Multi-state models provide an extension of the usual survival/event-history analysis setting. In the medical domain, multi-state models give the possibility of further investigating intermediate... Show moreMulti-state models provide an extension of the usual survival/event-history analysis setting. In the medical domain, multi-state models give the possibility of further investigating intermediate events such as relapse and remission. In this work, a further extension is proposed using relative survival, where mortality due to population causes (i.e. non-disease-related mortality) is evaluated. The objective is to split all mortality in disease and non-disease-related mortality, with and without intermediate events, in datasets where cause of death is not recorded or is uncertain. To this end, population mortality tables are integrated into the estimation process, while using the basic relative survival idea that the overall mortality hazard can be written as a sum of a population and an excess part. Hence, we propose an upgraded non-parametric approach to estimation, where population mortality is taken into account. Precise definitions and suitable estimators are given for both the transition hazards and probabilities. Variance estimating techniques and confidence intervals are introduced and the behaviour of the new method is investigated through simulations. The newly developed methodology is illustrated by the analysis of a cohort of patients followed after an allogeneic hematopoietic stem cell transplantation. The work has been implemented in the R package mstate. Show less
Benchmarking is commonly used in many healthcare settings to monitor clinical performance, with the aim of increasing cost-effectiveness and safe care of patients. The funnel plot is a popular tool... Show moreBenchmarking is commonly used in many healthcare settings to monitor clinical performance, with the aim of increasing cost-effectiveness and safe care of patients. The funnel plot is a popular tool in visualizing the performance of a healthcare center in relation to other centers and to a target, taking into account statistical uncertainty. In this paper, we develop a methodology for constructing funnel plots for survival data. The method takes into account censoring and can deal with differences in censoring distributions across centers. Practical issues in implementing the methodology are discussed, particularly in the setting of benchmarking clinical outcomes for hematopoietic stem cell transplantation. A simulation study is performed to assess the performance of the funnel plots under several scenarios. Our methodology is illustrated using data from the European Society for Blood and Marrow Transplantation benchmarking project. Show less
Hoven, P. van den; Tange, F.; Valk, J. van der; Nerup, N.; Putter, H.; Rijswijk, C. van; ... ; Vorst, J. van der 2022
Purpose: Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) is gaining popularity for the quantification of tissue perfusion, including foot perfusion in patients with lower... Show morePurpose: Near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) is gaining popularity for the quantification of tissue perfusion, including foot perfusion in patients with lower extremity arterial disease (LEAD). However, the absolute fluorescence intensity is influenced by patient-and system-related factors limiting reliable and valid quantification. To enhance the quality of quantitative perfusion assessment using ICG NIR fluorescence imaging, normalization of the measured time-intensity curves seems useful. Materials and Methods: In this cohort study, the effect of normalization on 2 aspects of ICG NIR fluorescence imaging in assessment of foot perfusion was measured: the repeatability and the region selection. Following intravenous administration of ICG, the NIR fluorescence intensity in both feet was recorded for 10 mins using the Quest Spectrum platform(R). The effect of normalization on repeatability was measured in the nontreated foot in patients undergoing unilateral revascularization preprocedural and postprocedural (repeatability group). The effect of normalization on region selection was performed in patients without LEAD (region selection group). Absolute and normalized time-intensity curves were compared. Results: Successful ICG NIR fluorescence imaging was performed in 54 patients (repeatability group, n = 38; region selection group, n = 16). For the repeatability group, normalization of the time-intensity curves displayed a comparable inflow pattern for repeated measurements. For the region selection group, the maximum fluorescence intensity (Imax) demonstrated significant differences between the 3 measured regions of the foot (P = .002). Following normalization, the time-intensity curves in both feet were comparable for all 3 regions. Conclusion: This study shows the effect of normalization of time-intensity curves on both the repeatability and region selection in ICG NIR fluorescence imaging. The significant difference between absolute parameters in various regions of the foot demonstrates the limitation of absolute intensity in interpreting tissue perfusion. Therefore, normalization and standardization of camera settings are essential steps toward reliable and valid quantification of tissue perfusion using ICG NIR fluorescence imaging. Show less
