Tuberculosis in the street population: a systematic review

Objective: To analyze evidence of the occurrence of tuberculosis in people living on the streets provided by the literature. Method: Systematic review conducted in the databases PubMed, EMBASE, LILACS, and SciELO electronic library. Analysis of the empirical material was guided by Hermeneutics. The main themes which give shape to the association between tuberculosis and street population were sought to be understood. Results: Initially, 343 articles were identified, but only seven met the eligibility criteria. The literature shows that homeless people with tuberculosis presented unfavorable treatment outcomes when compared to the population with fixed residence. Some of the associated reasons were abusive consumption of alcohol and other drugs and associated diseases, such as human immunodeficiency virus and others. Conclusion: Despite the importance of this theme, analysis of the scientific production has provided evidence of the need for studies aimed not only at comprehending the occurrence of disease in this vulnerable group, but specially ways of fighting it. DESCRIPTORS Tuberculosis; Homeless Persons; Vulnerable Populations; Community Health Nursing; Review. Corresponding author:


Paula Hino 1 Thais Tiemi Yamamoto 2 Shyrlaine Honda Bastos 1 Aline Ale Beraldo 3 Tânia Maria Ribeiro Monteiro de Figueiredo
Maria Rita Bertolozzi 5 INTRODUCTION Tuberculosis (TB) is a worldwide public health problem which is particularly severe in Brazil. The magnitude of this disease as of 2018 is shown by indexes such as an incidence rate of 34.8/100,000 inhabitants, human immunodeficiency virus (HIV) tests conducted in 75.5% of new cases, and TB/ HIV co-infection of 8.8%. Regarding treatment outcome, the results fall short of recommendations by the Brazilian Ministry of Health, since the percentages of cure and treatment abandonment among new cases confirmed by laboratory were, respectively, 71.4% and 10.8%, with a mortality rate of 2.2/100,000 inhabitants in 2017. Regarding special populations, in 2018, prison population corresponded to 10.5% of new cases and people living on the streets (PLS) were in the second position, with 2.5% of the total new cases of TB (1) .
Launched in 2017, the National Plan for Ending Tuberculosis as a Public Health Problem (Plano Nacional pelo Fim da Tuberculose como Problema de Saúde Pública) reinforces the political commitment and is based on strategies of access to prevention, diagnosis, and disease treatment. This enables planning actions to improve epidemiological indicators, with the goals of reducing, until 2035, the incidence rate of TB to less than 10 cases/100,000 inhabitants and the mortality rate to less than one death/100,000 inhabitants. Aiming at this, the Plan is based on three pillars (Prevention and integrated care centered on people with TB, Dynamic policies and support system, and Intensification of research and innovation), considering the analysis of socioeconomic and health status in the different scenarios (2) .
Given the specificities of life on the streets, revealing the consequences of social exclusion and extreme poverty, PLS are highly vulnerable to many diseases, including TB. PLS have a 56 times higher risk of acquiring TB in comparison to the general population (1) . Also, some conditions which aggravate disease control in this group are emphasized, especially the unawareness of being ill and of health precautions, lack of a life project, the difficulties of accessing health services, stigma, prejudice, among other factors (3) .
Although there are some public policies aimed at PLS, there are many challenges to developing actions aimed at controlling TB, given the complexity of guaranteeing quality assistance which accounts for this group's life situation and health needs (3) . Poverty and social exclusion result from society's organization, whose mode of production privileges some to the detriment of many others' lives. Social reproduction processes derive from this form of production.
The important contribution from professionals in the teams of Consultório na Rua (Street Clinic) for TB control is emphasized (3)(4)(5) . These teams, created in 2011, represent advancements in health care for PLS, as they started offering integral care to people who faced many obstacles to access health services. A new way of providing care results from the profile and competence of health professionals who understand the role of social determinants in the healthdisease-care process (6) .
PLS are a key population in TB control and priority actions were thus selected by the Ministry of Health, some of which were the conduction of an active search for respiratory symptoms in any opportunity of contact with health professionals and regardless of time coughing, and the conduction of bacilloscopy or fast molecular test, in addition to culture with a sensitivity test (1) .
TB is a socially determined disease; therefore, the way of life on the streets reinforces vulnerability to this disease for diverse reasons which consequently emerge, such as: homelessness, insufficient sleep, rest and nutrition, alcohol and drug abuse, struggle for survival, difficulties in performing self-care, and other reasons.
An increase in this theme's visibility is currently observed; this is mainly due to an increase in people living in this condition and the growing presence of studies which deal with the population living on the streets. The number of people in this situation in Brazil has increased due to the ongoing destruction of the role of the state and of other social and labor rights, in addition to social inequality.
Such contexts require broadening the discussion on this group, reflecting hence about health practices and improving care offered to these people. Thus, given the impact of TB on this vulnerable group and the scarcity of Brazilian studies on this theme, this Systematic Review is justified. It aims at providing a minimal support for improving health care offered to this group, with the main objective of analyzing evidence available in the literature on TB in people living on the streets.

