Background::Arterial stiffening increases with age and blood pressure and is associated with cardiovascular disease (CVD), but the relationship between blood pressure lowering and arterial stiffening is still uncertain, especially in older people. This study aimed to evaluate the effect of intensive blood pressure treatment on the progression of arterial stiffness and risk of CVD in older patients with hypertension.Methods::The Strategy of Blood Pressure Intervention in the Elderly Hypertensive Patients (STEP) trial was a multicenter, randomized, controlled trial performed at 42 clinical centers throughout China, and 8511 patients aged 60–80 years with essential hypertension were enrolled and randomly assigned to systolic blood pressure (SBP) target of 110 mmHg to <130 mmHg (intensive treatment) or 130 mmHg to <150 mmHg (standard treatment). Patients underwent repeated examinations of the brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI) at baseline, and the arterial stiffness was evaluated at the 3-year follow-up. A total of 5339 patients who had twice repeated measurements were included in this study. Changes in arterial stiffness between the intensive and standard treatment groups were analyzed using a multivariate linear regression model. The Cox proportional hazard regression model was used to evaluate the effect of intensive treatment on primary CVD outcomes.Results::The changes in baPWV were 61.5 cm/s (95% confidence interval [CI]: 49.8–73.2 cm/s) in the intensive treatment group and 98.4 cm/s (95% CI: 86.7–110.1 cm/s) in the standard treatment group ( P <0.001). Intensive treatment significantly delayed the progression of arterial stiffness, with an annual change of 23.1 cm·s –1·year –1vs. 36.7 cm·s –1·year -1 of baPWV in the intensive and standard treatment groups, respectively. During a median follow-up period of 3.36 years, primary CVD outcomes occurred in 77 (2.9%) patients in the intensive treatment group compared with 93 (3.5%) in the standard treatment group. Intensive treatment resulted in a significantly lower CVD risk in patients aged 70–80 years or with SBP <140 mmHg. Conclusion::Intensive blood pressure control with an SBP target of 110 mmHg to <130 mmHg could delay the progression of arterial stiffness and reduce the risk of CVD in older patients with hypertension.Clinical trial registration::http://www.clinicaltrials.gov; No. NCT03015311.

AIM: To evaluate the performance of three distinct large language models(LLM), including GPT-3.5, GPT-4, and PaLM2, in responding to queries within the field of ophthalmology, and to compare their performance with three different levels of medical professionals: medical undergraduates, master of medicine, and attending physicians.METHODS: A total of 100 ophthalmic multiple-choice tests, which covered ophthalmic basic knowledge, clinical knowledge, ophthalmic examination and diagnostic methods, and treatment for ocular disease, were conducted on three different kinds of LLM and three different levels of medical professionals(9 undergraduates, 6 postgraduates and 3 attending physicians), respectively. The performance of LLM was comprehensively evaluated from the aspects of mean scores, consistency and confidence of response, and it was compared with human.RESULTS: Notably, each LLM surpassed the average performance of undergraduate medical students(GPT-4:56, GPT-3.5:42, PaLM2:47, undergraduate students:40). Specifically, performance of GPT-3.5 and PaLM2 was slightly lower than those of master's students(51), while GPT-4 exhibited a performance comparable to attending physicians(62). Furthermore, GPT-4 showed significantly higher response consistency and self-confidence compared with GPT-3.5 and PaLM2.CONCLUSION: LLM represented by GPT-4 performs well in the field of ophthalmology, and the LLM model can provide clinical decision-making and teaching aids for clinicians and medical education.

