Clinical Trial Details
— Status: Recruiting
Administrative data
| NCT number |
NCT04693182 |
| Other study ID # |
303671 |
| Secondary ID |
|
| Status |
Recruiting |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
January 1, 2021 |
| Est. completion date |
May 31, 2022 |
Study information
| Verified date |
February 2022 |
| Source |
Norwegian Institute of Public Health |
| Contact |
Anette Harris, PhD |
| Phone |
+47 55 58 32 19 |
| Email |
anette.harris[@]uib.no |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
Introduction In shift work, quick returns refer to transitions between two shifts with less
than 11 hours available rest time. Twenty-three per cent of employees in European countries
reported having quick returns. Quick returns are related to short sleep duration, fatigue,
sleepiness, work-related accidents, and sickness absence. The present study is the first
randomized controlled trial (RCT) to investigate the effect of a work schedule without quick
returns for six months, compared to a work schedule that maintains quick returns during the
same time frame.
Methods and analysis A parallel-group cluster RCT in a target sample of more than 4000
healthcare workers at Haukeland University Hospital in Norway will be conducted. More than 70
hospital units will be assessed for eligibility and randomized to a work schedule without
quick returns for six months or continue with a schedule that maintains quick returns. The
primary outcome is objective records of sickness absence; secondary outcomes are
questionnaire data (n ≈ 4000 invited) on sleep and functioning, physical and psychological
health, work-related accidents, and turnover intention. For a subsample, sleep diaries and
objective sleep registrations with radar technology (n ≈ 50) will be collected.
Ethics and dissemination The study protocol was approved by the Regional Committee for
Medical and Health Research Ethics in Western Norway (2020/200386). Findings from the trial
will be disseminated in peer-reviewed journals and presented at national and international
conferences. Exploratory analyses of potential mediators and moderators will be reported.
User-friendly outputs will be disseminated to relevant stakeholders, unions and other
relevant societal groups.
Description:
Aims This is a two-arm cluster randomized controlled trial that assesses the consequences of
a shift work schedule without quick returns for six months, compared to a schedule that
include quick returns. First, we will examine any differential change in sickness absence,
during the six-month intervention period. Second, we will examine if there are differential
changes in sleep and functioning, physical and mental health, work-related accidents, and
turnover intention, among others. Third, we will investigate if individual characteristics
associated with shift work tolerance including sex, age, personality and subjectively
reported sleep need will moderate the negative effects of quick returns on the primary and
secondary outcomes. Finally, the study will investigate if individual factors like
satisfaction with work schedule, job satisfaction, job engagement and work-family
interference will moderate the negative effects of quick returns on the primary and secondary
outcomes.
Research design A cluster randomized controlled trial comparing a work schedule abolishing
quick returns (intervention) with that of a work schedule maintaining a normal amount of
quick returns (control) will be conducted. The clusters represent hospital units that are
randomly selected to receive (or not receive) the intervention. 'Normal amount of quick
returns' refer to that which is the common practice at the respective hospital unit in recent
years (i.e., when no explicit changes have been made to the work schedule), which means that
the total number of quick returns at the unit will vary from 329-2356 per year. The hospital
units were randomized to one of the two conditions in September 2020, of which the autumn of
2020 was spent planning the shift schedule for 2021 (i.e., removing quick returns for the
intervention group and leaving quick returns untouched for the control group), with the
intervention period commencing from February/March 2021 for most units. The intervention
period in this study is six calendar months. Most units in this trial start the intervention
period in February/March 2021, but some units will, for practical reasons, start the
intervention period in the second half of the rotation year, i.e. from August/September 2021
or later.
The primary outcome is sickness absence retrieved from the local records kept by the hospital
(including short- and long-term sick leave). The baseline measurements will be sickness
absence from the year preceding the intervention, which for each individual participant will
be matched on duration and season to that of the intervention period. Sickness absence data
will be retrieved from the local records kept by the hospital (Vedaa, Pallesen et al. 2017).
This record includes information about the date of any absence of the individual employee,
implying that it includes information about both short- and long-term sickness absence.
Further, these data include information on whether the absence is self-certified or whether
it is certified by a physician, whether the absence is due to a sick child of whom the
employee has caretaker responsibility of, and whether the absence is due to COVID-19 related
issues (e.g., quarantine). The use of register data will not require individual consent.
However, a consent-based part of the trial will also be conducted, in which secondary outcome
measures will be collected via questionnaire at baseline and six-month follow-up. All
employees (n ≈ 4000) at the randomized units will be asked to complete a digital
questionnaire made available via the hospital's internal website. Baseline assessment will
occur prior to the intervention period, and follow-up assessment will occur towards the end
of the intervention period. A subsample (n ≈ 50) will be asked to objectively record their
sleep with advanced radar technomogy (Somnofy™) and subjectively with sleep diaries for ≥1
week at the baseline and follow-up assessments, respectively.
Participants and procedure Recruitment This trial is carried out in close collaboration with
the human resources department at Haukeland University Hospital. All hospital care units that
have 24-hour staffing at the hospital will be randomized, in which all healthcare workers
working shifts will be included, with the exception of physicians. Physicians will not be
included since they often have a different shift schedule and compensation scheme compared to
the other occupational groups. Hereinafter, 'all employees' refer to all healthcare workers
engaged in shift work at the randomised hospital units, with the exception of physicians. All
employees (n ≈ 4000) at the randomized hospital units will be asked to complete a
questionnaire prior to and at the end of the intervention period. Recruitment for this part
of the trial will take place via the hospital's internal website. Researchers and human
resources personnel at the hospital will attend staff meetings at all included units to
inform about the research project and encourage participation. A subsample of n ≈ 50 randomly
selected employees (evenly distributed from the intervention and the control units) will be
recruited for the sleep monitoring section of the trial.
