Confidence intervals of prediction accuracy measures for multivariable prediction models based on the bootstrap-based optimism correction methods

In assessing prediction accuracy of multivariable prediction models, optimism corrections are essential for preventing biased results. However, in most published papers of clinical prediction models, the point estimates of the prediction accuracy measures are corrected by adequate bootstrap-based correction methods, but their confidence intervals are not corrected, e.g., the DeLong's confidence interval is usually used for assessing the C-statistic. These naive methods do not adjust for the optimism bias and do not account for statistical variability in the estimation of parameters in the prediction models. Therefore, their coverage probabilities of the true value of the prediction accuracy measure can be seriously below the nominal level (e.g., 95%). In this article, we provide two generic bootstrap methods, namely (1) location-shifted bootstrap confidence intervals and (2) two-stage bootstrap confidence intervals, that can be generally applied to the bootstrap-based optimism correction methods, i.e., the Harrell's bias correction, 0.632, and 0.632+ methods. In addition, they can be widely applied to various methods for prediction model development involving modern shrinkage methods such as the ridge and lasso regressions. Through numerical evaluations by simulations, the proposed confidence intervals showed favourable coverage performances. Besides, the current standard practices based on the optimism-uncorrected methods showed serious undercoverage properties. To avoid erroneous results, the optimism-uncorrected confidence intervals should not be used in practice, and the adjusted methods are recommended instead. We also developed the R package predboot for implementing these methods (https://github.com/nomahi/predboot). The effectiveness of the proposed methods are illustrated via applications to the GUSTO-I clinical trial

Risk factors for lower limb lymphedema after lymph node dissection in patients with ovarian and uterine carcinoma

<p>Abstract</p> <p>Background</p> <p>Lymph node dissection has proven prognostic benefits for patients with ovarian or uterine carcinoma; however, one of the complications associated with this procedure is lymphedema. We aimed to identify the factors that are associated with the occurrence of lymphedema after lymph node dissection for the treatment of ovarian or uterine carcinoma.</p> <p>Methods</p> <p>A total of 694 patients with histologically confirmed ovarian (135 patients) or uterine cancer (258 with cervical cancer, 301 with endometrial cancer) who underwent lymph node dissection were studied retrospectively. Logistic regression analyses were used to identify the risk factors associated with occurrence of lymphedema.</p> <p>Results</p> <p>Among ovarian and uterine cancer patients who underwent pelvic lymph node dissection, post-operative radiotherapy (odds ratio: 1.79; 95% confidence interval: 1.20–2.67; p = 0.006) was statistically significantly associated with occurrence of lymphedema.</p> <p>Conclusion</p> <p>There was no relationship between any surgical procedure and occurrence of lymphedema among patients undergoing pelvic lymphadenectomy. Our findings are supported by a sound biological rationale because they suggest that limb lymphedema is caused by pelvic lymph node dissection.</p

Prognostic factors for survival after first recurrence in breast cancer: a retrospective analysis of 252 recurrent cases at a single institution.

[Introduction]Previous studies have shown that primary breast cancer patients with estrogen receptor (ER)-positive status have better outcomes in terms of both overall survival and disease-free intervals (DFI). However, 25.2 % of our ER-positive patients experienced recurrence. This study aimed to define factors potentially predicting survival after first recurrence in surgically treated patients with stage I–III breast cancer. [Methods]We retrospectively analyzed 252 females with recurrent breast cancer who had undergone surgery and been followed at Kyoto University Hospital in Japan. Age, clinical stage, pathological stage, axillary lymph node involvement, ER status at the time of diagnosis, progesterone receptor status, human epidermal growth factor receptor 2 status, operative method, adjuvant chemotherapy, adjuvant endocrine therapy, use of trastuzumab after recurrence, site of recurrence, DFI, and time of recurrence were examined for possible influences on survival after the first recurrence. [Results]Positive ER status and positive PR status at the time of diagnosis were significantly favorable factors of survival after first recurrence for patients with recurrence, p < 0.001 and p = 0.021, respectively. More than two sites of recurrence (p < 0.001) were associated with shorter survival time after the first recurrence on multivariate analysis. Survival of patients with recurrent breast cancer steadily improved from 1980–1994 to 1995–2008, significantly in ER-negative subgroups. [Conclusions]Positive ER status at the time of diagnosis is a powerful predictor for favorable survival after first recurrence. Survival time after first recurrence of breast cancer has steadily increased in recent decades. Advances in treatments and attitudes about breast cancer have contributed to this improvement in survival after first recurrence