Objective:To investigate the risk factors and long-term prognosis of major adverse cardiovascular events(MACEs) in patients with dilated cardiomyopathy (DCM).Methods:This study was a single-center retrospective cohort study. Clinical information from 300 patients with DCM hospitalized in Peking Union Medical College Hospital from April 2013 to April 2023 was collected. Based on echocardiography results, the patients were divided into two groups: isolated DCM and DCM with left ventricular non-compaction cardiomyopathy (LVNC). The MACEs, including major heart failure events, severe ventricular arrhythmias, and cardiovascular death, were recorded by outpatient or telephone follow-up. Univariate and multivariate Cox proportional hazard regression models were used to analyze the risk factors affecting the prognosis of patients with DCM. Kaplan-Meier curve and log-rank were used for survival analysis to compare the difference in the incidence of cardiovascular events between the two groups.Results:The included 300 DCM patients were (47.8±16.8) years old, with 197 males (65.7%), of which 237 (79.0%) were isolated DCM and 63 (21.0%) were DCM with LVNC. The follow-up time was 4.0 (1.9, 6.2) years. A total of 142 (47.3%) MACEs occurred, including 117 (39.0%) major heart failure events, 20 (6.7%) severe ventricular arrhythmia events, and 53 (17.7%) cardiovascular death events. Multivariate Cox proportional hazard regression analysis showed that increased left ventricular end-diastolic diameter ( HR=1.21, 95% CI: 1.01-1.44, P=0.042), moderate or severe mitral regurgitation ( HR=1.71, 95% CI: 1.19-2.47, P=0.004), increased ln (N-terminal pro-B-type natriuretic peptide) ( HR=1.30, 95% CI: 1.10-1.54, P=0.002) were independent risk factors for dverse cardiovascular events in DCM patients, and angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB)/angiotensin receptor neprilysin inhibitor (ARNI) treatment ( HR=0.45, 95% CI: 0.26-0.78, P=0.004) was independent protective factor. Kaplan-Meier survival analysis found no significant difference in the risk of MACEs between isolated DCM and DCM with LVNC ( P=0.22). Similarly, there were no significant differences in the incidence of major heart failure, severe ventricular arrhythmia, and cardiovascular death between the two groups (all P>0.05). Conclusion:An increase in left ventricular end-diastolic diameter, moderate or severe mitral regurgitation, elevated N-terminal pro-B-type natriuretic peptide, and non use of ACEI/ARB/ARNI are independent predictors of cardiovascular events in DCM patients. There was no significant risk of MACEs in patients with isolated DCM and DCM with LVNC, and suggested that LVNC may be a unique phenotype and should be accurately managed in combination with genetic background.

Objective:To explore the clinical characteristics and prognostic value in hereditary transthyretin amyloidosis cardiomyopathy (hATTR-CM) patients based on cluster analysis, and to explore the risk factors for cardiovascular composite events.Methods:This retrospective cohort study included hATTR-CM patients who were admitted to Peking Union Medical College Hospital from January 2000 to January 2024. These patients were divided into two clusters using cluster analysis, based on genetic information, demographic information and clinical information. During the follow-up period, cardiovascular composite events were defined as all-cause death and hospitalization for heart failure. Both cardiovascular composite events and all-cause death were the endpoints. Kaplan-Meier survival curves and log-rank method were used to compare the prognostic significance of cluster analysis subgroups. Univariate and multivariate Cox proportional hazard regression models were used to analyze the risk factors affecting the incidence of cardiovascular composite events.Results:A total of 43 patients were included in this study, 30 were male (69.8%). In cluster 1 ( n=27), whose age of onset was (49.9±13.9) years old, 24(88.9%) of them started with neuropathy or gastrointestinal symptoms, and all clinical phenotypes were mixed type (neurological and cardiac). In cluster 2 ( n=16), whose age of onset was (59.0±10.6) years old, 15(93.8%) of them started with heart failure symptoms, and 13(81.3%) were pure cardiomyopathy. During the median follow-up time of 2.6 years, a total of 16 patients (37.2%) experienced composite cardiovascular events, and a total of 12 patients (27.9%) died. Kaplan-Meier survival curves showed a significantly lower cumulative survival rate for cardiovascular composite endpoint events (log-rank P=0.04) and all-cause death (log-rank P=0.04) in cluster 2 than in cluster 1. Univariate Cox proportional hazard regression model analysis showed that hATTR-CM patients with reduced estimated glomerular filtration rate, left ventricular ejection fraction≤40%, and moderate to severe mitral regurgitation were risk factors for vascular composite events (all P<0.05). Multivariate Cox proportional hazard regression analysis showed that left ventricular ejection fraction≤40% was an independent risk factor ( P<0.01). Conclusions:Cluster analysis is a valuable prediction tool on the prognostic stratification of hATTR-CM. Cluster 2, which is late-onset with onset of heart failure symptoms has a worse prognosis during follow-up period. The occurrence of composite cardiovascular events in hATTR-CM is related to left ventricular ejection fraction≤40%. Cluster analysis is helpful for clinical identification of high-risk groups.