METHOD
This is a Systematic Review whose purpose was to understand the state-of-the-art of the occurrence of TB in the population living on the streets by analyzing scientific articles. To meet this objective, the following guiding question was proposed: what is the scientific evidence for the occurrence of TB in PLS?
A bibliographic research of scientific articles was performed in the databases PubMed, EMBASE, LILACS, and SciELO.  The following eligibility criteria were defined: available scientific articles published in Portuguese, English or Spanish and with no restrictions of year of publication. Review articles were excluded from this study. The data was collected in October 2018 and resulted in the selection of seven articles.
The selected studies were evaluated based on title and abstract and were analyzed by two independent reviewers. In case of doubt or disagreement, a third reviewer would participate in the analysis. All the selected studies were thoroughly read.
Concerning the study's protocol, this Systematic Review was based on the reviewing protocols established by the Cochrane collaboration, aiming at obtaining evidence related to the study object.
Evaluation of methodological quality is conducted by the guaranteeing that the studies' design and report are unbiased. The instrument used for study evaluation was Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), which provides for classifying studies as A (meeting 80% of the criteria), B (50 to 80% of the criteria), and C (inferior to 50% of the criteria) (7) .

RESULTS
The bibliographic search led to the identification of 343 studies, 229 of which were in PubMed, 105 in Embase, and nine in LILACS. During screening, two duplicate articles were excluded, and 341 studies remained, 321 of which were excluded, since they did not correspond to the study's theme, and other two had no abstract. Eighteen studies were selected; however, 11 were excluded due to not including the study population and/or not meeting the eligibility criteria. Seven articles were thus selected as illustrated in Figure 1.
The seven studies are summarized in Chart 2 with reference, study design, time of follow-up, main findings, outcome, and STROBE category.    to those that deal with biological factors. Only one Brazilian study on the epidemiological characteristics of TB in street population was identified. The results of this study reveal that, in São Paulo state, there is a high load of the disease in PLS and that homelessness and associated conditions impact on treatment adherence. The findings reveal that homelessness led to a sharp reduction in treatment success, which demands the implementation of specific interventions to reach this vulnerable population through public policies (12) . PLS are known to be more susceptible to falling ill and dying from TB, given the vulnerability context imposed by life on the streets. Death was observed to be proportional in the two populations (with and without fixed residence) in both studies conducted in the United States of America, with 8% (9) and 9% (8) ; however, other studies revealed a higher rate for the street population (10)(11)(12)(13) .

