Epidemiology of tuberculosis in Qatar: Eight-year retrospective cohort study

doi:10.21203/rs.3.rs-4942336/v1

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Epidemiology of tuberculosis in Qatar: Eight-year retrospective cohort study

https://doi.org/10.21203/rs.3.rs-4942336/v1

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Introduction/Objectives: Tuberculosis (TB) remains a significant global health challenge, with substantial morbidity and mortality worldwide. This retrospective cohort study aimed to elucidate the epidemiological landscape of TB in Qatar over an eight-year period, from 2016 to 2023. Data were collected from the Communicable Disease Center (CDC) TB registry, encompassing individuals with confirmed Mycobacterium tuberculosis infection. Demographic characteristics, incidence rates, mortality trends, drug resistance patterns and associated factors were analyzed.

Results: TB incidence rate in Qatar remained below the global average and WHO 2025 milestone target. Across all age groups, TB incidence showed a notable variation, with a peak among individuals aged 25-54 years. Males had higher TB incidence rates. A significant proportion of TB cases originated from high-incidence countries. Qatar demonstrated fluctuations in multidrug-resistant TB (MDR-TB) cases over the study period, the percentage remained below the global average, indicating effective TB control efforts.

Conclusion: This study provides valuable insights into the epidemiology of TB in Qatar, emphasizing the need for comprehensive strategies to mitigate TB transmission and improve control measures in high-risk populations.

Tuberculosis

World Health Organization

Extrapulmonary tuberculosis

Drug susceptibility testing

Multidrug-resistant Tuberculosis

Rifampicin-resistant Tuberculosis

Extensively drug-resistant Tuberculosis

Tuberculosis (TB)remains a major cause of death worldwide. According to World Health Organization (WHO), around 10.6 million people got infected with TB in 2021(1). TB is a communicable disease that is caused by bacillus Mycobacterium tuberculosis. It mainly affects the lungs (pulmonary TB) but can also affects other organs in the body such as the kidneys, brain and bones and referred to as extrapulmonary tuberculosis (EPTB) (3). According to the global TB report 2022, adults account for 90% of all TB cases reported each year (3). If untreated, death from active TB is approximately 50%. In 2021, global deaths caused by TB were estimated at 1.4 million. Low-middle income countries bear the vast majority (90%) burden of the disease, reflecting poor accommodation and overcrowding environments. The highest rates of TB infections are seen in eight countries: India (26% of global cases), Indonesia (9%), China (8%), the Philippines (6%), Pakistan (6%), Nigeria (4%), Bangladesh (4%), and South Africa (4%) (4). Addressing multisectoral actions to target TB determinants such as poverty, undernourishment, HIV infection, smoking and diabetes may also reduce the burden of the disease globally (3). HIV positive patients are at increased risk of TB due to their weakened immunological system and to frequent co-existence of deprived social conditions (2). About 6.7% of all incident cases of TB in 2021 were people living with HIV. The rate of TB/HIV co-infection was highest the African region (3). It is important to highlight the threat of Drug resistance TB. According to WHO, TB cases are classified into 5 distinct categories based on drug susceptibility testing of clinical isolates confirmed to be Mycobacterium tuberculosis. These comprise isoniazid-resistant TB, rifampicin-resistant TB (RR-TB) and MDR-TB multidrug-resistant TB (MDR-TB), extensively drug-resistant TB (XDR-TB) and pre-XDR-TB (5). Immigration from high-incidence settings to low-incidence settings may lead to higher TB rates (6). It is important to understand the epidemiology of TB comprehensively to be able to combat the disease through developing prevention and control measures such as screening programs and prevention programs (2). To date, there is no published data that demonstrate the epidemiological status of the disease in Qatar. The aim of this retrospective cohort study is to provide a comprehensive understanding of the distribution and determinants of TB in Qatar.

