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Purpose: Matrix Metalloproteinase (MMP) 9 is a gelatinase shown to be increased in wounds that demonstrate delayed healing. MMPs have an intricate role in extracellular matrix remodeling and are the rate-limiting step in degradation of collagen, elastin, fibronectin, and proteoglycan core proteins. MMPs are secreted as inactive zymogens, are zinc-dependent for catalytic activity, and are inhibited by tissue-derived inhibitors. MMP 9 is found to be increased in the obese. Previous reports of surgical weight loss patients revealed that MMP 9 concentrations decreased after weight loss, but not to baseline levels. The purpose of this prospective study is to investigate MMP 9 as a potential marker for wound complications after panniculectomy in patients that had undergone bariatric surgery.
Methods: IRB approval was obtained and all patients provided informed consent prior to participation in the study protocol. 16 sequential patients undergoing panniculectomy following surgical weight loss were enrolled. Panniculectomy design patterns were left to the discrimination of the operating surgeon. All patients had subcutaneous drains placed at the time of surgery. Wound fluid was collected from each drain on postoperative day 2 and 4 on each patient. The fluid was then centrifuged to remove cellular debris and the supernatant was homogenized and split. Sandwich enzyme-linked immunosorbent assays were performed for albumin (AssayMax Human Albumin ELISA Kit, Assaypro) and MMP 9 (Quantikine Human MMP-9 Immunoassay, R&D Systems). MMP 9 concentration was then normalized to the fluid albumin concentration. All statistical analyses were completed using Prism 5 (La Jolla, California) and IBM SPSS 19 (Chicago, Illinois).
Results: Of the 15 patients, 7 (47%) had complications with 5 (33%) patients having multiple complications. The complications included hematoma (3), seroma (4), wound infection (1), wound dehiscence (3), and deep venous thrombosis (1). MMP 9 to albumin ratios were not statistically different among patients with subsequent complications on postoperative day 2 and those without complications (p = .67). (Figure 1) MMP 9 to albumin ratios were statistically different on postoperative day 4 in those that had complications to those that did not (p = .032). Using an independent, non-parametric, correlation the MMP 9 ratio to albumin on postoperative day 4 was statistically significant (Spearman’s Rho correlation coefficient .557, p = .031).
Conclusions: Wound fluid MMP 9 to albumin ratio correlates with operative complications following panniculectomy following surgical weight loss. Failure of MMP 9 to albumin ratios to decrease below 3 x 10-5 predicts wound complications following panniculectomy with a sensitivity of 71% and a specificity of 88% in this small pilot study. Further work needs to be done to see if this ratio
can be used clinically to guide early therapy for complications following panniculectomy.