Underascertainment, underreporting, representativeness and timeliness of the Iranian communicable disease surveillance system for tuberculosis

Abstract Objectives A well-functioning disease surveillance system is essential for effective control of diseases. Therefore, conducting evaluation studies on the performance of disease surveillance systems is necessary. This study was conducted to evaluate the performance of the Iranian syndrome-based surveillance system for tuberculosis (TB) in rural areas of Fars, the third largest province located in southern Iran. Study design This was an evaluation study. Methods Two independent sources of information (data from a population-based survey and data from the surveillance system) were used in this evaluation. A group of trained female nurses used a specially designed interview-administered questionnaire to obtain data on the health status of family members from mothers or other adult women in rural houses. Subsequently, the nurses obtained data from individuals who reported a history of TB during a specified period and defined whether the patients presented themselves to a rural or urban health centre or clinic. Results A total of 48,771 individuals participated in this study. Of 156 cases who reported a history of TB, 137 (87.82%) presented themselves to at least one medical care provider seeking diagnosis and treatment services. Of patients who visited a health or medical centre, only 18 (13.14%) were reported to the highest level of the surveillance system. Accordingly, the rates of underascertainment and underreporting of the Iranian surveillance system for TB were 12.18% and 86.86%, respectively. Moreover, underascertainment was significantly higher for men (19.40%) than for women (6.74%). The mean time between the date at which TB was noticed and the date of diagnosis was 56.24 days, which was longer for men (79.29 days) than for women (40.10 days). The highest and lowest levels of underreporting were observed for private general practitioners (100%) and the health centres run by the government (87%), respectively. Conclusion The quality of the communicable disease surveillance system for TB in Iran is facing important challenges, including underascertainment, underreporting and timeliness, in addition to different types of bias. Informing the general population and health workforce about TB and the importance of timely diagnosis is a good approach to improve the performance of Iran's national communicable disease surveillance system.