Perioperative collagen deposition in elderly and young men and women

Hypothesis: Women deposit more collagen after major abdominal surgery than men. Design: A post hoc analysis of data obtained from 2 prospective, randomized , double-blind clinical trials. Setting: University hospital general surgical service. Patients: One hundred sixteen patients undergoing colon resection. Main Outcome Measures: Protein and hydroxyproline (collagen) deposition dur ing the first 7 postoperative days in expanded polytetrafluoroethylene impl ants positioned subcutaneously. Results: On univariate analysis, men and women deposited comparable amounts of collagen (257 +/- 120 vs 281 +/- 117 ng/mm, respectively). When potenti al confounding factors were entered into a generalized mixed-effects model, only the interaction between age and sex was a significant factor (P = .04 7). Collagen deposition decreased with age in men, being 317 +/- 133 ng/mm in men younger than 45 years, but only 238 +/- 113 ng/mm in those older tha n 45 years (P = .03). In contrast, collagen deposition was virtually identi cal in women younger than 45 years (280 +/- 133 ng/mm) and in those older t han 45 years (281 +/- 110 ng/mm). Only 3 of these women were receiving horm one replacement therapy. Conclusions: Collagen deposition after surgery decreased significantly with age in men, while remaining unchanged in women. Younger men and women depo sited similar amounts of collagen. Therefore, older men made less collagen after surgery than older women, perhaps explaining the consistent observati on that wound dehiscence is twice as common in men than in women. Our resul ts differ from previous studies conducted in healthy, nonsurgical volunteer s, which showed that (1) young women made significantly more collagen than young men and (2) collagen deposition was reduced in postmenopausal women, but deposition returned to premenopausal values with hormone replacement th erapy. Differences between our results and those reported previously likely stem from the populations studied. In particular, multiple perioperative f actors decrease collagen deposition, which apparently obscures the differen ces observed previously in healthy, unstressed volunteers.