Healthy ageing at work— Efficacy of group interventions on the mental health of nurses aged 45 and older: Results of a randomised, controlled trial

Objective This multicentre, randomised controlled trial (RCT) aimed to evaluate the efficacy of a small-group intervention promoting successful ageing at work in older nurses (aged ≥45). Method A sample of 115 nurses aged ≥45 from 4 trial sites in Germany were randomly assigned to either the intervention group (IG), that received a small-group intervention of seven weekly sessions of 120 min with a booster session after six weeks or to a wait-list control condition (WLC). Outcomes were measured via validated self-report questionnaires at baseline (T1) and at post-treatment (T2). Primary outcomes were mental health-related well-being and mental health-related quality of life (QOL). The secondary outcomes included mental health-related and work-related measures. Results The intention to treat (ITT) analysis showed significant positive effects of the intervention on mental health. A significant small effect (d = 0.3) in favour of the IG was found for psychological health-related quality of life. Positive small effects (d = 0.24 to d = 0.31) were also found for work related mental strain. Conclusions Our small-group intervention based on a theory of successful ageing for nurses aged ≥45 was found to be effective with regard to improvements of psychological health related quality of life and other mental health-related outcomes. Thus, our study shows that the ageing workforce can be reached through specifically designed preventive interventions. The components of our intervention could be easily adapted to the belongings of other professions. Our results suggest that these components should be evaluated in various settings outside the healthcare sector.

As a result of demographic change nursing shortage and changes within the composition of staffs in the nursing sector are expected. Self-reported workability decreases at the age of 45 years due to psychological and physical strain. Therefore, the aim of this study is to evaluate a preventive group intervention for older nurses.
Before designing the intervention, qualitative interviews and focus groups were performed, to allow to consider the view of the target population in the development process. Based on a needs assessment and theory, the invervention was created.
Together with the staff during the intervention concepts for labour organization of an ageing workforce will be created and applied und and personal ressources are strengthened, to better deal with strain and to preserve health.
As a result, the nursing department will obtain an evidence based intervention to preserve health of healthcare workers.
One important theory of successful ageing will be applied. The theory of Selection (focusing on fewer important goals), Optimization (utilise resources in an effective manner) and Compensation (the use of adaptive aids to preserve performance) can help to preserve health and performance in old age.
Due to the setting of small groups the intervention will be inexpensive.

Introduction
Demographic change leads to shortfalls in nursing numbers. According to projections by German Statistics office these changes will entail a shortage of more than 112.000 full time nurses (1). In addition, nursing is associated with high physical and psychological strain. To deal with them, many skills such as physical strength, cognitive skills or adaption to desynchronization are necessary. Those skills diminish in older age. Therefore, self-reported workability declines at the age of 45 years. Further, low workability is linked to a high intention to leave the job (2).
To preserve the work force of nurses, it is important to develop preventive intervention to support nurses in preserving health and performance status.
Conceptual foci will be set on ageing at work, stress prevention, reflecting the working biography (10), Health, Work-Life Balance, strengthen personal resources and coping strategies and supportive group intervention (8).
One important theory of successful ageing will be applied. The theory of Selection (focusing on fewer important goals), Optimization (utilize resources in an effective manner) and Compensation (the use of adaptive aids to preserve performance) can help to preserve health and performance in old age. There is a large body of evidence on SOC in the work context (5).
Preliminary work was performed at the university hospital of Düsseldorf. Knowledge about SOC in the work place could be expanded. Results suggest, that a) beyond general strategies of SOC nurses use context-specific strategies of SOC (4) and b) SOC can be helpful if working environment is favorable (4). Therefore, the working environment should be designed in a manner that allows the application of SOC-strategies. An intervention that aims to enable the application of SOC has to consider the individual and the organizational level of preventive strategies (6).
Interventional strategies that are known to be effective (10) with regard to coping with stress, health, work-wife balance, work-life balance, strengthen personal resources and coping strategies and supportive group intervention are considered (35).

