Evaluation of the proportional hazards assumption and covariate adjustment methods in comparative surgical observational studies with time-to-event endpoints.

INTRODUCTION: Comparative studies on surgical treatments with time-to-event endpoints have provided substantial evidence for clinical practice, but the accurate use of survival data analysis and the control of confounding bias remain big challenges. METHODS: This was a survey of surgical studies with survival outcomes published in four general medical journals and five general surgical journals in 2021. The two most concerned statistical issues were evaluated, including confounding control by propensity score analysis (PSA) or multivariable analysis and testing of proportional hazards (PH) assumption in Cox model. RESULTS: A total of 74 studies were included, comprising 63 observational studies and 11 randomized controlled trials. Among the observational studies, the proportion of studies utilizing PSA in surgical oncology and non-oncology studies was similar (40.9 % versus 36.8 %, P = 0.762). However, the former reported a significantly lower proportion of PH assumption assessments compared to the latter (13.6 % versus 42.1 %, P = 0.020). Twenty-five observational studies (25/63) used PSA methods, but two-thirds of them (17/25) showed unclear balance of baseline data after PSA. And the proportion of PH assumption testing after PSA was slightly lower than that before PSA, but the difference was not statistically significant (24.0 % versus 28.0 %, P = 0.317). Comprehensive suggestions were given on confounding control in survival analysis and alternative resolutions for non-compliance with PH assumption. CONCLUSION: This study highlights suboptimal reporting of PH assumption evaluation in observational surgical studies both before and after PSA. Efforts and consensus are needed with respect to the underlying assumptions of statistical methods.

The hospitalization burden of inflammatory bowel disease in China: a nationwide study from 2013 to 2018.

Background: The past decade has witnessed a dramatic increase in the number of patients with inflammatory bowel disease (IBD) in China. The nationwide burden of hospitalization remains unclear, however. We aimed to address this gap by conducting analysis using a nationwide database. Methods: Population-based hospitalization rates from 2013 to 2018 were calculated by extrapolating the number of patients in the database to the national level. Surgical rates, annual hospital charges, and length of stay were also used for quantification of hospitalization burden. The Poisson regression analysis and the Cochran-Armitage trend test were conducted to analyze temporal trends as expressed as annual percentage of change (APC) with 95% confidential intervals (CIs). Results: From 2013 to 2018, the hospitalization rates for Crohn's disease (CD) and ulcerative colitis (UC) in China increased from 2.20 (95% CI = 2.17-2.22) to 3.62 (3.59-3.65) per 100,000 inhabitants (p < 0.0001) with an APC of 10.68% (6.00-15.36%) and from 6.24 (6.20-6.28) to 8.29 (8.23-8.33) per 100,000 inhabitants (p < 0.0001) with an APC of 5.73% (2.32-9.15%), respectively. Surgical rates decreased from 7.96% (7.29-8.63%) to 5.56% (5.11-6.00%) for CD patients (p < 0.0001) with APC of -6.30% (-11.33 to -1.27%) and from 3.54% (3.26-3.82%) to 2.52% (2.32-2.72%) for UC patients (p < 0.0001) with APC of -6.35% (-16.21 to 3.51). In 2018, there were estimated 166,000 IBD patients hospitalized costing a total of $426.37 million ($149.91 + $276.46 million) across the entire China. Conclusion: The population-based hospitalization rate of IBD increased, whereas the surgical rate decreased from 2013 to 2018 in China.

A biotechnological process efficiently co-produces two high value-added products, glucose and xylooligosaccharides, from sugarcane bagasse.

In this study, a co-production of two high value-added products, glucose and xylooligosaccharides (XOS), was investigated by utilizing sugarcane bagasse (SB) within a multi-product bio-refinery framework optimized by Box-Behnken design-based response surface methodology. The developed process resulted in a maximum cellulose conversion of xylan-removed SB, 98.69±1.30%, and a maximum extracted SB xylan conversion into XOS (xylobiose and xylotriose) of 57.36±0.79% that was the highest SB xylan conversion reported in the literature, employing cellulase from Penicillium oxalicum EU2106 and recombinant endo-ß-1,4-xylanase in Pichia pastoris. Consequently, a mass balance analysis showed that the maximum yields of glucose and XOS were 34.43±0.32g and 5.96±0.09 g per 100 g raw SB. Overall, this described process may be a preferred option for the comprehensive utilization of SB.