Authors’ conclusions
Mindfulness-based therapy was moderately to largely effective for a variety of psychological problems, especially for reducing anxiety, depression and stress.
CRD commentary
The review question and inclusion criteria were clearly defined. Only two databases were searched, but there were no language restrictions and it appears that unpublished data were included, reducing the potential for publication bias. The formal assessment of publication bias found no evidence of it. Study quality was assessed and scores were reported for each study. It appears that quality was generally low for controlled studies; it was better for before-and-after studies, but this design is open to several sources of bias. Many studies were uncontrolled, which prevents definitive conclusions.
Appropriate methods to reduce reviewer error and bias were used for selecting studies and assessing quality, but it was unclear whether they were used for data extraction. The methods of analysis seem to have been appropriate and various moderator analyses were conducted. Statistical variation was high for a number of analyses. The authors acknowledged the wide variation between the studies in their design, interventions, participants, outcomes and quality. Attrition rates were high in some studies.