The Study On The Prevalence Of Latent Tuberculosis Infection And Risk Of Active Pulmonary Tuberculosis Among Coal Workers' Pneumoconiosis

Due to the damage of lung tissue,pneumoconiosis can decrease respiratory function of patients and body's effective immunity,which is susceptible to tuberculosis(TB)or other bacterial infection.It was estimated that one third of the world's population was estimated to be infected with Mycobacterium tuberculosis.The latent tuberculosis infection(LTBI)have no signs or symptoms of TB disease and are not infectious,but they are at risk for developing active TB disease and becoming infectious.The lifetime risk of reactivation TB for a person with documented LTBI is estimated to be 5-15%,with the majority developing TB disease within the first five years after initial infection.Systematic testing and treatment of LTBI was recommended for risk groups by the World Health Organization(WHO):people living with HIV,adult as well as child contacts of pulmonary TB cases and patients with silicosis,which can effectively prevent the prevalence of active tuberculosis in these groups.However,few studies have reported the prevalence of LTBI among pneumoconiosis patients in the world.In this study,we conducted firstly a cross-sectional study to assess the prevalence of LTBI among coal workers'pneumoconiosis(CWP)patients,which can provide a scientific basis for prevention of pulmonary tuberculosis among CWP patients in China.Pulmonary tuberculosis is the most serious complication of pneumoconiosis,which is the leading cause of death of pneumoconiosis patients.It is crucial to prevent and control the risk of contracting pulmonary TB in pneumoconiosis patients with to prevent the development of pulmonary TB.The risk of developing tuberculosis will depend on many factors impinging on the host and environmental factors.And previous studies have reported the occupational risks of developing active pulmonary TB among pneumoconiosis patients by cross-sectional study.However,few studies have analyzed the host characteristics and environmental factors of pulmonary TB among pneumoconiosis patients.We conducted a matched case-control study to assess occupational,environmental and behavioral risk factors of active pulmonary TB in patients with CWP.The diagnoses of pulmonary tuberculosis among pneumoconiosis patients were mainly based on clinical features and chest radiology findings.The bacteriological methods were used as auxiliary diagnostics.However,the diagnoses of pulmonary tuberculosis among pneumoconiosis patients were difficult because of atypical clinical features of pulmonary tuberculosis and distinguishabe X-ray chest radiographs among pneumoconiosis-associated tuberculosis patients.Therefore,it is particularly important for the diagnosis of pulmonary tuberculosis with the use of laboratory methods to detect Mycobacterium tuberculosis among pneumoconiosis-associated tuberculosis patients.We evaluated the performance of GeneXpert MTB/RIF on detecting Mycobacterium tuberculosis and rifampicin resistance among pneumoconiosis-associated tuberculosis patients,which can provide scientific basis for the early detection,accurate diagnosis and treatment for pneumoconiosis-associated tuberculosis patients.Part One Prevalence of latent tuberculosis infection among coal workers' pneumoconiosis patients in China:a cross-sectional study Objectives:To estimate the prevalence of latent tuberculosis infection(LTBI)and identify its associated risk factors among coal workers' pneumoconiosis patients.Methods:All blood samples were collected from coal workers' pneumoconiosis patients treated by the Hospital from Beijing.Information on factors was collected using a standardized questionnaire by quering medical records and face-to-face interview.The prevalence of LTBI was estimated by using descriptive analysis methods and its associated factors were estimated by using Log-binomial regression model.Results:244 participants actually participated in the investigation and received the IGRA test.The prevalence of LTBI in the 244 CWP patients,based on IGRA positivity,was 66.4%(162/244).The multivariate Log-binomial regression analyses that the poor workplace ventilation(adjusted PR=1.26,95%CI:1.03-1.52)was found to be independent risk factor and>4 days of every week of intake of fruit(adjusted PR=0.81,95%CI:0.65-0.99)was found to be independent protective factor associated with a positive IGRA result.Conclusions:The coal workers' pneumoconiosis patients are the high risk groups for latent tuberculosis infection in China.Poor workplace ventilation could be a risk factor and intake of fruits regularly(?4 days of every week)found to be a protective factor for latent tuberculosis infection.Part Two Risk of active pulmonary tuberculosis among coal workers'pneumoconiosis patients:a case-control study in ChinaObjectives:To estimate risk factors of active pulmonary tuberculosis(PTB)among coal workers' pneumoconiosis(CWP)patients.Methods:A matched case-control study was conducted at the Hunan Institute for Tuberculosis Control and the Hunan Prevention and Treatment Center for Occupational Diseases.Cases comprised CWP patients with active PTB(CWP-TB)and controls were non-TB cases with CWP only.The selection of controls(CWP only)was started after completion of the selection of cases(CWP-TB)to allow for age(±3),sex,and ethnicity differences.A standardized questionnaire was completed and factors were assessed for acquiring active PTB.Analysis was conducted using conditional logistic regression model,with active TB as an outcome.Results:86 cases(CWP-TB)and matched controls(CWP only)were recruited.The multivariate conditional logistic regression analyses that stage ? of CWP(adjusted OR=19.64,95%CI:1.02-378.13),moderate(adjusted OR=12.88,95%CI:1.24-132.21)and poor workplace ventilation(adjusted OR=45.08,95%CI:3.42-594.40),a family history of TB(adjusted OR=15.44,95%CI:1.03-233.98)and an exposure history of TB(adjusted OR=14.94,95%CI:1.28-174.17)remained independent risk factors for active PTB among CWP patients.Conclusions:This study verified that the stage ? of CWP,poor workplace ventilation,a family history of TB and an exposure history of TB were independent risk factors for active PTB in patients with CWP.Part Three Evaluation of GeneXpert MTB/RIF for the detection of tuberculosis among pneumoconiosis-associated tuberculosis patientsObjective:To evaluate the performance of GeneXpert MTB/RIF on detecting Mycobacterium tuberculosis and rifampicin resistance for pneumoconiosis-associated tuberculosis patients.Methods:Recruited 133 suspected active pneumoconiosis associated tuberculosis hospitalized cases,morning sputum samples were collected to do modified L-J culture,conventional proportion method drug susceptibility test,GeneXpert MTB/RIF and BACTEC-MGIT 960.Analyze the sensitivity,specificity and their 95%CIs of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting tuberculosis and rifampicin resistance.The confidence interval method was used for hypothesis testing.The test level is 0.05,Results:Of 133 patients,the positive rate of patients with tuberculosis in GeneXpert MTB/RIF test(37.59%)was significantly higher than BACTEC-MGIT 960(34.59%)and modified L-J culture(30.08%).There was significant difference among the three tests respectively(all P<0.05).According to the modified L-J culture,the sensitivity of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting tuberculosis were 92.5%and 95.0%respectively,and specificity in rifampicin resistance were 86.0%and 91.4%respectively.There was no significant difference between GeneXpert MTB/RIF and BACTEC-MGIT 960(all P>0.05).According to conventional proportion method drug susceptibility test,the sensitivity of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting rifampicin resistance were 90.0%and 100%,and specificity were 92.6%and 96.4%.There was no significant difference between GeneXpert MTB/RIF and BACTEC-MGIT 960(all P>0.05).Conclusion:The GeneXpert MTB/RIF has good performence of detecting tuberculosis and rifampicin resistance.It has good application value among pneumoconiosis-associated tuberculosis patients.