Incidence/prevalence And Surveillance Results For Keshan Disease In Jilin Province

BackgroundKeshan disease (KSD) was formerly considered to be an endemic cardiomyopathy of unknown causation in China, which poses a great hazard to the health of peasants. The fatality rate and disabled rate of KSD were high. From it was discovered to now, it has been one hundred years. Jilin province which was one of the most seriously stricken regions, has found this disease in all 7 cities, including 37 towns, 323 countries, but besides Baichen City and Songyuan City. About 12,720,000 populations were directly threaten by KSD, who were distributed among mountain areas in east of Jilin. Surveillance data from those years indicated that although acute KSD and sub-acute KSD had been basically controlled, there also existed latent KSD and chronic KSD, which meant factors of pathopoiesia had not yet totally eliminated.In 1995, a survey on KSD was carried out which was a survey across all cities of Jilin province. Until now, it has been ten years pasted. How has the disease developed? What are the situations of heart function of populations? Does KSD appear new features and trends? Do the basic doctors have good knowledge of KSD? All those need to be answered. Thus, from 2003 to 2006, a survey on KSD was carried out in regions of slight suffered, moderate suffered and seriously suffered, respectively. This survey would help to grasp the newest KSD development and do better guidance to prevention work in further.Objective1. To investigate KSD in three areas, and to estimate situation of KSD in Jilin province by calculating prevalence rate, incidence rate.2. To find out heart function of people in survey sites.3. To understand how basic doctors have knowledge of KSD by tracking the current situation of registered patients.4. To evaluate efficacy of preventive measurements of KSD so as to offer suggestions to prevention work.MethodsAccording to the distribution of KSD we used classified sampling to confirm survey sites. People who wanted to participant the survey should fit the following criteria: (1) resident in survey sites, and (2) voluntary. Every participant would finish a questionnaire and then do a clinical check, mark electrocardiogram (ECG). People who were confirmed to suffer KSD would ask to take chest orthophoric X-ray photography. Track registered patients with Keshan disease to re-diagnose. Carry out social investigation to every country in Tonghua district, such as"three prevention and four improvement measurements"(including cold prevention, soot prevention, damp prevention; residence condition improvement, environment improvement, water quality improvement and nutrition improvement), economic income, meal structure and so on.Database establishment was performed using Excel. Data analysis was performed using SPSS version 12.0 (SPSS, Chicago, IL) software. Mean and standard deviation were used to analyze measurement data; ratio and proportion were used to analyze count data. Chi-square test was used to analyze the classification data. Prevalence rate of Keshan disease and number of patients in Jilin province were estimated by using sampling prevalence rate and 95% confidence interval. Univariate linear correlation analysis was used to analyze the correlation between prevalence rate of KSD e and economic income, meal structure in those yearsResults1. Among 12347 participants, 569 people suffered KSD, and the prevalence rate was 4.61%. Five hundreds and three patients were discovered at this time. Twenty-six patients who were all children were diagnosed as new sufferers, and the incidence rate was 0.21%. According to the current prevalence rate of KSD in Jilin province, which was 5.7‰(95%CI: 0.7%～0.4%), there would be 73226 patients who suffered KSD all over the province conservatively. And among those, 15314 patients would suffer chronic KSD, 57912 patients would suffer latent KSD. There would be 3346 new patients, and 64732 patients who discovered first time. No acute and sub-acute patients with KSD would appear. 2. Many people in KED areas had bad heart function, and with heart enlarged. There were significant differences in abnormal ECG among people in Tonghua, the west, and Jilin districts(χ~2 =42.959,P<0.001).More people in Jilin district then those in Tonghua district (χ~2 =6.762,P =0.009) or in the west (χ~2 =43.078,P<0.001) had abnormal ECG; more people in Tonghua district then those in the west had abnormal ECG (χ~2 =12.905,P<0.001).Comparing people in three regions with ECG in approximately normal, there existed significant differences (χ~2 =62.464,P<0.001). Less people in Tonghua district then those in the west(χ~2 =45.848,P<0.001) or in Jilin district (χ~2 =56.733,P<0.001) had approximately normal ECG.. There were no significant differences in approximately normal ECG between people in the west and in Jilin district (χ~2 =0.659,P=0.417).Comparing the testing results of heart enlargement in three regions, there were significant differences (χ2 =10.667,P=0.005).Higher rates of heart enlargement among people in Tonghua district (χ2 =7.691,P =0.006) and in Jilin district (χ2 =9.227,P =0.002) then those in the west. There was no significant difference between people with heart enlargement in Tonghua district and Jilin district (χ2 =0.012,P=0.912).3. Tracking 374 registered patients with KSD (including 148 patients in Tonghua district, 130 patients in the west, and 96 patients in Jilin district), 39.04% of them re-checked. Among those re-checked, 40 patients (27.40%) kept former diagnosis, 106 patients (72.60%) excluded former diagnosis. Among 228 patients who did not re-check, 41(17.98%) moved out, 42 (18.42%) dead, the rest were not tracked. 4. The result of cardiac antibody testing among people in Tonghua district: it was negative in both patient group and control group; there were no Coxsackievirus positive besides one case appeared in control group.5. Rice, flour and corn were the main sections in people's meal structure in Tonghua area. There were good correlations between KED and meal structures, KED and economic income, which indicated that improvement of meal structures and economic did good to control KED.6. A total of 8756 people had been tested by the national KED sentinels from 1990 to 2007. No people suffered nither acute KED nor sub-acute KED in the ten sentinels. But both latent KED and chronic KED incidence rates and prevalence rates raised yearly. About 208 KED sufferers out of 6074 people had been found among the last seven years in the provincial sentinels. About 153 patients were found as latent KED sufferers, 55 patients were found as chronic KED sufferers. The average prevalence rate was 3.42%, which was lower compared to the rate which was reported by the national sentinel surveillance.7. In the first surveillance, KED patients accounted for 66.70% in the patients who had heart englargement. And in the surveillance which was performed in 2000 to 2004, the rate was 45.59%. The rates of suffering hypertention and hypertentional heart englargment were much higher than before, accounting for 9.37% in the heart disease patients.8. The lowest levelof selenium in hair among the key population in the sentinel was 0.3623mg/kg, which was higher than national average level, and had attained to the level in non-KED districts. Besides, the level maintained stably in five years. Compared to meal structures and living standard of peasants in 1990, meal structures and living standard of peasants had improved a lot in 1994. There were no significantly differences in nutrition levels between KED districts and non-KED districts.Conclusions1. Jilin province was still one of the most seriously suffered KED areas. Although no changed in the whole structure, slight degree of changes appeared in part.2. Many people in KED areas had bad heart function, and with heart enlarged. In the light of good social environment, KED developed as usual. No sign showed it would break out. But considering the hidden risks, such as new KSD patients existed in children, it might break out, which should make people have high attention to.3. There were good correlations between KED and meal structures, KED and economic income, which indicated that improvement of meal structures and economic did good to control KED.4. There were good relationship between state of KED and meal structure, income level. Although improving those could help to reduce the prevalence rate of KED, discision factors would also be found.5. According to surveillance data, KED prevalence was increasing steadily from 1990 to 2007. The structure of age showed senility and those patients who suffered chronic KED lived longer than before.6. The income level was increasing, the meal structure was improving yearly in the national sentinels. The levelof selenium in hair had reach to the level in non-KED districts.