Can summarising trials of public health strategies by camparator design improve interpretation?

Article type
Authors
Baker P, Thomas R, Lorenzetti D
Abstract
Background: Head-to-head comparisons of two active strategies, intervention vs. control / usual care and incremental interventions (the strategy as an add-on to another strategy) are often encountered by reviewers. The assessment against a control/usual practice is the classical approach to assess whether the strategy is effective. Head-to-head studies are helpful to decision makers in assessing whether one intervention is better, or equivalent. The finding of equivalence in a head-to-head study relies on the assumption of the effect of the comparator and therefore it may be more difficult to identify effectiveness. Like comparisons against control/usual care, incremental comparisons can also identify effectiveness. However, like head-to-head studies, incremental studies are difficult to interpret as it is unknown whether the base intervention is required to obtain an effect, or whether on its own the intervention of interest is equivalent.

Objects: To assess the value of reporting and interpreting the individual studies by comparator design in a Public Health review.

Methods: Studies included in the Systematic Review of Family-based Interventions to Prevent Smoking by Children and Adolescents were summarised by comparator design.

Results: Seventeen studies were identified for inclusion. There was variation both in the intervention strategies and the comparison methods. Nine studies contained analysis of a comparator of usual care/control, five with comparisons against another active strategy for smoking prevention (e.g. School-based interventions) and five with comparison of family interventions in addition to another strategy (e.g. school based). The findings varied both within and between the studies. Of the 17 studies, 4 studies included two comparison methods, and 1 study included all three methods.

Conclusions: It was difficult to draw firm conclusions as to the efficacy of family interventions to prevent children/adolescent smoking by either collective assessment or assessment by comparator design. There is face-validity in reporting by study design as findings might be masked by the noise of including unequal design as it is likely to be useful when further trials of better quality are available.
(Views expressed are those of the authors)