Objective:To analyze the influencing factors of patient loyalty in internet diagnosis and treatment, for references for improving the service quality and promoting the sustainable development of internet diagnosis and treatment.Methods:In November 2023, a simple random sampling method was used to select patients who had received internet diagnosis and treatment as the survey objects and conduct a questionnaire survey on performance expectations, effort expectations, social influence, promotion conditions, price values, patient trust and patient loyalty. By establishing an unified theory of acceptance and use of technology model of influencing factors of patient loyalty in internet diagnosis and treatment, the hypotheses were put forward. The structural equation model (SEM) test and mediation effect test were used to verify the hypothesis path and variable mediation effect, and explore the influencing factors of internet patient loyalty.Results:A total of 1 800 patients were included in this study, including 1 188 patients(66.0%) who received internet diagnosis and treatment≥3 times/month. According to the SEA test, performance expectations ( β=0.296, P<0.001), social influence ( β=0.146, P=0.014), promotion conditions ( β=0.366, P<0.001), price values ( β=0.452, P=0.017), and patient trust ( β=0.459, P<0.001) had a direct positive impact on patient loyalty; Social influence ( β=0.147, P<0.001) and promotion conditions ( β=0.084, P<0.001) had a direct positive impact on patient trust. According to the mediation effect test, patient trust partially mediated the relationship between social influence and patient loyalty ( β=0.071, P=0.018), as well as the relationship between promoting conditions and patient loyalty ( β=0.748, P=0.041). Conclusions:Performance expectations, social influence, promotion conditions, price values, and patient trust had a positive impact on patient loyalty, among which social influence and promotion conditions could enhance patient loyalty by strengthening patient trust. It was suggested that relevant institutions should focus on the service quality of internet diagnosis and treatment, further improve performance expectations, expand social impact, improve promotion conditions and regulate price values, so as to enhance the patient loyalty, promote the wide application and rapid development of internet diagnosis and treatment.

Objective To investigate the effect of Shenqi Dihuang decoction combined with recombinant erythropoietin and L-carnitine on renal function in patients with end-stage renal disease and the regulation of Janus activated kinase/signal transducer and activator of transcriptions(JAK/STAT)pathway.Methods A total of 144 patients with end-stage renal disease who were treated in the Second Affiliated Hospital of Xingtai Medical College from October 2019 to October 2021 were selected as the study objects.Patients were divided into Shenqi Dihuang decoction treatment group and conventional treatment group according to random number table method,72 cases in each group.Maintenance hemodialysis was performed in both groups.The conventional treatment group received recombinant erythropoietin and L-carnitine,while the Shenqi Dihuang decoction treatment group had Shenqi Dihuang decoction(prescription composition:30 g each of raw Astragalus,Parasitic loranthus,Eclipta,Polyporus,Poria bark,Raw coix seed,Salvia miltiorrhiza,and Pyrrosia,15 g each of Codonopsis pilosula,Dogwood,Herba lycopi,and Common yam rhizome,10 g each of raw Rehmannia glutinosa,Litchi core,Silkworm sand and Curcuma zedoary,6 g Cassia seed),once a day for 3 months.The clinical efficacy,renal function,microinflammatory status and serum JAK/STAT pathway related protein levels were observed after treatment in two groups of patients with different treatment modalities,and the occurrence of adverse reactions was recorded.Results The total effective rate of Shenqi Dihuang decoction was higher than that of conventional treatment group[90.28%(64/72)vs.77.78%(55/72),P<0.05].After treatment,the residual renal function(RRF),24-hour urine protein,blood urea nitrogen(BUN),blood creatinine(SCr)and inflammatory factors[hypersensitive C-reactive protein(hs-CRP),interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)]were lower than before treatment,the post-treatment RRF of the Shenqi Dihuang decoction treatment group was higher than that of the conventional treatment group(mL/min:4.82±1.18 vs.3.96±1.05),while 24 hours urine protein(mg:62.26±12.16 vs.97.71±16.28),BUN(mmol/L:16.25±3.64 vs.20.65±4.13),SCr(μmol/L:242.25±25.62 vs.280.62±26.63),hs-CRP(mg/L:5.86±1.15 vs.7.78±1.32),IL-6(ng/L:3.26±0.64 vs.4.62±1.13)and TNF-α(μg/L:29.23±5.64 vs.32.66±6.13)were significantly lower than those in the conventional treatment group(all P<0.05).After treatment,JAK and STAT in Shenqi Dihuang decoction group were increased compared with before treatment,phosphorylated JAK(p-JAK)and phosphorylated STAT(p-STAT)were decreased compared with before treatment(both P<0.05),while the serum JAK/STAT pathway related protein levels in conventional treatment group were not significantly changed(all P>0.05).Therefore,JAK and STAT in the Shenqi Dihuang decoction treatment group after treatment were significantly higher than those in the conventional treatment group[JAK(μg/L):1.46±0.28 vs.1.26±0.26,STAT(μg/L):1.37±0.25 vs.0.99±0.24,both P<0.05],p-JAK and p-STAT were significantly lower than those in the conventional treatment group[p-JAK(μg/L):0.45±0.08 vs.0.65±0.13,p-STAT(μg/L):0.66±0.13 vs.0.82±0.28,both P<0.05].There was no statistically significant difference in the incidence of adverse reactions between the two groups[13.88%(10/72)vs.9.72%(7/72),P>0.05].Conclusion Taking Shenqi Dihuang decoction based on recombinant erythropoietin and L-carnitine treatment can effectively inhibit the JAK/STAT signaling pathway,and improve renal function and micro-inflammatory status in patients with end-stage renal disease,thereby improving the therapeutic effect.

