Tuberculosis remains, according to the World Health Organization (WHO), a global public health emergency. In 2015, it was estimated that there were 10.4 million new cases and 1.4 million deaths attributable to this disease, making it the leading cause of death from a single infectious agent ahead of HIV [1]. In sub-Saharan Africa, the burden of tuberculosis is particularly heavy due to the coexistence of risk factors such as poverty, overcrowding, malnutrition, and the HIV epidemic [2].

In Senegal, tuberculosis is a major public health concern. The country reported 10,975 tuberculosis cases in 2008 and 11,734 cases in 2009. According to officials from the National Tuberculosis Control Program (PNT), 70% of cases are expected to be detected each year, and 80% of these must be cured to hope to break the chain of transmission. The Thiès region ranks third in terms of national prevalence with 68%, ahead of Diourbel at 60% and after Ziguinchor and Dakar with 102% and 79%, respectively. Some patients do not hesitate to turn to traditional medicine, with traditional practitioners being the first point of contact in the Thiès region [3,4].

The Thiès region, an economic and demographic hub, has a high incidence and active transmission dynamics. However, precise local data on the epidemiological profile, clinical characteristics, and treatment outcomes remain fragmented.

Moreover, extrapulmonary tuberculosis (EPTB) accounts for 15 to 30% of cases in high-endemic countries [5]. Its diagnosis is often delayed due to polymorphic and nonspecific clinical presentations, which can worsen the prognosis. A better understanding of the characteristics of EPTB compared to pulmonary tuberculosis (PTB) is therefore necessary to optimize screening and management strategies.

The main objective of this study was to describe the epidemiological, clinical, and developmental aspects of tuberculosis at the Thiès health center between 2012 and 2015. The secondary objective was to compare these characteristics between patients with PTB and those with EPTB.

Patients and methods

Study framework and type : A retrospective, descriptive, and analytical study was carried out at the Thiès Health Center, which serves as the focal point for tuberculosis management in the Thiès health district. The study period extended from January 1, 2012, to December 31, 2015.

Population : All patients diagnosed with tuberculosis, of any form, who were put on standard antituberculosis treatment according to national recommendations (2RHZE/4RH regimen) and who completed this treatment during the study period were included. Patients whose treatment was still ongoing as of December 31, 2015, were excluded.

Data collection : A standardized data collection form was used to extract information from the National Tuberculosis Control Program (NTCP) registers and patient records. The variables collected included :

1. Sociodemographic characteristics : age, gender, occupation, marital status.
2. History and risk factors: tuberculosis exposure, BCG vaccination, diabetes, high blood pressure (hypertension), HIV infection, smoking, alcoholism.
3. Clinical data: location of tuberculosis (purely pulmonary, purely extrapulmonary, mixed), type of patient (new case, relapse, transfer).
4. Therapeutic and progress data: treatment plan, duration, treatment outcome (recovery, death, lost to follow-up, treatment completed).

Statistical analysis : The data were entered and analyzed using SPSS version 20.0 and Excel. Qualitative variables were described using frequencies and percentages, while quantitative variables were described using means and standard deviations. Comparisons between the pulmonary and extrapulmonary tuberculosis groups (PT and EPT) were performed using the Chi-square test (or Fisher's exact test when appropriate) for qualitative variables and the Student's t-test for quantitative variables. The significance level was set at p < 0.05.

Ethical considérations : The study was conducted in compliance with data confidentiality. Patient anonymity was maintained. Authorization from the administration of the Thiès Health Center and the University Ethics Committee was obtained prior to data collection.

Results

Out of the 1,035 files reviewed, 948 (91.6%) met the inclusion criteria and were analyzed.

Sociodemographic characteristics

The average age of the patients was 33.6 years (± 14.4 years), with a median of 31 years. The most represented age groups were 20-39 and 40-59 years, accounting for 56.6% and 23.3%, respectively. The sex-ratio (M/F) was 2.29. The patients were unmarried (57.2%), and 63.1% were unemployed at the time of diagnosis (Table I).

Medical history and risk factors

The concept of tuberculosis exposure was reported by 29.0% of patients. The majority (96.3%) stated that they had received the BCG vaccine. Among comorbidities, hypertension was the most common (5.5%), followed by diabetes (2.7%) and HIV infection (1.9%). Regarding lifestyle habits, 14.2% of patients were smokers, 2.8% consumed alcohol, and 0.7% used illicit drugs.

Clinical and therapeutic characteristics

Pure pulmonary tuberculosis accounted for 86.6% of cases (n=821), pure extrapulmonary tuberculosis for 12.7% (n=120), and mixed forms (pulmonary + extrapulmonary) for 0.7% (n=7). Among pure extrapulmonary TB cases, the most frequent sites were pleural (52.5%), lymph node (14.2%), and osteoarticular (11.7%) – Table VII. The vast majority of patients (94.2%) were new cases. All patients received standard first-line treatment (2RHZE/4RH).

Progress under treatment

The outcome of the treatment was favorable, with a cure rate of 71.2%. Death occurred in 5.3% of cases, treatment abandonment or loss to follow-up in 2.8% of cases, and 17.3% of patients had a "treatment completed" outcome without bacteriological confirmation of cure.

Table I: Sociodemographic, clinical, developmental, and therapeutic characteristics of the overall population of TB patients

Comparison of pulmonary tuberculosis (PT) versus extrapulmonary (EPT)

The comparison of the 821 cases of pure TP and the 120 cases of pure EPT revealed several statistically significant differences :

- Age : The 20-39 age group was more represented in the TP group (58.6% vs 45.0%, p<0.02).

- Sex : The male predominance was more pronounced in the TP group (sex ratio TP=2.4; PET=1.7; p<0.03).

- Marital status : Unmarried patients were more numerous in the TP group (58.3% vs 49.2%, p<0.02).

- Job : The proportion of unemployed patients was higher in the PET group (68.3% vs 62.1%, p<0.02).

- Comorbidities : The prevalence of HIV infection was significantly higher in the PET group (5.8% vs. 1.3%, p<0.03). No significant differences were observed for diabetes or hypertension.

- Evolution : The cure rate was higher in the TP group (75.9% vs 33.3%), while the proportion of 'treatment completed' (without bacteriological evidence) was higher in the TEP group (50.0% vs 12.4%). Mortality was also higher in the TEP group (11.7% vs 4.4%). However, the overall difference in outcomes was not statistically significant (p=0.55).

Extrapulmonary tuberculosis was significantly associated with older age groups, female sex, marital status, unemployment and HIV infection (tableII).

Tableau II : Comparison between pulmonary tuberculosis and extrapulmonary tuberculosis