Identification
A study developed in a city in Spain showed that infectious diseases represent the second most frequent disease group in PLS, and TB was observed in 6.1% of this group, in relation to 0.1% of people with residence. Homelessness, use of injection drugs, and difficulties in maintaining healthy life habits may contribute to the emergence of TB, hepatitis B and C, HIV, among other infectious and contagious diseases, and PLS presented 40 times more chances of developing TB when compared to people with residence (15) . Another study, conducted in Portugal, also revealed that PLS presented a higher use of alcohol and drugs, in addition to other conditions, such as previous TB treatment, TB/HIV co-infection, and higher rates of unfavorable treatment outcomes (16) .
The results for this study demonstrate that PLS were more likely to use alcohol and other drugs, abandon TB treatment, and die as a consequence in comparison with people with residence. Such fact emphasizes the importance of offering health care that accounts for these questions and for the singularities of life on the streets. In addition to social vulnerability, health professionals should be aware of other possible situations which may compromise treatment adherence. The need for continuous follow-up of PLS is thus reinforced (1) .
The studies included in this review showed no significant differences in relation to DOT coverage when comparing PLS and people with residence. The World Health Organization recommends conducting medication supervision; however, an alternative to this modality is articulation with social assistance services, which may be partners in administering DOT and generally have professionals with competence to apply social protection mechanisms to PLS. In case of failure of strategies which maintain people supported by social assistance, it is possible to resort, as a last alternative, to the social hospitalization regime, which may make treatment adherence possible and guarantee a favorable outcome (1) , even if it takes place in an extreme situation. However, such strategy does not modify life situation, assuming that these people's situation is a product of a process which belongs, before anything, to the social sphere and is a consequence of social inequality, in addition to the absence of a providing State which shelters the population.
Three of the studies were from the United States of America (8)(9)14) , one was from Korea (13) , one from Japan (10) , one from Poland (11) , and one from Brazil (12) . The findings regarding the epidemiological characteristics revealed that, regardless of residence status (homeless or with residence), TB afflicted mostly males, predominantly in the economically active age group, ranging from 15 to 64 years (10) , 25 to 64 years (9,12) , and 40 to 60 years or more (8,11,(13)(14) . Concerning skin color, some studies pointed the predominance of black people among PLS and in people with fixed residence (8,14) and brown among PLS (12) , whereas people with fixed residence were mostly white (12) and Asian (9) . Some studies pointed that the use of alcohol and drugs was most frequent in the PLS when compared to people with residence (8)(9)(12)(13)(14) . Only one Brazilian article was included in this study (12) .
Corroborating that PLS presented a higher vulnerability to TB disease, in addition to difficulties of access to TB diagnosis and treatment, among other conditioning factors, a study conducted in the United States of America identified that 6.4% of TB cases occurred in PLS between 1994 and 2003. The authors affirm that, given the relation between TB and precarious life conditions, planning actions for reducing the incidence of this disease in the population living under such circumstances requires knowledge of characteristics and singularities of this group, in addition to comprehension of socioeconomic indexes such as education and income (8) .
The context of vulnerability, which includes aspects related to individual and social vulnerability, is also associated to a difficulty in adhering to TB treatment. A study conducted in the United States of America from 1994 to 2010 investigated 270,948 TB notifications, 6% of which were in PLS. It showed a nearly ten times increase in incidence in this period, lower adherence to treatment, and a higher likelihood of substance abuse. In this sense, the authors emphasize the challenge of incorporating actions aimed at reducing the load of the disease in this population, aiming at complying with the national goal of TB elimination (9) .