Objective:To analyze the costs and effectiveness of five common screening modes and genetic screening for thalassemia in China in order to find the optimal way and provide evidence for the implementation of thalassemia prevention and control projects in Hunan Province.Methods:From June 2020 to April 2021, 12 971 couples from 14 cities and autonomous prefectures in Hunan Province were selected as the study population. The diagnosis of thalassemia was based on the results of genetic testing. Results of routine blood test and hemoglobin electrophoresis were collected and analyzed. The efficacy of five screening modes, at the cut-off value of <80 fl or 82 fl for the mean corpuscular volume (MCV), was analyzed by positive predictive value, negative predictive value, Jorden index and cost-effectiveness ratio. Sensitivity analysis was used to assess the feasibility of genetic screening at different costs after fixing the costs of routine blood and hemoglobin electrophoresis. The five thalassemia screening models are as follows: Mode 1: The woman had a blood routine test first. If the result was positive, the spouse required a blood routine test. If both results were positive, a thalassemia gene test should be offered to the couple. Mode 2: Both husband and wife were screened by blood routine and hemoglobin electrophoresis. If one or both of them were positive, both would be tested for thalassemia gene. Mode 3: The couple received blood routine tests initially. If either was positive, both should receive hemoglobin electrophoresis testing. If either was positive, both parties will conduct thalassemia gene testing. Mode 4: The woman was screened by blood routine and hemoglobin electrophoresis. If any one of them was positive, the woman would be tested for thalassemia gene. If the gene test result was positive, the spouse should receive thalassemia gene. Mode 5: Both spouses conducted a blood routine test. If either was positive, both would conduct hemoglobin electrophoresis test. If both were positive, both spouses should receive thalassemia gene testing. Gene testing mode: The woman would be tested for thalassemia, and her spouse would have thalassemia test too if her result was positive.Results:When using MCV<80 fl as the cut-off for diagnosing thalassemia, the Youden indices of the five prenatal screening modes in Hunan Province were 0.551, 0.639, 0.898, 0.555 and 0.356, while when using MCV<82 fl as the cut-off, the Youden indices were 0.549, 0.629, 0.851, 0.548 and 0.356. When the MCV cut-off value was <80 fl, the missed diagnosis rates of the five screening modes were 44.44%, 0.00, 0.00, 18.52% and 62.96%, and the cost-effectiveness ratios were 21 709, 250 939, 76 870, 138 463 and 92 860 yuan (RMB)/couple, respectively. When the price of genetic testing was lower than 55 yuan (RMB), the cost-effectiveness ratio of genetic screening was lower than that of Mode 3.Conclusions:MCV<80 fl can be considered as the positive criteria in blood routine screening for thalassemia in Hunan Province, and the cost-effectiveness ratio of Mode 3 (the couple received blood routine tests initially. If either was positive, both should receive hemoglobin electrophoresis testing. If either was positive, both parties will conduct thalassemia gene testing) is the best. Genetic screening has certain advantages with the decreasing price.