Background: In diagnosing peripheral arterial disease (PAD), medial arterial calcification (MAC) hampers arterial compression and could lead to unreliable ankle brachial index (ABI), toe brachial... Show moreBackground: In diagnosing peripheral arterial disease (PAD), medial arterial calcification (MAC) hampers arterial compression and could lead to unreliable ankle brachial index (ABI), toe brachial index (TBI) and toe pressure (TP). Doppler ultrasonography (DUS) derived maximal systolic acceleration (ACCmax) might be more accurate to diagnose PAD. In an in vitro study, a strong correlation between ACCmax and the severity of stenotic disease was determined. The aim of this study was to investigate the ACCmax in correlation with conventional non-invasive diagnostics in an in vivo setting. Methods: In twelve healthy individuals, an arterial stenosis was mimicked by compression on the common femoral artery by an ultrasounds probe, creating a local stenosis of 50%, 70% and 90%. The ABI, TBI, TP and several DUS parameters (including ACCmax) were assessed at the ankle during these different degrees of stenosis. All DUS parameters were measured separately by two observers to determine the interobserver variability. Results: Overall the ABI, TBI, TP, ACCmax, ACCsys and PSV decreased significantly when the degree of stenosis increased. The ACCmax showed the highest correlation with the degree of stenosis (r -.884), compared to ABI (r -.726), TBI (r -.716) and TP (r -.758). Furthermore, the interobserver variability of ACCmax was excellent, with an intraclass correlation coefficient (ICC) of .97. Conclusion: ACCmax is an accurate non-invasive DUS parameter to diagnose and assess the severity of a mimicked arterial stenosis in healthy individuals. Further prospective assessment of the clinical value of ACCmax and its potential benefits in patients with PAD is needed. Show less
Background: The evaluation of health-related quality of life (HRQoL) in clinical trials has become increasingly important because it addresses the impact of treatment from the patient's perspective... Show moreBackground: The evaluation of health-related quality of life (HRQoL) in clinical trials has become increasingly important because it addresses the impact of treatment from the patient's perspective. The primary aim of this study was to investigate the effect of postoperative chemotherapy and chemoradiotherapy (CRT) after neoadjuvant chemotherapy and surgery with extended (D2) lymphadenectomy on HRQoL in the CRITICS trial. Second, we investigated the potential prognostic value of pretreatment HRQoL on event-free survival (EFS) and overall survival (OS). Patients and Methods: Patients in the CRITICS trial were asked to complete HRQoL questionnaires (EORTC Quality-of-Life Questionnaire-Core 30 and Quality-of-Life Questionnaire gastric cancer-specific module) at baseline, after preoperative chemotherapy, after surgery, after postoperative chemotherapy or CRT, and at 12 months follow-up. Patients with at least 1 evaluable questionnaire (645 of 788 randomized patients) were included in the HRQoL analyses. The predefined endpoints included dysphagia, pain, physical functioning, fatigue, and Quality-of-Life Questionnaire-Core 30 summary score. Linear mixed modeling was used to assess differences over time and at each time point. Associations of baseline HRQoL with EFS and OS were investigated using multivariate Cox proportional hazards analyses. Results: At completion of postoperative chemo(radio)therapy, the chemotherapy group had significantly better physical functioning (P=.02; Cohen's effect size = 0.42) and less dysphagia (P=.01; Cohen's effect size = 0.38) compared with the CRT group. At baseline, worse social functioning (hazard ratio [HR], 2.20; 95% CI, 1.36-3.55; P=.001), nausea (HR, 1.89; 95% CI, 1.39-2.56; P<.001), worse WHO performance status (HR, 1.55; 95% CI, 1.13-2.13; P=.007), and histologic subtype (diffuse vs intestinal: HR, 1.94; 95% CI, 1.42-2.67; P<.001; mixed vs intestinal: HR, 2.35; 95% CI, 1.35-4.12; P=.003) were significantly associated with worse EFS and OS. Conclusions: In the CRITICS trial, the chemotherapy group had significantly better physical functioning and less dysphagia after postoperative treatment. HRQoL scales at baseline were significantly associated with EFS and OS. Show less
Wortman, B.G.; Post, C.C.B.; Powell, M.E.; Khaw, P.; Fyles, A.; D'Amico, R.; ... ; Boer, S.M. de 2022
