Investigation of Disease Spectrum and Analysis of Risk Factor for Digestive System Diseases of Chinese Army During a Field Training on The Midland of China

Objective To investigate the digestive disease spectrum of Chinese army servicemen during a eld training on the midland and to analyze risk factors of diseases in order to discuss the relative prevention and treatment strategies. Methods Seven troops during a eld training on the midland of China were randomly selected by using stratied cluster random sampling methods, all soldiers in that received a questionnaire survey, and then we collected all questionnaires and summarized the soldiers’ digestive system disease spectrum, and discussed risk factors for diseases. Results 3055 valid questionnaires were nally collected,896 soldiers had digestive symptoms, and of all symptoms diarrhea was the most common,whose ratio was 29.3%; 507 soldiers suffered from digestive system diseases, including gastritis, enteritis,digestive ulcer, functional bowel disease, which were more common. By the logistic regression analysis, length of military service time, identity of army ocer,length of a eld training time,training pressure, chilled abdomen, and deled food were possible risk factors for digestive diseases. Conclusions During a eld training, a healthy and regular diet, the thermal outt, appropriate decompression of negative emotions and reasonable training time may effectively decrease the risk of digestive diseases, so that to reduce attrition. gastrointestinal bleeding, inammatory bowel disease, functional bowel disease, gastroesophageal reux disease, pancreatitis, abnormal liver function nausea;(4)Related symptoms: vomiting, abdominal distension, diarrhea, abdominal pain, constipation, poor appetite, acid reux;(5)Treatment: medical institutions, examination items, treatment effect, etc.


Introduction
Diseases of the digestive system have a high incidence among internal medical diseases. According to the research of depletion of Chinese soldier numbers in modern wars, digestive system diseases also contributed to a high incidence in wartime. In Chinese Resistance War against Japanese Aggression and China National War of Liberation, the incidence of digestive diseases took the rst place among all internal medical diseases, and it took the second place in the war to resist U.S. aggression and aid Korea and Sino-Vitnamese War [1] .In the war to resist U.S. aggression and aid Korea, the ratio of Chinese soldiers hospitalized for digestive diseases to internal diseases was 30.2%, which was signi cantly higher than 19.3% of China domestic troops [1] . At that time, due to the poor training conditions and poor medical cares, these four types of digestive diseases,gastroenteritis, stress ulcer, functional abdominal pain and gastrointestinal bleeding, were the most common [1][2] . Since the 19th National Congress of the Communist Party of China, China has entered a new era, and the reform of armed forces has made steady progress.Army soldiers are more highly trained and submitted to more strictly imposed discipline than before, but the life conditions and medical cares are signi cantly better. However,there are few studies on the investigation and analysis of the digestive diseases spectrum change of Chinese soldiers in recent years. So the aim of our study is to investigate the new digestive system disease spectrum of army soldiers during a eld training in the midland of China, and then to look for relevant strategies for disease control and prevention, which may reduce non-combat attrition and improve the forces ghting capacity.
Materials And Methods

1.Objects
According to the results of previous research, the incidence of digestive diseases in the Chinese general population is about 30%. By using this as a reference baseline prevalence rate, with an accuracy of ± 2%, the sample size of this study is estimated to be at least 2,017. Finally, a total of 3,055 army servicemen during a eld training in the midland of China from January 2021 to May 2021 were selected as investigation objects in our study.So our study meets the requirement of sample size.

2.Methods
One basic unit was selected from each of seven provinces in the midland of China by the strati ed cluster random sampling method. Questionnaire survey was carried out on all military o cers and soldiers in the units by military doctors who had a good command of medical knowledge and received professional training before the survey. The datas from the questionnaires were recorded and input into the excel by one person and meanwhile were checked by another one to ensure the authenticity and validity of results.

