Study design
The study is described in accordance to the guidelines of the Consort Statement [50]. In clinical intervention research, the randomized controlled trial (RCT) is considered the gold standard. However, in workplace settings the introduction of control groups not receiving intervention can hamper implementation due to logistical issues and impaired organizational commitment [48, 49]. Moreover, it is impossible to implement the intervention in many clusters simultaneously because of practical and logistical reasons. These difficulties can be overcome in the more feasible stepped wedge design [48, 49] with gradual implementation of the intervention in different teams. Therefore, this study uses a stepped-wedge cluster-randomized controlled trial design with 4 groups (594 participants in total) (Figure 2). A stepped-wedge design is a type of crossover study in which clusters cross over from the control arm to the intervention arm at different time points [48, 49]. Twenty-one clusters were formed based on working teams, and randomly assigned to four successive time periods three months apart and enrolled in the study in accordance with the stepped-wedge group order. The project began in November 2012 with baseline measurements and was followed by a 3 months burn-in period without intervention activities but with repetitive baseline measures. The intervention began in February 2013.
The study has been approved by the Danish Data Protection Agency and the Ethics Committee for the regional capital of Denmark (journal number H-4-2012-115) and will be conducted in accordance with the Helsinki declaration. The study is registered as ISRCTN78113519 in the current controlled trials register.
Study population
Employees in elderly care (nursing homes and home care) in a larger municipality in Denmark participate in the study. The main employees in the elderly care in the municipality are nurses’ aides who are either social and health service (SHS) aides or helpers. In Denmark, SHS helpers have 14 months of training and are qualified for providing care of elderly people. SHS aides have an additional 6 months of training and are qualified for working in the eldercare sector, hospitals, and psychiatry. Eligible participants were nurses’ aides employed in elderly care more than 20 hours a week and being 18–65 years of age. For supporting implementation, participation was also offered to the kitchen and cleaning personnel as well as janitors belonging to the participating teams. Thus, the study population consists of low-educated service- and blue-collar workers in elderly care, but will be referred to as nurses’ aides. They were required to sign informed consent in order to participate. The exclusion criteria to the study were unwillingness to participate in the multi-faceted intervention, long term sick-listed or not being permanently employed.
Recruitment of study population
The first contact with the municipality was established by contacting the director general of the health and care administration office in the municipality by email and telephone. A meeting was subsequently arranged between working environment consultants from the municipality, working environment representatives from the nurses’ aides as well as local union representatives. At the meeting, the aim, content and activities of the project were described in overall terms and the possibility of enrolment in the study was discussed.
After formal confirmation of collaboration the details about the recruitment of employees were settled. In this municipality, the administration of elderly care is divided into nine districts, representing geographically separated districts managed by separate district managers and counting approximately 4350 employees in total of which approximately 3000 are nurses’ aides. Each of the nine districts has between 3–6 nursing centers spread out geographically in the districts in which there are multiple working teams. The researchers then presented the study at a meeting for the district managers. Afterwards, they were given the opportunity to discuss the study with their employees and whether or not their district wanted to participate in the study. The district managers were encouraged to provide the reasons and motivations to participate in the study. The study was dimensioned to enroll 3–5 of the districts. Four of the nine districts consented to participate in the study.
In the fall 2012, all employees in the four districts were invited to a short information meeting of 30 minutes’ duration providing information about the project, and participants indicated their interest in participation. Prior to the information meeting, written information about the aim and activities was distributed to all employees in a short information brochure. Because of the team structure in the municipality, it was necessary to conduct several information meetings (>40) in order to reach as many of the employees as possible.
Funding of the project
In Denmark, workplaces can apply for a grant through the national Prevention Fund (established in 2007), which covers the cost of implementation of workplace interventions in order to reduce musculoskeletal disorders, impaired health and work ability and sickness absence and thereby prevent exclusion from the labour market [51]. It was decided that the municipality should apply for a grant in order to cover some of the expenses of participating in the study. A project description was prepared for the application and the municipality was granted 6.8 million DKK (approximately 900.000 €) for the implementation of the intervention.
Randomization
The employees who volunteered for participation in the study were randomized to four successive time periods, three months apart in the stepped wedge design. Since the intervention is group-based, the randomization was performed across clusters based on working teams. Since the work-site locations of the participants are widely distributed over a large geographical area and the number of participants on the work-locations differs, a balanced cluster randomization was applied. Strata were formed by each of the four districts and clusters were formed within each stratum. To promote comparability between the clusters they were balanced on number of participants in each cluster to minimize imbalance over several strata. Therefore, we randomized the clusters according to their size with the four largest clusters randomized first. Due to logistics related to the intervention delivery, small teams were merged to a cluster when located in geographical proximity (Figure 3).
