RiskFix: Supporting Expert Validation of Predictive Timeseries Models in High-Intensity Settings

Many real-world machine learning workflows exist in longitudinal, interactive machine learning (ML) settings. This longitudinal nature is often due to incremental increasing of data, e.g., in clinical settings, where observations about patients evolve over their care period. Additionally, experts may become a bottleneck in the workflow, as their limited availability, combined with their role as human oracles, often leads to a lack of ground truth data. In such cases where ground truth data is small, the validation of interactive machine learning workflows relies on domain experts. Only those humans can assess the validity of a model prediction, especially in new situations that have been covered only weakly by available training data. Based on our experiences working with domain experts of a pediatric hospital's intensive care unit, we derive requirements for the design of support interfaces for the validation of interactive ML workflows in fast-paced, high-intensity environments. We present RiskFix, a software package optimized for the validation workflow of domain experts of such contexts. RiskFix is adapted to the cognitive resources and needs of domain experts in validating and giving feedback to the model. Also, RiskFix supports data scientists in their model-building work, with appropriate data structuring for the re-calibration (and possible retraining) of ML models

Dynamic risk profiling of HCC recurrence after curative intent liver resection

Background and Aims: Following liver resection (LR) for HCC, the likelihood of survival is dynamic, in that multiple recurrences and/or metastases are possible, each having variable impacts on outcomes. We sought to evaluate the natural progression, pattern, and timing of various disease states after LR for HCC using multistate modeling and to create a practical calculator to provide prognostic information for patients and clinicians. Approach and Results: Adult patients undergoing LR for HCC between January 2000 and December 2018 were retrospectively identified at a single center. Multistate analysis modeled post-LR tumor progression by describing transitions between distinct disease states. In this model, the states included surgery, intrahepatic recurrence (first, second, third, fourth, fifth), distant metastasis with or without intrahepatic recurrence, and death. Of the 486 patients included, 169 (34.8%) remained recurrence-free, 205 (42.2%) developed intrahepatic recurrence, 80 (16.5%) developed distant metastasis, and 32 (7%) died. For an average patient having undergone LR, there was a 33.1% chance of remaining disease-free, a 31.0% chance of at least one intrahepatic recurrence, a 16.3% chance of distant metastasis, and a 19.8% chance of death within the first 60 months post-LR. The transition probability from surgery to first intrahepatic recurrence, without a subsequent state transition, increased from 3% (3 months) to 17.4% (30 months) and 17.2% (60 months). Factors that could modify these probabilities included tumor size, satellite lesions, and microvascular invasion. The online multistate model calculator can be found on https://multistatehcc.shinyapps.io/home/. Conclusions: In contrast to standard single time-to-event estimates, multistate modeling provides more realistic prognostication of outcomes after LR for HCC by taking into account many postoperative disease states and transitions between them. Our multistate modeling calculator can provide meaningful data to guide the management of patients undergoing postoperative surveillance and therapy

Low utilization of adult-to-adult LDLT in Western countries despite excellent outcomes: International multicenter analysis of the US, the UK, and Canada

Background & Aims: Adult-to-adult living donor liver transplantation (LDLT) offers an opportunity to decrease the liver transplant waitlist and reduce waitlist mortality. We sought to compare donor and recipient characteristics and post-transplant outcomes after LDLT in the US, the UK, and Canada. Methods: This is a retrospective multicenter cohort-study of adults (≥18-years) who underwent primary LDLT between Jan-2008 and Dec-2018 from three national liver transplantation registries: United Network for Organ Sharing (US), National Health Service Blood and Transplantation (UK), and the Canadian Organ Replacement Registry (Canada). Patients undergoing retransplantation or multi-organ transplantation were excluded. Post-transplant survival was evaluated using the Kaplan-Meier method, and multivariable adjustments were performed using Cox proportional-hazards models with mixed-effect modeling. Results: A total of 2,954 living donor liver transplants were performed (US: n = 2,328; Canada: n = 529; UK: n = 97). Canada has maintained the highest proportion of LDLT utilization over time (proportion of LDLT in 2008 – US: 3.3%; Canada: 19.5%; UK: 1.7%; p <0.001 – in 2018 – US: 5.0%; Canada: 13.6%; UK: 0.4%; p <0.001). The 1-, 5-, and 10-year patient survival was 92.6%, 82.8%, and 70.0% in the US vs. 96.1%, 89.9%, and 82.2% in Canada vs. 91.4%, 85.4%, and 66.7% in the UK. After adjustment for characteristics of donors, recipients, transplant year, and treating transplant center as a random effect, all countries had a non-statistically significantly different mortality hazard post-LDLT (Ref US: Canada hazard ratio 0.53, 95% CI 0.28–1.01, p = 0.05; UK hazard ratio 1.09, 95% CI 0.59–2.02, p = 0.78). Conclusions: The use of LDLT has remained low in the US, the UK and Canada. Despite this, long-term survival is excellent. Continued efforts to increase LDLT utilization in these countries may be warranted due to the growing waitlist and differences in allocation that may disadvantage patients currently awaiting liver transplantation. Lay summary: This multicenter international comparative analysis of living donor liver transplantation in the United States, the United Kingdom, and Canada demonstrates that despite low use of the procedure, the long-term outcomes are excellent. In addition, the mortality risk is not statistically significantly different between the evaluated countries. However, the incidence and risk of retransplantation differs between the countries, being the highest in the United Kingdom and lowest in the United States