Smoking and pulmonary tuberculosis: An analysis based on a study of volunteers for mass miniature radiography

Prevalence and risk factors for adult pulmonary tuberculosis in a metropolitan city of South India

Background

The present study measured the community prevalence and risk factors of adult pulmonary tuberculosis (PTB) in Chennai city, and also studied geographical distribution and the presence of different M. tuberculosis strains in the survey area.

Methods

A community-based cross sectional survey was carried out from July 2010 to October 2012 in Chennai city. Prevalence of bacteriologically positive PTB was estimated by direct standardization method. Univariate and multivariate analyses were carried out to identify significant risk factors. Drug susceptibility testing and spoligotyping was performed on isolated M. tuberculosis strains. Mapping of PTB cases was done using geographic positioning systems.

Results

Of 59,957 eligible people, 55,617 were screened by X-ray and /or TB symptoms and the prevalence of smear, culture, and bacteriologically positive PTB was estimated to be 228 (95% CI 189–265), 259 (95% CI 217–299) and 349 (95% CI 330–428) per 100,000 population, respectively. Prevalence of smear, culture, and bacteriologically positive PTB was highest amongst men aged 55–64 years. Multivariate analysis showed that occurrence of both culture and bacteriologically positive PTB disease was significantly associated with: age >35 years, past history of TB treatment, BMI <18.5 Kgs/m², solid cooking fuel, and being a male currently consuming alcohol. The most frequent spoligotype family was East African Indian. Spatial distribution showed that a high proportion of patients were clustered in the densely populated north eastern part of the city.

Conclusion

Our findings demonstrate that TB is a major public health problem in this urban area of south India, and support the use of intensified case finding in high risk groups. Undernutrition, slum dwelling, indoor air pollution and alcohol intake are modifiable risk factors for TB disease.

Particle exposures and infections

Particle exposures increase the risk for human infections. Particles can deposit in the nose, pharynx, larynx, trachea, bronchi, and distal lung and, accordingly, the respiratory tract is the system most frequently infected after such exposure; however, meningitis also occurs. Cigarette smoking, burning of biomass, dust storms, mining, agricultural work, environmental tobacco smoke (ETS), wood stoves, traffic-related emissions, gas stoves, and ambient air pollution are all particle-related exposures associated with an increased risk for respiratory infections. In addition, cigarette smoking, burning of biomass, dust storms, mining, and ETS can result in an elevated risk for tuberculosis, atypical mycobacterial infections, and meningitis. One of the mechanisms for particle-related infections includes an accumulation of iron by surface functional groups of particulate matter (PM). Since elevations in metal availability are common to every particle exposure, all PM potentially contributes to these infections. Therefore, exposures to wood stove emissions, diesel exhaust, and air pollution particles are predicted to increase the incidence and prevalence of tuberculosis, atypical mycobacterial infections, and meningitis, albeit these elevations are likely to be small and detectable only in large population studies. Since iron accumulation correlates with the presence of surface functional groups and dependent metal coordination by the PM, the risk for infection continues as long as the particle is retained. Subsequently, it is expected that the cessation of exposure will diminish, but not totally reverse, the elevated risk for infection.

Epidemiology of tuberculosis immunology

Immunological impairment plays a major role in the epidemiology of TB. Globally, the most common causes of immunological impairment are malnutrition, diabetes, HIV/AIDS, aging, and smoking. With the notable exception of HIV, each factor leads to relatively mild immunological impairment in individuals. However, as these conditions affect a significant proportion of the population, they contribute substantially to the incidence of TB at a global scale. Understanding immunological impairment is central to understanding the global TB pandemic, and vital to the development of effective disease control strategies.

Burden of obstructive lung disease in a rural setting in the Philippines

BACKGROUND AND OBJECTIVE

The aim of this study was to determine the prevalence of and risk factors associated with COPD in a rural setting in the Philippines.

METHODS

The study was conducted in two municipalities in Nueva Ecija province in the Philippines. Using the Burden of Obstructive Lung Disease (BOLD) protocol and study design, non-hospitalized men or women, aged 40years or older, were recruited by multi-stage random sampling procedures. Participants completed questionnaires on respiratory symptoms and exposure to potential risk factors for COPD, including smoking, occupation and exposure to burning of biomass fuel. Spirometry was performed according to American Thoracic Society criteria.

