Our results show that 10.7% and 30.9% of TB patients in the six participating counties were under-reported to IDRS and not recorded for treatment in TBIMS, respectively. The discrepancy in the under-reporting rate between the two systems is mainly because the systems play different roles in the field of public health. Patients diagnosed with PTB in all health facilities should be reported to IDRS, while only patients referred and verified in TB designated health facilities are recorded in TBIMS. There is value in both vertical (TBIMS) and integrated (IDSR) surveillance systems for capturing data, however there are potential implications for double reporting or discordance of variables when both surveillance systems are utilized to capture information for the same disease. For example, patients who were misdiagnosed in non-designated health facilities and those who were not traced by TB designated health facilities could be reported to IDRS, but not recorded in TBIMS. This could account for the difference of the under-reporting rate between the two surveillance systems. The under-reporting rate in both IDRS and TBIMS suggests China’s TB surveillance systems may still miss some TB patients. More than one fourth of under-reporting rate to TBIMS reminds that there may exist greater risks of under-reporting in certain settings than WHO estimated national level (13%) [23]. The under-reported patients, who may not have received proper treatment and support by NTP management, may continue to contribute to TB transmission within their communities.
Our findings are similar to some studies conducted in other countries in which the under-reporting rate of TB ranged from 6–68% [14, 16, 17, 24–30]. Fatima et al. estimated that almost 68% of persons with TB were not notified to the NTP in Pakistan, many because a large private sector did not report to the NTP [28]. A study conducted in the Republic of Korea estimated 6% of persons with TB were not reported to the national surveillance system [29]. Our current study shows that the under-reporting rate in TBIMS of the six counties is 30.9%, while a previous study conducted in other areas in China reported the under-reporting rate was 19.3%. The difference between the results of the two studies was mainly because the previous study did not include EPTB except TB pleurisy [12].
Though type of TB was removed from IDRS model, type of TB was found to be significant for under-reporting to TBIMS. Compared with patients with laboratory-confirmed and clinically-diagnosed PTB, patients with TB pleurisy or other EPTB were significantly more likely to be underreported. This under-reporting associated with type of TB was also described in other studies [8, 12, 14, 31, 32]. Additionally, the reporting requirements of TB pleurisy and other EPTB vary by province. In most provinces, medical institutions are not required to report patients with TB pleurisy. Mandatory reporting of other EPTBs is also not required in every province. This is a major challenge and issue; non-standard definitions and reporting requirements severely limits the ability to make comparisons and follow trends.
It is notable from our analysis that the odds of under-reporting are significantly higher in tertiary health facilities compared to primary health facilities. In China, tertiary health facilities are all general hospitals with high medical level, have more than 501 beds, and large numbers of patients being referred to or seeking diagnosis and treatment in these hospitals. Consequently, physicians who are responsible for reporting PTB patients to surveillance systems in tertiary health facilities may spend more time seeing patients than reporting to surveillance systems. Our finding is supported by a study conducted in Kenya, where larger facilities and heavy workload were associated with under-reporting [13]. However, other studies indicated that diagnosis in general hospitals contributes to the notification of TB patients [29, 33]. Our findings emphasize the importance of increasing human resource capacity for data collection, management and reporting of TB patients or shifting these tasks to nurses or non-clinical staff in tertiary health facilities.
Our study revealed substantial under-reporting both to IDRS and TBIMS among non-residents, while the proportion underreported to TBIMS is much higher. This may be due to economic factors. Most non-resident TB patients are more likely to have low income and lack medical insurance [34]. Non-residents with medical insurance generally received less proportion of reimbursement outside of the location to which they are a resident, which may result in refusal of anti-TB treatment. In addition, many non-resident TB patients do not have regular work and a permanent place of residence, which may lead to difficulty in linking the patient to TB services. To strengthen the surveillance of non-resident TB patients, it is necessary to focus on reporting of non-residents and ensure funding devoted to supporting and following-up of low income and non-resident patients. Though information on which facilities had paper records was not collected, facilities that are smaller and located in lower income areas are more likely (anecdotally) to be paper based, which could potentially contribute to decreased data quality and reporting.
In our study, under-reporting to TBIMS was also associated with old age. Patients over 65 years old were more likely to be under-reported compared to 15–64 years old. This may be related to a higher rate of comorbidity in patients aged 65 or older, which could necessitate treatment in non-TB-designated health facilities. This is consistent with the bivariate analysis in a study conducted in Spain [14]. We also found that the risk of under-diagnosis was high among patients under 15, which is corroborated by various studies indicated younger age as a risk factor of under-reporting [8, 12, 33]. However, Kang et al. found that age did not significantly affect TB reporting [29]. The number of TB patients under 15 years old influences study results. In 2016, WHO estimated about 11% of TB patients in China were under 15 years old [23]. However, in our study, only 0.9% of TB patients identified were under 15 years old. This may be related to the difference in where children seek healthcare services and the facilities sampled in this study. Most pediatric TB patients are treated in children’s hospitals and therefore reported by regional or national referral hospitals located in big cities. However, none of the hospitals in our selected six counties included this type of hospital. Further studies including children’s hospitals are needed to understand the association between young age and under-reporting of TB patients.
Concordance between systems and reporting of TB patients has been researched in other studies [30, 33, 35–37]. Salyer et al. reported inconsistent smear status of TB patients between records in health facilities and national surveillance database [30]. Podewils et al. reported the poor agreement of HIV status among TB patients [35]. In our study, address and dates in IDRS and TBIMS were the variables most discordant with medical records. Podewils et al. showed similar findings in their study [35]. This may be due to multiple reasons. Physicians may not have time for adequate epidemiological investigation due to high workload burden in both general hospitals and designated facilities. And patients may also have stigma pressure to not give their private information [38]. Address is important for tracing patients and facilitating full course follow-up, thus important to include in reporting and recording as an essential variable. Timeliness of reporting was evaluated in multiple studies by different variables, making comparisons difficult. Some studies reported the proportion of patients with delayed reporting (> 7 days) varied from 18.2–25.7% [29, 33]. Johnson et al. reported 11% of TB patients were not reported to electronic communicable disease surveillance system in one business day [39]. Some studies reported average duration of delay in reporting TB patients (ranged from 4 days to 3 months) [40–42]. There was greater under-reporting to TBIMS compared to IDRS. However, when patients were reported, there was greater delay to reporting in IDRS compared to TBIMS (12.3% vs. 6.5%).
Our study has several limitations. First, we used purposive sampling to select six counties, for ease of introducing and implementing matching software, however this made our findings not representative of other areas in China. Second, in our study, we focused on healthcare facilities that had capacity to perform chest x-rays (CXR) and had diagnosed at least one TB patient during the project period, which means patients seeking healthcare in the facilities not meeting the criteria were excluded, thus limiting the inclusion of EPTB. It is crucial to ensure that these patients were diagnosed and treated properly. Therefore, under-reporting of under-diagnosed patients deserves further study. Third, children’s hospitals were not included in our study, which could bias our results of under-reporting among children.