3.Questionnaire
The questionnaire was designed by gastroenterologists, epidemiologists and statistics experts on the foundation of literature review. And the contents of this questionnaire include ve aspects: (1)Basic information: Gender, age, height, weight, educational background, military services, military service time, status, smoking, diet habits, family history of digestive diseases and use history of NSAIDs(aspirin, clopidogrel, ibuprofen,etc.); (2)Training and education: the daily military training time, education on digestive disease prevention knowledge; (3)digestive diseases: acute gastroenteritis, digestive ulcer, gastrointestinal bleeding, in ammatory bowel disease, functional bowel disease, gastroesophageal re ux disease, pancreatitis, abnormal liver function nausea;(4)Related symptoms: vomiting, abdominal distension, diarrhea, abdominal pain, constipation, poor appetite, acid re ux;(5)Treatment: medical institutions, examination items, treatment effect, etc.
Before a formal investigation, we had to check the reliability and validity of the questionnaire. So the questionnaires were distributed to 100 people and then 98 valid questionnaires were collected. The datas were input into IBM SPSS Statistics Software. Through reliability analysis the questionnaire, Crobach's α coe cient was calculated to be 0.86, so the reliability of the questionnaire was good. Through the validity analysis of the questionnaire, the results that KMO value 0.6, the signi cance of Bartlett test of spherical degree <0.01 and load coe cient of each item 0.05 were obtained, so the validity of the questionnaire was also good.

4.Statistical analysis
Page 3/10 The valid questionnaire information was input into the excel form to establish a database. And descriptive statistical analysis was carried out by SPSS 26 software. Counting datas were tested by X 2 test. Grade datas were tested by Mann-Whitney test. The correlation analysis on risk factors of the digestive diseases was conducted by logistics regression analysis. If P <0.05, the difference was statistically signi cant.

1.The distributed questionnaires
A total of 3,200 questionnaires were sent out,and then 3,070 were collected, and nally 3,055 were valid through the check, so an effective rate of this survey was 95.5%.
2.Servicemen's Symptom and disease spectrum of digestive system in the eld training A total of 896 patients had digestive symptoms, with a prevalence of 29.3%, and diarrhea was the most common symptom, with a prevalence of 13.7%. A total of 507 patients ever had digestive diseases during a eld training period in the midland, with a prevalence of 16.6%, among which, gastritis, enteritis, gastrointestinal ulcers and functional bowel diseases were more common. The details are listed in Tables 1 and 2.

3.Comparison of symptoms and diseases of digestive system among different groups
There were signi cant differences in the incidence of digestive symptoms and diseases of servicemen among different groups of age, military service time, status, smoking amount,digestive disease family history,the eld training time, irregular diet times,training pressure,chilled abdomen,de led food history and disease prevention knowledge education(P 0.01). There was no signi cant difference in the incidence of digestive symptoms and diseases between different groups of NSAIDs use history(P 0.05). The details are listed in Tables 3 and 4.     Table 5.

