Even with the higher TB incidence and prevalence rate of the homeless compared to those of the general population, elements of their lifestyle, such as alcohol abuse or unstable living conditions, made it difficult for them to persist with the treatment.
According to the tuberculosis statistics of World Health Organization for the 30 richest countries, the treatment success rate for new smear-positive TB cases in Korea was 84%; according to public health centers, 79% in 2010;2)
and in this study, 35.2%. If the factors of TB treatment success are predictable, they will help control the rise in the number of TB patients by improving their treatment compliance. Some studies on the risk factors that lower the treatment compliance of TB patients showed no significant differences in the clinical manifestations (e.g., age, gender, adverse events of anti-TB drugs, pulmonary symptom, and smear-positive TB) of pulmonary and extrapulmonary TB,18)
and in underlying diseases.19)
This study independently evaluated the risk factors of treatment failure by comparing the clinical characteristics of homeless TB patients in the successfully treated group and the incompletely treated group.
In the successfully treated group, there were more patients who lived in facilities (55.3%) such as shelters than those who lived on the streets (27.7%); whereas in the incompletely treated group, there were more street homeless patients (67.1%) (P < 0.001) and the treatment failure rate was 4.77 times higher (95% CI, 2.05 to 11.10; P < 0.001) than that for those who lived in homeless shelters and facilities. TB patients are required to complete their treatment by visiting a clinic regularly and taking anti-TB drugs. As the homeless who lived normal lives in shelters and facilities showed higher compliance to the treatment than the street homeless,17)
stable housing and socio-economic support for homeless patients are deemed to be key factors of treatment success.
Of the patients in the successfully treated group, 48% developed diseases with risk factors; whereas in the incompletely treated group, 78.2% did (P = 0.003), and the treatment failure rate was 2.72 times higher (95% CI, 1.13 to 6.53; P = 0.025). Of all the 142 patients, 89 developed underlying diseases with risk factors. In many studies, a low albumin level was the independent risk factor that was associated with the death of a TB patient;20
and in this study, more than half of the subjects had a poor nutritional status, with a low albumin level and anemia, including 83 with alcohol dependence and 16 with liver cirrhosis. These became risk factors of TB by increasing the frequency of adverse events of anti-TB drugs, delaying the use of anti-TB drugs, and finally lowering the TB treatment success rate. Most homeless people have a low level of awareness of health management and lack regular access to medical checkups. Through regular checkups, early diagnosis and treatment of TB among the homeless who are at high risk of infection should reduce public spending on TB treatment.
A history of TB treatment is not a risk factor of treatment failure, though the percentage of the patients with such history in the incompletely treated group (51.3%) was significantly higher than that in the successfully treated group (28%) (P = 0.009). A study by Park19)
reported that the high treatment default rate led to the low treatment success rate; in this study, 33.8% of the patients did not adhere to the treatment after their discharge or experienced treatment interruption after they escaped from the hospital. In particular, of the 40 patients with a history of TB treatment in the incompletely treated group, 30 had an interruption in their taking of anti-TB drugs, 20 had two or more interruptions, and five, three or more. It has been reported that the TB treatment success rate significantly increased to 69.9% and 85.4% since the implementation of the public-private mix for TB care and control in 2009.19)
The socio-economic characteristics of the homeless make it difficult to control them, compared to those of general patients, whereas comprehensive care by TB nurses or medical staff will raise the effectiveness of TB treatment through education and counseling for the promotion of adherence to the treatment after discharge.
In this study, no significant difference in drug resistance between the successfully treated group and the incompletely treated group was seen, but 25% of the study population was resistant to one or more drugs and 11.5% was multidrug-resistant. These figures are higher than the drug resistance rate (14.9%) and the multidrug resistance rate (4.9%) of public health centers, and the drug resistance rate (19.8%) and the multidrug resistance rate (9.5%) of the private health sector based on the data released by Centers for Disease Control and Prevention.22)
The default rate of the homeless in this study was high and may lead to a high treatment failure rate. As a result, there may be a rise in acquired resistance, which occurs due to inappropriate regimens or use of drugs, and it may be followed by primary resistance. To prevent the spread of drug-resistant TB to the general population, active surveillance of high-risk populations is very important, and particularly, the drug resistance rate of the homeless who have a high risk of TB should be identified, followed by proper TB control.
This study assessed the clinical characteristics of 142 homeless patients with pulmonary TB at Busan Medical Center, which provide public health services in the Busan region, and evaluated the independent risk factors of the treatment success of homeless TB patients by comparing the successfully treated group and the incompletely treated group. This study had an insufficient sample size (142 patients), however, and the clinical characteristics of the subjects were based merely on their medical records.
Due to the poor nutritional status, unstable living circumstances, and crowded living conditions of homeless people, they have a higher risk of developing TB than the general population once they are exposed to M. tuberculosis, and of becoming active sources of TB infection. Therefore, identifying the current status of homeless TB patients, followed by their early treatment and successful treatment, is very important in lowering the prevalence of TB in Korea. Moreover, more extensive studies on homeless TB patients are needed.