Purpose: Radiation therapy techniques have developed from 3-dimensional conformal radiation therapy (3DCRT) to intensity modulated radiation therapy (IMRT), with better sparing of the surrounding... Show morePurpose: Radiation therapy techniques have developed from 3-dimensional conformal radiation therapy (3DCRT) to intensity modulated radiation therapy (IMRT), with better sparing of the surrounding normal tissues. The current analysis aimed to investigate whether IMRT, compared to 3DCRT, resulted in fewer adverse events (AEs) and patient-reported symptoms in the randomized PORTEC-3 trial for high-risk endometrial cancer.Methods and materials: Data on AEs and patient-reported quality of life (QoL) of the PORTEC-3 trial were available for analysis. Physician-reported AEs were graded using Common Terminology Criteria for Adverse Events v3.0. QoL was assessed by the European Organisation for Research and Treatment of Cancer QLQC30, CX24, and OV28 questionnaires. Data were compared between 3DCRT and IMRT. A P value of = .01 was considered statistically significant due to the risk of multiple testing. For QoL, combined scores 1 to 2 ("not at all" and "a little") versus 3 to 4 ("quite a bit" and "very much") were compared between the techniques.Results: Of 658 evaluable patients, 559 received 3DCRT and 99 IMRT. Median follow-up was 74.6 months. During treatment no significant differences were observed, with a trend for more grade =3 AEs, mostly hematologic and gastrointestinal, after 3DCRT (37.7% vs 26.3%, P = .03). During follow-up, 15.4% (vs 4%) had grade >= 2 diarrhea, and 26.1% (vs 13.1%) had grade >= 2 hematologic AEs after 3DCRT (vs IMRT) (both P < .01). Among 574 (87%) patients evaluable for QoL, 494 received 3DCRT and 80 IMRT. During treatment, 37.5% (vs 28.6%) reported diarrhea after 3DCRT (vs IMRT) (P = .125); 22.1% (versus 10.0%) bowel urgency (P = 0039), and 18.2% and 8.6% abdominal cramps (P = .058). Other QoL scores showed no differences.Conclusions: IMRT resulted in fewer grade >= 3 AEs during treatment and significantly lower rates of grade >= 2 diarrhea and hematologic AEs during follow-up. Trends toward fewer patient-reported bowel urgency and abdominal cramps were observed after IMRT compared to 3DCRT. (C) 2021 The Authors. Published by Elsevier Inc. Show less
The problem of dynamic prediction with time-dependent covariates, given by biomarkers, repeatedly measured over time, has received much attention over the last decades. Two contrasting approaches... Show moreThe problem of dynamic prediction with time-dependent covariates, given by biomarkers, repeatedly measured over time, has received much attention over the last decades. Two contrasting approaches have become in widespread use. The first is joint modeling, which attempts to jointly model the longitudinal markers and the event time. The second is landmarking, a more pragmatic approach that avoids modeling the marker process. Landmarking has been shown to be less efficient than correctly specified joint models in simulation studies, when data are generated from the joint model. When the mean model is misspecified, however, simulation has shown that joint models may be inferior to landmarking. The objective of this article is to develop methods that improve the predictive accuracy of landmarking, while retaining its relative simplicity and robustness. We start by fitting a working longitudinal model for the biomarker, including a temporal correlation structure. Based on that model, we derive a predictable time-dependent process representing the expected value of the biomarker after the landmark time, and we fit a time-dependent Cox model based on the predictable time-dependent covariate. Dynamic predictions based on this approach for new patients can be obtained by first deriving the expected values of the biomarker, given the measured values before the landmark time point, and then calculating the predicted probabilities based on the time-dependent Cox model. We illustrate the approach in predicting overall survival in liver cirrhosis patients based on prothrombin index. Show less
Background Anti-cancer drugs commonly adversely affect fertility and sexual function. Despite this, patients report a lack of counselling of these potential adverse effects. The aim was to... Show moreBackground Anti-cancer drugs commonly adversely affect fertility and sexual function. Despite this, patients report a lack of counselling of these potential adverse effects. The aim was to determine Dutch oncologists' knowledge about the adverse effects of various cancer drugs on fertility and sexual function. Methods A cross-sectional survey was sent to members of the Dutch Society for Medical Oncology (n = 433). The survey questions included various cancer drugs' adverse effects on fertility, ovulation, spermatogenesis, and sexual function. Results One hundred and five of 392 oncologists responded (26.8%). Oncologists were more aware of the adverse effects on fertility compared to sexual function. Drugs that were mostly believed to negatively affect fertility were cisplatin (n = 81, 80.2%), epirubicin (n = 78, 78.0%) and cyclophosphamide (n = 80, 77.7%). Regarding sexual function, most mentioned drugs were tamoxifen (n = 67, 65.7%), GnRH-agonists (n = 64, 63.4%) and cisplatin (n = 58, 57.4%). Oncologists with expertise in urology possessed more awareness regarding sexuality-related adverse effects (cisplatin p = 0.038, etoposide p = 0.025, ifosfamide p = 0.06, vinblastine p = 0.000). Conclusion Results revealed that oncologists have different beliefs about possible sexual and fertility-related adverse effects concerning medication resources and literature. Based on our results, oncologists do not possess sufficient knowledge to inform patients about sexual and fertility-related adverse effects. Show less