Interstitial lung disease in gefitinib-treated Japanese patients with non-small cell lung cancer – a retrospective analysis: JMTO LC03-02

<p>Abstract</p> <p>Background</p> <p>In Japan, high incidences of interstitial lung disease (ILD) and ILD-related deaths have been reported among gefitinib-treated patients with non-small cell lung cancer (NSCLC). We investigated the efficacy of gefitinib, the incidence of ILD and risk factors for ILD in these patients.</p> <p>Findings</p> <p>We obtained patient data retrospectively using questionnaires sent to 22 institutions. We asked for demographic and clinical data on NSCLC patients for whom gefitinib treatment had begun between July 2002 and February 2003. Data from a total of 526 patients were analyzed. The patient characteristics were as follows: 64% male, 69% with adenocarcinoma, 61% with a performance score of 0–1, and 5% with concurrent interstitial pneumonitis. The objective response proportion was 80/439 (18.2%; 95% CI: 14.7–22.0). ILD developed in 17 patients (3.2%; 95% CI 1.9–5.1%), of whom 7 died. According to multivariate analysis, female sex, history of prior chemotherapy, low absolute neutrophil count before gefitinib treatment, and adenocarcinoma histology were associated with response to gefitinib treatment. None of the factors we evaluated were associated with the development of ILD.</p> <p>Conclusion</p> <p>The results of this study are consistent with previously published values for treatment response proportions and incidence of ILD during gefitinib treatment in Japanese patients. Future studies should be aimed at identifying factors indicating that a patient has a high probability of receiving benefit from gefitinib and a low risk of developing ILD.</p

Alterations of circulating endothelial cell and endothelial progenitor cell counts around the ovulation.

Context:Circulating endothelial cells (CECs) and progenitor cells (CEPs) have been intensively studied as a promising tool for treating ischemic diseases and monitoring cancer treatments, but how the menstrual cycle affects the variation in their counts remains unclear. Objective:The aims of the study were to determine the influence of the menstrual cycle on the number of CECs and CEPs and to investigate the association of their counts with circulating hormones and angiogenesis-associated factors. Design:CEP and CEC counts by flow cytometry and the CellSearch system and circulating factor levels were measured eight times during the menstrual cycle in 18 volunteers. The menstrual cycle was divided into six phases based on hormone concentrations. Results:CEP counts peaked in the periovulatory and middle luteal phases with a drop in the early luteal phase. CEC counts showed no significant variation. There were significant correlations between the CEP counts and the serum concentrations of estradiol (E2), LH, and granulocyte colony-stimulating factor (G-CSF) (P < 0.0001, P < 0.0001, and P = 0.01, respectively). The difference in CEP counts between two adjacent phases was significantly correlated with that in E2, LH, G-CSF, and serum vascular endothelial growth factor (P < 0.0001, P < 0.0001, P = 0.02, and P = 0.006, respectively). Conclusion:CEP counts peaked in the periovulatory and middle luteal phases, with a drop in the early luteal phase, and were correlated with serum E2, LH, and G-CSF concentrations. Consideration of the variation in CEP counts would be important for the clinical application of CEPs

Pretransplant serum hepatitis C virus RNA levels predict response to antiviral treatment after living donor liver transplantation.

[Background]Given the limited efficacy and high adverse event rate associated with treatment of recurrent hepatitis C after liver transplantation, an individualized treatment strategy should be considered. The aim of this study was to identify predictors of response to antiviral therapy for hepatitis C after living donor liver transplantation (LDLT) and to study the associated adverse events. [Methods]A retrospective chart review was performed on 125 hepatitis C virus (HCV)-positive LDLT recipients who received interferon plus ribavirin and/or peginterferon plus ribavirin therapy at Kyoto University between January 2001 and June 2011. [Results]Serum HCV RNA reached undetectable levels within 48 weeks in 77 (62%) of 125 patients, and these patients were defined as showing virological response (VR). Of 117 patients, 50 (43%) achieved sustained VR (SVR). Predictive factors associated with both VR and SVR by univariate analysis included low pretransplant serum HCV RNA levels, a non-1 HCV genotype, and low pretreatment serum HCV RNA levels. In addition, LDLT from ABO-mismatched donors was significantly associated with VR, and white cell and neutrophil counts before interferon therapy were associated with SVR. Multivariate analysis showed that 2 variables–pretransplant serum HCV RNA level less than 500 kIU/mL and a non-1 HCV genotype–remained in models of both VR and SVR and that an ABO mismatch was associated with VR. No variables with a significant effect on treatment withdrawal were found. [Conclusions]Virological response to antiviral therapy in patients with hepatitis C recurring after LDLT can be predicted prior to transplant, based on pretransplant serum HCV-RNA levels and HCV genotype. LDLT from ABO-mismatched donors may contribute to more efficacious interferon therapy