DISCUSSION
This systematic review has provided an analysis of the main findings of studies investigating the epidemiological profile of TB in street population. Most of the literature indicates similarities regarding the occurrence of disease in this group.
TB is still a public health problem and a challenge in many countries, since its control depends on the conjugation of intersectoral, institutional, and social actions, in addition Because it is a socially determined disease, TB mostly afflicts PLS, given the situation imposed on them by life on the streets. One emphasizes the importance of health professionals who are sensible to work with this vulnerable group through a human, multidisciplinary approach and help this population search for possibilities of overcoming this condition. In Brazil, activities developed by the teams of Consultório na Rua enable providing care to PLS in the health service, so that their health needs are valued, fostering bonds with and trust of health professionals (17) .
A study conducted in Curitiba, Paraná state, has analyzed the constitutive elements of the work process of health professionals engaged in Consultório na Rua as related to ideological knowledge, represented by the public policies which guided the process of teamwork, such as: access to health, health as a constitutional right, intersectoral work, and the needs of PLS (18) .
In a study conducted with professionals of the Consultório na Rua team, reports showed that health assistance of PLS demanded training the health team to recognize this population's health needs, which derive from diverse conditions that increase vulnerability to TB, treatment abandonment, and death. Thus, the performance of a trained team may contribute to disease control, considering that this situation is beyond the health sphere and demands intersectoral actions (5) .
A systematic review reinforced the importance of developing intersectoral actions for the street population, considering the high occurrence of TB in this group and the difficulties to control the disease, such as prevention, early diagnosis, and treatment (19) .
To promote treatment adherence, in addition to creating bonds between health professionals and people living on the streets, recommended actions include: Projeto Terapêutico Singular (Singular Therapeutic Project), partnering up with the Psychosocial Support Network, and offering incentives to guarantee treatment success (community restaurant, free transportation, shelters, and others). Health professionals should work in teams to identify respiratory symptoms and, by doing so, speeding up TB diagnosis and guaranteeing immediate and timely treatment commencement (1) . Health practices aimed at PLS should be understood from a broad perspective, understanding people as protagonists of their own care (20) .
Controlling TB in PLS poses a challenge to society, especially in current times, when social inequality and unemployment are growing, with a significant increase of PLS as an implication. This group's health needs impact on treatment adherence, considering that TB is socially determined and stigmatized. Comprehending this disease as a social phenomenon is thus fundamental. The Theory of Social Determination of the Health-Disease Process reinforces and contributes to the interpretation of the health-disease process and to overcoming traditional models of care (5) .
As TB is considered a neglected disease, with low social visibility, mainly for affecting people with difficulties or no access to dignity in life and work, the need for understanding falling ill as a social phenomenon is emphasized. This demands interventions that consider their singularities, including actions which go beyond the health sector. Recognizing social inequality implies understanding the process which produces it and identifying the mediating elements between macrosocial processes and epidemiological profiles in different social groups. Such interpretation is indispensable to fight social inequality in the sphere of public policy, in the daily life in health assistance, and in citizen practice (21) .
The evidence found in the articles selected to comprise this study show relevant health data, which reinforces the need for a political commitment so that care practices are incorporated into PLS both through state and civil society efforts with the objective of fighting the singularities deriving from the dynamics of life of this vulnerable group (22) .
The studies selected in this systematic review proposed a description of the occurrence of TB in PLS. Variable health statuses were observed, which makes comparison between different realities difficult.
Considering that PLS are vulnerable to TB, the participation of nurses in the multiprofessional team is emphasized, since their specific qualification enables the creation of bonds with PLS. In addition to this, nurses have instruments to identify needs and thus actively work for the control of this disease, conducting actions that range from the development of health promotion activities, prevention, and early diagnosis to treatment and cure. Health actions for PLS must include not only early diagnosis, but also strategies for treating TB on an individual basis, accounting for health needs, social context, and necessary resources to enable treatment adherence, aiming at reducing bacillus transmission and deaths in this population.

CONCLUSION
The efforts for controlling TB must include specific actions for the street population, given their singularities. Analysis of the scientific literature has shown that there are many challenges to be faced in controlling TB in PLS, since this population is more susceptible to falling ill and there are many obstacles to treatment adherence.
Even though Brazil represents one of the 22 countries with the highest concentration of TB worldwide, this study has pointed the scarcity of studies on Brazilian epidemiological characteristics which deal with the occurrence of TB in street population.
The need for studying contents related to neglected diseases -such as TB -In health courses is emphasized to sensitize future professionals to provide proper care, with an integral approach, and to provide them with instruments which enable the recognition of health needs. Public policies to contribute with social protection for this group are emphasized as urgent. Finally, new studies that investigate this theme, dealing with issues that range from health-disease process in the context of PLS to fighting strategies, are extremely important. The reduction of inequalities through public policies for this population is also emphasized as fundamental; these should guarantee their exercise of citizenship so as to provide them access to housing, health care, education, and jobs.