Ravensbergen, C.J.; Kuruc, M.; Polack, M.; Crobach, S.; Putter, H.; Gelderblom, H.; ... ; Mesker, W.E. 2022
Simple Summary Liquid biopsy offers a novel minimally invasive approach to tumor sampling and is believed to capture a comprehensive overview of the molecular tumor landscape. However, current... Show moreSimple Summary Liquid biopsy offers a novel minimally invasive approach to tumor sampling and is believed to capture a comprehensive overview of the molecular tumor landscape. However, current liquid biopsy analytes in cancer are principally derived from the malignant cells without regard to the tumor microenvironment. The Stroma Liquid Biopsy(TM) (SLB) proteomics panel contains proteins from key stromal pathways in cancer and was designed to address the tumor microenvironment in liquid biopsy. We aimed to explore and characterize SLB panel constituents using an in-silico transcriptomics approach in colon cancer. Additionally, the association between the SLB panel constituents and histologic intratumoral stromal content, a poor prognostic tumor characteristic, was investigated. This explorative study presents an alternative workflow to gene signature development and provides a molecular characterization of the SLB panel. We believe that our findings contribute to the ever-increasing appreciation of the tumor microenvironment in cancer. Liquid biopsy has emerged as a novel approach to tumor characterization, offering advantages in sample accessibility and tissue heterogeneity. However, as mutational analysis predominates, the tumor microenvironment has largely remained unacknowledged in liquid biopsy research. The current work provides an explorative transcriptomic characterization of the Stroma Liquid Biopsy(TM) (SLB) proteomics panel in colon carcinoma by integrating single-cell and bulk transcriptomics data from publicly available repositories. Expression of SLB genes was significantly enriched in tumors with high histologic stromal content in comparison to tumors with low stromal content (median enrichment score 0.308 vs. 0.222, p = 0.036). In addition, we identified stromal-specific and epithelial-specific expression of the SLB genes, that was subsequently integrated into a gene signature ratio. The stromal-epithelial signature ratio was found to have prognostic significance in a discovery cohort of 359 colon adenocarcinoma patients (OS HR 2.581, 95%CI 1.567-4.251, p < 0.001) and a validation cohort of 229 patients (OS HR 2.590, 95%CI 1.659-4.043, p < 0.001). The framework described here provides transcriptomic evidence for the prognostic significance of the SLB panel constituents in colon carcinoma. Plasma protein levels of the SLB panel may reflect histologic intratumoral stromal content, a poor prognostic tumor characteristic, and hence provide valuable prognostic information in liquid biopsy. Show less
Background: The optimal treatment strategy for postoperative pain following pancreatoduodenectomy remains unknown. The aim of this study was to investigate whether sublingual sufentanil tablet (SST... Show moreBackground: The optimal treatment strategy for postoperative pain following pancreatoduodenectomy remains unknown. The aim of this study was to investigate whether sublingual sufentanil tablet (SST) is a non-inferior analgesic compared to our standard-of-care (patient-controlled epidural analgesia [PCEA] or PCA morphine) in the treatment of pain following pancreatoduodenectomy. Methods: This was a pragmatic, strategy, open-label, non-inferiority, parallel group, randomized (1:1) trial. The primary outcome was an overall mean pain score (Numerical Rating Scale: 0-10) on postoperative days 1 to 3 combined. The non-inferiority margin was - 1.5 since this difference was considered clinically relevant. Results: Between October 2018 and July 2021, 190 patients were assessed for eligibility and 36 patients were included in the final analysis: 17 patients were randomized to SST and 19 patients to standard-of-care. Early treatment failure in the SST group occurred in 2 patients (12%) due to inability to operate the SST system and in 2 patients (12%) due to severe nausea despite antiemetics. Early treatment failure in the standard-of-care group occurred in 2 patients (11%) due to preoperative PCEA placement failure and in 1 patient (5%) due to hemodynamic instability caused by PCEA. The mean difference in pain score on postoperative day 1 to 3 was - 0.10 (95% CI -0.72-0.52), and therefore the non-inferiority of SST compared to standard-of-care was demonstrated. The mean pain score, number of patients reporting unacceptable pain (pain score >4), Overall Benefit of Analgesia Score, and patient satisfaction per postoperative day, perioperative hemodynamics and postoperative outcomes did not differ significantly between groups. Conclusion: This first randomized study investigating the use of SST in 36 patients following pancreatoduodenectomy showed that SST is non-inferior compared to our standard-of-care in the treatment of pain on postoperative days 1 to 3. Future research is needed to confirm that these are applicable to other settings. Show less
Peters, R.M.; Have, B.L.E.F.T.; Rykov, K.; Steenbergen, L. van; Putter, H.; Rutgers, M.; ... ; Zijlstra, W.P. 2022
