The Institute for Global Health and Development
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Item Qualitative system dynamics modelling to support the design and implementation of tuberculosis infection prevention and control measures in South African primary health care facilities(Oxford University Press (OUP), 2024-08-31) Diaconu, Karin; Karat, Aaron; Bozzani, Fiametta; McCreesh, Nicky; Falconer, Jennifer; Voce, Anna; Vassall, Anna; Grant, Alison D; Kielmann, KarinaTuberculosis infection prevention and control (TB IPC) measures are a cornerstone of policy, but measures are diverse and variably implemented. Limited attention has been paid to the health system environment which influences successful implementation of these measures. We used qualitative system dynamics and group-model-building methods 1) develop a qualitative causal map of the interlinked drivers of Mycobacterium tuberculosis (Mtb) transmission in South African primary health care facilities which in turn, helped us to 2) identify plausible IPC interventions to reduce risk of transmission. Two one-day participatory workshops were held in 2019 with policy- and decision-makers at national and provincial level, and patient advocates and health professionals at clinic and district level. Causal loop diagrams were generated by participants and combined by investigators. The research team reviewed diagrams to identify the drivers of nosocomial transmission of Mtb in primary health care facilities. Interventions proposed by participants were mapped onto diagrams to identify anticipated mechanisms of action and effect. Three systemic drivers were identified: 1) Mtb nosocomial transmission is driven by bottlenecks in patient flow at given times; 2) IPC implementation and clinic processes are anchored within a staff “culture of nominal compliance”; and 3) limited systems-learning at policy level inhibits effective clinic management and IPC implementation. Interventions prioritised by workshop participants included infrastructural, organisational, and behavioural strategies that target three areas: 1) improve air quality; 2) improve use of personal protective equipment; and 3) reduce the number of individuals in the clinic. In addition to core mechanisms, participants elaborated specific additional enablers that would help sustain implementation. Qualitative system dynamics modelling (SDM) methods allowed us to capture stakeholder views and potential solutions to address the problem of sub-optimal TB IPC implementation. The participatory elements of SDM facilitated problem-solving and inclusion of multiple factors frequently neglected when considering implementation.Item Commentary: Time to change the way we think about tuberculosis infection prevention and control in health facilities: insights from recent research(Cambridge University Press, 2023-07-17) Yates, Tom A.; Karat, Aaron S.; Bozzani, Fiammetta; McCreesh, Nicky; MacGregor, Hayley; Beckwith, Peter G.; Govender, Indira; Colvin, Christopher J.; Kielmann, Karina; Grant, Alison D.In clinical settings where airborne pathogens, such as Mycobacterium tuberculosis, are prevalent, they constitute an important threat to health workers and people accessing healthcare. We report key insights from a 3-year project conducted in primary healthcare clinics in South Africa, alongside other recent tuberculosis infection prevention and control (TB-IPC) research. We discuss the fragmentation of TB-IPC policies and budgets; the characteristics of individuals attending clinics with prevalent pulmonary tuberculosis; clinic congestion and patient flow; clinic design and natural ventilation; and the facility-level determinants of the implementation (or not) of TB-IPC interventions. We present modeling studies that describe the contribution of M. tuberculosis transmission in clinics to the community tuberculosis burden and economic evaluations showing that TB-IPC interventions are highly cost-effective. We argue for a set of changes to TB-IPC, including better coordination of policymaking, clinic decongestion, changes to clinic design and building regulations, and budgeting for enablers to sustain implementation of TB-IPC interventions. Additional research is needed to find the most effective means of improving the implementation of TB-IPC interventions; to develop approaches to screening for prevalent pulmonary tuberculosis that do not rely on symptoms; and to identify groups of patients that can be seen in clinic less frequently.Item Cost-effectiveness of tuberculosis infection prevention and control interventions in South African clinics: a model-based economic evaluation informed by complexity science methods(BMJ Publishing Group, 2023-02-15) Bozzani, Fiammetta Maria; McCreesh, Nicky; Diaconu, Karin; Govender, Indira; White, Richard G; Kielmann, Karina; Grant, Alison D; Vassall, AnnaIntroduction: Nosocomial