A Meta-analysis of the Efficacy of Phototherapy in Tissue Repair

Objective: The effect of phototherapy on tissue repair was determined by aggregating the literature and using statistical meta-analysis to analyze pertinent studies published between 2000 and 2007. Background Data: Phototherapy has been used for more than 40 y; however, its efficacy on tissue repair remains contentious. Method: Related original studies were gathered from every available source. The papers were then screened and coded; those meeting pre-established inclusion criterion were subjected to meta-analysis, using Cohen's d statistic to determine treatment effect size. Results: Seventy effect sizes were computed from the 23 papers that met the inclusion criteria. The overall mean effect obtained was highly significant, d = +1.94 (95% confidence interval 0.58-2.50). Further analyses revealed a similarly positive effect of phototherapy on tissue repair in experimental animal studies, d = +2.60, and a small to moderately positive effect in human cases of tissue repair, d = +0.34. The fail-safe number associated with the overall effect was 869; i.e., the number of additional studies in which phototherapy has negative or no effect on wound healing needed to negate the overall large effect size of +1.94. The corresponding fail-safe numbers for experimental animal and human tissue repair studies were 612 and 64, respectively. Conclusion: These findings indicate that phototherapy is a highly effective form of treatment for tissue repair, with stronger supporting evidence resulting from experimental animal studies than human studies.