He Wu

The role of propionic acid at diagnosis predicts mortality in patients with septic shock.

Purpose: This study aims to assess the diagnostic and prognostic value of propionic acid in patients with septic shock on a medical intensive care unit (ICU). Methods: Serum propionic acid and clinical common cytokines levels were measured within 24 h after the diagnosis of sepsis, and the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Sequential Organ Failure Assessment (SOFA) score, and Mortality were recorded in ICU. A 28‐day and 90‐day follow‐up was performed for all patients. Results: A total of 118 septic patients were enrolled in this study. The propionic acid was higher in patients with septic shock compared with sepsis. Multivariate logistic regression analysis showed that propionic acid was independent predictor of sepsis (odds ratio: 1.279; 95% confidence interval: 1.069–1.530; P = 0.007) and septic shock (odds ratio: 1.859; 95% confidence interval: 1.342–2.576; P < 0.001) and ICU mortality (odds ratio: 1.331; 95% confidence interval: 1.107–1.600; P = 0.002), 28‐day mortality (odds ratio: 1.259; 95% confidence interval: 1.046–1.514; P = 0.015) and 90‐day mortality (odds ratio: 1.304; 95% confidence interval: 1.092–1.558; P = 0.003). The receiver operating characteristic curve (AUC) analysis showed the areas under of propionic acid on ICU admission day for predicting sepsis and septic shock were 0.773 and 0.85 respectively, the areas under of propionic acid for predicting ICU mortality, 28‐d and 90‐d mortality were 0.779, 0.739 and 0.809 respectively. Using a PA cutoff of 0.053 and 0.095 for predicting sepsis and septic shock respectively, the sensitivity was 97.62% and 85.5%, and the specificity was 58% and 83.5%, respectively. Using a PA cutoff of 0.139 for predicting ICU mortality, 28‐ and 90‐day mortality, the sensitivity was 69.39%, 67.44% and 69.09% respectively, and the specificity was 78.26%, 73.33% and 82.54% respectively. Conclusions: Propionic acid showed diagnostic capacity to diagnose septic shock and revealed prognostic information for mortality.

Risk Factors for Early Postoperative Small Bowel Obstruction after Anterior Resection for Rectal Cancer: Methodological Issues

Dear Editor, We were interested to read the paper authored by Suwa and colleagues published in the World Journal of Surgery in 2017 [1]. Their study was to assess the risk factors for small bowel obstruction (SBO) in early postoperative period after anterior resection (AR) for rectal cancer. The results provide evidence that the D3 lymph node dissection and DI formation are independent risk factors for EPSBO in AR [1]; however, some methodological issues should be noticed. In this study, multivariate analysis was performed using the factors that were considered significant in the univariate analysis (factors with p values less than 0.05). The risk factors with p values less than 0.05 which have large effect on outcome and p values less than 0.2 may have a relatively small effect on outcome. If we selected only those with p value0.05 in multivariable analysis, the effect of such predictors will be overestimated and in following the prediction power will be decreased. So, independent variables with p values less than 0.2 should be selected to be imported into the multivariable model. Otherwise, it can induce testimation bias in the results [2]. In the study, some odds ratios (ORs) and CIs were relatively large such as 17.25 (3.49–312.55) for low anterior resection and 13.61 (2.75–246.69) for D3 lymph node dissection in Table 2. This is probably due to the multicollinearity [2]. Although, the authors have mentioned it in their study, the multivariate model may be affected by bias because of the multicollinearity [2]. The authors concluded that D3 lymph node dissection and DI formation are independent risk factors for early postoperative SBO in AR. However, the prediction models were not be validated through using some appropriate methods such as cross-validation and bootstrapping, otherwise, these results would be optimistic interpretation. Correcting optimism problem in study with small sample size have been more emphasized [3].

Incidence and predictors of postoperative delirium after cytoreduction surgery-hyperthermic intraperitoneal chemotherapy: Methodological issues

Dear Editor, Wewere interested to read the article “Incidence and predictors of postoperative delirium after cytoreduction surgery-hyperthermic intraperitoneal chemotherapy” published in Journal of Surgical Oncology recently, which shows an incidence of 28% of delirium, occurring after cytoreduction surgery-hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) and suggests a role for systemic inflammation in the development of postoperative delirium. Although the results were interesting, some methodological issues should be noticed. In the study, some odds ratios (ORs) and CIs were relatively large such as 18.19 (2.11-156.82) for sepsis in Table 3. This is probably due to the multicollinearity. So, the multicollinearity between independent variables must be initially examined. Otherwise, regression model may be affected by bias because of the multicollinearity. The authors concluded that surgery extensiveness and serum level of CRP were independent predictors for delirium postoperatively. However, the prediction models were not be validated through using some appropriatemethods such as cross-validation and bootstrapping, otherwise, these results would be optimistic interpretation. Correcting optimism problem in study with small sample size have been more emphasized.