Mycobacterium tuberculosis (Mtb) transmission substantially impacts health workers, patients and communities. Guidelines for tuberculosis infection prevention and control (TB IPC) exist but implementation in many settings remains suboptimal. Evidence is needed on cost-effective investments to prevent Mtb transmission that are feasible in routine clinic environments. Methods: A set of TB IPC interventions was codesigned with local stakeholders using system dynamics modelling techniques that addressed both core activities and enabling actions to support implementation. An economic evaluation of these interventions was conducted at two clinics in KwaZulu-Natal, employing agent-based models of Mtb transmission within the clinics and in their catchment populations. Intervention costs included the costs of the enablers (eg, strengthened supervision, community sensitisation) identified by stakeholders to ensure uptake and adherence. Results: All intervention scenarios modelled, inclusive of the relevant enablers, cost less than US$200 per disability-adjusted life-year (DALY) averted and were very cost-effective in comparison to South Africa’s opportunity cost-based threshold (US$3200 per DALY averted). Two interventions, building modifications to improve ventilation and maximising use of the existing Central Chronic Medicines Dispensing and Distribution system to reduce the number of clinic attendees, were found to be cost saving over the 10-year model time horizon. Incremental cost-effectiveness ratios were sensitive to assumptions on baseline clinic ventilation rates, the prevalence of infectious TB in clinic attendees and future HIV incidence but remained highly cost-effective under all uncertainty analysis scenarios. Conclusion: TB IPC interventions in clinics, including the enabling actions to ensure their feasibility, afford very good value for money and should be prioritised for implementation within the South African health system.Item Direct estimates of absolute ventilation and estimated Mycobacterium tuberculosis transmission risk in clinics in South Africa(Public Library of Science, 2022-11-02) Beckwith, Peter G.; Karat, Aaron S.; Govender, Indira; Deol, Arminder K.; McCreesh, Nicky; Kielmann, Karina; Baisley, Kathy; Grant, Alison D.; Yates, Tom A.Healthcare facilities are important sites for the transmission of pathogens spread via bioaerosols, such as Mycobacterium tuberculosis. Natural ventilation can play an important role in reducing this transmission. We aimed to measure rates of natural ventilation in clinics in KwaZulu-Natal and Western Cape provinces, South Africa, then use these measurements to estimate Mycobacterium tuberculosis transmission risk. We measured ventilation in clinic spaces using a tracer-gas release method. In spaces where this was not possible, we estimated ventilation using data on indoor and outdoor carbon dioxide levels. Ventilation was measured i) under usual conditions and ii) with all windows and doors fully open. Under various assumptions about infectiousness and duration of exposure, measured absolute ventilation rates were related to risk of Mycobacterium tuberculosis transmission using the Wells-Riley Equation. In 2019, we obtained ventilation measurements in 33 clinical spaces in 10 clinics: 13 consultation rooms, 16 waiting areas and 4 other clinical spaces. Under usual conditions, the absolute ventilation rate was much higher in waiting rooms (median 1769 m3/hr, range 338–4815 m3/hr) than in consultation rooms (median 197 m3/hr, range 0–1451 m3/hr). When compared with usual conditions, fully opening existing doors and windows resulted in a median two-fold increase in ventilation. Using standard assumptions about infectiousness, we estimated that a health worker would have a 24.8% annual risk of becoming infected with Mycobacterium tuberculosis, and that a patient would have an 0.1% risk of becoming infected per visit. Opening existing doors and windows and rearranging patient pathways to preferentially use better ventilated clinic spaces result in important reductions in Mycobacterium tuberculosis transmission risk. However, unless combined with other tuberculosis infection prevention and control interventions, these changes are insufficient to reduce risk to health workers, and other highly exposed individuals, to acceptable levels.Item Estimating waiting times, patient flow, and waiting room occupancy density as part of tuberculosis infection prevention and control research in South African primary health care clinics(Public Library of Science, 2022-07-20) Karat, Aaron S.; McCreesh, Nicky; Baisley, Kathy; Govender, Indira; Kallon, Idriss I.; Kielmann, Karina; MacGregor, Hayley; Vassall, Anna; Yates, Tom A.; Grant, Alison D.Transmission of respiratory pathogens, such as Mycobacterium tuberculosis and severe acute respiratory syndrome coronavirus 2, is more likely during close, prolonged contact and when sharing a poorly ventilated space. Reducing overcrowding of health facilities is a recognised infection prevention and control (IPC) strategy; reliable estimates of waiting times and ‘patient flow’ would help guide implementation. As part of the Umoya omuhle study, we aimed to estimate clinic visit duration, time spent indoors versus outdoors, and occupancy density of waiting rooms in clinics in KwaZulu-Natal (KZN) and Western Cape (WC), South Africa. We used unique barcodes to track attendees’ movements in 11 clinics, multiple imputation to estimate missing arrival and departure times, and mixed-effects linear regression to examine associations with visit duration. 