Stefan Elbers

86 Chapter 4 during treatment, because a recent systematic review had been conducted on this topic (Eccleston et al., 2014). Only studies that were published in Dutch or English languages were included. We used the online application software ‘Rayyan’ to screen the abstracts (Ouzzani et al., 2016). Study Selection, Data Collection and Risk of Bias Two researchers independently (HW and SE) performed the study selection, data collection and assessment of risk of bias in five stages. For each stage (abstract screening; full text inclusion; BCT data extraction; patient, intervention, comparison, outcome and study design data extraction; risk of bias assessment), we held pilot test sessions where we calibrated our procedures. At regular intervals within each stage, meetings were held to compare results and to reach consensus. If differences in scoring remained, a third researcher (JP) made the final decision. In the first stage, all abstracts were screened on eligibility criteria with respect to study design and patients. In the second stage, full text articles were read and checked on all eligibility criteria. Data collection started in the third stage and involved (1) copying all information regarding the intervention that was provided in the study or in the protocol; (2) extracting all individual intervention components from this information; and (3) classifying these components according to the BCT taxonomy v1 (Michie et al., 2013). In the fourth stage, we extracted all relevant data with respect to our analysis, including patient characteristics, means and standard deviations for all outcome measures of interest. For each study, we selected the measures that best fitted our definition for the primary outcomes. In accordance with the Cochrane Handbook, we considered studies as our primary source of interest (Higgins and Green, 2011). As a consequence, we also extracted data from study protocols and articles with follow-up data, when they were available. In the fifth stage, we determined risk of bias using the Cochrane's Collaboration's tool for assessing risk of bias. The following types of bias were assessed: random sequence generation (selection bias); allocation concealment (selection bias); blinding of outcome assessment (detection bias); incomplete outcome data (attrition bias), selective reporting (reporting bias) and other sources of bias. Blinding of participants and personnel was not included in the bias assessment, as the characteristics of self-management interventions do not allow for appropriate blinding. Due to the nature of the studies, we scored the default blinding of outcome assessment as high risk of bias, but upgraded to unclear or low if attempts to blind the outcome assessment for patients or assessors were described (e.g. blinding of patients to former assessment). All other types of bias were assessed according to the guidelines in the Cochrane Handbook (Higgins and Green, 2011). The risk of bias was used as input for the assessment of the quality of evidence for each outcome measure. Studies were considered high risk of bias when three or more items were scored unclear or high, or when two items were scored high.