Many workers suffer from work‐related stress and are at increased risk of work‐related
cardiovascular, musculoskeletal, or mental disorders. In the European Union the prevalence
of work‐related stress was estimated at about 22%. There is consensus that stress,
absenteeism, and well‐being of employees can be influenced by leadership behaviour.
Existing reviews predominantly included cross‐sectional and non‐experimental studies,
which have limited informative value in deducing causal relationships between leadership
interventions and health outcomes. To assess the effect of four types of human resource
management (HRM) training for supervisors on employees' psychomental stress, absenteeism,
and well‐being. We included training aimed at improving supervisor‐employee interaction,
either off‐the‐job or on‐the‐job training, and training aimed at improving supervisors'
capability of designing the work environment, either off‐the‐job or on‐the‐job training.
In May 2019 we searched CENTRAL, MEDLINE, four other databases, and most relevant
trials registers (ICTRP, TroPHI, ClinicalTrials.gov). We did not impose any language
restrictions on the searches. We included randomised controlled trials (RCT), cluster‐randomised
controlled trials (cRCT), and controlled before‐after studies (CBA) with at least
two intervention and control sites, which examined the effects of supervisor training
on psychomental stress, absenteeism, and well‐being of employees within natural settings
of organisations by means of validated measures. At least two authors independently
screened abstracts and full texts, extracted data and assessed the risk of bias of
included studies. We analysed study data from intervention and control groups with
respect to different comparisons, outcomes, follow‐up time, study designs, and intervention
types. We pooled study results by use of standardised mean differences (SMD) with
95% confidence intervals when possible. We assessed the quality of evidence for each
outcome using the GRADE approach. We included 25 studies of which 4 are awaiting assessment.
The 21 studies that could be analysed were 1 RCT, 14 cRCTs and 6 CBAs with a total
of at least 3479 employees in intervention and control groups. We judged 12 studies
to have an unclear risk of bias and the remaining nine studies to have a high risk
of bias. Sixteen studies focused on improving supervisor‐employee interaction, whereas
five studies aimed at improving the design of working environments by means of supervisor
training. Training versus no intervention We found very low‐quality evidence that
supervisor training does not reduce employees' stress levels (6 studies) or absenteeism
(1 study) when compared to no intervention, regardless of intervention type or follow‐up.
We found inconsistent, very low‐quality evidence that supervisor training aimed at
employee interaction may (2 studies) or may not (7 studies) improve employees' well‐being
when compared to no intervention. Effects from two studies were not estimable due
to missing data. Training versus placebo We found moderate‐quality evidence (2 studies)
that supervisor training off the job aimed at employee interaction does not reduce
employees' stress levels more than a placebo training at mid‐term follow‐up. We found
low‐quality evidence in one study that supervisor training on the job aimed at employee
interaction does not reduce employees' absenteeism more than placebo training at long‐term
follow‐up. Effects from one study were not estimable due to insufficient data. Training
versus other training One study compared the effects of supervisor training off the
job aimed at employee interaction on employees' stress levels to training off the
job aimed at working conditions at long‐term follow‐up but due to insufficient data,
effects were not estimable. Based on a small and heterogeneous sample of controlled
intervention studies and in contrast to prevailing consensus that supervisor behaviour
influences employees' health and well‐being, we found inconsistent evidence that supervisor
training may or may not improve employees' well‐being when compared to no intervention.
For all other types of interventions and outcomes, there was no evidence of a considerable
effect. However, due to the very low‐ to moderate‐quality of the evidence base, clear
conclusions are currently unwarranted. Well‐designed studies are needed to clarify
effects of supervisor training on employees' stress, absenteeism, and well‐being.
Effects of training supervisors on employees' stress, absenteeism, and well‐being
Background Supervisors are assumed to play a crucial role in creating the working
conditions of their employees and thus promoting their health and well‐being. Training
programmes are widely used to improve supervisors' skills in improving health and
well‐being of their employees. Review question We examined the effects of four types
of training for supervisors on employees' stress, absenteeism, and mental well‐being.
We assessed the effects of training aiming to improve interaction between supervisors
and employees, either off‐the‐job or on‐the‐job.We also assessed training aimed at
improving supervisors' capabilities to design the work environment, either off‐the‐job
or on‐the‐job. Study characteristics We included 25 studies of which 4 studies are
awaiting assessment. The 21 studies that could be analysed included a total of 3479
employees. Sixteen studies trained supervisor‐employee interaction, either off‐the‐job
(9 studies) or on‐the job (7 studies). Five studies trained the design of working
environments, off‐the‐job in 2 studies and on‐the job in 3 studies. The 21 studies
compared 23 interventions with no training, sham training or other training at various
times of follow‐up. Key results There is no considerable effect of supervisor training
on employees' stress (6 studies) or absenteeism (1 study) when compared to no training.
There is inconsistent evidence that supervisor training may (2 studies) or may not
(7 studies) improve employees' well‐being when compared to no training. Data were
missing from two studies, so we could not calculate the effects of training on employee
well‐being. There is no effect of supervisor training on employees' stress (2 studies)
or absenteeism (1 study) when compared to a placebo training. Data were missing from
one study, so we could not calculate the effects of training on employee well‐being.
One study that evaluated supervisor training compared to another type of training
to reduce employees' stress did not provide enough data to calculate its effects.
Quality of the evidence The quality of the evidence was very low for most outcomes
due to risk of bias in the studies, inconsistent results, and imprecise effects. Researchers
should consider the shortcomings of studies included in this review in order to conduct
well‐designed studies in the future and report them appropriately. Conclusions Overall,
the data suggest that training of supervisors may not lead to reduced levels of stress
and absenteeism, or improved levels of well‐being in their employees. The discrepancy
between the apparent scientific consensus and the empirical evidence might be attributed
to weak study designs.High quality studies are needed to clarify if supervisor training
affects employees' stress, absenteeism, and well‐being.