Tuberculosis treatment outcomes among prisoners and general population in Zomba, Malawi

Tuberculosis (TB) remains a major global health problem. Globally in 2018, there were an estimated 10 million new TB cases of which 8.6% were among People living with HIV [1]. There were an estimated 1.4 million TB deaths worldwide with 17% (0.2 million deaths) resulting from TB disease among people living with HIV [1]. TB is the most common severe opportunistic infection associated with HIV in many resource-limited countries [2] with 68% of incident TB cases reported in the World Health Organization (WHO) South East Asia and African Regions [1]. TB is more common in prison populations than in the general populations [2] and HIV epidemic, poor living conditions, low socioeconomic status and poor general health, appears to have contributed directly to higher rates of TB within prisons [2]. Prisons therefore serve as reservoirs for TB infection, not only for inmates and staff but also for the general population as visitors come and go and released prisoners return to society [2]. A systematic review showed that 8.5 and 6.3% of TB in the general population in high- and middle/low income countries, respectively, was attributed to the TB in prisons [3].

In 2018, Malawi reported an estimated 15,000 TB case notifications (181 cases per 100,000 population) with a 48% HIV/TB co-infection rate (99% on ART {anti-retroviral therapy}) and 86% TB treatment success rate [1]. Malawi is one of the focus countries in the End TB Strategy era (2016–2035), as it is in the top 30 countries of high TB incidence among people living with HIV [1].

Data from the WHO epidemiological surveillance for TB treatment outcomes of 2017 cohort showed TSR of 76% in the WHO Region of the Americas(due to high levels of loss to follow up and missing data), 78% in the European Region (due to high rates of treatment failure and deaths, from high rates of MDR-TB),; 83% in South East Asia; and82% in sub – Saharan Africa [1]. In contrast, Prison settings have shown sub-optimal TB treatment success rates than the recommended 90% set by the End TB Strategy. TB treatment outcomes’ studies among prisoners showed TSR of 50, 45, 48% in Brazil(2011) [4], South Africa(2009) [5] and Uganda(2012, [6]), respectively. The poor TB TSR in prisons might compromise TB control and contribute to the development of Multi Drug Resistant Tuberculosis (MDR-TB), currently at a rate 7.7 per 100,000 population in the WHO African Region [1]. In Malawi (2014), the prevalence of MDR-TB was 0.4% among new cases and 4.8% among retreatment cases [7].

Standard TB treatment outcomesare known to be influenced by a number of factors including HIV co-infection, but the evidence on factors that are most influential for prisoners,is not known [2]..

While some studies found lower TB treatment success rates among TB/HIV patients [8‐10], other reported comparable rates to those infected only with TB [11]. Since 2011 Dignitas International (DI) in conjunction with the Ministry of Health has been providing integrated HIV/TB services to Zomba Central Hospital and Zomba Central Prison in Zomba, Malawi. The Zomba Central Prison is overcrowded (houses approximately 2500 prisoners at any point in time for a facility meant for 800 prisoners). Despite the evidence on the higher TB cases in prisons than the general population, TB TSR are not disaggregated according to prisonsTB TSR serves as a proxy for the quality of TB control as a secondary prevention. Therefore,we investigated the TB treatment outcomes and predictors of unsuccessful treatment outcomes among prisoners and non – prisoners to audit the effectiveness of TB control in identifying gaps in the national treatment policy and practice in prisons to initiate evidence based practice. .

In this 6 year retrospective study, the results show differences in the trend of all forms of TB and TB treatment success rates among the prisoners and the general population. Age greater than 35 years, HIV positive status and extra – Pulmonary TB were independently associated with unsuccessful TB treatment outcomes (death and treatment failure). In addition, it was found that the prison only registered male TB patients over the course of the 6 years.

There was an increase in the TB cases at the Zomba Central Prison from 2014 to2016 due to the introduction of the TB mass screening campaigns using a mobile X-ray machine while at the Zomba Central Hospital, the TB cases peaked in 2012 and thereafter there was a steady decline from 2013 to 2016. This might be attributed to the further scale up of antiretroviral therapy program through the Option B plus which was rolled out in 2011 in Malawi [12].

