study sample was very small and the types of outcomes
– i.e. typing speed and errors – were not relevant to all
seated workers. It is an assumption that ergonomic intervention
correlates with productivity [9,27]. However, this
review found no supporting evidence for positive gains in
productivity and this factor should be incorporated as an
outcome in future research. No studies reported on cost
aspects of the intervention.
Although all five studies conducted follow-up assessments
of the symptoms, the longest follow-up period
was only a year [4]. This indicates a gap in showing
whether the effectiveness of a chair intervention has
long-term benefits, particularly with respect to musculoskeletal
symptoms, as well as the recurrence of symptoms
and the consequent cost of care. Chronicity in
work-related musculoskeletal pain is multifactorial, with
risk profiles relating to psychosocial factors dominating
the literature [28]. We believe future studies, addressing
long-term effects, need to be designed to take these factors
into account.
The effect of bias on the interpretation and trustworthiness
of the evidence cautions against making conclusive
recommendations pertaining to the effect of a
chair intervention. The key methodological shortcomings
which introduced bias were absent/unclear randomization
procedures and concealed allocation. These may introduce
selection bias which can result in a higher association
(odds ratio) between the exposure and the subject. Because
of the occurrence of selection bias, it is also not possible
to relate the results to the general population. A
further methodological issue arose in that two papers used
the same overall population to report two different subgroups
(based on two regions of pain). We therefore treated
these sub-groups as two studies, assuming pain regions
were independent events. Across the board the authors of
the reviewed articles failed to mention whether confounding
factors, such as female gender, were controlled for
as the allocation procedures were not mentioned. Future
research should address these methodological shortcomings
to improve the validity of the findings and thereby
increase the quality of the evidence to support a chair
intervention.
Recommendations
Clinical implications - clinicians can cautiously support
or advocate for the provision of adjustable chairs in the
workplace and offer appropriate training in how to adjust
and manage posture whilst seated. Monitoring of pain reduction/
increased comfort ratings will confirm effectiveness
in individual cases.
Research implications – further urgent research is required
to clarify the relationship between environmental
features (such as chairs), poor posture and symptoms as
currently these relationships are inferred. Furthermore