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Quattrocchi et al’s recent publication explored the association between tuberculosis (TB) stigma and delays in care among Italians.1 As the authors note, this investigation distinguishes itself from other research on the topic of tuberculosis stigma and its impact on delays in care by assessing this association in a European population in contrast to prior work, which has primarily focused on Asian and African populations. Thus, while the results add to a growing body of literature, several limitations and biases, many of which the authors acknowledge, narrow the generalizability of the results. Specifically, selection bias may have underestimated the findings with regard to patient delay (PD).
In this investigation, healthcare providers at participating clinics collected data during an in-person visit in which tuberculosis patients were diagnosed or initiating treatment. If the underlying question of interest is Does increased TB stigma lead to longer delays in care? and the answer is Yes, then the current study is not constructed to accurately capture that association since those with the highest levels of perceived TB stigma may never present at the clinic and would therefore be excluded from the study. This is of particular concern given the estimated 10.4 million cases of TB worldwide, 4 million of which are presumed missing.2
For illustrative purposes, we can use data provided in the paper to roughly construct a contingency table that would yield the r...
For illustrative purposes, we can use data provided in the paper to roughly construct a contingency table that would yield the reported unadjusted OR examining the association between stigma and patient delay. Assuming that 231 patients were included in the analysis (number with measured PD), and that the authors mistakenly reported the number and percent of participants without PD in column 1 of Table 1, the following values would yield the reported OR: 90 with low stigma and PD-; 30 with low stigma and PD+; 59 with high stigma and PD-; and 52 with high stigma and PD+. If stigma does cause individuals to delay seeking TB treatment to the point that they never present to a clinic, then the number of people with high stigma and PD+ is underestimated. If even 5% of cases in this group (3 people) are missing, then the unadjusted OR increases from 2.64 to 2.80, and to 3.31 if 20% of cases (11 people) in this group are missed. Thus, depending on the degree of this bias results are either slightly or largely skewed. Fortunately, even in the presence of the selection bias, the authors observed a significant association between TB stigma and PD, which has not been the case for other investigations suffering this same bias.4
Overall, the investigation was well-conducted and produced results concordant with those from other studies using similar metrics,3,5 but it also serves as an example of many issues facing researchers in the arena of TB stigma and the delays in care it [may] impart. To rectify the selection bias inherent in using clinic-based cohorts and to help identify the reported 40% of missing TB cases worldwide, it is imperative that funding institutions support endeavors that seek to enroll prospective community-based cohorts.
1. Quattrocchi A, Barchitta M, Nobile CGA on behalf of the CCM 2013 TB network, et al Determinants of patient and health system delay among Italian and foreign-born patients with pulmonary tuberculosis: a multicentre cross-sectional study. BMJ Open 2018; 8:e019673. doi: 10.1136/bmjopen-2017-019673
2. World Health Organization. Global tuberculosis report 2016. WHO/HTM/TB/2016.13. Geneva, Switzerland: WHO, 2016.
3. World Health Organization. Diagnostic and treatment delay in tuberculosis. WHO; Geneva, Switzerland. 2006 http://applications.emro.who.int/dsaf/dsa710.pdf
4. Pungrassami P, Kipp A, Stewart P, Chongsuvivatwong V, Strauss R, Van Rie A. Tuberculosis and AIDS stigma among patients who delay seeking care for TB symptoms. The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease. 2010;14(2):181-187.
5. Adenager G, Alemseged F, Asefa H, Gebremedhin A. Factors Associated with Treatment Delay among Pulmonary Tuberculosis Patients in Public and Private Health Facilities in Addis Ababa, Ethiopia. Tuberculosis Research and Treatment 2017. doi: 10.1155/2017/5120841.