Statistical design and analysis in trials of proportionate interventions: a systematic review

Background: In proportionate or adaptive interventions, the dose or intensity can be adjusted based on individual need at predefined decision stages during the delivery of the intervention. The development of such interventions may require an evaluation of the effectiveness of the individual stages in addition to the whole intervention. However, evaluating individual stages of an intervention has various challenges, particularly the statistical design and analysis. This review aimed to identify the use of trials of proportionate interventions and how they are being designed and analysed in current practice. Methods: We searched MEDLINE, Web of Science and PsycINFO for articles published between 2010 and 2015 inclusive. We considered trials of proportionate interventions in all fields of research. For each trial, its aims, design and analysis were extracted. The data synthesis was conducted using summary statistics and a narrative format. Results: Our review identified 44 proportionate intervention trials, comprising 28 trial results, 13 protocols and three secondary analyses. These were mostly described as stepped care (n=37) and mainly focussed on mental health research (n=30). The other studies were aimed at finding an optimal adaptive treatment strategy (n=7) in a variety of therapeutic areas. Further terminology used included adaptive intervention, staged intervention, sequentially multiple assignment trial or a two-phase design. The median number of decision stages in the interventions was two and only one study explicitly evaluated the effect of the individual stages. Conclusions: Trials of proportionate staged interventions are being used predominantly within the mental health field. However, few studies consider the different stages of the interventions, either at the design or the analysis phase, and how they may interact with one another. There is a need for further guidance on the design, analyses and reporting across trials of proportionate interventions

Development of the Childbirth Perception Scale (CPS) : perception of delivery and the first postpartum week

Some caregivers suggest a more positive experience of childbirth when giving birth at home. Since properly developed instruments that assess women’s perception of delivery and the early postpartum are missing, the aim of the current study is to develop a Childbirth Perception Scale (CPS). Three focus groups with caregivers, pregnant women, and women who recently gave birth were conducted. Psychometric properties of 23 candidate items derived from the interviews were tested with explorative factor analysis (EFA) (N = 495). Confirmatory factor analysis (CFA) was performed in another sample of women (N = 483) and confirmed a 12-item CPS. The EFA in sample I suggested a two-component solution: a subscale ‘perception of delivery’ (six items) and a subscale ‘perception of the first postpartum week’ (six items). The CFA in sample II confirmed an adequate model fit and a good internal consistency (α = .82). Multivariate linear regression showed a positive effect of home delivery on perception of delivery in multiparous but not in primiparous women. The 12-item CPS with two dimensions (perception of delivery and perception of first postpartum week) has adequate psychometric properties. In multiparous women, home delivery showed to be independently related to more positive perception of delivery