Strata were named alphabetically and clusters named consecutively within each stratum. One of the authors (CNR) stratified the participants into the strata and clusters, but was blinded to the succeeding randomization. All grouped clusters belonging to a specific stratum were drawn from a deck of cards with each color presenting a step from 1 to 4 in the study. Researchers blinded to the identity of the strata and clusters carried out the randomization. The participants do not receive information about which group they are randomized to until shortly before crossing over from control to intervention.
Delivery of the intervention
Local therapists (3 occupational therapists and 3 physiotherapists) were trained to carry out the intervention activities. The training is guided by a written intervention protocol describing all intervention activities and 6 days of training and sparring sessions throughout the study period with CNR. The instructors will be delivering the intervention to the nurses’ aides. The intervention will be scheduled in the working time of the participants if feasible for the individual team. The working time spend on the activities by the employees will be compensated to the workplace by external funding obtained by the municipality.
Organization of the implementation support system
Prior to the intervention, a formative effort was made to ensure organizational support for the intervention. The effort involved six overall steps.
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Obtaining organizational commitment
Organizational commitment was obtained through broad information and informed commitment from the director general, the worker safety and work environment board and volunteer commitment from each of the district managers and their teams of nurses’ aides’ supervisors as described in the section "Recruitment of study population".
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Forming a steering group and a working group
A steering committee was formed. The steering committee consists of a chairman (a manager of one of the four participating districts), the managers of each of the remaining three participating districts, a local project leader, two of the researchers, a local union representative (an employee), and a local working environment representative. A working group was also formed. The working group’s main task is to deliver material to the steering group for decision-making. The working group consists of a local project leader, the researchers and other relevant resources needed for specific tasks.
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Integration of the programme to the organizational health system
Linkage to the higher administration as well as local occupational health system was arranged with training in the intervention’s aim and content. Target persons were the occupational working environment consultants, work environment representatives among the workers and top management of the administrative department. Furthermore, the intervention was designed to be delivered by local therapists to plant the knowledge and experience in the organization.
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Focus on supervisors
The supervisors of the teams were trained in the interventions aim and content prior to the beginning of the study (in October 2012). Moreover they were required to form a support system with knowledge sharing meetings for supervisors in the three months when their team receives the intervention.
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Local implementation planning groups
In each district local implementation planning groups are to be established with local work environment consultants, local employee’s representatives, supervisors of the teams, the project leader, the researcher and the therapist responsible for conducting the intervention. Approximately 8–10 weeks before each of the 4 groups enter the intervention they will meet and plan in details the logistics of implementation of the activities in the intervention for the participating teams, e.g. date and time for the different activities.
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Employee ambassadors
In each team, an employee has been appointed a specific role as an ambassador and will be motivating the colleagues to participate in the study.
Throughout the intervention period, tailored information material about the process and role expectations will be sent to the ambassadors, supervisors, work environment consultants and managers.
Intervention development and content
Development of the intervention
The intervention lasts 3 months and integrates participatory ergonomics, physical training and CBT tailored to the target group. The activities are specified and adjusted by a modified intervention mapping approach [52]. The intervention mapping facilitates participation and consultation of all participating stakeholders. The development of the intervention activities is based on four key points: 1) effectiveness; the activities should be effective 2) feasibility; the activities could be executed at the workplace during working hours, 3) motivation; workers should find the activities appealing and relevant and 4) evaluation; it should be possible to conduct a sound scientific evaluation meaning that the activities follows a standardized protocol [52].
The tailoring of the intervention to the nurses’ aides started with a needs assessment by using existing registrations of the working environment in the municipality and searching relevant scientific literature. This helped specifying the objective of the intervention to both include prevention and reduction of LBP as well as preventing the consequences of LBP (e.g. work ability and sickness absence) among nurses’ aides (Figure 4).
To further tailor the intervention to the workers, the researchers performed a small qualitative evaluation of the work environment and occupational health services among the workers. The evaluation involved 1) observations of daily work life activities among the nurses’ aides as well as a short interview with the nurses’ aides and 2) observation of ergonomic classes held biannually in the municipality for the nurses’ aides. The data gathered in this phase indicated that activities should be carried out in proximity of their workplace and during their working time. The ergonomic classes focused on information of risk factors and training in manual patient handling and these factors were considered in the final content of the intervention activities, and documented in the intervention protocol. Finally, from the planning groups further adjustments will be made regarding the logistics of the activities, e.g. the one-hour physical training pr. week will be planned as once a week for one hour, twice a week for 30 minutes or whatever proves to be the most feasible for the individual team. The content of each of the activities will be described in further details in the following.
