Influencing factors and their predictive value of skin graft survival after Meek grafting in severe burn patients

Objective To investigate the influencing factors and their predictive value of skin graft survival after Meek grafting in severe burn patients. Methods A retrospective case-control study was conducted in 115 severe burn patients (95 males, 20 females, aged 1-74 years) who met the inclusion criteria and received Meek grafting in the First Affiliated Hospital of Army Medical University (the Third Military Medical University) from January 2013 to December 2019. The patients were divided into good skin graft survival group with skin graft survival rate≥70% (68 cases) and poor skin graft survival group with skin graft survival rate<70% (47 cases). The statistics of patients in the two groups were recorded during their first Meek grafting after admission including the gender, age, body mass index, full-thickness burn area, burn index, complication of inhalation injury, time from injury to operation, preoperative cystatin C level, preoperative albumin level, preoperative neutrophil, preoperative hemoglobin level, preoperative platelet count, and platelet count on the first, third, and fifth day after operation. The above indicators were statistically analyzed between the two groups with independent sample

test, Mann-Whitney

test, and chi-square test. A 1∶1 propensity score matching (PSM) of the gender, age, body mass index, full-thickness burn area, burn index, complication of inhalation injury, time from injury to operation of patients in the two groups were performed to eliminate the differences in baseline data, and then the above indicators of the remaining patients in the two groups were recorded and analyzed again. The indicators with statistically significant differences between the two groups after 1∶1 PSM were selected for multivariate logistic regression analysis to screen the independent risk factors affecting the skin graft survival after Meek grafting in severe burn patients. The receiver operating characteristic (ROC) curve of independent risk factors for predicting poor skin graft survival after Meek grafting in severe burn patients after 1∶1 PSM was drawn, and the area under the curve, the cut-off value, and the sensitivity and specificity under the cut-off value were calculated. The patients after 1∶1 PSM were divided into independent risk factor>the cut-off value group and independent risk factor≤the cut-off value group with the incidence of poor skin graft survival after Meek grafting compared using the chi-square test, and the relative risk of poor skin graft survival after Meek grafting was calculated. Results Before 1∶1 PSM, there were no statistically significant differences in gender, age, body mass index, complication of inhalation injury, time from injury to operation, preoperative cystatin C level, preoperative albumin level, preoperative neutrophil, preoperative hemoglobin level of patients between the two groups (

>0.05); the full-thickness burn area and burn index of patients in poor skin graft survival group were significantly higher than those in good skin graft survival group (

=-2.672, -2.882,

<0.01); the preoperative platelet count and the platelet count on the first, third, and fifth day after operation of patients in poor skin graft survival group were significantly lower than those in good skin graft survival group (

-3.411, -3.050, -2.748, -2.686

<0.01). After 1∶1 PSM, 46 cases were remained in each group. There were no statistically significant differences in gender, age, body mass index, full-thickness burn area, burn index, complication of inhalation injury, time from injury to operation, preoperative cystatin C level, preoperative albumin level, preoperative neutrophil, preoperative hemoglobin level of remaining patients between the two groups (

>0.05); the preoperative platelet count and the platelet count on the first, third, and fifth day after operation of patients in poor skin graft survival group were significantly lower than those in good skin graft survival group (

=-3.428, -2.940,

=-2.427, -2.316,

<0.05 or

<0.01). Multivariate logistic regression analysis showed that the preoperative platelet count was the only independent risk factor affecting the skin graft survival after Meek grafting in severe burn patients (odds ratio=0.994, 95% confidence interval=0.989-0.998,

<0.01). The area under the ROC curve of preoperative platelet count predicting poor skin graft survival after Meek grafting in 92 patients was 0.707 (95% confidence interval=0.603-0.798,

<0.01), and the cut-off value of preoperative platelet count was 98×10⁹/L, with sensitivity of 54.3% and specificity of 78.3% under the cut-off value. The incidence of poor skin survival after Meek grafting of patients in preoperative platelet count≤98×10⁹/L group was 71.4% (25/35), which was obviously higher than 36.8% (21/57) in preoperative platelet count>98×10⁹/L group (

²=10.376,

<0.01). compared="" with="" that="" in="" preoperative="" platelet="" count="">98×10⁹/L group, patients in preoperative platelet count≤98×10⁹/L group had a relative risk of poor skin graft survival after Meek grafting of 2.211 (95% confidence interval=1.263-3.870). Conclusions Preoperative platelet count is an independent risk factor affecting the skin graft survival after Meek grafting in severe burn patients and has a good predictive value. Meek grafting should be performed with caution when the preoperative platelet count of patients is≤98×10⁹/L.