Aims of the study
For the prevention of nursing shortfalls, it is important, to develop a working environment, enabling nurses to remain on the job until retirement age.
One strategy to develop the working environment could be the application of the theory of SOC (3,4): The theory of Selection (focusing on fewer important goals), Optimization (utilize resources in an effective manner) and Compensation (the use of adaptive aids to preserve performance) has shown to be helpful in preserving health and performance in old age. The main aim of the study is to test a group intervention for nurses, aged 45 and older that aims to preserve workability of ageing nurses. Compared to other interventions such as stress prevention (7), individual needs, resources and motivation to apply well-tried strategies shall be considered.
Another goal is the development of personal health competencies. The application of such competencies requires a good working environment (8).

Aims
One aim ist he application of SOC strategies and stress prevention strategies (such as relaxation, mindfulness) a good Work-Life Balance while profiting from personal resources to preserve health and workability of nurses. Another aim is the development of an age-based working environment.
The implementation of the intervention "healthy ageing at work" will… Nurses aged ≥45 are teached in strategies to preserve their health. Sources of strain will be identified and specific

Test procedere General description
Comparison between participants and non-participants (control) with regard to strain. To assess wether nurses benefit from stress prevention programs.

Therapeutic effect
Prior studies have shown high job strain in nurses [9] and an augmented psychological strain in higher age [9].
There is already some evidence about the effectiveness of the application of SOC in another Setting without the supplement of age-related, stress reducing, resource-strengthening modules (such as Work life balance, body, health).
There can be expected, that elderly workers suffer from mental strain. Further, they have few coping strategies with regard to the working environment.
There can be expected that elderly workers with high mental strain benefit from interventions.
Resilience will be promoted, stress can be reduced. Further resource-strengthening with regard to ageing, self-efficacy are also supported by the intervention. Individual projects are developed and implemented at the workplace

Undesirable effects, risk for adverse events
From our point of view there are no risks. -no negative therapeutic effects or undesirable effects are expected. Several validated questionnaires that have been applied in several studies will be used (e.g. [22], [23], [24]). Assessment could even have a relieving (positive) effect, as the assessment is linked to a helpful intervention. If any questions arise or there´s a need for a therapeutic contact, our Department of Psychosomatic Medicine including the emergency service, is available 24/7. Participants will be informed about that. The only strain that could be caused by the intervention is the investment of time, as the sessions are held weekly.

Psychometric testing
Questionnaires before starting the intervention and 2 other measurement time points will be used. The respective questionnaire is handed out to participants.
Sociodemographic data (age, gender, nationality etc.) are also assessed with questionnaires, including job-related information (Experience, Specialization, Place and kind of job -e.g. OR, ICU, Ward, Outpatient Clinic).
The WHOQOL-BREFM serves at assessing quality of life. A quality adjusted life year or QALY ist a measure for rating of one year in a lifetime in Relation to health. A QALY with the value of 1 represents a year of good health, a QALY with a value of 0 stands for passing away.
The following aspects of quality of life will be considered: psychological subscale, autonomy, social relations, environment and spirituality. There are five subscales representing intensity, capacity, frequency, rating or importance the respective aspect of quality of life.
The GAD-7 is part of the PHQ-D (Patient Health Questionnaire) for diagnosing anxiety disease [11]. It comprises 7 items with 4 possible answers. (0=not at all "3" nearly every day).
The PHQ-D allows monitoring depression [15] and has a good validity [12] [13] [14] and sensitivity of change [18]. In the present study the module for monitoring depression (PHQ-9) will be used.
Work-related self-efficacy is a measure derived from a general self-efficacy scale [18]. The questionnaire measures work related self-confidence. The scale comprises 6 Items; with a 5-Point-Likertscale (1 = not at all; 5 = entirely correct), from which the sum score is calculated. Reliability and Validity are good [18].
The Maslach Burnout Inventory (MBI) allows screening for burnout symptoms -it is the by far most used questionnaire in burn-out research [20]. The German version [21] comprises 22 Items, with a 7-step Likert-scale between 0 (never) and 6 (every day). Die Items there are three subscales: emotional exhaustion (nine Items), depersonalization (five Items), reduced performance (8 Items). For every subscale means are calculated [20]. The MBI showed good validity and reliability [21].
Wellbeing (physical and psychological) and Workability: Psychological Wellbeing will be measured by the WHO-5 [22]. The questionnaire "Irritation" assesses psychological aspects, that are influenced by work strain [25]. Physical wellbeing will be assessed by the nordic questionnaire [26] which is valid in assessing musculoskeletal problems [27]. The short version of the Work Ability Index (WAI, German version from [28] [29]) will be used. SOC will be measured by the SOC-questionnaire of Baltes, Baltes, Freund and Lang (1999; [30].) eingesetzt werden. Further a nurse-specific SOC questionnaire will be applied (Müller et al., in preparation) (36).