2,903 attendees were included. Median visit duration was 2 hours 36 minutes (interquartile range [IQR] 01:36–3:43). Longer mean visit times were associated with being female (13.5 minutes longer than males; p<0.001) and attending with a baby (18.8 minutes longer than those without; p<0.01), and shorter mean times with later arrival (14.9 minutes shorter per hour after 0700; p<0.001). Overall, attendees spent more of their time indoors (median 95.6% [IQR 46–100]) than outdoors (2.5% [IQR 0–35]). Attendees at clinics with outdoor waiting areas spent a greater proportion (median 13.7% [IQR 1–75]) of their time outdoors. In two clinics in KZN (no appointment system), occupancy densities of ~2.0 persons/m2 were observed in smaller waiting rooms during busy periods. In one clinic in WC (appointment system, larger waiting areas), occupancy density did not exceed 1.0 persons/m2 despite higher overall attendance. In this study, longer waiting times were associated with early arrival, being female, and attending with a young child. Occupancy of waiting rooms varied substantially between rooms and over the clinic day. Light-touch estimation of occupancy density may help guide interventions to improve patient flow.Item Estimating the contribution of transmission in primary healthcare clinics to community-wide TB disease incidence, and the impact of infection prevention and control interventions, in KwaZulu-Natal, South Africa(BMJ, 2022-04-08) McCreesh, Nicky; Karat, Aaron S.; Govender, Indira; Baisley, Kathy; Diaconu, Karin; Yates, Tom A.; Houben, Rein M. G. J.; Kielmann, Karina; Grant, Alison D.; White, RichardBackground: There is a high risk of Mycobacterium tuberculosis (Mtb) transmission in healthcare facilities in high burden settings. WHO guidelines on tuberculosis (TB) infection prevention and control (IPC) recommend a range of measures to reduce transmission in healthcare settings. These were evaluated primarily based on evidence for their effects on transmission to healthcare workers in hospitals. To estimate the overall impact of IPC interventions, it is necessary to also consider their impact on community-wide TB incidence and mortality. Methods: We developed an individual-based model of Mtb transmission in households, primary healthcare (PHC) clinics, and all other congregate settings. The model was parameterised using data from a high HIV prevalence community in South Africa, including data on social contact by setting, by sex, age, and HIV/antiretroviral therapy status; and data on TB prevalence in clinic attendees and the general population. We estimated the proportion of disease in adults that resulted from transmission in PHC clinics, and the impact of a range of IPC interventions in clinics on community-wide TB. Results: We estimate that 7.6% (plausible range 3.9%–13.9%) of non-multidrug resistant and multidrug resistant TB in adults resulted directly from transmission in PHC clinics in the community in 2019. The proportion is higher in HIV-positive people, at 9.3% (4.8%–16.8%), compared with 5.3% (2.7%–10.1%) in HIV-negative people. We estimate that IPC interventions could reduce incident TB cases in the community in 2021–2030 by 3.4%–8.0%, and deaths by 3.0%–7.2%. Conclusions: A non-trivial proportion of TB results from transmission in clinics in the study community, particularly in HIV-positive people. Implementing IPC interventions could lead to moderate reductions in disease burden. We recommend that IPC measures in clinics should be implemented for their benefits to staff and patients, but also for their likely effects on TB incidence and mortality in the surrounding community.Item Modelling the effect of infection prevention and control measures on rate of Mycobacterium tuberculosis transmission to clinic attendees in primary health clinics in South Africa(BMJ, 2021-10-25) McCreesh, Nicky; Karat, Aaron S.; Baisley, Kathy; Diaconu, Karin; Bozzani, Fiammetta; Govender, Indira; Beckwith, Peter; Yates, Tom A.; Deol, Arminder K.; Houben, Rein M. G. J.; Kielmann, Karina; White, Richard G.; Grant, Alison D.Background Elevated rates of tuberculosis in health care workers demonstrate the high rate of