Strengths and limitations
The main strength of the study is the cluster randomized
waiting-list control design evaluating the intervention effectiveness.
This study fills the knowledge gaps on the effectiveness of
implementation support of a guideline for the prevention of mental
ill-health on health-related outcomes and social and organizational
risk factors at the workplace, as well as the association of the
guideline adherence with the above outcomes. The majority of the
studies evaluating organizational-level interventions, as recommended
in the implemented guideline, have been identified as having a high
risk of bias making it difficult to draw conclusions on the causality
of the interventions. Another strong feature of this study includes
the high response rate of 83% of personnel within the participating
schools. The participants are therefore likely to be a representative
sample of these schools. Finally, a strength of the study is that
implementation support was evaluated as recommended by Schelvis et al
(A limitation of the present study is the relatively short follow-up
period of 12-months, as organizational changes often require a long
time to take place. To be able to observe larger effects on risk
factors in the school’s work environment as a result of these
organizational changes, a timespan of more than 12 months is most
likely needed (