Twelve trials (n=5,458 patients) were included in the review, including 10 RCTs and two controlled trials. Trial sample sizes ranged from 61 to 1,374 patients. Follow-up ranged between six weeks to 12 months.
Short term effects (nine trials; 10 comparisons; n=4,009 patients): Feedback provision led to significant beneficial effects on short term outcomes (overall effect d=0.10, 95% CI 0.01 to 0.19). Moderate heterogeneity across the trials was observed (I2=31%, p=0.16).
Long term effects (five trials; n=573 patients) There were no differences observed between feedback provision and control groups. Heterogeneity between the trials for this outcome was low (I2=0%, p=0.69).
Treatment duration (five trials; 981 patients): In the analysis of data on treatment length as an indicator of costs, there were no differences found between the feedback and control groups. Heterogeneity was moderate across the trials (I2=42.03%, p=0.12).
There were no statistically significant differences between groups observed for any of the subgroup analyses.
There was no evidence of publication bias (p=0.76).