This retrospective cohort study was conducted at the Communicable Disease Center (CDC) in Qatar. The CDC TB registry was reviewed to include all individuals (all ages) with confirmed Mycobacterium tuberculosis over a 6 year period, between 1st January 2016 and 31st December 2022. Patients whose records were not available were excluded. Ethics approval for this study was obtained from the Institutional Review Board of Hamad Medical Corporation, under protocol number (MRC-01-24-034). The study was conducted in accordance with the principles outlined in the Declaration of Helsinki and other applicable ethical guidelines.

The demographic and characteristics profiles of participants were summarized using descriptive statistics. Categorical variables were presented as frequencies and percentages, while continues data were expressed as mean ± standard deviation for normally distributed data or as median and interquartile range depending on the normality distribution of the data. Continuous data were examined using either Mann–Whitney or t-test, depending on the normality of the data and categorical data were analyzed with the chi-square test. P value < 0.05 was considered statistically significant. All statistical analyses were done using statistical package Stata 16.

Over the eight-year period (2016–2023), 5462 TB cases were reported in Qatar. The TB incidence in Qatar fluctuated between 20 to 37 cases per 100,000 population. Qatar successfully managed to keep the incidence below the global average and below WHO 2025 milestones target of 55 cases per 100,000 (Fig. 1). TB related deaths in Qatar increased from 1 in 2016 to 22 in 2021, before decreasing to 8 in 2022 (Fig. 2). TB incidence rate varied across different age groups with distinct patterns. Data from the year 2022 shows no TB cases reported among children aged 0–4 years. The majority of TB cases were found among the 25–54 age group. The incidence was lower in the 55–64 years group (Fig. 3). Over the years, the male’s incidence rates reached maximum of 39 while the peak in the female group was 29. A notable peak was noticed in both males and females in 2021 (Fig. 4). There wasn’t a significant difference between extrapulmonary and pulmonary sites (Fig. 5). Over the years, the number of confirmed rifampicin-resistant TB (RR-TB) or multidrug-resistant TB (MDR-TB) cases showed an upward trend. However, the percentage remained between 0.5 to 1.8% over the eight years period. In 2022, 6 out of 12 cases were reported from individuals originating from India, Pakistan and Nepal (Table 1) (Fig. 6). The is a notable increase in number of active TB cases among Non-Qataris compared to Qataris. Overall, 2018 onwards the number of active TB cases was higher that the previous years (Fig. 7).

Table 1

Drug-resistant TB
Year	2016	2017	2018	2019	2020	2021	2022
Total number of active TB cases	536	601	750	859	861	983	872
Number of Lab confirmed RR-TB or MDR-TB cases	10	7	4	9	10	5	12
Percentage of RR-TB or MDR-TB cases	1.87%	1.16%	0.53%	1.05%	1.16%	0.51%	1.38%
MDR-TB cases	No data	7	4	9	9	5	11
Number tested for lab susceptibility to 2nd line drugs among the confirmed RR-TB or MDR-TB cases	No data	7	4	7	10	5	12
Number lab confirmed XDR-TB cases	No data	0	0	0	1	0	1

his study demonstrate the epidemiological landscape of TB over an eight-year period shedding light on its prevalence, trends and associated factors. Qatar managed to maintain a TB incidence rate below the global average and below WHO 2025 milestones target of 55 cases per 100,000 population per year. Analysis of TB incidence rate by age showed that the majority of cases were among individuals aged 25–54 years. TB incidence rate in males appeared to be higher through the years. Moreover, the percentage of confirmed

RR-TB or MDR-TB cases remained fluctuating between 0.5 to 1.8% over eight years period.

