Further Studies are Still Needed to Test Whether Fat Grafting Reduce Postmastectomy Pain

To test the effects of autologous fat grafting for reducing postmastectomy pain is important since post-operative pain bothers many patients with postmastectomy pain syndrome (PMPS), and one session autologous fat grafting for this condition is also investigated in some studies. Most of them show the positive effect on pain control, but the most recent randomized controlled trial (RCT) does not. The relatively small sample size with incomplete follow-up in the RCT might limit the certainty of evidence, and cases for the final analysis is lesser than expected numbers by sample size determination. Besides, there is no futility analysis to show the non-significant finding could be conclusive evidence. To check the conclusiveness of comparative evidence on this topic becomes a critical task for guiding clinicians and further studies in the future, therefore the purpose of this letter is to test whether evidence on fat grafting for alleviating pain amongst patients with PMPS is conclusive using sequential analysis.

This supplementary analysis used the data from the comparative evidence on fat grafting for PMPS based on the most recent RCT and previous systematic reviews. Complete data of pain score of two comparative studies from Italy were presented in a pooled report, therefore, this letter used data of pooled report for the Italy studies. Pooled mean difference (MD) in pain score between fat grafting and control groups was based on random-effects model. Quantitative synthesis consisted of cumulative meta-analysis and leave-one out sensitivity analysis due to heterogeneity from clinical setting across the included studies. Then, sequential analysis was further done with a conservative effect size (standardized mean difference = 0.2), type I error (α = 0.05), and power of 0.80 based on O'Brien Flemming method. All analyses were carried out using R version 4.1 via RStudio for Microsoft Windows.

Sequential analysis exhibited a non-significant and inconclusive evidence on fat grafting for pain control in PMPS if this synthesis included the newest RCT. Although the pooled result with unmet expectation of z-score in sequential analysis, it might not fall in futility. If the newest RCT was removed from the synthesis, sequential analysis showed significant but inconclusive evidence on fat grafting for pain control in PMPS.

There is no conclusive evidence to support or refuse the use of fat grafting in postmastectomy pain control. This topic is worthy of further studies in investigating the effects of fat grafting on pain control amongst patients with PMPS.

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