Study design
Study design (with waiting control-group) (Figure 1).

Figure 1: Waitinglist-Interventiongroup-Design for development and evaluation of the group intervention "ageing at work"
After written Informed consent has been obtained from the participants, baselinemeasurements will be performed. The intervention group will attend a 10-week group intervention "Ageing at work" including a booster-session after 4 weeks. At T2 (14 weeks from T1) new analyses of CG und der IG will be performed. Then, the CG will attend the intervention. CG and IG will be measured again 28 weeks after T1. The waitinglistcontrolgroup design ensures that all participants profit from the participation/intervention. and (for all participants), written informed consent, sufficient knowledge of the German language. The intervention shall be offered to all nurses in the respective age-range to avoid any stigmatization. A Screening with inclusion of high risk would lead to a stigmatization of these people that should be avoided.

Exclusion criteria
Exclusion criteria are disability with permantent inability to work or long-lasting inability to work, cognitive impairment or severe physical and mental diseases or emotional strain that does not allow participation to the study.

Process of the study
Results of a preliminary qualitative study that aimed to assess the needs and expectations of future participants are considered to design the intervention.
After approval by the nursing management and the staff council, participants will be informed by a letter with general Information about the study. All nurses in the respective age-group at the university hospitals of Heidelberg, Ulm and Düsseldorf will be asked to participate.

Abort criteria
Participants are allowed to stop participation at any time without giving any reason by withdrawing the declaration of informed consent. Abort of participation is possible at any time if the employee is no longer willing to participate in the study.

Statistical design
To eliminate different kinds of bias, the following methods will be applied: -Study registration -Randomisation by a validated randomisation program -Standardization of the intervention -Training and supervision of group leaders -Blinding of person that is responsible for data acquisition and management

Sample size estimation
Effect size of the main outcome to detect clinical relevance should be 0.5. To estimate sample size we consider similar studies that were implemented in the working and organizational context (33). A sample size of 64 participants has a 80 percent Power do detect such an effect based on a t-test for independent samples with a significance of 0.05 (two sided). Assuming a drop out of 10% we need to include 141 participants in our RCT.

Statistical analyses
Analyses follow the "intention to treat"-principle. Primary outcomes will be analyzed by analysis of covariance. Quality of life and depression at baseline will be considered as covariate in the model respectively. Continuous Outcome-Variables will be analyses by analyses of variance. Dichotomous Outcome-Variables will be tested by Chi-Quadrat-Test or logistic Regression.

Ethical principles
The investigation will be performed in accordance with the declaration of Helsinki and the professional code for physicians of the chamber of physicians of Baden-Württemberg in the current version. Participation is voluntary. Declaration of consent can be withdrawn at any time of the study, without giving any reasons and without penalty/disadvantage. Die Participants will be informed by verbal and written information about the consequences of the investigation, especially about the possible benefit for their health status and potential risks.
Approval will be documented by a signature on a written informed consent form. In case of withdrawal data will be destructed or the participant will be asked if he is allowing the evaluation of his data.

Legal bases
The study protocol is sent to the ethics commitee of the der medical faculty of heidelberg for evaluation. Recruitment will not start, until the written approval of the ethics commitee is available. Names of the participants and all other confidential information will be used according to the Federal data protection act (BDSG). A transfer of data will only be performed in in a pseudonymous version. Third parties will not be allowed to access original medical files.