OBJECTIVE: To study the effect of nano-cerium oxide on the early development of zebrafish embryos. METHODS: The well-developed zebrafish embryos were randomly divided into the control group and the 50, 100, 200, 400 and 800 mg/L dose groups, with 40 embryos in each group. The dose groups were treated with nano-cerium oxide at the corresponding mass concentration for 5 days. The control group received no treatment. The death and malformation of embryos were observed. The heart rate of zebrafish embryos was recorded using confocol microscope. The protein expression of microtubule-associated protein 1 light chain 3(LC3) and cleaved Caspase-3 and were observed by Western blot technology. RESULTS: The death and embryonic malformation rate of zebrafish embryos increased with the increase of doses, showing statistical significance(P<0.01). The heart rate of the 800 mg/L dose group was decreased compared with the control group [(77±8) vs(93±4) beats/min, P<0.01]. There was no statistical significant difference in LC3-Ⅱ protein expression in each groups(P>0.05). The cleaved Caspase-3 protein expression increased in all dose groups compared with the control group(P<0.05). The cleaved Caspase-3 protein expression in the 200 mg/L dose group was higher than that in the 50 mg/L dose group(P<0.05). CONCLUSION: The nano-cerium oxide may induce cell apoptosis, causing toxic effect in early development of zebrafish embryos.

Objective To explore the relationship between training burnout, sleep quality and heat regulation response, severe heatstroke in people performed 5-km armed cross-country training. Methods 600 male officers and soldiers who participated in 5-km armed cross-country training in summer from 2017 to 2018 were enrolled. All trainees participated in 5-km armed cross-country training in environment with ambient temperature > 32 ℃ and (or) humidity > 65%. They were divided into two groups according to whether severe heatstroke occurred during 5-km armed cross-country training. The age, military age, body mass index (BMI), physical fitness score, external environment (such as ambient temperature, relative humidity, wind speed, heat index), training burnout score and Pittsburgh sleep quality index scale (PSQI) score, heart rate (HR), core temperature (Tc), sweating volume and serum Na+, K+, Cl- levels were compared between the groups. The risk factors of severe heatstroke during 5-km armed cross-country training were screened by binary multivariate Logistic regression analysis. Results There were 26 cases of severe heatstroke in 600 trainees who participated in 5-km armed cross-country training, with an incidence of 4.33%. There was no significant difference in age, military age, BMI, physical fitness score and external environment of 5-km armed cross-country training between people with or without severe heatstroke. Compared with those without severe heatstroke, the dimensions of training burnout and the total average scores of training burnout of severe heatstroke personnel before 5-km armed cross-country training were increased significantly (physical and mental exhaustion score: 12.4±2.5 vs. 9.4±3.5, training alienation score: 8.8±2.8 vs. 5.8±2.3, low sense of achievement score: 8.2±2.7 vs. 5.6±2.3, total score of training burnout: 9.8±3.2 vs. 6.9±3.2, all P < 0.01), all factors except daytime dysfunction (DD) of PSQI and total PSQI score were also increased significantly [sleep quality (SQ) score: 1.0 (1.0, 2.0) vs. 1.0 (1.0, 1.0), fall asleep time (SL) score: 2.0 (1.0, 3.0) vs. 1.0 (1.0, 1.0), sleep time (SH) score: 1.0 (0.8, 2.0) vs. 1.0 (0, 1.0), sleep efficiency (SE) score: 1.0 (0, 1.0) vs. 0 (0, 0.8), sleep disorder (SD) score: 2.0 (1.0, 3.0) vs. 1.0 (0, 2.0), total PSQI score: 1.0 (1.0, 2.0) vs. 1.0 (0, 1.0), all P < 0.01], HR was increased significantly at onset (bpm: 120.00±10.57 vs. 86.49±14.91, P < 0.01), Tc was increased significantly (℃: 41.46±0.57 vs. 37.97±0.83, P < 0.01), serum electrolyte contents were decreased significantly [Na+ (mmol/L): 130.54±5.97 vs. 143.15±10.56, K+ (mmol/L): 3.72±0.44 vs. 4.37±0.50, Cl- (mmol/L):97.58±4.80 vs. 102.10±2.39, all P < 0.01], and the amount of sweat during training was increased significantly (g: 395.81±16.16 vs. 371.88±40.76, P < 0.01). Binary multivariate Logistic regression analysis showed that total score of training burnout [odd ratio (OR) = 0.653, 95% confidence interval (95%CI) = 0.563-0.757], total PSQI score (OR =0.693, 95%CI = 0.525-0.916), HR (OR = 0.871, 95%CI = 0.838-0.908), Tc (OR = 0.088, 95%CI = 0.043-0.179), sweating volume (OR = 0.988, 95%CI = 0.979-0.997), Na+ (OR = 1.112, 95%CI = 1.069-1.158), K+ (OR = 13.900, 95%CI = 5.343-36.166), Cl- (OR = 1.393, 95%CI = 1.252-1.550) were independent risk factors for severe heatstroke during 5-km armed cross-country training (all P < 0.01). Conclusion Increase in training burnout, total PSQI score, excessive changes of body heat regulation response and excessive loss of Na+, K+, Cl- in serum are independent risk factors for severe heatstroke during 5-km armed cross-country training under the same conditions with high temperature and humidity environment.