Discussion
Looking back at the history of human wars, we can nd out that many troops were defeated because of diseases. According to annual statistics from the United States Naval Medical Service, during World War I, gastrointestinal diseases were the third most common diseases that led to American navy servicemen's medical admissions. In World War II, both the American army and navy had a large number of hospital admissions for digestive disorders which were the third most common in the medical diseases [1][2][3] .Digestive diseases were the fourth most common medical disease that caused American navy's hospital admissions during the Korean War.And gastrointestinal diseases were again the third most common diseases that led to American navy servicemen's medical admissions during the Vietnam War.Judging from disease attrition of Chinese army in previous wars,the incidence of the digestive system diseases was also very high, which took the rst place in the War of Resistance Against Japanese Aggression and in the National War of Liberation, and took the second place in the War of Resistance Against American Aggression and Aid Korea and in Sino-Vitnamese War.In recent years, relevant investigations and studies have shown that the incidence of digestive system diseases of soldiers is still quite high in all medical diseases, of which, functional bowel disease and gastrointestinal ulcer are more common during the training period, and the risk of functional bowel disease may increase with the extension of military service time [4][5] .
The digestive system is closely related to the nervous system and is sensitive to changes of the external environment. Due to living in a relatively closed and depressing space, and receiving intense physical training,the army servicemen often have great psychological pressure.Therefore, army servicemen are prone to digestive diseases,which can further aggravate their psychological burden, reduce the quality of life, and even seriously affect combat capacity [6] . As we know,the study on the spectrum of soldiers' digestive system diseases is quite rare. So the purpose of our study is to investigate and analyze the spectrum of army servicemen's digestive system diseases and nd out relevant disease prevention and treatment strategies, so as to protect the health of servicemen and reduce non-combat personnel loss.
This study randomly selected 7 basic units of the army which had a eld training in the midland of China and collected data related to the digestive system symptoms and diseases of 3,055 servicemen. It was found that 896 people had symptoms of the digestive system during the training period, with an incidence of 29.3%, and the diarrhea was the most common symptom, with an incidence of 13.7%. A total of 507 servicemen had gastrointestinal diseases, with a prevalence rate of 16.6%, among which, gastritis, enteritis, gastrointestinal ulcers and functional bowel diseases were more common. It is worth mentioning that the incidence of gastroenteritis for servicemen exceeded 15%, which was much higher than that of other diseases, and the result was similar to the nding of previous researchers [6][7] . As is known to all, vomiting, poor appetite, diarrhea, abdominal pain,and abdominal distension,were common clinical manifestations of gastroenteritis, which was consistent with our research. Therefore, we have to take measures to decrease the occurrence of gastroenteritis, gastrointestinal ulcer and functional bowel disease during a eld training, which include not only hygienic diet and healthy living habits, but also the prevention and treatment of helicobacter pylori (Hp) infection. Hp can destroy the gastric and duodenal mucosal barrier by the self-colonization and secretion of toxins and toxic enzymes. So the standard anti-Hp treatment for patients can effectively reduce the occurrence and recurrence of gastritis and gastrointestinal ulcer [8] . During the eld training, the army servicemen have intense physical training in the tough environment, because the regions in the midland such as Hubei and Shaanxi Province are rainy, humid and very hot. And long-term high temperature and high pressure working environment increase the risk for functional bowel disease. Moreover, the army servicemen often have inadequate sleep time, which also increase the occurrence of functional bowel disease [9] . Hence, for servicemen who always have training tasks every year, it's quite necessary to receive regular blood test and abdominal ultrasound examination. To detect abnormal indicators early, and then adjust the diet structure timely, have a appropriate rest, and accept early intervention and treatment can prevent the progress of liver and gallbladder diseases.
In this study, we focused on the comparison of with the occurrence of digestive diseases. And some researchers also discover long time of service is the risk factor for functional bowel disease [10][11] . A study of the US Army also con rms that the prevalence of functional bowel disorder for soldiers is related to stressors, the service years is one of which [12] . However, the investigation results in the basic units of the air force shows that the risk of functional bowel disease peaks at the age of 18-25 and over 41, which is quite different from the onset age of army as we discuss before [13][14] . This seems to suggest that there are differences in the characteristics of the disease among different services, which still needs further veri cation.The lectures on prevention and treatment knowledge can strengthen awareness of servicemen for digestive diseases, understand the characteristics, inducements and simple diagnosis and treatment rules of diseases. Our study also con rmed this view, the publicity of prevention and treatment knowledge once or twice a year can reduce the incidence of digestive diseases.
Non-steroidal drugs inhibit the synthesis of prostaglandin by inhibiting coxidase, which leads to the disruption of gastrointestinal mucosal balance and causes mucosal in ammatory lesions. Therefore, the long-term use of non-steroidal drugs is a risk factor for the occurrence of digestive system diseases. But in our study, there was no signi cant difference in the incidence of digestive symptoms and diseases between different groups of NSAIDs use history(P 0.05) Maybe it is associated with shorter duration of non-steroidal drug use, and after all, the time of a eld training is generally not more than half a year.Also it may be related with the sample size, because the number of military personnel taking non-steroidal drugs is relatively less. Some studies believe that there is no clear relationship between smoking and the occurrence of digestive system diseases such as functional bowel disease [14][15] . The study also found that smoking did not increase the risk of digestive diseases by regression analysis. However, other studies have con rmed that large smoking amount is a risk factor for digestive system diseases [11,15] . So the relation remains to be con rmed by large-scale epidemiological studies.
In addition to focusing on the possible risk factors discussed in this study, the training on skills for military doctors such as online teaching and technical guidance from medical experts, is also very important for the prevention and treatment of digestive system diseases. Expanding the number coverage of gastroscopy, accelerating the development of 5G network application in endoscopy and the promotion of portable endoscopy will also help improve the professional level of medical personnel in the health center and the diagnosis and treatment rate of diseases.
As a regression investigation, this study cannot clearly determine the causal relationship between digestive system symptoms and diseases. Besides, digestive system symptoms and diseases in the questionnaire are mainly from servicemen's clinic experience,not from doctors' real-time diagnoses, which may be not reliable,and then lead to the biased investigation. So the next step is to follow up servicemen and conduct a large-scale prospective investigation and study.