Joris van Dongen

250 Chapter 11 METHODS Protocol, information sources and search This study was performed in accordance with the PRISMA statement. 29 The study was not registered. MEDLINE, Embase, Cochrane Central, Web of Science and Google Scholar databases were searched (08-12-2017). An update search was performed on 05-10-2018. The search was restricted to humans. Keywords used for the search on the effect of lipografting on human facial skin quality can be found in table 1, supplemental content. Eligibility criteria Studies were included if lipografting or a component of adipose tissue i.e. tSVF, cSVF or ASCs was used to improve human facial skin quality. Changes in skin quality were defined as clinical changes in skin texture, color and elasticity or any histological changes in skin epidermis or dermis (Table 1). Studies were included if adipose tissue was obtained by liposuction. Studies including patients with diseases and trauma that could affect skin quality or subcutaneous adipose tissue e.g. burn wounds, scars and disease-caused lipoatrophy were excluded. Studies only evaluating wrinkles or volumetric effect of lipografting or any components of adipose tissue without analyzing the skin elasticity were excluded as well. A decreased wrinkle depth after lipografting can be caused by either a volumetric effect of lipografting or increased skin elasticity. Improved skin elasticity is considered to be a positive effect on skin quality, while a volumetric effect of lipografting does not influence the skin quality. Furthermore, studies evaluating the effect of lipografting on infraorbital dark circles were excluded, because the therapeutic effect is based on reducing transparency of the orbicularis oculi muscle through the lower eyelid skin by increasing subcutaneous volume. 30,31 Additionally, studies analyzing the outcome of facial lipografting or any substance of adipose tissue in conjunctionwith other surgical procedures e.g. botulinum toxin injection or fillers were excluded. Case reports, conference abstracts and reviews were excluded as well i.e. only peer-reviewed original research papers were included (Table 1). The literature search was not restricted by date or publication status (Table 1, supplemental content). Study selection Two authors (JvD and ML) independently selected prospective and retrospective clinical studies that met the eligibility criteria (Fig. 1). Reference lists of the included studies were hand-searched for relevant studies that were not initially included using the aforementioned inclusion criteria. Inconsistences were discussed during a consensus meeting. In case of disagreement, the senior author (BvdL) gave a binding verdict.