Background and purpose - In the last decade, the direct anterior approach (DAA) for total hip arthroplasty (THA) has become more popular in the Netherlands. Therefore, we investigated the learning... Show moreBackground and purpose - In the last decade, the direct anterior approach (DAA) for total hip arthroplasty (THA) has become more popular in the Netherlands. Therefore, we investigated the learning curve and survival rate of the DAA in primary THA, using data from the Dutch Arthroplasty Register (LROI).Patients and methods - We identified all patients who received a primary THA using the DAA in several high -volume centers in the Netherlands between 2007 and 2019 (n = 15,903). Procedures were ordered per surgeon, using date of operation. Using the procedure number, operations were divided into 6 groups based on the number of previous procedures per surgeon (first 25, 26-50, 51-100, 101-150, 151-200, > 200). Data from different surgeons in different hospitals was pooled together. Revision rates were calculated using a multilevel time-to-event analysis. Results - Patients operated on in group 1-25 (hazard ratio [HR] 1.6; 95% CI 1.1-2.4) and 26-50 (HR 1.6; CI 1.1-2.5) had a higher risk for revision compared with patients operated on in group > 200 THAs. Between 50 and 100 procedures the revision risk was increased (HR 1.3; CI 0.9-1.9), albeit not statistically significant. From 100 proce-dures onwards the HR for revision was respectively 1.0 (CI 0.6-1.6) and 0.8 (CI 0.5-1.4) for patients in operation groups 101-150 and 151-200. Main reasons for revision were loosening of the stem (29%), periprosthetic infection (19%), and dislocation (16%). Interpretation - We found a 64% increased risk of revision for patients undergoing THA using the DAA for the first 50 cases per surgeon. Between 50 and 100 cases, this risk was 30% increased, but not statistically significant. From 100 cases onwards, a steady state had been reached in revision rate. The learning curve for DAA therefore is around 100 cases. Show less
Geloven, N. van; Giardiello, D.; Bonneville, E.F.; Teece, L.; Ramspek, C.L.; Smeden, M. van; ... ; Steyerberg, E. 2022
Thorough validation is pivotal for any prediction model before it can be advocated for use in medical practice. For time-to-event outcomes such as breast cancer recurrence, death from other causes... Show moreThorough validation is pivotal for any prediction model before it can be advocated for use in medical practice. For time-to-event outcomes such as breast cancer recurrence, death from other causes is a competing risk. Model performance measures must account for such competing events. In this article, we present a comprehensive yet accessible overview of performance measures for this competing eventsetting, including the calculation and interpretation of statistical measures for calibration, discrimination, overall prediction error, and clinical usefulness by decision curve analysis. All methods are illustrated for patients with breast cancer, with publicly available data and R code. Show less
Bakunina, K.; Putter, H.; Versluis, J.; Koster, E.A.S.; Holt, B. van der; Manz, M.G.; ... ; Wreede, L.C. de 2021
Clofarabine is an active antileukemic drug for subgroups of patients with acute myeloid leukemia (AML). Multi-state models can provide additional insights to supplement the original intention-to... Show moreClofarabine is an active antileukemic drug for subgroups of patients with acute myeloid leukemia (AML). Multi-state models can provide additional insights to supplement the original intention-to-treat analysis of randomized controlled trials (RCT). We re-analyzed the HOVON102/SAKK30/09 phase III RCT for newly diagnosed AML patients, which randomized between standard induction chemotherapy with or without clofarabine. Using multi-state models, we evaluated the effects of induction chemotherapy outcomes (complete remission [CR], measurable residual disease [MRD]), and post-remission therapy with allogeneic stem cell transplantation [alloSCT] on relapse and death. Through the latter a consistent reduction in the hazard of relapse in the clofarabine arm compared to the standard arm was found, which occurred irrespective of MRD status or post-remission treatment with alloSCT, demonstrating a strong and persistent antileukemic effect of clofarabine. During the time period between achieving CR and possible post-remission treatment with alloSCT, non-relapse mortality was higher in patients receiving clofarabine. An overall net benefit of treatment with clofarabine was identified using the composite endpoint current leukemia-free survival (CLFS). In conclusion, these results enforce and extend the earlier reported beneficial effect of clofarabine in AML and show that multi-state models further detail the effect of treatment on competing and series of events. Show less