Serial Assessment of Immune Status by Circulating CD8+ Effector T Cell Frequencies for Posttransplant Infectious Complications

To clarify the role of CD8+ effector T cells for infectious complications, 92 recipients were classified according to the hierarchical clustering of preoperative CD8+CD45 isoforms: Group I was naive, Group II was effector memory, and Group III was effector (E) T cell-dominant. The posttransplant infection rates progressively increased from 29% in Group I to 64.3% in Group III recipients. The posttransplant immune status was compared with the pretransplant status, based on the measure (% difference) and its graphical form (scatter plot). In Groups I and II, both approaches showed a strong upward deviation from pretransplant status upon posttransplant infection, indicating an enhanced clearance of pathogens. In Group III, in contrast, both approaches showed a clear downward deviation from preoperative status, indicating deficient cytotoxicity. The % E difference and scatter plot can be used as a useful indicator of a posttransplant infectious complication

Study protocol of the SACURA trial: a randomized phase III trial of efficacy and safety of UFT as adjuvant chemotherapy for stage II colon cancer

BACKGROUND: Adjuvant chemotherapy for stage III colon cancer is internationally accepted as standard treatment with established efficacy, but the usefulness of adjuvant chemotherapy for stage II colon cancer remains controversial. The major Western guidelines recommend adjuvant chemotherapy for “high-risk stage II” cancer, but this is not clearly defined and the efficacy has not been confirmed. METHODS/DESIGN: SACURA trial is a multicenter randomized phase III study which aims to evaluate the superiority of 1-year adjuvant treatment with UFT to observation without any adjuvant treatment after surgery for stage II colon cancer in a large population, and to identify “high-risk factors of recurrence/death” in stage II colon cancer and predictors of efficacy and adverse events of the chemotherapy. Patients aged between 20 and 80 years with curatively resected stage II colon cancer are randomly assigned to a observation group or UFT adjuvant therapy group (UFT at 500–600 mg/day as tegafur in 2 divided doses after meals for 5 days, followed by 2-day rest. This 1-week treatment cycle is repeated for 1 year). The patients are followed up for 5 years until recurrence or death. Treatment delivery and adverse events are entered into a web-based case report form system every 3 months. The target sample size is 2,000 patients. The primary endpoint is disease-free survival, and the secondary endpoints are overall survival, recurrence-free survival, and incidence and severity of adverse events. In an additional translational study, the mRNA expression of 5-FU-related enzymes, microsatellite instability and chromosomal instability, and histopathological factors including tumor budding are assessed to evaluate correlation with recurrences, survivals and adverse events. DISCUSSION: A total of 2,024 patients were enrolled from October 2006 to July 2010. The results of this study will provide important information that help to improve the therapeutic strategy for stage II colon cancer. TRIAL REGISTRATION: ClinicalTrials.gov NCT00392899

Prognostic value of the neutrophil-to-lymphocyte ratio in patients with laryngeal squamous cell carcinoma

© 2015 Wiley Periodicals, Inc.. Background The neutrophil/lymphocyte ratio (NLR) has been found to be predictive of survival outcome in a range of tumors. The purpose of this study was to investigate the prognostic value of pretreatment (NLR) in patients with laryngeal squamous cell carcinoma (SCC). Methods A retrospective analysis of 140 patients with laryngeal SCC treated between 2005 and 2010 in the Hull and East Yorkshire Hospitals NHS Trust was carried out. Patient records were evaluated and both pretreatment neutrophil and lymphocyte counts were documented together with survival data, sex, smoking status, nodal classification, and disease staging. Results An elevated NLR was significantly associated with advanced disease stage (eg, node-positive and tumors stage III and IV). In addition, a high NLR was significantly associated with poor overall survival (OS) but not disease-free survival (DFS) on multivariate analysis, with the greatest significance seen in patients with the highest NLR. Conclusion Pretreatment NLR may serve as a useful prognostic marker in laryngeal SCC; however, a large prospective study is required to determine an optimal NLR cutoff value