RESULTS

Of the 1188 individuals selected for recruitment, 722 had acceptable post-bronchodilator spirometry and were classified according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage. The overall prevalence of COPD for all stages was 20.8%. The prevalence of COPD at GOLD Stage I or higher was greater in men compared with women (26.5% vs 15.3%), and increased between the ages of 40 to >70years. Logistic regression analysis showed a significant association between all stages of COPD and farming for >40years (odds ratio (OR) 2.48, 95% confidence interval (CI): 1.43-4.30), use of firewood for cooking for >60years (OR 3.48, 95% CI: 1.57-7.71), a smoking history of ≥20 pack-years (OR 2.86; 95% CI: 1.78-4.60), and a history of tuberculosis (OR 6.31, 95% CI: 2.67-15.0).

CONCLUSIONS

The prevalence COPD in a rural community in Nueva Ecija, Philippines was 20.8% for GOLD Stage I or higher, and 16.7% for GOLD Stage II or higher. In addition to smoking history, the use of firewood for cooking, working on a farm and a history of tuberculosis were significantly associated with fixed airflow obstruction, as assessed by spirometry.

Association between tobacco smoking and pulmonary tuberculosis

Background/Aim. Numerous studies evaluate the influence of tobacco smoking on the tuberculosis (TB) development, with the results indicating that smoking can be also considered as important risk factor in TB. The aim of this study was to assess the influence of tobacco smoking as the risk factor in the development of TB as well as in its clinical course. Methods. We analyzed data from the medical records of 192 consecutively hospitalized TB patients (124 males and 68 females) in the Institute of Pulmonary Diseases and Tuberculosis, Clinical Center of Serbia, Belgrade in the period from 2005 to 2007. Results. Among the analyzed TB patients there were more smokers (63.5%) than nonsmokers (36.5%). The majority of the smokers (73.8%) belonged to a middle age group (35-54 years) while the majority of nonsmokers (64.3%) were older than 55 years. Sex ratio among the smokers showed the domination of males (80.3%). There were significantly more males in the smoking group and more females in the nonsmoking group (?2 = 34.402, p < 0.0001). Most smokers (68.9%) smoked more than 20 cigarettes daily. The average index of pack/years among all of the examinated patients was 32.75 ? 18.26. Cavitary pulmonary lesions were more frequently verified in the smokers (64.2%) than in the nonsmokers (35.8%). The sputum acid-fast bacillus smear-positive finding was more frequent in the smokers (78%) than in the nonsmokers (22%). The nonsmoking TB patients had more accompanied immunodeficient diseases (34%) than the smoking ones (19%). Body-mass index was lower in the smokers (21.75) than in the nonsmokers (23.80), although this difference did not reach the statistical significance. Conclusion. There are more smokers than nonsmokers in TB patients. Smokers more frequently have cavitary forms of TB with sputum acid-fast bacillus smear - positive finding than nonsmokers.

Passive smoking and risk of pulmonary tuberculosis in children immediately following infection. A case-control study

SETTING

Passive smoking-related respiratory disorders in children.

OBJECTIVES

To assess the effect of passive smoking on the development of active pulmonary tuberculosis (PTB) in children immediately following infection by Mycobacterium tuberculosis within the family.

DESIGN

An unmatched case-control study in which 93 contacts who became cases (active PTB diagnosed) and 95 contacts who did not became cases (tuberculin-positive children without evidence of active disease) were included. All were household contacts of a new case of pulmonary bacillary tuberculosis. Smoking habits were investigated by a questionnaire. Urinary cotinine was analysed. Odds Ratio (OR) was adjusted for age and socio-economic status using multiple logistic regression analysis.

RESULTS

Passive smoking was a risk factor for PTB (OR: 5.29; 95% confidence interval (CI): 2.33-12.82; P < 0.00005). The adjusted OR was 5.39 (95% CI: 2.44-11.91; P < 0.00001). The risk increased when contacts were passive smokers both at home and outside the home within the family (OR: 6.35; 95% CI: 3.20, 12.72; P < 0.00001). Contacts 0-4 and 5-9 years old showed a significantly higher risk than those aged > or = 10. There was a dose-response relationship between the risk of developing active PTB immediately following infection and the number of cigarettes smoked daily by the household adults (P < 0.001). Mean (SD) urinary continine detectable concentrations (ng/ml) were different between disease contacts (119.46 [68.61]) and non diseased contacts (91.87 [73.10]). The difference was statistically significant (P < 0.001).

CONCLUSIONS

Passive exposure to tobacco smoke in children was associated with an increased risk of developing pulmonary tuberculosis immediately following infection. This is an association of great concern requiring health education programmes and antitobacco medical advice.

Cigarette smoking as a risk factor for tuberculosis in young adults: a case-control study

SETTING

The association between smoking and pulmonary tuberculosis has not often been studied.

OBJECTIVE

To assess the influence of cigarette smoking on the development of active pulmonary tuberculosis in young people who were close contacts of new cases of smear-positive pulmonary tuberculosis.