Intervention
Participatory ergonomics
The overall aim of the participatory ergonomics in this study is to prevent physical exertion and pain through minimizing physical risk factors for LBP at work and reducing the work tasks perceived as physically demanding. Participatory ergonomics covers "the involvement of the workers in planning and controlling significant amount of their own work activities, with sufficient knowledge and power to influence both processes and outcomes to achieve desirable goals" [53]. The literature highlights participatory ergonomics as not being a unitary concept, but rather as an umbrella term covering a fairly broad range of ideas and practices [54]. In this study, inspiration from the framework suggested by Haines et al. [54] as well as the blueprint suggested by Wells et al., [55] was used in the development of the participatory ergonomics intervention. Therefore the participatory ergonomic process follows 6 steps: 1) identification of physically demanding work tasks, 2) analysis of physically demanding work tasks, 3) solution building, 4) prototype implementation, 5) evaluate prototype and 6) adopt solution. These steps will be carried out in two workshops of 3 hours and two follow-up meetings of one hour.
The participatory ergonomic process is initiated by a one-hour start-up meeting in each team. At this meeting, the ergonomic work group is formed. The ergonomic work group will consist of 5–7 employee team members and the instructor (a local therapist) will serve as the ergonomist. No supervisors are involved in the ergonomic work group. However they will be involved between workshops, as an employee (the ambassador) will present the decisions taken at the workshops for the supervisor. At the start-up meeting, all employees will have the opportunity to identify which work tasks they consider physically demanding and therefore a risk for development, maintenance and reoccurrence of pain. They are further encouraged to write down their suggestions and put it in an ergonomics mailbox situated at the workplace. The mailbox will be used throughout the intervention period and remain open for suggestions for the participatory ergonomic process from all the employees.
At the first workshop, the ergonomic work group will prioritize the identified physically demanding work tasks and analyze these. The results of this workshop should be 3–4 prioritized work tasks that should be 1) relevant (e.g. many workers perform the task or the task is done many times during a working day) and 2) be a significant risk factor for pain or it causes a high physical work exertion. At the second workshop, the ergonomic work group will come up with solutions to the prioritized work tasks and make an implementation plan. They are again asked to prioritize the solutions according to 1) efficiency (i.e. can this solution reduce pain or physical work exertion?) and 2) feasibility (i.e. is this solution likely to be implemented within the project period?). After the workshops, the solutions are to be implemented. At two follow-up meetings, the implementation of the solutions will be evaluated and possible adjustments made.
Physical training
The overall aim with the physical training in the study is to introduce different types of physical activities to the participants and motivate them to maintain the preferred physical training. The different types of physical training are chosen based on the evidence of efficiency as physical capacity building activities and their possible impact on preventing and reducing LBP. The physical training types are presented in 3 blocks: 1) body awareness and body postures, 2) strength and coordination training and 3) general physical activity. The physical training will be carried out each week for one hour with an instructor. It consists of twelve sessions with separate focus areas. The first four sessions will be introduction to physical training and the three different types of training. In the remaining sessions, the participants will be able to choose from the different types of training and develop their own training regime. During the sessions, different tasks will be incorporated that refers to ergonomic principles (e.g. manual handling of patients and good body postures) or cognitive behavioral principles (e.g. experience of acute vs. long term muscle discomfort/soreness/pain and training in relaxation techniques). Each training session starts with a warm up routine that will be the same for all twelve sessions and lasts approximately 15 minutes. The warm up routine consists of conditioning exercises involving large postural muscle groups as well as strengthening exercises for the abdomen and the lower back. The participants also receive a short brochure with description and illustrations of the exercises.
Cognitive behavioral training (CBT)
The CBT programme is a modified version of the program developed by Linton [56] and further developed for a working population by Jørgensen et al. [32]. The purpose of the programme is to reduce and prevent pain, and diminish negative effects of pain. All participants will be participating in two workshops of 3 hours. The workshops follow the same structure with a short lecture on the themes, problem-solving training and training of new skills (e.g. applied relaxation training). The first workshop will focus on improving the participants’ understanding of pain, the experience of pain, and the anticipation of pain by performing cognitive exercises on how physical activity may negatively or positively relate to pain. Another main focus will be on pain in relation to physical demanding work. The second workshop will focus on the ability to function and have a good life quality despite pain (i.e. pain coping, increasing health behavior, adapt skills to daily life). Moreover, the positive long-term effects from appropriate pain coping will be discussed [56]. Finally, the participants will make their own individual plan for using the new skills and each team will make a plan on how to implement the new skills in their working day.
