HIV infection is one of the risk factors for contracting tuberculosis [1]. According to the World Health Organization, (WHO) the risk of people with HIV developing TB is much higher than in non-infected individuals [2].

According to the WHO, in 2011, there were approximately 34 million people suffering from HIV worldwide, with 2.5 million new cases and 1.7 million people who died from HIV/AIDS [3].

As HIV infection progresses and immunity declines, such individuals become more susceptible to infections, which is characteristic of the AIDS profile. The atypical or disseminated pulmonary tuberculosis is one of the main infections striking immunocompromised individuals [4].

One third of the world population is estimated to be infected with tuberculosis, approximately 9.2 million ill individuals every year [5], with estimates of 8.8 million new cases and 1.4 million deaths in 2011 [2].

In 2011, of the 8.7 million new cases of tuberculosis in the world, 13% (approximately 1.04 million) suffered from an HIV/TB coinfection and there were 430,000 deaths [2]. In Brazil, in 2011, 91 thousand people were co-infected with HIV/TB, 83 thousand new cases and an incidence rate of 42 cases per 100,000 inhabitants [6].

In the municipality of Ribeirão Preto, 1,273 cases of tuberculosis were reported between 1998 and 2003, with 377 of them presenting reactive serology for HIV, which represents a mean of 30% of coinfection [7].

In individuals infected with HIV, TB is known to be harder to diagnose, due to the possibility of modification in the clinical and radiological situation because of the immunodeficiency, as well as the lesser sensitiveness of the baciloscopy. Patients with HIV have a lower performance in the BAAR sputum test, a greater prevalence of infection by other mycobacteria and a greater incidence of multidrugresistant tuberculosis [8].

The delay in the diagnosis of TB in the individual with HIV is associated with the increased risk for death and the contamination of closer contacts [9].

In light of this, the aim of this study is to characterize individuals co-infected comparing them to with others individuals with HIV/ tuberculosis, as reported in Ribeirão Preto in 2010 and 2011, according to sociodemographic and clinical data.

This is an epidemiological, descriptive, cross-sectional and retrospective study, conducted in 2012, in the city of Ribeirão Preto, which is located in the state of São Paulo, Brazil, and whose population, in 2010, was 604,682 inhabitants [10].

The study population consisted of all individuals with HIV/ tuberculosis co-infection, over 18 years, residing in the city of Ribeirão Preto, who received care during 2010 and 2011, and whose case of tuberculosis was reported in the TB web system.

The data was collected from the TBweb, which is the information system used in the state of São Paulo for storing the data related to the reporting, evolution and end of treatment of TB patients [11]. The variables available in this system, and which were evaluated in the study are: sex, age range, education, clinical form of TB, baciloscopy and x-ray tests, treatment outcome (cure, abandonment, death). The variables of interest in the study were gender, age range, education, tests performed, clinical form of tuberculosis, type of treatment, end of treatment.

Fisher’s exact test and the prevalence ratio were estimated to meet the study purpose. The prevalence ratio was estimated by means of the log-binomial model implemented in the procedure PROC GENMOD of the program SAS, version 9.0.

This study was approved by the Research Ethics Committee of the University of São Paulo at Ribeirao Preto College of Nursing, Protocol No. 135/2012, in accordance with the recommendations of Resolution 196/96 of the National Health Council.

Of the 375 individuals reported with tuberculosis reported during the study period, 307 underwent HIV serologic testing, where 222 (72.3%) of the results were negative and 85 (27.7%) were positive.

In the cases of individuals who only had tuberculosis, as well as those who were co-infected, most were male-68.5% and 70.6% respectively.

The predominant age range was from 40 to 49 years (40.0%) among co-infected individuals and over 50 years (31.2%) among the others. In terms of education, 36.7% had 4 to 7 years of education the both groups, and in 47.9% no information was available (Table 1).

Table 1: Distribution of individuals with HIV and tuberculosis, according to sociodemographic variables and prevalence ratio, Ribeirão Preto-SP, 2010-2011.