Background & aims: Acute-on-chronic liver failure (ACLF) is usually associated with a precipitating event and results in the failure of other organ systems and high short-term mortality.... Show moreBackground & aims: Acute-on-chronic liver failure (ACLF) is usually associated with a precipitating event and results in the failure of other organ systems and high short-term mortality. Current prediction models fail to adequately estimate prognosis and need for liver transplantation (LT) in ACLF. This study develops and validates a dynamic prediction model for patients with ACLF that uses both longitudinal and survival data.Methods: Adult patients on the UNOS waitlist for LT between 11.01.2016-31.12.2019 were included. Repeated model for end-stage liver disease-sodium (MELD-Na) measurements were jointly modelled with Cox survival analysis to develop the ACLF joint model (ACLF-JM). Model validation was carried out using separate testing data with area under curve (AUC) and prediction errors. An online ACLF-JM tool was created for clinical application.Results: In total, 30,533 patients were included. ACLF grade 1 to 3 was present in 16.4%, 10.4% and 6.2% of patients, respectively. The ACLF-JM predicted survival significantly (p <0.001) better than the MELD-Na score, both at baseline and during follow-up. For 28- and 90-day predictions, ACLF-JM AUCs ranged between 0.840-0.871 and 0.833-875, respectively. Compared to MELD-Na, AUCs and prediction errors were improved by 23.1%-62.0% and 5%-37.6% respectively. Also, the ACLF-JM could have prioritized patients with relatively low MELD-Na scores but with a 4-fold higher rate of waiting list mortality.Conclusions: The ACLF-JM dynamically predicts outcome based on current and past disease severity. Prediction performance is excellent over time, even in patients with ACLF-3. Therefore, the ACLF-JM could be used as a clinical tool in the evaluation of prognosis and treatment in patients with ACLF.Lay summary: Acute-on-chronic liver failure (ACLF) progresses rapidly and often leads to death. Liver transplantation is used as a treatment and the sickest patients are treated first. In this study, we develop a model that predicts survival in ACLF and we show that the newly developed model performs better than the currently used model for ranking patients on the liver transplant waiting list. (C) 2021 The Author(s). Published by Elsevier B.V. Show less
Marang-van de Mheen, P.J.; Putter, H.; Bastiaannet, E.; Bottle, A. 2021
When comparing hospitals on their readmission rates as currently done in the Hospital Readmission and Reduction Program (HRRP) in the USA, should we include the competing risk of mortality after... Show moreWhen comparing hospitals on their readmission rates as currently done in the Hospital Readmission and Reduction Program (HRRP) in the USA, should we include the competing risk of mortality after discharge, which precludes the readmission, in the analysis? Not including competing risks in current HRRP metrics was raised recently as a limitation with possible unintended consequences, as financial penalties for higher readmission rates are more severe than for higher mortality rates. Incorrectly including or ignoring competing risks can both induce bias. In this paper, we present a framework to clarify situations when competing risks should be taken into account and when they should not. We argue that the research question and the perspective from which it is asked determine whether the competing risk is also of interest and should be included in the analysis, or if only the event of interest should be considered. This information is often not explicitly reported but is needed to interpret whether the results are valid. Using the examples of readmissions and cancer, we show how different research questions fit different perspectives from which these are asked (patient, system, regulatory/insurance). Slightly changing the research question or perspective may thus change the analysis. Even though some may argue that any introduced bias is likely to be small, in the context of the HRRP, even small changes may mean that a hospital will face (higher) financial penalties. The impact of getting it wrong matters. Show less
Fu, E.L.; Evans, M.; Carrero, J.J.; Putter, H.; Clase, C.M.; Caskey, F.J.; ... ; Diepen, M. van 2021
OBJECTIVE To identify the optimal estimated glomerular filtration rate (eGFR) at which to initiate dialysis in people with advanced chronic kidney disease.DESIGNNationwide observational cohort... Show moreOBJECTIVE To identify the optimal estimated glomerular filtration rate (eGFR) at which to initiate dialysis in people with advanced chronic kidney disease.DESIGNNationwide observational cohort study.SETTINGNational Swedish Renal Registry of patients referred to nephrologists.PARTICIPANTSPatients had a baseline eGFR between 10 and 20 mL/min/1.73 m(2) and were included between 1 January 2007 and 31 December 2016, with follow-up until 1 June 2017.MAIN OUTCOME MEASURESThe strict design criteria of a clinical trial were mimicked by using the cloning, censoring, and weighting method to eliminate immortal time bias, lead time bias, and survivor bias. A dynamic marginal structural model was used to estimate adjusted hazard ratios and absolute risks for five year all cause mortality and major adverse cardiovascular events (composite of cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke) for 15 dialysis initiation strategies with eGFR values between 4 and 19 mL/min/1.73 m(2) in increments