The review question was clearly stated. Inclusion criteria for study design, intervention and participants were evident from a combination of information in the text and the abstract of the review. Criteria for outcomes were not stated. Limiting the search to English-language publications identified in one database plus references raised the potential for publication and language bias, and may have resulted in the omission of other relevant studies. Methods were used to minimise reviewer errors and bias in the selection of studies and extraction of data.
Only RCTs were included in the review, but study validity was not assessed, so results from these trials, and any synthesis, may not be reliable. No details were reported of the medical conditions underlying the constipation or incontinence of patients, so the generalisability of findings could not be judged. Data were pooled using meta-analysis. The diversity of control groups, lack of assessment of statistical heterogeneity, and lack of information about measures used to assess outcomes in individual studies, meant it was unclear whether studies were sufficiently statistically and clinically homogeneous for meta-analysis to be appropriate. In addition, it was not clear what outcome the reported odds ratios referred to.
The authors’ conclusions refer to the positive effects of biofeedback therapy on pelvic floor dyssynergia, but findings for this patient group were not reported in the review and cannot be verified. In addition, lack of assessment of study quality, the limited search, limited information about patients and outcome measures, and diversity among trials, mean that the conclusions may not be reliable.