A sputum smear test showed positive results in 55.1% individuals, with co-infected individuals presenting the lowest rate (18.5%); 88.0% of the thoracic radiographies showed a suggestive image of tuberculosis, the information regarding these variables was not available in 30.0% and 29.0% of the cases, respectively. Regarding the clinical form, 35.6% of the co-infected patients presented the extrapulmonary form; with this rate being 64.4% among other TB patients, the information regarding this variable was not available in 2.3% of the cases (Table 2).

Table 2: Distribution of individuals with tuberculosis and HIV/AIDS, according to clinical variables related to tuberculosis. Ribeirão Preto-SP, 2010-2011.

Regarding the treatment outcome, there was an 80.5% rate of cure, 8.5%of abandonment and 11.1% of deaths (Table 3); however, regarding the groups, the death rate was higher among co-infected individuals (61.8%).

Table 3: Distribution of individuals with HIV and tuberculosis, according to end of treatment. Ribeirão Preto - SP, 2010-2011.

The prevalence ratio was computed for each variable in order to compare individuals with and without tuberculosis. The variables presenting chance of risk with the co-infected group were: age range between 30 and 39 years (PR=3.24; IC=1.41; 7.45) and between 40 and 49 years (PR=3.04; IC=1.29; 7.14), education between 4 and 7 years (PR=2.51;IC=1.14; 5.55), extrapulmonary tuberculosis (PR=1.83;IC=1.08; 3.10), negative baciloscopy (PR=2.63; IC=1.51; 4.56),with normal x-ray image (PR=2.08; IC=1.17; 3.69) and outcome of abandonment (PR=3.07; IC=1.89; 4.99).

Of the total cases of tuberculosis reported in Brazil in 2006, 20.8% were diagnosed as infection by HIV/AIDS [5]. In this study, it was found that co-infection occurred in 27.7% of the cases, which corroborates a study done in Porto Alegre [12] where the rate was 29.2%, but contrasts with other studies that show this population as being smaller [13-15].

The co-infection rate was higher than that found in another study conducted in the same city between 1998 and 2003 [7]. This demonstrates the need for further actions aimed at reducing this rate, because the interaction between these two pathologies has a strong impact on their behavior and is responsible for increased mortality [16].

In our study, there was a predominance of males in cases of coinfection, which is consistent with other studies conducted in Brazil [7,13,17]. This high prevalence indicates that the male population is more vulnerable to both HIV and TB [14].

The high co-infection rate among working age people is in accordance with other studies conducted with this same population [17,18]. The prevalence of the HIV/TB link in this group of productive age is reflected in the socioeconomic issue and has social consequences for both the individual and his/her family [18].

Several studies highlight the importance of performing a sputum smear test [13,19], which is one of the complementary exams used for diagnosing tuberculosis, apart from being fast and cheap [20]. In this study, 85.7% of the individuals did the test, a higher result than in João Pessoa-PB [19]. Nevertheless, the percentage of negative tests among the co-infected individuals was higher than among other individuals (36.6% and 40.6% respectively), reinforcing the difficulty in the diagnosis of tuberculosis with this method among individuals with HIV. In addition, the greater number of extrapulmonary cases among co-infected individuals (30.6%, whereas it was 18% among non-coinfected individuals) also demonstrates the need for other methods to diagnose tuberculosis in these patients.

The results related to the clinical form agree with another study [7] carried out in the same city between 1998 and 2003, where the extrapulmonary type had the highest rate among individuals with HIV/TB coinfection.

As for the treatment outcome, a greater death rate was associated with the group of co-infected patients (24.7%). The high incidence of death may be related to the interaction itself between both pathologies, which leads to increased mortality rates [17]. A greater rate of abandonment was also observed among patients with HIV (12.9% against 6.8%), which agrees with other studies in Brazil [21-23]. A limitation to this study was the incomplete reporting of information in the data bank, resulting in much information not being available for use.

The co-infected individuals were mostly male, predominantly 30-49 years old, of working age and with little education.

The sputum smear was the main test performed, and over 80% presented the pulmonary form.

A high mortality rate detected demonstrates the seriousness of the link between these two diseases and the need to promote multidisciplinary measures to reduce its incidence.

The superposition of the epidemics of tuberculosis and aids, as well as the epidemiological behavior of tuberculosis in co-infected individuals reflect the need for a partnership between the programs that control both diseases.