Evaluation of occupational health interventions using a randomized controlled trial: challenges and alternative research designs.

Occupational health researchers regularly conduct evaluative intervention research for which a randomized controlled trial (RCT) may not be the most appropriate design (eg, effects of policy measures, organizational interventions on work schedules). This article demonstrates the appropriateness of alternative designs for the evaluation of occupational health interventions, which permit causal inferences, formulated along two study design approaches: experimental (stepped-wedge) and observational (propensity scores, instrumental variables, multiple baseline design, interrupted time series, difference-in-difference, and regression discontinuity). For each design, the unique characteristics are presented including the advantages and disadvantages compared to the RCT, illustrated by empirical examples in occupational health. This overview shows that several appropriate alternatives for the RCT design are feasible and available, which may provide sufficiently strong evidence to guide decisions on implementation of interventions in workplaces. Researchers are encouraged to continue exploring these designs and thus contribute to evidence-based occupational health.

A cost-effectiveness and return-on-investment analysis of a worksite vitality intervention among older hospital workers: results of a randomized controlled trial.

OBJECTIVE: To conduct a cost-effectiveness and return-on-investment analysis comparing a worksite vitality intervention with usual care. METHODS: A total of 730 older hospital workers were randomized to the intervention or control group. The 6-month intervention consisted of yoga and aerobic exercising, coaching, and fruit. At baseline, and 6 and 12 months, general vitality, work-related vitality, and need for recovery were determined. Cost data were collected on a 3-monthly basis. The cost-effectiveness analysis was performed from the societal perspective and the return-on-investment analysis from the employer's perspective using bootstrapping techniques. RESULTS: No significant differences in costs and effects were observed. Incremental cost-effectiveness ratios in terms of general vitality (range, 0 to 100), work-related vitality (range, 0 to 6), and need for recovery (range, 0 to 100) were, respectively, €280, €7506, and €258 per point improvement. Per euro invested, €2.21 was lost. CONCLUSIONS: The intervention was neither cost-effective nor cost-saving.

Effectiveness of a worksite lifestyle intervention on vitality, work engagement, productivity, and sick leave: results of a randomized controlled trial.

OBJECTIVES: A worksite lifestyle intervention aiming to improve lifestyle behaviors could be an effective tool to keep older workers vital, and thereby prolong their labor participation. Therefore, this study evaluates the effectiveness of such an intervention on vitality, work engagement, productivity and sick leave. METHODS: In a randomized controlled trial design, 367 workers (control group: N=363) received a 6-month intervention, which included two weekly guided group sessions: one yoga and one workout, as well as one weekly session of aerobic exercising, without face-to-face instruction, and three individual coach visits aimed at changing workers' lifestyle behavior by goal setting, feedback, and problem-solving strategies. Furthermore, free fruit was provided at the guided sessions. Data on work-related vitality (UWES vitality scale), general vitality (RAND-36 vitality scale), work engagement (UWES), productivity (single item scoring 0-10), and sick leave (yes/no past 3 months) were collected using questionnaires at baseline (N=730), and at 6- (N=575) and 12-months (N=500) follow-up. Effects were analyzed according to the intention-to-treat principle with complete cases (N=500) and imputed data (N=730). RESULTS: There were no significant differences in vitality, work engagement, productivity, and sick leave between the intervention and control group workers after either 6- and 12-months follow-up. Yoga and workout subgroup analyses showed a 12-month favorable effect on work-related vitality [ß=0.14, 95% confidence interval (95% CI) 0.04-0.28] and general vitality (ß=2.9, 95% CI 0.02-5.9) among high yoga compliers. For high workout compliers, this positive trend was also seen, but it was not statistically significant. CONCLUSIONS: Implementation of worksite yoga facilities could be a useful strategy to promote vitality-related work outcomes, but only if high compliance can be maximized. Therefore, impeding factors for participation should be investigated in more detail in future research.

A worksite vitality intervention to improve older workers' lifestyle and vitality-related outcomes: results of a randomised controlled trial.

