INTRODUCTION
New contributions of the thesis
This groundbreaking thesis presents a vital scientific investigation into the effectiveness of the Mg-B6 drug in preventing hearing loss among soldiers in the Tank Armed Forces It thoroughly assesses the prevalence of hearing loss and its contributing factors, ultimately evaluating the efficacy of Mg-B6 supplementation as a preventive measure for these military personnel.
Actual noise condition of armored tanks : The average overall sound pressure level measured on the armored tank training ground was 76.08 ± 25.66 dBA
A study on hearing loss among armored tank soldiers revealed that 17.78% experienced hearing loss in one ear, while 45.08% were affected in both ears The predominant clinical symptoms reported included tinnitus in 78.4% of cases, sore throat in 69.8%, and dizziness in 61%.
Hearing loss is significantly associated with age and military service, showing a proportional increase (p85dB and have worked for more than 6 months
- Have a complete record of health managed at the military medical unit b) Exclusion criteria:
- Those were not present at the unit during the study period
Objective 2: The effectiveness of Mg-B6 supplementation in preventing hearing loss a) Selective criteria
- New male soldiers, the rookies working in units of Armored Tank Army participated in the crew training course
- Have no ear diseases a) - Monotone hearing test, normal tympanic volume b) Exclusion criteria
- Have chronic ENT disease b) Criteria for selection of control group
Same as the study group, participated in the same training section c) Case definition of hearing loss after training:
- Has a listening threshold of > 20dB at any frequency of 500, 1000,
- Examination of the outer and middle ear was normal with the normal tympanic volume.
Research methods
- Objective 1: a cross-sectional descriptive study design was used
- Objective 2: Community intervention using double-blind, controlled design
Sample size and sample selection method
The sample size of military soldiers was determined by the following formula:
In which: p = 0.125 (rate of hearing loss found by Ho Xuan An's study in armored tank drivers); α = 0.05, 𝑧 1− 𝛼
2 =1.96; d: the accepted absolute error level is 0.04 The calculated sample size is 263, in fact we collected 315 objects
In the selection of environmental noise samples, measurements were taken from 15 positions both inside and outside the vehicle Inside the vehicle, noise levels were recorded from the positions of the vehicle commander, driver, gunner, and loader Outside the vehicle, measurements were taken from the front (2), back (2), turret (1), and at distances of 10m (4), 100m (1), and 200m (1) away For each engine start, the average noise intensity was calculated at each specified distance from the tank.
Select sample of soldiers: make a list of soldiers in the unit with numbering Select a simple random sample using Stata 14 randomization software based on the compiled list
The formula for estimating the difference of the two rates according to WHO was applied as follows: n1 = n2 (𝑍 1− α
In this study, the minimum sample size for both the intervention and control groups was denoted as n The control group exhibited a hearing loss rate of p1 = 0.15, based on Gordon's research on conscripts post-training Conversely, the intervention group demonstrated a significantly lower hearing loss rate of p2 = 0.03 during the intervention The mean change rate in hearing loss, represented as p, is calculated as the average of p1 and p2.
(corresponds to a sample force of 80%)
Filling in the values, we have a calculated sample size for each group of 89 subjects In fact 100 soldiers per group was taken
+ Out of 2 battalions of armored tank soldiers, one battalion was randomly assigned to the intervention group and other one battalion to the control group
+ At each selected battalion, a list of recruits was made, then 100 soldiers were randomly selected by computer for each group.
Data processing
Data entry and management system was established The collected questionnaires were cleaned and entered into the Epi Data 3.0 program Data were entered twice independently
Data analysis was conducted using STATA 14.0, ensuring that continuous variable data were assessed for normal distribution prior to analysis For small sample sizes (n ≤ 30) and non-normally distributed data, non-parametric statistical tests, including the Mann-Whitney test and Wilcoxon test, were employed to evaluate differences between two mean values Rate comparisons were carried out using the χ2 test Additionally, both univariate and multivariable logistic regression models were analyzed to identify related factors.
Research results were presented as ratios (%), odds ratios (ORs) in univariate and multivariate analyzes with confidence interval (CI): 95% 2 test, Fisher's exact test were used to find the significant difference
Incidence rate, relative risk (RR), confidence interval (95% CI) and 2 test were calculated to assess the effectiveness of the intervention.
Research ethics
The study was conducted with the voluntary consent of all participants, ensuring that their information remains confidential and utilized solely for research purposes The design of the study received approval from both the Scientific Council of the Armored Tank Command and the Ethics Committee.
Committee in Biomedical Research of the Institute of Hygiene and Epidemiology through IRB-VN01057-26/2017.
RESULTS
The effectiveness of Mg-B6 supplement in prevention of hearing
- Rate of hearing loss after intervention of control group was 0.26;
The relative risk of hearing loss was 15.38% (95%CI: 0.06-0.42), or the rate of hearing loss was reduced by 84.62% in the intervention group compared with the control group.
DISCUSSION
Current situation of noise, hearing loss and related factors among
The overall sound pressure level recorded at the armored tank training ground was 76.08±25.66dB, with measurements taken from 105 noise intensity sites Notably, 4 out of 7 sites exhibited negative sound pressure levels, and 60.95% of the measurement points surpassed the permissible noise threshold of 85dB These findings indicate that the training environment poses significant exposure to harmful noise levels.
4.1.2.1 General characteristics of the study group
The study group had an average age of 38.67 years and a mean military service duration of 18.94 years, with many soldiers holding various roles such as teaching staff and training personnel Senile hearing loss, commonly affecting individuals over 50, can lead to an annual hearing decline of 0.5 to 1 dB In this study, only two participants were over the age of 50, highlighting the relatively younger demographic of the group.