of 1 mL/min/1.73 m(2). An eGFR between 6 and 7 mL/min/1.73 m(2) (eGFR(6-7)) was taken as the reference.RESULTSAmong 10 290 incident patients with advanced chronic kidney disease (median age 73 years; 3739 (36%) women; median eGFR 16.8 mL/min/1.73 m(2)), 3822 started dialysis, 4160 died, and 2446 had a major adverse cardiovascular event. A parabolic relation was observed for mortality, with the lowest risk for eGFR(15-16). Compared with dialysis initiation at eGFR(6-7), initiation at eGFR(15-16) was associated with a 5.1% (95% confidence interval 2.5% to 6.9%) lower absolute five year mortality risk and 2.9% (0.2% to 5.5%) lower risk of a major adverse cardiovascular event, corresponding to hazard ratios of 0.89 (95% confidence interval 0.87 to 0.92) and 0.94 (0.91 to 0.98), respectively. This 5.1% absolute risk difference corresponded to a mean postponement of death of 1.6 months over five years of follow-up. However, dialysis would need to be started four years earlier. When emulating the intended strategies of the Initiating Dialysis Early and Late (IDEAL) trial (eGFR(10-14)v eGFR(5-7)) and the achieved eGFRs in IDEAL (eGFR(7-10)v eGFR(5-7)), hazard ratios for all cause mortality were 0.96 (0.94 to 0.99) and 0.97 (0.94 to 1.00), respectively, which are congruent with the findings of the randomised IDEAL trial.CONCLUSIONSVery early initiation of dialysis was associated with a modest reduction in mortality and cardiovascular events. For most patients, such a reduction may not outweigh the burden of a substantially longer period spent on dialysis. Show less
Oonk, M.H.M.; Slomovitz, B.; Baldwin, P.J.W.; Doorn, H.C. van; Velden, J. van der; Hullu, J.A. de; ... ; Zee, A.G.J. van der 2021
PURPOSE The Groningen International Study on Sentinel nodes in Vulvar cancer (GROINSS-V)-II investigated whether inguinofemoral radiotherapy is a safe alternative to inguinofemoral lymphadenectomy ... Show morePURPOSE The Groningen International Study on Sentinel nodes in Vulvar cancer (GROINSS-V)-II investigated whether inguinofemoral radiotherapy is a safe alternative to inguinofemoral lymphadenectomy (IFL) in vulvar cancer patients with a metastatic sentinel node (SN).METHODS GROINSS-V-II was a prospective multicenter phase-II single-arm treatment trial, including patients with early-stage vulvar cancer (diameter < 4 cm) without signs of lymph node involvement at imaging, who had primary surgical treatment (local excision with SN biopsy). Where the SN was involved (metastasis of any size), inguinofemoral radiotherapy was given (50 Gy). The primary end point was isolated groin recurrence rate at 24 months. Stopping rules were defined for the occurrence of groin recurrences.RESULTS From December 2005 until October 2016, 1,535 eligible patients were registered. The SN showed metastasis in 322 (21.0%) patients. In June 2010, with 91 SN-positive patients included, the stopping rule was activated because the isolated groin recurrence rate in this group went above our predefined threshold. Among 10 patients with an isolated groin recurrence, nine had SN metastases > 2 mm and/or extracapsular spread. The protocol was amended so that those with SN macrometastases (> 2 mm) underwent standard of care (IFL), whereas patients with SN micrometastases (<= 2 mm) continued to receive inguinofemoral radiotherapy. Among 160 patients with SN micrometastases, 126 received inguinofemoral radiotherapy, with an ipsilateral isolated groin recurrence rate at 2 years of 1.6%. Among 162 patients with SN macrometastases, the isolated groin recurrence rate at 2 years was 22% in those who underwent radiotherapy, and 6.9% in those who underwent IFL (P = .011). Treatment-related morbidity after radiotherapy was less frequent compared with IFL.CONCLUSION Inguinofemoral radiotherapy is a safe alternative for IFL in patients with SN micrometastases, with minimal morbidity. For patients with SN macrometastasis, radiotherapy with a total dose of 50 Gy resulted in more isolated groin recurrences compared with IFL. (C) 2021 by American Society of Clinical Oncology Show less
Objectives: The utilization of liver allografts could be optimized if nonacceptance is predicted. This study aimed to evaluate the prognostic ability of an updated Discard Risk Index in... Show moreObjectives: The utilization of liver allografts could be optimized if nonacceptance is predicted. This study aimed to evaluate the prognostic ability of an updated Discard Risk Index in Eurotransplant.Materials and Methods: Potential deceased donors from January 2010 to December 2015 who had been reported to Eurotransplant were included in our analyses. Liver utilization was defined by transplant status as the primary outcome to evaluate the performance of the Eurotransplant-developed Discard Risk Index.Results: Of 11 670 potential livers, 9565 (81%) were actually transplanted. Donor sex, age, history of diabetes, drug abuse, use of vasopressors, body mass index category, serum sodium, cause of death, donor type, and levels of C-reactive protein, bilirubin, aspartate and alanine aminotransferases, international normalized ratio, and gamma-glutamyl transpeptidase were associated with discard and combined in the Eurotransplant-developed Discard Risk Index. Correlation between the two Discard Risk Indexes was high (r = 0.86), and both achieved high C statistics of 0.72 and 0.75 (P <.001), respectively. Despite strong calibration, discard rates of 0.8% for overall donors and 6% of donors after circulatory death could be predicted with 80% accuracy.Conclusions: The Eurotransplant-developed Discard Risk Index showed a high prognostic ability to predict liver utilization in a European setting. The model could therefore be valuable for identifying livers at high risk of not being transplanted in an early stage. These organs might profit the most from modified allocation strategies or advanced preservation techniques. Show less