OBJECTIVE: To evaluate the effectiveness of a worksite vitality intervention on vigorous physical activity (VPA), fruit intake, aerobic capacity, mental health and need for recovery after work among older hospital workers (ie, 45 years and older). METHODS: The 6-month intervention was evaluated using a randomised controlled trial design. Workers who were randomised to the intervention group (n=367; control: n=363) received the Vital@Work intervention containing (1) a Vitality Exercise Program (VEP) combined with (2) three visits to Personal Vitality Coach. The VEP consisted of a weekly yoga session, a weekly workout session and weekly unsupervised aerobic exercising. Free fruit was provided at the VEP. Data on the outcome measures were collected (ie, year 2009-2010) at baseline (n=730) and 6 months of follow-up after baseline (n=575) using questionnaires, accelerometers and 2 km walk tests. Effects were analysed according to the intention-to-treat principle with complete cases (n=575) and imputed data (n=730) using linear regression analyses. Additional analyses were performed for high yoga and workout compliance (ie, >mean number of sessions). RESULTS: Effects were found for sports activities (ß=40.4 min/week, 95% CI 13.0 to 67.7) and fruit intake (ß=2.7 pieces/week, 95% CI 0.07 to 4.7) and were stronger for workers with high compliance to yoga (sport: ß=49.6 min/week, 95% CI 13.9 to 85.2; fruit: ß=3.8 pieces/week, 95% CI 1.1 to 6.4) and workout sessions (sport: ß=72.9 min/week, 95% CI 36.1 to 109.8; fruit: ß=4.0 pieces/week, 95% CI 1.1 to 6.4). The intervention group lowered their need for recovery, when compared to controls (ß=-3.5, 95% CI -6.4 to -0.54), with stronger effects for high workout compliance (ß=-5.3, 95% CI -9.3 to -1.3). No effects were found on VPA, aerobic capacity or mental health. CONCLUSIONS: Implementation of worksite yoga and workout facilities and minimal fruit interventions should be considered by employers to promote transitions into healthier lifestyles and thereby health.

A process evaluation of a worksite vitality intervention among ageing hospital workers.

BACKGROUND: The process evaluation of the Vital@Work intervention was primary aimed at gaining insight into the context, dose delivered, fidelity, reach, dose received, and participants' attitude. Further, the differences between intervention locations were evaluated. METHODS: Eligible for this study were 730 workers, aged ≥ 45 years, from two academic hospitals. Workers randomised to the intervention group (n = 367) received a 6-months intervention consisting a Vitality Exercise Programme (VEP) combined with three visits to a Personal Vitality Coach (PVC), aimed at goal setting, feedback, and problem solving. The VEP consisted of a guided yoga session, a guided workout session, and aerobic exercising without direct face-to-face instruction, all once a week. Data were collected by means of a questionnaire after the intervention, attendance registration forms (i.e. attendance at guided VEP group sessions), and coaching registration forms (filled in by the PVCs). RESULTS: The dose delivered of the yoga and workout sessions were 72.3% and 96.3%. All PVC visits (100%) were offered. The reach for the yoga sessions, workout sessions and PVC visits was 70.6%, 63.8%, and 89.6%, respectively. When taken these three intervention components together, the reach was 52%. This differed between the two locations (59.2% versus 36.8%). The dose received was for the yoga 10.4 sessions/24 weeks and for the workout 11.1 sessions/24 weeks. The attendance rate, defined as the mean percentage of attended group sessions in relation to the total provided group sessions, for the yoga and workout sessions was 51.7% and 44.8%, respectively. For the yoga sessions this rate was different between the two locations (63.2% versus 46.5%). No differences were found between the locations regarding the workout sessions and PVC visits. Workers attended on average 2.7 PVC visits. Overall, workers were satisfied with the intervention components: 7.5 for yoga sessions, 7.8 for workout sessions, and 6.9 for PVC visits. CONCLUSIONS: The implementation of the intervention was accomplished as planned with respect to the dose delivered. Based on the reach, most workers were willing to attend the guided group sessions and the PVC visits, although there were differences between the locations and between intervention components. Overall, workers were positive about the intervention. TRIAL REGISTRATION: Trial registration NTR1240.

The role of work ability in the relationship between aerobic capacity and sick leave: a mediation analysis.

