Objective To investigate the effect of formative assessment on skill acquisition of basic life support (BLS) among medical students. Methods Totally 206 undergraduates were ran-domized into control group (C group) and interventional group (F group). A BLS lecture was given in both groups. And then, 45 min BLS training and BLS skill assessment (after training) were given in C group. Undergraduates in F group received BLS skill assessment (formative assessment) before training, and 15 min feedback was delivered based on the assessment, then 30 min BLS training was conducted. Skills assessment was conducted again in F group after the training. Student's-t-test was used to compare the difference of skills between the two groups and P<0.05 signifies statistically sig-nificant differences. Results Score of F group (85.2±7.3) were higher than that in C group (68.2± 13.2), with statistical difference. Conclusion A formative assessment could significantly improve skill acquisition of BLS among medical students.

【Objective】 To assess the prevalence of chronic diseases and associated influencing factors among residents in Ali so as to provide reference for local prevention and control of chronic diseases. 【Methods】 Stratified cluster random sampling was used to investigate the prevalence of chronic diseases and their influencing factors among permanent residents over 18 years of age in Aili. 【Results】 Totally 606 subjects were included, with a prevalence of chronic diseases of 39.93% and the highest prevalence of rheumatoid arthritis of 14.03%. The prevalence of chronic diseases was significantly different among ethnicity, age, education, occupation, personnel category, family living standard, amateur physical exercise, fuel type and self-rated health (P<0.05). Logistic regression showed that the risk of chronic diseases among the residents aged 50 years and above was 2.656 (95% CI: 1.439-4.901) times higher than that of residents under 30 years; the risk of chronic diseases among the residents with elementary school education and below was 3.528 (95% CI: 1.519-8.197) times higher than that of residents with college education and above; housework personnel could reduce the risk of chronic diseases (OR=0.365, 95% CI: 0.161-0.828); residents with poor self-rated health had 5.814 (95% CI: 3.243-10.423) times higher risk of chronic diseases than those with good self-rated health; and those with a weight gain of more than 2.5 kg in the past year could increase the risk of chronic diseases (OR=2.029, 95% CI: 1.226-3.358). 【Conclusion】 The prevalence of chronic diseases is high in residents of Ali. Attention should be paid to the elderly population with poor self-rated health and tendency of weight gain. Personalized behavioral lifestyle health education is helpful in preventing the occurrence of chronic diseases.

【Objective】 To clarify the hematological characteristics and current situation of chronic mountain sickness among Tibetan residents in extreme high altitude area (more than 5 000 m above the sea level) of Ali district based on the analysis of physical examination and blood test results. 【Methods】 Totally 250 Tibetan residents were selected by convenient sampling for blood oxygen saturation (SpO2), heart rate, and blood routine examination. Chronic mountain sickness was determined according to the hemoglobin (Hb) level and SpO2. 【Results】 The red blood cell (RBC), Hb and hematocrit (HCT) of the Tibetan residents at 5 200-meter altitude were all higher than the normal physiological reference range of China. Mean red blood cell volume (MCV), mean red blood cell hemoglobin content (MCH), mean red blood cell hemoglobin concentration (MCHC), white blood cell (WBC) and platelet (PLT) were in the upper limit of the reference value. The RBC, Hb, HCT and MCHC of male Tibetan residents were higher than those of females, while PLT was lower than that of females, with significant differences. There were no statistical differences in MCV, MCH or WBC among different genders of Tibetan residents. The SpO2 of the Tibetan residents was about 85% of the normal value, and the males had higher SpO2 than the females in the same age group, and the difference was statistically significant, but the heart rate did not differ significantly. The prevalence rate of chronic mountain sickness in this area was as high as 16.4%, and the prevalence rate of heavy manual workers was significantly higher than that of light manual workers, with significant differences. 【Conclusion】 The high-altitude anoxic environment causes the changes in red blood cells, hemoglobin, and oxygen saturation of local residents, and the prevalence of chronic mountain sickness increases significantly. Labor intensity is one of the risk factors for chronic mountain sickness in high-altitude areas.