Maintenance
At the end of the intervention, the teams will prepare for the maintenance phase. In the maintenance phase, the ergonomic work groups will transform into an ergonomics and health promotion group. That means, that they will continue using the skills obtained during the participatory ergonomics programme (identification, analyses, solution building, prototype implementation, evaluate prototype and adopt solution), but will now broaden their scope to also include health-related challenges and solutions within health promotion methods. Still, the groups’ work will be based on input and suggestions from all employees and they will develop action plans on how to continue and maintain the activities after the 3 months of intervention.
Knowledge sharing
Throughout the three months period of intervention, the supervisors of the participating teams will attend three one-hour meetings, one each month. The main topics of these knowledge sharing meetings will be barriers and facilitators for implementation of the intervention. At these meetings, the researcher will be participating and guide the discussions. Minutes from the meetings will be distributed to the involving supervisors afterwards.
Efforts for high compliance
An important focus in this study is to maintain high compliance throughout the study. It is well known that maintaining participants in the study and high participation is a difficult process in intervention studies at the workplace [41]. Therefore, initiatives are taken to make participation more attractive and to minimize dropout. Firstly, the concepts of the project are participatory to ensure that the intervention is tailored to the specific needs of the participants facilitating ownership and motivation to participate in the study. We ensure that the entire organization is informed about the main features, purposes and processes of the project by having regular meetings. Written materials such as information letters, brochures and posters are distributed to the participants throughout the study period.
Furthermore, particularly for the stepped-wedge design, it is important that the same intervention content is delivered at each step (i.e. introduction of a new intervention group). To support this, the intervention mapping process was conducted to ensure the intervention was optimally tailored to the organization. Also, the intervention protocol was written with specific measureable criteria for delivery of the intervention. Finally, pre-developed expectation materials are delivered to all stakeholders of the intervention. Moreover information to support organizational level decisions about dissemination of the intervention content to other departments is withheld as long as possible until proper systematic evaluation can be conducted when all four intervention deliveries are finalized.
Data collection
The data collection consists of text messages and questionnaires. At baseline the participants also received physiological health measures for describing the health of the population.
Physiological health measures
To map the health of the employees and to motivate them to participate in the intervention, all participants were invited to physiological health measures at baseline. The height was measured with no shoes and in upright standing position (Seca 230). Body weight, body mass index (BMI) and body fat percentage was determined using bio impedance (TANITA BC-418). Resting blood pressure was measured on the left arm after at least 15 minutes sitting rest (Omron M3) [57]. Participants received individual feedback on the results from the health measures in regard to Danish and international guidelines [57, 58]. All measurements were performed by trained clinical personnel (physiologists and physiotherapists).
Evaluation
Analyzing the effects and processes of a complex intervention requires a comprehensive evaluation. In order to match the design and context of this project, the efficiency of the study will be evaluated. The study efficiency will be a result of both efficacy and implementation (Efficiency = Efficacy X Implementation) [59].
Primary outcome measures
Because LBP is a fluctuating condition, which can be difficult to recall [60], monthly monitoring will be conducted by using mobile phone text messages. In addition to the frequent measuring of LBP, consequences (i.e. bothersomeness due to LBP) will also be measured monthly by text messages delivered by the SMS Track® system [61, 62]. The setup of the software is designed for the study in close cooperation with researchers. Every month (on a Monday) the respondents receive an automated text message to their private mobile phone, which they are expected to answer by using a text message. LBP is measured as days with pain and intensity of pain in the lower back each month throughout the data collection period. The questions posed are "During the previous four weeks, how many days have you had low back pain?" and "What was the highest intensity of your low back pain, with 0 being no pain and 10 being the worst imaginable pain?" Consequences of pain will be measured by days with bothersomeness due to LBP each month throughout the data collection period. In a recent consensus report to standardize LBP measures, the description "limit your usual activities or change your daily activities" was suggested to measure the severity of pain [63]. Moreover, bothersomeness has shown to correlate well with quality of life [64], thus making a good measure for consequences of LBP. The question posed is "How many days during the previous four weeks has your low back pain been bothersome (i.e. affected your daily activities or routines)?"