Mycobacterium tuberculosis (Mtb) transmission in health facilities in high burden settings. In the context of a project taking a whole systems approach to tuberculosis infection prevention and control (IPC), we aimed to evaluate the potential impact of conventional and novel IPC measures on Mtb transmission to patients and other clinic attendees.Item Estimating ventilation rates in rooms with varying occupancy levels: Relevance for reducing transmission risk of airborne pathogens(PLoS, 2021-06-24) Deol, Arminder K.; Scarponi, Danny; Beckwith, Peter; Yates, Tom A.; Karat, Aaron S.; Yan, Ada W. C.; Baisley, Kathy S.; Grant, Alison D.; White, Richard G.; McCreesh, Nicky; Lo Iacono, GiovanniBackground: In light of the role that airborne transmission plays in the spread of SARS-CoV-2, as well as the ongoing high global mortality from well-known airborne diseases such as tuberculosis and measles, there is an urgent need for practical ways of identifying congregate spaces where low ventilation levels contribute to high transmission risk. Poorly ventilated clinic spaces in particular may be high risk, due to the presence of both infectious and susceptible people. While relatively simple approaches to estimating ventilation rates exist, the approaches most frequently used in epidemiology cannot be used where occupancy varies, and so cannot be reliably applied in many of the types of spaces where they are most needed. Methods: The aim of this study was to demonstrate the use of a non-steady state method to estimate the absolute ventilation rate, which can be applied in rooms where occupancy levels vary. We used data from a room in a primary healthcare clinic in a high TB and HIV prevalence setting, comprising indoor and outdoor carbon dioxide measurements and head counts (by age), taken over time. Two approaches were compared: approach 1 using a simple linear regression model and approach 2 using an ordinary differential equation model. Results: The absolute ventilation rate, Q, using approach 1 was 2407 l/s [95% CI: 1632–3181] and Q from approach 2 was 2743 l/s [95% CI: 2139–4429]. Conclusions: We demonstrate two methods that can be used to estimate ventilation rate in busy congregate settings, such as clinic waiting rooms. Both approaches produced comparable results, however the simple linear regression method has the advantage of not requiring room volume measurements. These methods can be used to identify poorly-ventilated spaces, allowing measures to be taken to reduce the airborne transmission of pathogens such as Mycobacterium tuberculosis, measles, and SARS-CoV-2.Item Tuberculosis infection prevention and control: Why we need a whole systems approach(BMC, 2020-05-25) Kielmann, Karina; Karat, Aaron S.; Zwama, Gimenne; Colvin, Christopher; Swartz, Alison; Voce, Anna S.; Yates, Tom A.; MacGregor, Hayley; McCreesh, Nicky; Kallon, Idriss; Vassall, Anna; Govender, Indira; Seeley, Janet; Grant, Alison D.Infection prevention and control (IPC) measures to reduce transmission of drug-resistant and drug-sensitive tuberculosis (TB) in health facilities are well described but poorly implemented. The implementation of TB IPC has been assessed primarily through quantitative and structured approaches that treat administrative, environmental, and personal protective measures as discrete entities. We present an on-going project entitled Umoya omuhle (“good air”), conducted in two provinces of South Africa, that adopts an interdisciplinary, ‘whole systems’ approach to problem analysis and intervention development for reducing nosocomial transmission of Mycobacterium tuberculosis (Mtb) through improved IPC. We suggest that TB IPC represents a complex intervention that is delivered within a dynamic context shaped by policy guidelines, health facility space, infrastructure, organisation of care, and management culture. Methods drawn from epidemiology, anthropology, and health policy and systems research enable rich contextual analysis of how nosocomial Mtb transmission occurs, as well as opportunities to address the problem holistically. A ‘whole systems’ approach can identify leverage points within the health facility infrastructure and organisation of care that can inform the design of interventions to reduce the risk of nosocomial Mtb transmission.Item Tuberculosis from transmission in clinics in high HIV settings may be far higher than contact data suggest(International Union Against Tuberculosis and Lung Disease, 2020-04-01) McCreesh, Nicky; Grant, Alison D.; Yates, Tom A.; Karat, Aaron S.; White, Richard G.Background: In South Africa, it is estimated that only 0.5-6% of people’s contacts occur in clinics. Both people with infectious tuberculosis and people with increased susceptibility to disease progression may spend more time in clinics however, increasing the importance of clinic-based transmission to overall disease incidence.