There were differences in the mean TB TSR among the two study populations (93% among prisoners and 88% among the general population. However, the 89% overall TB treatment Success Rate (TSR) is comparable to other studies done in resource limited settings and it is within reach of the End TB Strategy target of = > 90%. Similar studies conducted in the general population (from 2008 to 2010) at a Large District Hospital [8] and a Central Hospital [13] in Malawi and Ethiopia showed an 86% TSR ([14]. This is also higher than the 73% TSR [15] from 27 prisons in Malawi in 2007, 66% TSR reported in Zambian prison [16] in 2010–2011 and 48% TSR in Ugandan prisons [6] from 2011 to 2012. However, the TSR is comparable to recent studies done in prisons in sectionEthiopia [17] (89, 90%) but slightly lower than the study done in South Africa [5] (92%) and Ethiopia [17] (94%). The higher TSR in prison than the general population might be attributed to the maximum security prisons where the prisoners incarcerated for a longer sentences are bound to be within the prison and within reach of the wardens for the DOTS [16]. The varied intra prison differences may be due to the high turnover of prisoners andremandees (they are not yet sentenced and can be transferred out to another facility or released into the general public where they are lost to follow up) [16]. There can be poor linkage within prison facilities and the communities as once prisoners are released into the community, they are not adequately actively followed up for continuity of treatment [18, 19].

This studyshowed an overall 2.6% loss to follow-up which was lower than in other studies reported in similar limited resource setting in prisons in Uganda (43.0%) [6], and Brazil (13.0%) [4]. The lower rate of loss to follow up is attributed to the stable prison population at the Zomba Central Prison that is serving long term sentences hence not easily transferred or released [16].

The 5.5% death rate is comparable to the death rate observed in Uganda prison [6] but higher than the 1.4% death rate recorded in Ethiopia [17], 1.8% death rate recorded in South Africa [5] and 2% death rate recorded in Brazil [4]. This high death rate could be attributed to the poor prison living conditions -overcrowding [18], poor nutrition [19] and possibly to the rate of HIV/TB co-infection without use of antiviral therapy (due to the lower coverage of antiretroviral therapy use during this time period), which has been shown to be associated with unsuccessful treatment outcome [8, 20]. This study also showed that unsuccessful TB treatment outcome was associated with age greater than 35 years old. Similar studies in Botswana and Nigeria have shown that older age may be confounded by the high risk behaviorse.g. alcohol and drug use which are common in prison settings and general population especially among men. This leads to poor adherence which result to poor treatment outcomes.

A common risk factor for unsuccessful TB treatment outcome, Extra Pulmonary TB was also found in this study. This might be due to the severe nature of the EPTB,delays in diagnosing EPTB [21] duelimited diagnostic capacity and lack of treatment monitoring tests for EPTB cases [22].

In this study, gender comparisons were not possible among prisoners and the general population because the prison registered male TB patients only in the whole study period. Similar studies globally have shown unevenly distributed high proportions of male prisoners than female prisoners ([19, 23, 24]).Globally, there has been no universally accepted explanation to this disparity and most criminology studies point to the socialized gender roles and different expectationsof male and female behaviors [25].

The general findings from this study shows that prisoners can achieve good TB treatment outcomes which are comparable to the general population. The long serving prisoners in a maximum security prison provides an opportunity of uninterrupted treatment since they are not easily transferred out to other facilities. This calls for continued support to the prison health programs [26]. Several strategies can be combined to yield successful efforts in the fight against TB in the prison setting. TB mass screenings can be used to increase TBcase detection [24]. Since the TB treatment outcomes are worsened by HIV positive status [5, 8, 20] scaling up of the 3 phase integrated screening and treatment for HIV, TB and nutrition during entry, stay and exit of prison could increase access to HIV, TB and Nutritional screening and subsequent linkage to appropriate treatment services.

The strengths of this study include the following that we used routine program based data that is collected from the facility national TB registers which are used for TB patient registration, monitoring and evaluation from within a national public system. We studied a large number of TB patients and the results are representative of the national TB TSR. The study adhered to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines for the reporting of observational data.

Some noted limitationsinclude the use of retrospective data in which other important risk factors for unsuccessful TB treatment outcomes were not assessed (smoking status, alcohol status, body mass index, disaggregation of EPTB and HIV, and TB drug side effects). The analysis also excluded patients who were transferred out and those not evaluated which might posed a bias.

Good TB treatment outcomes which are comparable to the general population were achieved among Malawian prisoners despite the challenging prison conditions due to the stable nature of the long serving prisoners in a maximum security prison who do not have TB treatment interruptions and health care workers’ and technical assistance support from Dignitas International. This calls for continued support for prison health programs. Further longitudinal research is required to look at the other contributing factors in details.