To explore the effects of different fluid replenishment methods on the internal environment, body thermal regulatory response and severe heatstroke of 5-km armed cross-country training soldiers. Methods A Special Force officers and soldiers who participated in 5-km armed cross-country training (2-3 times a week, 25-30 minutes each time for 3 weeks) during summer training from June to July in 2018 were enrolled, and they were divided into three groups according to the random number table, with 300 trainees in each group. 200 mL of drinking fluids were given to each group 15 minutes before and after each 5-km armed cross-country training: A group with boiled water, B group with purified water, and C group with beverage prepared by pharmaceutical laboratory of the 990th Hospital of PLA Joint Logistics Support Force (100 mL containing 6 g carbohydrates, 42 mg sodium, and 11 mg potassium). The venous blood was collected before and after the last training or during the onset of severe heatstroke to do the following tests: serum cardiac troponin I (cTnI, chemiluminescence), MB isoenzyme of creatine kinase (CK-MB, immunosuppressive), serum creatinine (SCr, enzymatic method), urea nitrogen (BUN, enzymatic method), alanine aminotransferase (ALT, tryptase), aspartate transaminase (AST, tryptase), and Na+, K+, Cl- (electrode method). The heart rate (HR) and core temperature (Tc, anal temperature) were monitored at the same time. The amount of sweat in training and the occurrence of severe heatstroke were also recorded. Results There was no significant difference in heart, liver, kidney function, electrolyte and body heat regulation reaction among three groups of 5-km armed cross-country trainees before training. Compared with before training, the levels of serum cTnI, CK-MB, SCr, BUN, ALT, AST, HR and Tc were significantly increased after training or during the onset of severe heatstroke in three groups, while the contents of Na+, K+, Cl- were significantly decreased, but the increase or decrease of group C was relatively smaller compared with group A and group B [cTnI (μg/L): 0.9 (0.6, 1.4) vs. 1.1 (0.7, 2.8), 1.0 (0.6, 3.3); CK-MB (U/L): 7.0 (5.0, 11.0) vs. 9.0 (6.0, 14.5), 8.0 (6.0, 15.0); SCr (μmol/L): 92.09±18.64 vs. 102.78±18.77, 103.64±20.07; BUN (mmol/L): 7 (6, 9) vs. 9 (8, 11), 10 (8, 13); ALT (U/L): 27 (22, 34) vs. 36 (30, 43), 34 (27, 43); AST (U/L): 37 (31, 48) vs. 41 (34, 50), 39 (34, 51); HR (bpm):87.01±17.07 vs. 95.88±21.06, 96.59±22.04; Tc (℃): 37.73±0.81 vs. 38.03±1.05, 38.10±1.04; Na+ (mmol/L):150.14±3.86 vs. 144.18±8.89, 144.04±9.39; K+ (mmol/L): 4.32±0.57 vs. 4.15±0.62, 4.13±0.51; Cl- (mmol/L):100.43±3.71 vs. 98.42±4.24, 98.41±4.58; all P < 0.01]. The incidence of severe heatstroke in group C was significantly lower than that in group A and group B [1.67% (5/300) vs. 5.00% (15/300), 5.33% (16/300), χ2 = 6.424, P = 0.040]. There was no significant difference in sweating volume in groups A, B, C (g: 370.47±48.71, 370.85±50.66, 370.17±50.21, F = 0.014, P = 0.986). There was no significant difference in the above indexes between group A and group B (all P > 0.05). Bi-classification Logistic regression analysis showed that the increase of HR, Tc and excessive loss of Na+, K+, Cl- were risk factors for severe heatstroke [odds ratio (OR) was 0.848, 0.138, 1.565, 17.996 and 2.328 respectively, all P < 0.01]. Conclusions Timely supplementation of carbohydrate, sodium and potassium ions can effectively change the internal environment and body heat regulation reaction of 5-km armed cross-country trainees, so as to reduce the occurrence of severe heatstroke. The increases of HR, Tc and excessive loss of Na+, K+, Cl- are risk factors for severe heatstroke.