Hofmann, S.G., Sawyer, A.T., Witt, A.A., & Oh, D. (2010). The effect of mindfulness-based therapy on anxiety and depression: A meta-analytic review. Journal of Consulting and Clinical Psychology, 78, 169–183.

To provide a quantitative, meta-analytic review of the efficacy of mindfulness-based therapy (MBT) for improving anxiety and mood symptoms in clinical populations

• Databases: PubMed, PsycINFO, the Cochrane Library.
• Keywords: mindfulness plus meditation, program, therapy or intervention, anxiety, mood, depression or stress.
• Inclusion criteria: Studies that included a mindfulness-based intervention, a clinical sample, and adults 18–65 years. The mindfulness program was not coupled with treatment using acceptance and commitment therapy or dialectical behavior therapy. Researchers included a measure of anxiety and/or mood symptoms pre- and postintervention, and they provide sufficient data to perform effect-size analyses.
• Exclusion criteria: Studies in which the interventions differed substantially from mindfulness-based stress reduction (MBSR) or mindfulness-based cognitive therapy (MBCT) in length; studies in which the MBT was not delivered in person.

• Method of included-study evaluation: Two authors extracted data and analyzed changes pre- to posttreatment, pretreatment to follow-up, and intent to treat. Evaluation included a modified Jadad assessment of methodological quality. Two independent raters performed the assessment. Inter-rater reliability was r = 0.96.
• The total number of studies reviewed initially was 727.
• The study detailed publication bias and effect size.

• The report evaluated 39 studies. Sixteen of the studies included a control or comparison group.
• Total sample size: 1,140; individual study samples: 8–103. The most common clinical disorder was cancer (n = 9), followed by generalized anxiety disorder (n = 5), depression (n = 4), and 16 other clinical disorders. Many studies targeted more than one disorder.
• The report did not cite sample characteristics.

MBT was moderately effective for improving anxiety (Hedges’s g = 0.63) and mood symptoms (Hedges’s g = 0.59) from pre- to post-treatment in the overall sample. Eight studies met criteria for elevated levels of depression symptoms at pretreatment; none of these involved patients with cancer.

The effects of MBT on depression and anxiety related to chronic conditions, such as cancer, might be smaller than expected, because patients may experience physical symptoms listed on depression or anxiety scales as a result of their physical condition or as a side effect of medical treatment.

• The study does not present information about type, stage, and treatment of cancer. The study does not describe sample characteristics other than adult age.
• Researchers do not describe the specifics of the mindfulness interventions. 
• Researchers used many tools to measure anxiety and depression. Understanding if these tools measured the same things is difficult.
• Clinical populations varied. Many populations had only one study to represent them. Therefore, generalizability is limited.

MBT is a promising intervention in the treatment of anxiety and mood problems in patients with medical diagnoses, including cancer.