Plas-Krijgsman, W.G. van der; Giardiello, D.; Putter, H.; Steyerberg, E.W.; Bastiaannet, E.; Stiggelbout, A.M.; ... ; Glas, N.A. de 2021
Background Current prediction tools for breast cancer outcomes are not tailored to the older patient, in whom competing risk strongly influences treatment effects. We aimed to develop and validate... Show moreBackground Current prediction tools for breast cancer outcomes are not tailored to the older patient, in whom competing risk strongly influences treatment effects. We aimed to develop and validate a prediction tool for 5-year recurrence, overall mortality, and other-cause mortality for older patients (aged >= 65 years) with early invasive breast cancer and to estimate individualised expected benefits of adjuvant systemic treatment.Methods We selected surgically treated patients with early invasive breast cancer (stage I-III) aged 65 years or older from the population-based FOCUS cohort in the Netherlands. We developed prediction models for 5-year recurrence, overall mortality, and other-cause mortality using cause-specific Cox proportional hazard models. External validation was performed in a Dutch Cancer registry cohort. Performance was evaluated with discrimination accuracy and calibration plots.Findings We included 2744 female patients in the development cohort and 13631 female patients in the validation cohort. Median age was 74.8 years (range 65-98) in the development cohort and 76.0 years (70-101) in the validation cohort. 5-year follow-up was complete for more than 99% of all patients. We observed 343 and 1462 recurrences, and 831 and 3594 deaths, of which 586 and 2565 were without recurrence, in the development and validation cohort, respectively. The area under the receiver-operating-characteristic curve at 5 years in the external dataset was 0.76 (95% CI 0.75-0.76) for overall mortality, 0.76 (0.76-0.77) for recurrence, and 0.75 (0.74-0.75) for other-cause mortality.Interpretation The PORTRET tool can accurately predict 5-year recurrence, overall mortality, and other-cause mortality in older patients with breast cancer. The tool can support shared decision making, especially since it provides individualised estimated benefits of adjuvant treatment. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd. Show less
Baart, S.J.; Palen, R.L.F. van der; Putter, H.; Tsonaka, R.; Blom, N.A.; Rizopoulos, D.; Geloven, N. van 2021
BACKGROUND: Most patients with congenital heart disease survive into adulthood; however, residual abnormalities remain and management of the patients is life-long and personalized. Patients with... Show moreBACKGROUND: Most patients with congenital heart disease survive into adulthood; however, residual abnormalities remain and management of the patients is life-long and personalized. Patients with surgical repair of transposition of the great arteries, for example, face the risk to develop neoaortic valve regurgitation. Cardiologists update the prognosis of the patient intuitively with updated information of the cardiovascular status of the patient, for instance from echocardiographic imaging.METHODS: Usually a time-dependent version of the Cox model is used to analyze repeated measurements with a time-to-event outcome. New statistical methods have been developed with multiple advantages, of which the most prominent one being the joint model for longitudinal and time-to-event outcome. In this tutorial, the joint modeling framework is introduced and applied to patients with transposition of the great arteries after surgery with a long-term follow-up, where repeated echocardiographic values of the neoaortic root are evaluated against the risk of neoaortic valve regurgitation.RESULTS: The data are analyzed with the time-dependent Cox model as benchmark method, and the results are compared with a joint model, leading to different conclusions. The flexibility of the joint model is shown by adding the growth rate of the neoaortic root to the model and adding repeated values of body surface area to obtain a multimarker model. Lastly, it is demonstrated how the joint model can be used to obtain personalized dynamic predictions of the event.CONCLUSIONS: The joint model for longitudinal and time-to-event data is an attractive method to analyze data in follow-up studies with repeated measurements. Benefits of the method include using the estimated natural trajectory of the longitudinal outcome, great flexibility through multiple extensions, and dynamic individualized predictions. Show less