0.63%, so the influence of senile hearing on the rate of hearing loss was not much
In our study, we found that 17.78% of participants experienced hearing loss in one ear, while 45.08% had hearing loss in both ears This binaural hearing loss rate is significantly higher than the 12.5% reported by Ho Xuan An in 2003 among 240 crew members of the same armored tank unit Additionally, Toh's 2002 study on 818 Singaporean conscripts indicated a hearing loss rate of only 3.67% Joseph's 2016 research involving 16,500 marines reported a hearing loss rate of 39%, which is still lower than our findings The discrepancies in these results may be attributed to our comprehensive examination of all working positions across three armored units, as well as the potential impact of various factors contributing to hearing loss, including ear, nose, and throat diseases, acute or chronic otitis, and prior ear surgeries due to infections.
4.1.3 Some related factors to hearing loss
A univariate regression analysis examining age, military service duration, and noise exposure history revealed no significant correlation with hearing loss Consistent with these findings, Toh's 2002 study involving 818 Singaporean conscripts indicated that the risk of hearing loss was not influenced by age, education level, race, or frequency of personal audio device usage.
A study from 2011 revealed that as noise intensity rose from 80dB to 96dB, there was a slight increase in the rate of hearing loss, with occupational deafness becoming more evident after a decade or more of exposure Notably, the duration of noise exposure proved to be a more significant predictor of hearing loss than the intensity of the noise itself.
In a 2012 study by the US Army, 9.7% of 115,638 subjects reported tinnitus symptoms, while research by James in 2021 indicated that 8% experienced low-frequency hearing loss, 20% high-frequency loss, and 39% very high-frequency loss, with a tinnitus prevalence of 53% Our study found a significantly higher tinnitus prevalence of 78.41%, which was associated with hearing loss, showing an odds ratio of 2.69 (95% CI 1.56-4.66) This elevated rate highlights the unique conditions faced by armored tank troops, where high-intensity noise from large engines and vehicle operations contributes to hearing issues To address this, it is crucial to implement protective measures like ear caps, reduce engine noise, enhance equipment, and explore preventive treatments to safeguard the hearing of soldiers in armored tank units.
Our multivariate regression analysis revealed a significant relationship between various risk factors, including a history of noise exposure, insomnia, cardiovascular disease, and smoking, with hearing loss Notably, cardiovascular disease emerged as a key associated factor linked to hearing loss.
OR 1.63 (95% CI 1-2.66) and p 0.05), and all participants were confirmed to be in good health through military recruitment examinations and health check-ups upon returning to their units An ENT examination was conducted for all subjects to exclude any hearing-affecting conditions such as ear infections and rhinosinusitis Additionally, no notable differences were observed between the two groups regarding genetic factors, noise exposure history, or head injury history.
4.2.2 The effectiveness of Mg-B6 supplement in prophylaxis treatment for hearing loss due to the noise
Analysis of post-intervention symptoms revealed that subjects in the Mg-B6 supplement group experienced significantly lower rates of tinnitus, hearing loss, fatigue, headaches, stress, insomnia, and dizziness compared to the control group Specifically, only 37% of soldiers using the Mg-B6 supplement reported tinnitus, in contrast to 63% in the control group, aligning with previous findings by James (2021) that noted a 53% prevalence of tinnitus symptoms The Mg-B6 supplement, which combines magnesium and vitamin B6, is effective in protecting hearing from noise-induced damage due to its neuroprotective and vasodilatory properties, which help reduce oxidative stress Consequently, the incidence of symptoms such as hearing loss, fatigue, and insomnia was significantly lower in the Mg-B6 group compared to those not receiving the supplement.
The analysis of mean monophonic hearing at four PTA frequencies revealed no significant differences between the two study groups, likely due to the 6-10 year development period for occupational deafness After just six months of training, it is expected that no noticeable changes in frequency detection would occur The average hearing intensity values at the representative frequencies of 500Hz, 1kHz, 2kHz, and 4kHz indicated normal hearing levels Therefore, further investigation into frequency-specific changes is essential for identifying early signs of potential deafness and implementing timely treatment interventions.
A comparative analysis of hearing loss by frequency revealed that the Mg-B6 uptake group experienced a 4% rate of hearing loss, while the control group exhibited a significantly higher rate of 26% (p 0.05) Over 49% of soldiers exhibit mild hearing loss ranging from 21 to 40dB.
- The most common clinical symptoms were tinnitus (78.4%), sore throat (69.8%), and dizziness (61%)
The knowledge, attitude and practice of the armored tank soldiers:
A significant majority of soldiers, comprising 88-89%, recognize the detrimental impact of occupational deafness on overall health and hearing However, 26.03% mistakenly believe that this condition is curable.
- Although most of soldiers (97.78%), claimed that the annual health check-up is necessary, but only 0.3% express the necessarily of periodical hearing examination
- The percentage of research subjects who sometimes or do not wear hearing protection helmets when performing work was quite high (30.15%) 15.24% evaluated the poor quality of the helmet
The factors related to hearing loss
- Rate of hearing loss was found increased proportionally with age and military service duration (p < 0.05)
A univariate analysis revealed that tinnitus, insomnia, ear discharge, and cardiovascular disease symptoms are associated with an increased risk of hearing loss However, in a multivariate analysis, only cardiovascular disease manifestations were found to significantly elevate this risk, with an odds ratio of 1.63 (95% CI: 1.1 - 2.66).
2 Supplementation of Mg-B6 was evaluated effective in preventing hearing loss
- It reduced symptoms of tinnitus, hearing loss, fatigue, headache, nervousness, insomnia, dizziness in the intervention group compared with the control group (p