ObjectiveTo investigate the value of third lumbar skeletal muscle mass index （L3-SMI） in predicting the long-term prognosis of patients with acute-on-chronic liver failure （ACLF）， and to provide a useful tool for prognostic scoring of ACLF patients. MethodsA retrospective analysis was performed for the data of 126 patients who underwent abdominal computed tomography （CT） scanning and were diagnosed with ACLF in Shanxi Bethune Hospital from December 2017 to December 2021， including clinical indicators， biochemical parameters， and model for end-stage liver disease （MELD） score， and L3-SMI was calculated. The independent-samples t test was used for comparison of normally distributed continuous data between groups， and the Mann-Whitney U test was used for comparison of non-normally distributed continuous data between groups； the chi-square test was used for comparison of categorical data between groups. The receiver operating characteristic （ROC） curve was used to assess the diagnostic value of L3-SMI and other variables （MELD score and Child-Pugh score）， and the DeLong test was used for comparison of the area under the ROC curve （AUC）. ResultsAmong the 126 patients enrolled， 44 （35%） died within 2 years and 82 （65%） survived. Compared with the survival group， the death group had significantly higher age， incidence rate of ascites， international normalized ratio， MELD score， and Child-Pugh score （all P<0.05） and a significantly lower value of L3-SMI ［38.40 （35.95‍ ‍—‍ ‍46.29） cm²/m² vs 44.19 （40.20‍ ‍—‍ ‍48.58） cm²/m²， Z=-2.855， P=0.004］. L3-SMI had an AUC of 0.720 in predicting 2-year mortality in ACLF patients， with a sensitivity of 63.6% and a specificity of 80.5%， and a combination of L3-SMI， MELD score， and Child-Pugh score had a significantly better AUC than a combination of MELD score and Child-Pugh score in predicting 2-year mortality （0.809 vs 0.757， Z=2.015， P<0.05）. ConclusionL3-SMI has a high predictive value for the prognosis of ACLF patients， and the combination of L3-SMI、MELD score and Child-Pugh score has a higher predictive value for ACLF patients， and the inclusion of L3-SMI or sarcopenia in the conventional prognostic scores of ACLF patients may increase the ability to predict disease progression.

Background Swimming is becoming increasingly popular for its combined leisure and fitness benefits. However, polluted swimming pool water may pose various health risks. Previous studies have indicated that health indicators of swimming venues have lower qualification rates compared to other public places, highlighting the urgent need to optimize hygiene management measures. Objective To assess the overall hygiene status and identify the key factors influencing water quality in Shanghai’s swimming venues from 2010 to 2024, and to provide a scientific basis for optimizing water quality management. Methods Water quality was assessed in three stages (2010—2019, 2020—2022, and 2023—2024) based on the monitoring data of Shanghai’s swimming venues (2010—2024). The influences of monitoring stage, region, season, scale, day of week, and per capita attendance on water quality were analyzed using chi-square tests and logistic regression. Results From 2010 to 2024, water quality was monitored in 1478 swimming venues. The compliance rates of turbidity, pH, urea, oxidation-reduction potential, free residual chlorine, combined residual chlorine, total bacteria, coliforms, and heat-resistant coliforms in swimming pool water, and free residual chlorine in the foot disinfection basin water samples were 99.56%, 94.73%, 73.00%, 47.50%, 56.55%, 54.12%, 97.74%, 99.49%, 99.90%, and 69.19%, respectively. The overall water quality compliance rate was 85.28%. The main non-compliant indicators for swimming pool water were urea, ORP, free residual chlorine, and combined residual chlorine, along with free chlorine residual in the foot disinfection basin water samples. Using the period before the implementation of the new national standard as reference, the results of logistic regression revealed that the qualification rates of urea, ORP, and free residual chlorine in the swimming pool water samples, as well as free residual chlorine in foot disinfection basin water samples, were significantly higher during the two phases after launching the new standard (2020–2022 and 2023–2024), and the associated odds ratios (95%CI) were 1.28 (1.00, 1.64) and 1.48 (1.12, 1.95), 13.35 (7.63, 23.37) and 10.78 (7.00, 16.60), 2.54 (1.81, 3.58) and 3.18 (2.41, 4.20), and 3.14 (2.14, 4.60) and 2.83 (1.89, 4.23), respectively. Compared with the reference group, those sampled in urban pools and in non-summer seasons showed higher qualification rates of urea and ORP; in contrast, the pools with high visitor flow showed lower qualification rates of free residual chlorine in both water samples of swimming pools and foot disinfection basins (P<0.05). Conclusion The implementation of the new national standard has effectively enhanced the management standards and significantly improved overall water quality of swimming venues in Shanghai. However, the compliance rates of free residual chlorine and urea in swimming pool water still need further improvement. The compliance of some indicators is influenced by region, season, scale, and average passenger flow, particularly in small suburban swimming venues. Future efforts should focus on refining water quality management strategies and enhancing public health management.