OBJECTIVES: To examine: (1) the relationships between aerobic capacity, work ability and sick leave; (2) the potential mediating effect of work ability in the relationship between aerobic capacity and sick leave; and (3) the influence of age on these relationships. METHODS: Information on aerobic capacity (predicted VO(2max)), age, gender, type of work, cardiovascular risk and body mass index was collected from 580 workers at baseline. Work ability was assessed with the Work Ability Index at first follow-up (mean 3.4±1.3 years after baseline). The second follow-up period was defined as the time between completing the Work Ability Index and the first registered sick leave episode. Mediation analyses were performed using linear and Cox regression models. RESULTS: A lower aerobic capacity was found to be significantly related to sick leave (HR=0.98; τ=-0.018; 95% CI 0.970 to 0.994). There was a significant positive relationship between aerobic capacity and work ability (α=0.165; 95% CI 0.122 to 0.208). Also, lower work ability was significantly related to sick leave after controlling for aerobic capacity (HR=0.97; ß=-0.033; 95% CI 0.949 to 0.987). The mediating effect of work ability in the relationship between aerobic capacity and sick leave was -0.005 (SE=0.002), and mediated 27.8% (95% CI 10.4 to 45.2) of the total effect of aerobic capacity on sick leave. Age did not influence the relationship between aerobic capacity and sick leave. CONCLUSIONS: Fit workers had better work ability, and both fit workers and workers with higher work ability were at lower risk of starting an episode of sick leave.

Associations between VO2max and vitality in older workers: a cross-sectional study.

BACKGROUND: To prevent early exit from work, it is important to study which factors contribute to healthy ageing. One concept that is assumed to be closely related to, and therefore may influence healthy ageing, is vitality. Vitality consists of both a mental and a physical component, and is characterised by a perceived high energy level, decreased feelings of fatigue, and feeling fit. Since VO2max gives an indication of one's aerobic fitness, which can be improved by increased levels of physical activity, and because feeling fit is one of the main characteristics of vitality, it is hypothesised that VO2max is related to vitality. Therefore, the aim of this study was to investigate the associations between VO2max and vitality. METHODS: In 427 older workers (aged 45 + years) participating in the Vital@Work study, VO2max was estimated at baseline using the 2-km UKK walk test. Vitality was measured by both the UWES Vitality Scale and the RAND-36 Vitality Scale. Associations were analysed using linear regression analyses. RESULTS: The linear regression models, adjusted for age, showed a significant association between VO2max and vitality measured with the RAND-36 Vitality Scale (ß = 0.446; 95% CI: 0.220-0.673). There was no significant association between VO2max and vitality measured with the UWES (ß = -0.006; 95% CI:-0.017 - 0.006), after adjusting for age, gender and chronic disease status. CONCLUSIONS: VO2max was associated with a general measure of vitality (measured with the RAND-36 Vitality Scale), but not with occupational health related vitality (measured with the UWES Vitality Scale). The idea that physical exercise can be used as an effective tool for improving vitality was supported in this study. TRIAL REGISTRATION: NTR1240.

The Vital@Work Study. The systematic development of a lifestyle intervention to improve older workers' vitality and the design of a randomised controlled trial evaluating this intervention.

BACKGROUND: A major contributor of early exit from work is a decline in health with increasing age. As healthy lifestyle choices contribute to better health outcomes, an intervention aimed at an improved lifestyle is considered a potentially effective tool to keep older workers healthy and vital, and thereby to prolong labour participation. METHODS: Using the Intervention Mapping (IM) protocol, a lifestyle intervention was developed based on information obtained from 1) literature, 2) a short lifestyle questionnaire aimed at identifying the lifestyle behaviours among the target group, and 3) focusgroup (FG) interviews among 36 older workers (aged 45+ years) aimed at identifying: a) key determinants of lifestyle behaviour, b) a definition of vitality, and c) ideas about how vitality can be improved by lifestyle.The main lifestyle problems identified were: insufficient levels of physical activity and insufficient intake of fruit and vegetables. Using information from both literature and FG interviews, vitality consists of a mental and a physical component. The interviewees suggested to improve the mental component of vitality by means of relaxation exercises (e.g. yoga); physical vitality could be improved by aerobic endurance exercise and strength training.The lifestyle intervention (6 months) consists of three visits to a Personal Vitality Coach (PVC) combined with a Vitality Exercise Programme (VEP). The VEP consists of: 1) once a week a guided yoga group session aimed at relaxation exercises, 2) once a week a guided aerobic workout group session aimed at improving aerobic fitness and increasing muscle strength, and 3) older workers will be asked to perform once a week for at least 45 minutes vigorous physical activity without face-to-face instructions (e.g. fitness). Moreover, free fruit will be offered at the group sessions of the VEP. The lifestyle intervention will be evaluated in a RCT among older workers of two major academic hospitals in the Netherlands. At baseline, after 6 and 12 months, measurements (primary: lifestyle and vitality, and secondary: work-engagement and productivity) will take place. DISCUSSION: The lifestyle programme is developed specifically tailored to the needs of the older workers and which is aimed at improving their vitality. TRIAL REGISTRATION: NTR1240.