Date Published: June 21, 2019
Publisher: Public Library of Science
Author(s): Udodirim Onwubiko, Kristin Wall, Rose-Marie Sales, David P. Holland, Amy Davidow.
Latent tuberculosis infection (LTBI) treatment in persons at increased risk of disease progression is a key strategy with the strong potential to increase rate of tuberculosis (TB) decline in the United States. However, LTBI treatment in homeless persons, a population at high-risk of active TB disease, is usually associated with poor adherence. We describe the impact of using directly observed treatment (DOT) versus self-administered treatments (SAT) as an adherence-improving intervention to administer four months of daily rifampin regimen for LTBI treatment among homeless adults in Atlanta. Retrospective analysis of clinical care data on 274 homeless persons who initiated daily rifampin treatment for LTBI treatment at a county health department between January 2014 and December 2016 was performed. To reduce bias from non-random assignment of treatment, an inverse probability of treatment weighted (IPTW) logistic regression model was used to assess the effect of treatment type on treatment completion. Subgroup analyses were performed to assess heterogeneity of treatment effect on LTBI completion. Of 274 LTBI treatment initiators, 177 (65%) completed treatment [DOT 118/181 (65%), SAT 59/93 (63%)]. In the fully adjusted and weighted analysis, the odds of completing LTBI treatment on DOT was 40% higher than the odds of completing treatment by SAT [adjusted odds ratio (95% CI), aOR: 1.40 (1.07, 1.82), p = 0.014]. The unstable nature of homeless persons’ lifestyle makes LTBI treatment difficult for many reasons. Our study lends support to the use of DOT to improve LTBI treatment completion among subgroups of homeless persons on treatment with daily rifampin.
Tuberculosis (TB) is one of the top ten leading causes of death globally. In 2015, about 1.4 million deaths were attributed to TB, making it the global leading cause of death from an infectious disease, ahead of HIV/AIDS. Using strategic disease surveillance and prioritized TB control methods, the current incidence of TB in the United States (US) has been driven to the lowest in recorded history.  The role that implementation of the top three priorities of TB control (early identification of active TB cases, prompt initiation of treatment with recommended regimen and the identification with treatment of exposed contacts) has played in driving the decline in active TB in the US has been well documented.[3,4] Epidemiologic modeling, however, has shown that achieving the goal of TB elimination well before the end of this century in all at-risk populations in the US will require a stronger focus on identification and treatment of latent TB infection (LTBI) among persons at high-risk of TB disease.[3–5] These high-risk groups include HIV-infected persons, immigrants and refugees from countries with high TB burden, alcohol and drug abusers and persons dwelling in congregate settings such as incarceration centers and homeless housing facilities.[6,7] With four-fifths (80%) of all active TB disease in the US attributed to reactivation of latent TB infections (LTBI) rather than primary TB infections, the effective and prompt treatment of LTBI in these high risk groups remains the key strategy for eliminating TB in the US.
Detection and treatment of LTBI among homeless persons is of immense public health importance in achieving the goal of TB elimination in the United States[3,5]. The presence of unaddressed co-morbidities (mental health-related and non-mental health-related), substance addictions (alcoholic and non-alcoholic) and poor access to medical care make effective treatment of LTBI in these persons difficult. These factors in combination with poor adherence to LTBI treatment make the homeless population a fertile ground for frequent TB outbreaks.
Our study had some limitations. Data used for this analysis were abstracted from routine clinical care records and therefore, relied heavily on the accuracy and completeness of the clinical care notes. Social characteristics (alcohol use illicit drug use and mental health diagnoses) examined were self-reported findings noted in the clinical records of patient-clinician encounters and thus depended both on the thoroughness of the clinician in inquiring about and recording these responses and accuracy of the patient’s response. In addition, there may have been social desirability bias influencing the patient responses to inquiries about alcohol and drug use and the impact of this bias on the outcome was not examined. The DOT regimen used in this study was administered five days a week. There is no published data on the efficacy of rifampin given five days a week in latent tuberculosis treatment. This dosing regimen was used given the prevailing circumstances at the time.
As the march towards TB elimination in the United States progresses, stronger attention will need to be paid to the detection and treatment of latent TB among high-risk populations like persons who reside in emergency homeless shelters and transitional housing facilities. Given the low levels of treatment acceptance, adherence and completion seen in previous years in this population, it is imperative now to seek more effective means of improving LTBI treatment adherence and completion among homeless persons and decrease risk of progression to active disease and emergence of TB outbreaks. Our study provides the statistical evidence to support the use of DOT to treat LTBI in unstably-housed persons in urban cities within the United States. As a next step, we suggest that the potential for achieving similar improvement in LTBI treatment adherence as observed in our study with in-person DOT needs to be evaluated using video DOT due to its’ attractive benefit of reduced cost of implementation and manpower, particularly for rural areas where in-person DOT might be difficult to implement.