The fact that males constitute 72% of the total population suggests that there is a larger pool of males at risk of TB infection which could contribute to the higher incidence rate among males. In addition, expatriates working as laborers constitutes a significant proportion (62%) of the total male population in Qatar (7) suggesting that this demographic group may be particularly vulnerable to TB infection and transmission. Furthermore, the influx of expatriates, especially from high TB incidence countries, contribute to the TB burden among males in Qatar. For example, in 2022, India, Nepal, Bangladesh and Philippines constituted 75% of all TB cases in Qatar, reflecting the global TB pattern. World Health Organization identified those countries among the list of 30 countries with the highest TB burden globally (8), while Nepal was specifically listed among of the countries with the highest burden of MDR-TB (9). Additionally, the nature of the laborers’ work which often involves close contacts with others in confined spaces, further increases their risk of TB transmission (10). Comparative studies with neighboring countries, such as Oman, showed significant differences in TB incidences rates between nationals and non-nationals. For instance, between 2018 and 2020 Oman reported 33% of total registered TB cases were nationals, whereases non-national constituted 66% (11). Whereas, Qatar showed a different distribution, with nationals compromising only 2% of reported TB cases during the same period, compared to 98% among non-nationals. These contrasting trends underscore the importance of considering the impact of expatriate population variations on TB incidence trend. TB remains a concern in high-income countries (12). In Qatar, classified as one of the highest per capita incomes globally (13), more than 50% of reported MDR-TB cases originate from individuals from India, Pakistan and Nepal. Despite this, the percentage of MDR-TB remained fluctuating between 0.5 to 1.8% below the global average of 3.3% in 2022 indicating the effectiveness of TB control efforts in the country.

The robust healthcare system in Qatar played a vital role in maintaining TB incidence levels. In Qatar, effective TB control programs focused on prevention, diagnosis, and treatment of TB. To ensure early detection of TB cases, the country mandates TB screening for groups, including healthcare workers and individuals seeking residency or work permits. All TB patients have complete access to health care system in Qatar including free diagnosis and treatment regardless of nationality. To reduce TB severity in children, Bacille Calmette-Guerin (BCG) vaccination in Qatar is listed in the routine vaccination program after birth (14). In addition, Qatar health authorities are continuously leading public awareness campaigns to promote understanding of TB symptoms and emphasize on the importance of seeking medical care promptly (15).

While our study provides valuable insights into the epidemiology of TB in Qatar, there are several limitations. The use of secondary data limited our ability to capture detailed information or conduct in-depth analysis of risk factors. Furthermore, the nature of the study design precludes establishing causal relationships between demographic factors and TB incidence. To mitigate potential accuracy biases, infectious disease specialists were assigned to collect and validate the data. Their expertise in TB diagnosis and management ensured the accuracy and reliability of the collected information, thereby enhancing the robustness of our findings. Following our research, future research should focus on investigating socio-economic factors’ impact on TB burden and continued MDR-TB surveillance are also essential to tackle drug-resistant TB globally.

Tuberculosis

CDC

Communicable Disease Center

MDR-TB

Multidrug-resistant TB

WHO

World Health Organization

EPTB

Extrapulmonary tuberculosis

RR-TB

Rifampicin-resistant TB

XDR-TB

Extensively drug-resistant TB

Acknowledgements:

We thank CDC nurses for their hard work in collecting and keeping a record of TB data at CDC.

Funding:

This work didn’t receive any specific funding .

Conflicts of interest:

The authors declare no conflict of interests.

Ethics approval:

This study was consulted to the ethics committees of Hamd Medical Corporation. We didn’t include any data of patients’ personal information, including name, identity information, address, telephone number, etc. Therefore ethical consent was not needed.

Availability of data and material:

The authors confirms that all data generated or analyzed during this study are included in this published article.

Consent for publication:

Not applicable

Authors' contributions:

SB : Prepared the research protocol, prepared the figures and wrote the main manuscript, JN: Prepared the research protocol, Collected and provided data, review final manuscript and approved. MC, FH, HA, SH and MA reviewed final manuscript and approved. MA reviewed final manuscript, approved and provided resources.

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No competing interests reported.

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Epidemiology of tuberculosis in Qatar: Eight-year retrospective cohort study

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