Secondary outcome measures
Self-reported sickness absence due to LBP is obtained monthly by text message [65]. Additionally, every three months the following will be measured by text messages: Work ability [66], Occupational lifting and carrying [67], Self-rated physical exertion [68], Self-rated muscle strength [69], fear avoidance beliefs [70] as well as support from management regarding support to handle musculoskeletal pain.
Process evaluation (implementation)
An evaluation of the implementation will be performed, inspired by the framework by Steckler and Linnan [71] to gain insight into the extent to which the intervention is implemented as intended [59]. The implementation will be measured through dose delivered (the amount of intervention components actually delivered by the instructors) and dose received (employees participation in the activities) [71]. The delivery will be measured by asking the instructors to what extend they have followed the specific intervention activities in accordance to the defined criteria written in the intervention protocol (they will fill out a questionnaire after each activity). The dose will be measured by participation rate and by questionnaires to the participants after the intervention asking about their appraisal of the intervention [71].
Sample size calculation
For sample size calculation we used the method described by Woertman et al. [72] for the stepped wedge design. The sample size is calculated for LBP intensity (numeric rating scale 0–10). Due to the fact that we were not able to find any relevant studies on workplace interventions measuring LBP intensity, we estimated variance from the study by Kovacs et al. on patients with non-specific low back pain [73]. The variance was set to 2.1. With an α of 0.05, a power of 0.8, and an intracluster correlation coefficient of 0.05, we calculated that we needed 65 participants in a stepped-wedge trial to allow analyses of LBP intensity.
The sample size calculation was based on a patient group meaning that all subjects will have pain and thereby it is possible to reduce pain in all subjects. The present study is a workplace intervention where all employees are invited to participate. Therefore we expect to enroll both participants with and without pain, meaning that we need a bigger sample size in order to detect a difference in LBP intensity. Workplace studies often have a high drop-out rate and could be expected to be up to 50%. When conducting a stepped wedge design, the intervention period is prolonged. This can be an extra risk factor for a high drop-out rate due to a high turn-over rate or due to "fatigue" relating to waiting for receiving the intervention. Moreover there is a greater risk for organizational changes happening at the workplace during the study period, meaning that we could lose entire clusters in the evaluation. Giving that we have a workplace willing to offer the intervention to all employees, we chose to randomize all 594 who wanted to participate and therefore should have sufficient power to detect an effect on LBP intensity even when taking all of the above concerns into consideration.
Statistical analysis
Baseline characteristics will be described by questionnaires and the physiological health measures. Analyses regarding the effectiveness of the primary outcomes and secondary outcomes will be performed after three months of intervention by means of multilevel analyses suggested by Hussey & Hughes (linear mixed model (LMM) or generalized linear mixed models (GLMM)) [74]. Multilevel analyses take clustering of observations of workers within the same team into account, as well as repeated measurements within one participant [75]. The analyses will be conducted for the different measures of LBP; intensity, days and bothersomeness. Moreover, we will investigate whether the combined measure of the three measures of LBP will fulfill the criteria for a LBP index and investigate the effect on the LBP index.
All statistical analyses will be performed according to an intention-to-treat principle. In addition, per protocol analyses will be conducted for those groups that actually complete the intervention protocol. Further, in a subgroup analysis the effect on only the population of nurses’ aides will be evaluated.
Handling of missing data and loss to follow up
Efforts to avoid missing data are conducted. Questionnaires are distributed personally to the participants through the instructors. If they are not present, the supervisors or ambassadors are advised to hand out the questionnaire to the participants later on and to encourage the participants to complete the questionnaire and to send it back in a stamped and addressed envelope. The text messages are sent on a Monday around lunchtime and a reminder is sent Wednesday if an answer has not been received. Supervisors are told to support text message replies during working hours and posters are placed at the workplace to remind participants to answer. If answers are still missing, we call the participant by phone to get their response.
Withdrawal from the intervention requires that participants personally take contact with the researchers. If they voluntarily give their reason(s) for discontinuing the intervention, these are registered. A flow diagram describing the dropout rate in intervention and control group will be conducted. Furthermore, analyses to identify possible different baseline characteristics between participants who drop out and participants who continue in the study will be conducted to describe the dropout population and the possible confounding introduced by that.
For the analyses to test hypothesis 1 and 3 in an intention-to-treat-manner, missing data are imputed as last observation carried forward based on the assumption that missing data are missing at random. For the analysis to test hypothesis 2, missing data of participants will automatically be censured at the first missing data measurement during follow-up – no matter the reason for the missing data (i.e. spot-like missing or complete drop-out).