Randomisation and masking The randomization in this trial occurred at the cluster level, in
which hospital units constituted the clusters. Hospital units can vary in terms of how much
staff they need over the 24-hour day, hence, the work schedule and the occurrence of, for
example, quick returns and night shifts can vary across the units. Similar units were
therefore grouped together based on the fact that they shared some attributes or
characteristics. Then a stratified randomization was performed to the two study conditions in
a 1: 1 ratio. One subgroup could, for example, consist of units with emergency functions,
another with intensive care functions, one with mental health care, and one with maternity
care, etc. In total we had 10 strata and the sizes of each stratum varied between 2 and 19
hospital units. The randomization list for each stratum was generated by the online
randomization webpage, www.randomization.com, and the list for each stratum was saved.
It is not possible for participants to be blinded to the group to which they are assigned.
However, statistical analyses will be done by a researcher who is masked to group allocation.
Sample size In this trial, all available hospital units at Haukeland University Hospital with
healthcare workers who work rotating shifts will be assessed for eligibility. This includes
76 units and 4260 healthcare workers. Based on previous published data5 we have calculated
that a total of 2028 participants is sufficient to reveal a difference in days of sick leave
of 0.9 and 1.25 with an ICC of 0.1 and an average size of the units of 52 (calculation made
in: StataCorp. 2015).33 Thus, with the planned recruitment strategy (i.e., invite >70 units
and >4000 healthcare workers) we expect to exceed this number and be well within the number
of participants required for the primary outcome variable.
Data analysis plan All analyses will be conducted based on the intention-to-treat population,
unless otherwise stated. To examine the effects of a shift schedule abated of quick returns
on primary and secondary outcomes, the observed rates or scores will be analysed by means of
latent growth models (or other equivalent models such as generalized linear mixed models).
The observed rates or scores before and during the intervention period will be modelled by a
random intercept and a fixed slope. The effect of the intervention will be estimated by using
the group variable (intervention vs. control) as a predictor of the slope. Between-group
effect sizes (Cohen's d) will be calculated by dividing the mean difference in estimated
change in scores from baseline to the follow-up assessment by the pooled SD at baseline.
Robust maximum likelihood will be used as the estimator, providing unbiased estimates under
the assumption of data being missing at random,(Enders 2010) which might be partly met
through the inclusion of baseline scores to the model. The primary outcome measure in this
trial is sickness absence data retrieved from the register at the hospital, in which we
expect no missing data. However, it is reasonable to expect some missing data on the
secondary outcome measures, as data are collected through questionnaire or via the sleep
radar.
As some data for the follow-up questionnaire and sleep radar assessment will be missing not
at random, the robustness of the results under the missing-at-random assumption will be
tested by sensitivity analyses in which the missing scores at follow-up will be replaced by
baseline values for each respective individual. These sensitivity analyses will only be
performed on selected variables depending on the focus in the respective article.
The intention-to-treat analyses may be accompanied by selected per-protocol analyses in which
we, based on payroll data, define a group that has completely abolished or had a satisfactory
reduction in the number of quick returns over the intervention period.
The primary outcome of sick leave will mainly be analysed in terms of the total number of
sickness absence days and periods (spells) for a given period before compared to during the
intervention period (Vedaa, Pallesen et al. 2017). The models of sickness absence will take
into account the zero inflation in this type of data. Other operationalisations of sickness
absence might also be considered in accordance with recommendations in the literature
(Hensing, Alexanderson et al. 1998). For a further investigation of the sickness absence
data, we will consider the use of other models where we treat time differently. For example,
we will consider models where we look at the time to the first sick leave episode for the two
intervention groups, with a time-dependent covariate for the number of quick returns (ie, a
variable that increases by 1 each time the person has a quick return). Another possibility is
to say that participants start at "0" every time the person has a quick return, and to
measure time from the last quick return to the first subsequent sick leave episode, while
adjusting for repeated observations with e.g. robust variance estimate (the non-quick return
group will then only be followed from the start of the intervention, given that they in fact
have no quick returns). Another option is to set up a model for time from sick leave to
return to work.
Since the introduction of a work schedule without quick returns may entail an alternative
schedule with an increase in other undesirable characteristics (e.g., more consecutive
evening shifts), we will consider conducting analyses that adjust for such characteristics.
Mediator and moderator analyses will be performed for exploratory purposes, based on the
basic principle for such analyses in randomised controlled trials as described by others
((e.g., Kraemer, Wilson et al. 2002)). For example, some of the data collected on
demographics, sleep-related personality traits (rCTI and MEQ), mental health, among others,
can be used to examine factors that may moderate the impact of the intervention.
References
Enders, C. K. (2010). Applied missing data analysis. New York, NY, US, Guilford Press.
Hensing, G., et al. (1998). "How to measure sickness absence? Literature review and
suggestion of five basic measures." Scandinavian journal of public health 26: 133-144.
Kraemer, H. C., et al. (2002). "Mediators and moderators of treatment effects in randomized
clinical trials." Archives of General Psychiatry 59: 877-883.
Vedaa, Ø., et al. (2017). "Short rest between shift intervals increases the risk of sick
leave: a prospective registry study." Occupational and Environmental Medicine 74: 496-501.