Comment on “Body mass index and contralateral ratio predict outcome following unilateral adrenalectomy in primary aldosteronism”

We were interested to read the article “Body mass index and contralateral ratio predict outcome following unilateral adrenalectomy in primary aldosteronism”, authored by Bokuda K and colleagues and published recently in Hypertension Research [1]. The authors sought to investigate the preoperative factors contributing to postoperative blood pressure (BP) outcome in patients with primary aldosteronism who had undergone unilateral adrenalectomy. This study was interesting; however, some methodologic issues should be noted. First, all continuous variables in the study were expressed as the mean ± s.d. and analyzed by Student’s t-test. It is widely recognized that the mean ± s.d. is suitable only for data that follow the normal (Gaussian) distribution [2]. However, the authors ignored the normality of continuous variables in this study (some continuous variables listed in Table 1 clearly did not follow the normal distribution). Medians and interquartile ranges may be more appropriate than means and standard deviations when continuous variables are not normally distributed. We note that the normality assumption can be checked by graphical and statistical methods such as the Kolmogorov–Smirnov test. Nonparametric tests should be used when the normality assumption does not hold. The normality assumption should be considered seriously, as it is impossible to draw accurate and reliable conclusions when the assumption does not hold [2]. Second, the authors constructed a multivariate logistic regression model including all preoperative variables that demonstrated statistical significance (P-value < 0.05) between the “cured” and “not cured” groups for the BP outcome following unilateral adrenalectomy. First, bivariate correlations among preoperative variables should be assessed to identify potential multicollinearity before multivariate logistic regression analysis; second, a multivariate logistic regression model should be constructed using backward stepwise selection for those variables found to be associated with factors in univariate analysis with P-values less than 0.2. In the study conducted by Bokuda K and colleagues, bivariate correlation between preoperative variables was not assessed, and the preoperative variables with P-values less than 0.05 were entered into the multivariate analyses by the author, which can introduce estimation bias into the results [3, 4]. Finally, postoperative systolic BP and postoperative diastolic BP fluctuate within individuals over time, and we suggest that the mean of three or more measurements should have been used in this study. Instead, the authors used only one BP measurement per subject; overlooking within-person variability in this manner can lead to regression dilution bias in the findings [5].

Letter to the Editor concerning “Relationship between preoperative serum rapid turnover proteins and early-stage surgical wound infection after spine surgery” by D. Kudo et al. (Eur Spine J; 2016: DOI 10.1007/s00586-016-4855-z)

We read the article conducted by Kudo et al., which was published in European Spine Journal in 2016 [1]. The authors tried to investigate the relationship between preoperative serum rapid turnover proteins (RTPs) and postoperative surgical site infection (SSI). This study was valuable. However, some methodologic issues should be noted. First, all data are presented as means with standard deviation (SD) in this study. We know that mean ± SD is used in normality distribution or a Gaussian distribution [2, 3]. The normality of continuous variables was ignored by the authors (some continuous variables were not normality distribution obviously in Table 1. We suggest that the author conduct a normality assumption test first. Medians and interquartile ranges are more appropriate for abnormal distribution. The potential factors related to early-stage surgical wound infection after spine surgery were identified by univariate and multivariate logistic regression analysis. First, bivariate correlations among variables should be assessed to identify potential multicollinearity before multivariate logistic regression analysis; Second, multivariate logistic regression model is determined using backward stepwise selection for those variables found to be associated with factors on univariate analysis with p-values less than 0.2. In the study conducted by Kudo and colleagues, bivariate correlation between explanatory variables has not been assessed, and all of the variables from the univariate analysis were imported into the multivariate logistic regression analysis, this may lead to overparameterization [4]. The authors indicated that a low prealbumin level is a possible risk factor for earlystage SSI in spine surgery, and operative time was the most important risk factor for SSI. However, the prediction models need to be validated through using some appropriate methods such as cross-validation and bootstrapping, otherwise, these results would be optimistic interpretation [5].

Amiodarone induces epithelial-mesenchymal transition in A549 cells via activation of TGF-β1

Abstract Amiodarone is a high effectiveness anti-arrhythmia agent which is able to induce pulmonary fibrosis. Many studies have shown that the epithelial-mesenchymal transition (EMT) was a significant process in pulmonary fibrosis. So far, there are no studies about whether EMT was associated with amiodarone-induced pulmonary fibrosis, which was therefore explored in this study. In addition, the underlying mechanisms of amiodarone-induced pulmonary fibrosis were examined in vitro. We found the EMT marker (α-SMA) was significantly increased, while the E-cadherin was significantly decreased in adenocarcinomic human alveolar basal epithelial cells (A549) after amiodarone treatment, suggesting that the epithelial cells were an important source of mesenchymal cells. Transforming growth factor beta1 (TGF-β1) was also increased significantly after amiodarone treatment. In conclusion, this study suggested amiodarone could induce pulmonary fibrosis via EMT, and the TGF-β1 may be a key profibrotic cytokine in mechanisms of amiodarone-induced pulmonary fibrosis.

Risk factors for postoperative ileus after colorectal cancer surgery: methodological issues

We read the study by Rybakov and colleagues [1] in which the authors assess the rate and independent risk factors for postoperative ileus (POI) after colorectal cancer surgery. The results provide evidence of at least two surgeon-dependent risk factors, i.e. open approach and opioids in the postoperative period. Although the study was interesting, some methodological points need to be taken into account. This article is protected by copyright. All rights reserved.

HAQ score is an independent predictor of sustained remission in patients with rheumatoid arthritis: methodological issues

with p values < 0.2 should be selected to be imported into the multivariable model. The authors indicated that a lower HAQ score at baseline was an independent predictor of sustained remission at 2 years, according to DAS28-CRP. However, the validity of prediction models need to be validated through using some appropriate methods such as cross-validation and bootstrapping, otherwise, these results would be optimistic interpretation [3].