DESIGN

A case-control study in which 46 'cases' (patients with active pulmonary tuberculosis: isolation of Mycobacterium tuberculosis or clinical and/or radiographic evidence of current pulmonary tuberculosis, with a positive tuberculin skin test) and 46 'controls' (persons with positive tuberculin reaction, negative bacteriological test and without clinical and/or radiological evidence of pulmonary tuberculosis) were included. Smoking habits were investigated by questionnaire. Univariate and multivariate analysis was performed, and odds ratio (OR) was adjusted for age, gender and socio-economic status.

RESULTS

Statistically significant differences were found in active smokers (occasional and daily smokers) (OR: 3.65; 95% CI, 1.46 and 9.21; P < 0.01), daily smokers (OR: 3.53; 95% CI, 1.34 and 9.26; P < 0.05), and individuals who were both passive and active smokers (OR: 5.10; 95% CI, 1.97 and 13.22; P < 0.01) and passive and daily smokers (OR: 5.59; 95% CI, 2.07 and 15.10; P < 0.001). There was a dose-response relationship between the number of cigarettes smoked daily and the risk of active pulmonary tuberculosis.

CONCLUSIONS

The data studied show that cigarette smoking is a risk factor for pulmonary tuberculosis in young people, with a dose-response relationship with the number of cigarettes consumed daily.

Tuberculosis risk factors in adults in King County, Washington, 1988 through 1990

OBJECTIVES

Tuberculosis has become a resurgent public health problem in the United States. Because resources are limited, control programs frequently must target populations at greatest risk. The purpose of the study was to examine risk factors for tuberculosis in adults.

METHODS

In King County, Washington State, from 1988 through 1990, the characteristics of patients with tuberculosis were compared with census data, and a case-control study was conducted. Self-administered questionnaires were completed by 151 patients with active tuberculosis and 545 control subjects.

RESULTS

Infection with the human immunodeficiency virus, non-White race/ethnicity, and foreign birthplace were each associated with a sixfold or greater increase in risk. Each of the following was associated with at least a doubled risk: history of selected underlying medical conditions; low weight for height; low socioeconomic status; and age 70 years or older. Men had 1.9 times the risk of women, smokers of 20 years' or more duration had 2.6 times the risk of nonsmokers, and heavy alcohol consumers had 2.0 times the risk of nondrinkers.

CONCLUSIONS

Intervention targeting easily identified groups may be an effective way to reduce the incidence of tuberculosis.

Tuberculin testing in residential homes for the elderly

BACKGROUND

Evidence from the United States has shown that tuberculin sensitivity increases with length of stay among residents in homes for the elderly, implying an increasing risk of infection. There is no evidence as to whether or not residents in homes in the United Kingdom have a similar risk.

METHODS

A study was undertaken to determine whether residence in a home for the elderly increases the risk of tuberculosis infection. Over a six month period all residents in homes for the elderly in Liverpool received a tuberculin test. A health questionnaire was completed by the field team for each resident. A total of 2665 residents in homes for the elderly were surveyed.

RESULTS

Heaf test grade positivity declined with age, the odds ratio being 0.71 for each 10 year period. Adjusting for age, there was no change in Heaf test grade with length of stay in the home. Heaf test positivity was stronger in smokers (odds ratio 1.59) than ex-smokers (odds ratio 1.20) and non-smokers. Heaf test grade positivity was directly related to pack years. Allowing for age and smoking, the odds ratio for men compared with women for a positive test was 1.62 (95% confidence interval 1.32 to 1.99).

CONCLUSIONS

Heaf test positivity declines with age. Residence in a home for the elderly is not associated with increased rate of tuberculosis sensitivity. Smoking and male gender is associated with increased Heaf test positivity.

Risk factors associated with the prevalence of pulmonary tuberculosis among sanitary workers in Shanghai

The association between potential risk factors and the prevalence of pulmonary tuberculosis was studied in Shanghai Bureau of Sanitation. The study identified a total of 202 cases among 30,289 subjects, and showed that smoking, in particular heavy smoking, had a strong association with tuberculosis after simultaneous adjustment for other factors. Using a multivariate binomial regression, the factors adjusted included the age, sex, history of contact, area of housing and type of work. The relative risk of heavy smokers compared with nonsmokers was 2.17 (95% confidence interval 1.29-3.63). The study showed that although males and old age were associated with a higher risk of tuberculosis than females and young age respectively, these differences were due to the smoking factor. The study also found that the risk of tuberculosis among the subjects with previous patient contacts was twice as high as that among the non-contacts.