Another disappointing SR that fails to tell us anything new 😖

Systematic reviews are an academic exercise to ‘systematically review’ the existing literature on a particular research question. They are frequently performed by higher degree research students and their academic advisors to ensure their research project is novel and based on existing evidence. The value of them for the rest of us is that they follow rigorous guidelines to ensure all papers specific to the research question are included, and that none are left out due to bias of the reviewers. Discipline specific tools are used to appraise the methodology, data analysis, and interpretation for validity, and if possible combine the results into a meta-analysis.

There are two main problems here. One is to do with the nature of systematic reviews, and issues in trial design inherent in research on lymphoedema which I have posted on before if you want to read more.

In contrast, the Thompson review published in 2020 [2] is a much superior review, including 17 papers and offering a deeper and more nuanced interpretation of results. The authors extracted data on results by stage and age, so as well as the usual inconclusive overall results they were able to highlight evidence for MLD in volume reduction when applied early and in mild lymphoedema. Read more.

This report on the evidence for MLD in a systematic review is important, and fits well with our understanding of lymphatic function, progression of connective tissue pathology and the way we use MLD in lymphoedema management. I’m not at all surprised that MLD has the best effect in volume reduction when applied in the early fluid rich stages of oedema and we should feel confident in continuing to use it. As lymphoedema progresses MLD techniques in the affected area are also adapted, becoming firmer and applying greater shearing forces to address fibrosis. Studies and reviews which report primarily on volume reduction will miss measures on the benefits of these manual techniques, and Thompson et al noted this stating that (my precis) - "we need studies to provide a detailed description of the method of MLD, in terms of speed, pressure and drainage direction, and that we need to validate newer technologies for assessment, and conduct research on other forms of lymphedema, and not focus solely on BCRL."

Another recent review included research on health related qualify of life for people who received MLD in their lymphoedema treatment, also with inconclusive results [3]. But as the first ever SR to even ask something different, I applaud the authors and hope that other HDR students will be inspired to ask more interesting and patient-centred questions for their reviews.

In the meantime, in order to finally answer the question which every SR has failed to deliver on so far, we will need more original research on MLD as it is applied by lymphoedema stage. And we we will need to measure more than volume and include clinically useful measures of pathology such as tissue compressibility, and with a greater focus on patient-centred aspects such as the ability to function in daily life, qualify of life, and psycho-social aspects of lymphoedema care.