total component scores of the PSQI proved to have an overall Cronbach’s α of 0.83, indicating a good internal consistency.
Nutritional behaviour will be measured using a self-developed questionnaire. The questionnaire contains 13 questions concerning the regularity of meals taken, snacking, usage of breakfast, composition of meals, and drinking habits. The questionnaire comprises different types of questions, both open and multiple choice.
The amount of physical activity during leisure time will be measured using questions on the recommended quantity for physical activity and exercise in healthy adults [35, 36]. These measurements are often used in RCTs and comprise two open-ended questions.
Need for recovery will be measured using the 11-item ‘need for recovery scale’ from the Dutch Questionnaire on the Experience and Evaluation of Work (Dutch abbreviation VBBA), which has shown to be valid and reliable, and to have a good internal consistency of 0.88 [37]. All questions have two answering categories (yes / no).
Data on sickness absence (number of absence days and number of spells), will be collected from the records of the Occupational Health Service and Human Resource department of the airline company.
Work-private life balance will be measured using the shortened version of the SWING questionnaire [38]. This 17-item questionnaire has been developed to measure and distinguish four types of interaction; negative work-home interference, positive work-home interference, negative home-work interference, and positive home-work interference. It has been shown that the questionnaire measures all constructs reliably, with Cronbach’s α’s ranging from 0.75 to 0.84 [39].
General perceived health will be measured using two questions of the Dutch version of the SF-36 Health Survey which have proven to be moderately valid and reliable (0.81) [40].
During each measurement, the knowledge of the participants regarding the relevant fatigue-related information will be measured by means of 20 true or false statements, containing all sub-domains (exposure to daylight, sleeping, physical activity, and nutrition) of the intervention.
Participants will be asked for their body height and body weight. Afterwards BMI will be computed as body weight divided by the square of height (kg/m2).
Other study parameters
At baseline, socio-demographic data (age, gender, job title, flight unit, and household composition) will be collected.
At baseline, personal morningness-eveningness preference will be measured using the VOA, the Dutch version of the Morningness-Eveningness Scale (MEQ) [41].
Smoking tobacco and alcohol consumption are potential effect modifiers. Therefore, tobacco smoking behaviour and alcohol consumption will be assessed at baseline.
Having any kind of chronic disease might also be acting as an effect modifier. Therefore having a chronic disease will be measured by one yes or no question: “do you have a chronic disease?”
Process evaluation
Besides the effect evaluation, the process of the implementation of the intervention will be evaluated, in accordance with the Steckler&Linnan framework [42]. During the intervention period, an extensive userlog will be kept, and the delivery of the intervention will be quantified. Besides, the extent to which participants use the intervention will be objectively measured through the control management system (CMS) of the application. This system will measure the number of times the intervention participants will request an advice, and, each month, all data about usage will be stored in a database. Likewise, the number and duration of all the participants’ visits to the study website will be stored as well.
Using the questionnaires, the participants will be asked if they have read and used the advices, and if they think their behaviour (regarding exposure to daylight, sleep, physical activity and nutrition) and their timing of this behaviour, has changed due to the advices. Further, they will be asked about their satisfaction with the intervention program, concerning both the smartphone application and the website.
Statistical analysis
To investigate the success of the randomisation procedure, potential confounders or effect modifiers (age, gender, type of aircraft flown, household composition, morningness-eveningness) will be compared between the intervention and control group by Student t-tests for independent samples and Chi square tests (χ2).
The effectiveness of the intervention (time*group interaction) will be analysed using linear mixed model analyses with the outcome measures at follow-up (T1-T2) as the dependent variables. The dependent variables are fatigue, sleep, physical activity, nutrition, need for recovery, sickness absence, work-private life balance, general health and knowledge, whereas research condition (intervention or control group) is the independent variable. Possible confounding or mediating factors will be considered.
A detailed analysis plan will be developed prior to finalisation of the dataset. For all analyses a two-tailed significance level of <0.05 will be considered statistically significant. The analyses will be performed using PASW 20.0 (SPSS Inc. Chicago, Illinois, USA).
Sample size
The sample size is based on finding an effect on the primary outcome of the intervention, perceived fatigue. Fatigue will be measured using the 20-item CIS questionnaire [43]. The mean total score on this questionnaire for healthy employees is 47.3 (SD = 19.8) according to Beurskens et al. [43] (score range 0–140). Power calculations indicate that to detect a relevant 10% difference in fatigue, 246 subjects are necessary in each study group (with power = 0.80 and alpha = 0.05). Taking the expected loss to follow-up (25%) into account, a sample size of approximately 656 employees is required.