Our findings illustrate that laboratory, hospital, physician prescription (patient referral to the health center, patients receiving anti-tuberculosis drugs and medical TB diagnostic laboratories) data should be check and register for all TB cases. The study illustrates that the highest number of patients with new smear positive TB was observed in man (25-44 years).
Based on the results of this study, the completeness of reporting smear-positive pulmonary tuberculosis in Ahvaz city using the data of three sources of the hospital, laboratory, and physician reporting was 87.5%.
Also, result from this study demonstrated that the incidence of disease was estimated to be eleven and eight-tenths of a patient per one hundred thousand people based on the various three-source log-linear model capture-recapture model.
This underreporting leads to lack of timely and standard treatment (Dots) of TB patients, so improving the care system (TB) of tuberculosis by improving timely reporting of cases of positive pulmonary tuberculosis smear and subsequent timely treatment of patients leads to a decrease in cases of TB, death from disease and resistant TB will be treated.
Besides, timely reporting of tuberculosis cases and subsequent contact tracing will play an important role in preventing the spread of the disease.
Investigation of the relationship between smear-positive pulmonary tuberculosis parameters of gyms and density of Mycobacterium Tuberculosis needs to gather information such as age, sex, and living area. For human diseases, capture-recapture analysis has predominantly been applied to estimate the prevalence, incidence, or completeness of registers of specific groups of diseases, often diseases with a chronic character as mentioned earlier. Apparently the characteristics of most of these diseases, their patients and their registers best fulfil criteria for feasibility of capture-recapture studies as well as validity of the underlying assumptions .
The strategy to end tuberculosis by 2030 pursues goals such as a 90% reduction in mortality and an 80% reduction in disease incidence . To achieve these goals, diagnosis and treatment of patients has an important role to play, which also requires an optimal surveillance . The incidence rate of smear-positive pulmonary tuberculosis in Ahvaz based on information surveillance data, the data of the present study, and linear logarithm estimation were 9.8, 10.3, and 11.8 diseases per 100,000 people, respectively.
Also, result this study estimated to frequency of TB according to information surveillance data, the data of the present study, and linear logarithm estimation were 128, 134, and 153 persons, respectively. The number of differences in cases was six patients. Data about 4 (66%) cases of this was not registered in the surveillance system because of they were dead before the disease was diagnosed.
Edginton et al. was also mentioned this point in their study . This can have an impact the indicators of assessing the status of the surveillance, 3% in reducing the success rate of treatment and equally in increasing Mortality rate from the disease. Using the log-linear model, a model that includes the independent effect of each source, the number of cases not recorded in any of the sources was estimated to be 19, which is consistent with the results of the Dunbar et al. Study in South Africa . This study shows that, the completeness of reporting smear-positive pulmonary tuberculosis was 87.5%, which is similar to the results of studies in France and Romania [12, 32] and the World Health Organization’s Executive Task Force on Tuberculosis Control, which provides for the detection of at least 70% of positive smear tuberculosis cases . The highest percentage of completeness of reporting (79%) was related to laboratory data, which was consistent with Vanina Guerrier’s study in France, Cojocaru’s study in Romania, and Ibarz-Pavon’s study in Greece [12, 13, 32].
According to a 2016 World Health Organization report, the estimated incidence of all forms of tuberculosis in Iran is estimated at 16 per one hundred thousand and Therefore, considering the ratio between different forms of tuberculosis, the incidence estimated by this organization is lower than the rate calculated in this study. It should be noted, however, that this estimate is for the entire population of Iran, while the incidence and prevalence of tuberculosis are high in the marginal areas of Iran including, Khuzestan province . The assumptions of Capture-recapture studies, such as population closure, the possibility of finding commonality between sources, the independence of resources from each other, and the dependence of the catch on the specificity of the individuals at the time of these studies, should be considered . In this study, due to the use of Excel software and sort data by name, surname and, national code and manual review of all records, the default breach is that it is limited to find commonality between resources. The study also included a population closure assumption and included only patients who resided in the study area, but because this city is the center of the province, some patients may have mentioned their relatives’ address at the time of hospitalization and, so were included in the study. The default breach of catch dependency regarding individuals’ characteristics is limited due to the widespread use of primary health care at the county level and the free diagnosis and treatment of tuberculosis.
In Capture-recapture studies, by including the interaction between different sources, the effect of dependence (positive or negative) between the sources can be taken into account in the estimates and, bias due to the lack of default independence of resources can be largely eliminated .
In this study, the elimination of duplicates prevented overestimation and, since only those with laboratory confirmation were included in the study, the accurate default of diagnosis was considered and, no false positives remained in the data.
In another study, Smit et al. estimate the completeness of notification of incident tuberculosis cases in the Netherlands . They reported that between 1499 tuberculosis patients which were identified, of whom 1298 were notified, resulting in an observed under-notification of 13·4% . Also, prediction by Log-linear capture–recapture analysis initially a total number of 2053 (95% CI 1871–2443) tuberculosis cases . The result of this study showed that the total number of smear-positive pulmonary tuberculosis cases was estimated to be 153 (95% confidence interval: 134-142). This difference in the number of tuberculosis patients can be because of population, economic status of the society, level of awareness, and culture of the society and geographical conditions.
Huseynova et al. in Iraq studied tuberculosis burden and reporting in resource-limited countries . Based on the result of this study, a total of 1985 TB cases registered 1677 patients (observed completeness 84%). They investigated total number of TB cases was 2460 (95%CI 2381–2553), with identified TB cases representing 81% (95%CI 69–89) . Huseynova et al. administrated that TB surveillance needs to be strengthened to reduce under-reporting. This administrated is the same identical as our study.
In Egypt by Bassili et al. evaluation of tuberculosis case detection rate in resource-limited countries . According to result this study CDR of NTP surveillance and completeness of case ascertainment after record linkage was respectively 55% (95%CI 46–68) and 62% (95%CI 52–77). They stated that sputum smear-positive TB cases, these proportions were 66% (95%CI 55–75) and 72% (95%CI 60–82), respectively .
In the three-source capture analysis, data collected from each source should be more than 15% of the total catch and have sufficient overlap . In the present study, disease cases from laboratory, hospital, and physician reporting sources dedicated were 90%, 34%, and 18%, respectively.
The results of this study indicate that under-reporting of smear-positive tuberculosis cases in Ahvaz was about 12.4%. Based on our result study, the cases with positive smear pulmonary TB which had laboratory confirmation them were 3.9%.
The highest overlap was between the laboratory and hospital sources and, the lowest overlap was between hospital sources and physician reporting which, were inconsistent with the study results by Dunbar et al. . It is suggested to report the disease from the hospital and laboratory level using electronic systems to eliminate the challenge of not registering patients in the TB treatment system and given strengthening the approach of electronic medical records in recent years. In addition, the cases of tuberculosis admitted to the hospital can be seasonally extracted and compared with reported cases by examining the hospital registration system. Continuous evaluation of the disease care system using, the capture-recapture method is also recommended.
This study did not cover cultural factors and economical patient information. One of the main limitations of this study was discussed only the factors that influence compliance with TB.
Also, referred to specialist physicians in neighboring provinces for diagnosis, treatment and the inability to access these patients’ prescriptions were another of the limitation of this study. Observed findings showed that another significant limitation of this study includes the limitations of the population of individuals.
The limitations to capture-recapture studies estimating tuberculosis incidence or prevalence depend on the violation of the underlying assumptions.