Tuberculosis (TB) is still at epidemic levels in many places in Africa, but new research shows that smoking was not associated with disease severity or worse outcome. A researcher says that smoking cessation should therefore not be a priority measure in combating TB in western Africa.
Although TB has been mostly eradicated in high-income countries, many low-income countries are still plagued by this dangerous infectious disease, including countries in western Africa such as Guinea-Bissau.
Now new research from Guinea-Bissau shows that although researchers might think that smoking would affect the severity of TB, it did not.
So, although action is needed to stop TB in such places, according to the study, smoking-cessation interventions will not help much.
“Smoking should clearly not be a main focus area in combating TB in western Africa. In Denmark, smoking cessation would probably be more relevant, but in Guinea-Bissau, intervention is not warranted,” explains an author involved in the study, Christian Wejse, Professor, Department of Clinical Medicine, Aarhus University.
The research has been published in the International Journal of Infectious Diseases.
Assessed 1,780 cases of TB
The study is an offshoot of the Bandim Health Project, which aims to improve people’s health in several western African countries.
In this major project, which is closely linked to various hospitals and medical clinics in Guinea-Bissau, researchers identified 1,780 cases of TB over 14 years.
TB is a serious lung disease that is complicated to treat and requires taking four types of antibiotics for 6 months before the person can be declared healthy.
In the Bandim Health Project, researchers carried out many examinations and surveys of people with TB in Guinea-Bissau and asked whether they smoked tobacco.
The researchers thus had the opportunity to compare the outcome of TB between smokers and non-smokers.
Of the 1,780 cases of TB, 385 were among smokers. The average age of non-smokers was 30 years versus 36 years for the smokers.
“We hypothesised that smokers might have been slightly more ill when they were diagnosed with TB or that the outcome would be slightly more severe. Maybe their lung functioning would be slightly worse. We therefore followed these people during and after treatment to determine whether smoking affects people’s experience with TB,” says Christian Wejse.
Similar results for smokers and non-smokers
The results show that smoking or not smoking did not strongly affect the severity of TB. The clinical score describing the severity of TB did not differ between the groups.
Christian Wejse says that smokers had a slightly worse outcome of treatment for TB, but the difference was not statistically significant.
“This was surprising because other studies have found that smokers have worse outcome in TB treatment. But the literature also shows that other low-income countries have had similar results,” explains Christian Wejse.
Light smokers compared with high-income countries
Christian Wejse thinks that smoking did not strongly affect the outcome of TB in Guinea-Bissau for several reasons.
First, smoking in many low-income countries is not the same as smoking in high-income countries.
In high-income countries, smokers often smoke 20 cigarettes per day. In low-income countries, many people cannot afford to smoke so much, so they only smoke a few cigarettes per day, and some even less than one per day.
“This will clearly not have the same effect on the lungs as smoking 20 cigarettes a day,” says Christian Wejse.
Similarly, the smokers in low-income countries are often more affluent, since they are the only ones who can afford to smoke. This can also affect the risk of an unfavourable outcome when people develop TB, because affluent people can afford better treatment and care.
Finally, age probably also plays a role.
Smokers’ average age of 36 years means that these are young people who have not smoked all their lives and therefore have not destroyed their lungs to the same extent as if they had been 65 years or older and smoked all their lives.
“The average smoker in the study had smoked for 10 years, and although that is many years, it is nowhere near the number of years that most 60-year-old smokers in Denmark have smoked,” explains Christian Wejse.
Almost all smokers were men
Christian Wejse concludes that smoking does not seem to play a major role in TB in Guinea-Bissau. It should therefore not be an area of focus either.
However, he points out that there may be a gender difference, and examining this more closely will be relevant.
In the study, 98% of the smokers were men, and men generally have a slightly worse TB outcome than women.
“We corrected our data for gender differences to specifically see how smoking affects the risk of a worse outcome. This shows that smoking has very little effect and that we need to focus elsewhere to combat the TB epidemic in western Africa,” concludes Christian Wejse.