The integration of tuberculosis and HIV testing on GeneXpert can substantially improve access and same-day diagnosis and benefit tuberculosis programmes: A diagnostic network optimization analysis in Zambia

Diagnostic network optimization (DNO), a geospatial optimization technique, can improve access to diagnostics and reduce costs through informing policy-makers' decisions on diagnostic network changes. In Zambia, viral load (VL) testing and early infant diagnosis (EID) for HIV has been performed at centralized laboratories, whilst the TB-programme utilizes a decentralized network of GeneXpert platforms. Recently, the World Health Organization (WHO) has recommended point-of-care (POC) EID/VL to increase timely diagnosis. This analysis modelled the impact of integrating EID/VL testing for children and pregnant/breastfeeding-women (priority-HIV) with TB on GeneXpert in Zambia. Using OptiDx, we established the baseline diagnostic network using inputs for testing demand (October 2019-September 2020), referrals, testing sites, testing platforms, and costs for HIV/TB testing (transport, test, device) respectively in Zambia. Next, we integrated priority-HIV testing on GeneXpert platforms, historically only utilized by the TB-programme. 228,265 TB tests were conducted on GeneXpert devices and 167,458 (99%) of priority-HIV tests on centralized devices at baseline, of which 10% were tested onsite at the site of sample collection. With integration, the average distance travelled by priority-HIV tests decreased 10-fold (98km to 10km) and the proportion tested onsite increased (10% to 48%). 52% of EID tests are likely to be processed within the same-day from a baseline of zero. There were also benefits to the TB-programme: the average distance travelled/specimen decreased (11km to 7km), alongside potential savings in GeneXpert device-operating costs (30%) through cost-sharing with the HIV-programme. The total cost of the combined testing programmes reduced marginally by 1% through integration/optimization. DNO can be used to strategically leverage existing capacity to achieve the WHO's recommendation regarding POC VL/EID testing. Through DNO of the Zambian network, we have shown that TB/HIV testing integration can improve the performance of the diagnostic network and increase the proportion of specimens tested closer to the patient whilst not increasing costs.

Tuberculosis care cascade in Zambia - identifying the gaps in order to improve outcomes: a population-based analysis

OBJECTIVE

Tuberculosis (TB) remains a leading cause of morbidity and mortality in Zambia, especially for people living with HIV (PLHIV). We undertook a care cascade analysis to quantify gaps in care and align programme improvement measures with areas of need.

DESIGN

Retrospective, population-based analysis.

SETTING

We derived national-level estimates for each step of the TB care cascade in Zambia. Estimates were informed by WHO incidence estimates, nationally aggregated laboratory and notification registers, and individual-level programme data from four provinces.

PARTICIPANTS

Participants included all individuals with active TB disease in Zambia in 2018. We characterised the overall TB cascade and disaggregated by drug susceptibility results and HIV status.

RESULTS

In 2018, the total burden of TB in Zambia was estimated to be 72 495 (range, 40 495-111 495) cases. Of these, 43 387 (59.8%) accessed TB testing, 40 176 (55.4%) were diagnosed with TB, 36 431 (50.3%) were started on treatment and 32 700 (45.1%) completed treatment. Among all persons with TB lost at any step along the care cascade (n=39 795), 29 108 (73.1%) were lost prior to accessing diagnostic services, 3211 (8.1%) prior to diagnosis, 3745 (9.4%) prior to initiating treatment and 3731 (9.4%) prior to treatment completion. PLHIV were less likely than HIV-negative individuals to successfully complete the care cascade (42.8% vs 50.2%, p<0.001). Among those with rifampicin-resistant TB, there was substantial attrition at each step of the cascade and only 22.8% were estimated to have successfully completed treatment.

CONCLUSIONS

Losses throughout the care cascade resulted in a large proportion of individuals with TB not completing treatment. Ongoing health systems strengthening and patient-centred engagement strategies are needed at every step of the care cascade; however, scale-up of active case finding strategies is particularly critical to ensure individuals with TB in the population reach initial stages of care. Additionally, a renewed focus on PLHIV and individuals with drug-resistant TB is urgently needed to improve TB-related outcomes in Zambia.

What happened to patients with RMP-resistant/MDR-TB in Zambia reported as lost to follow-up from 2011 to 2014?

SETTING

University Teaching Hospital, Lusaka, and Ndola Central Hospital, Ndola, Zambia, which implemented active tracing of multidrug-resistant tuberculosis (MDR-TB) patients reported as lost to follow-up (LTFU).

OBJECTIVE

To determine 1) the number of patients treated for MDR-TB between 2011 and 2014; 2) the number, proportion, month when LTFU and characteristics of patients registered as LTFU; and 3) final outcomes observed following active patient tracing.

DESIGN

Retrospective cohort study.

RESULTS

Of 184 patients treated for confirmed MDR-TB, 76 (41%) were reported as LTFU. From 2011 to 2014, the proportions reported each year as LTFU were respectively 21%, 47%, 51% and 39%. Of patients who were LTFU, 43 (57%) had stopped attending the clinic during the intensive phase. These patients were predominantly male, aged 15-44 years, had pulmonary disease and had failed previous treatment. Of 57 (75%) patients with known human immunodeficiency virus (HIV) status, 42 (74%) were HIV-positive, 57% of whom were on antiretroviral treatment. After active patient tracing, 29 (38%) patients could not be found and the observed outcome remained LTFU. Of the remaining 47 patients, 29 (62%) were alive and had completed or were still on treatment, 14 (30%) were alive but had stopped treatment and 4 (8%) had died.

CONCLUSION

Zambia has been underreporting its favourable outcomes for MDR-TB treatment and should continue with active tracing of LTFU patients.

Assessment of the Xpert MTB/RIF assay for diagnosis of tuberculosis with gastric lavage aspirates in children in sub-Saharan Africa: a prospective descriptive study

BACKGROUND

Rapid and accurate diagnosis of pulmonary tuberculosis in children remains challenging because of difficulties in obtaining sputum samples and the paucibacillary nature of the disease. The Xpert MTB/RIF assay is useful for rapid diagnosis of childhood tuberculosis with sputum and nasopharyngeal samples. We assessed this assay for the detection of tuberculosis and multidrug resistant (MDR) tuberculosis with gastric lavage aspirate (GLA) samples in children admitted to hospital.

METHODS

We did a prospective study to assess the sensitivity and specificity of the Xpert MTB/RIF assay with GLA samples for the detection of pulmonary tuberculosis and MDR tuberculosis in new paediatric inpatient admissions at the University Teaching Hospital, Lusaka, Zambia. Children aged 15 years or younger were recruited between June, 2011, and May, 2012. GLA and sputum were analysed by standard smear-microscopy, mycobacterial growth indicator tube (MGIT) culture, MGIT drug-susceptibility testing, and the Xpert MTB/RIF assay. Sensitivity of the Xpert MTB/RIF assay was assessed with the Pearson χ(2) or Fishers exact test.

FINDINGS

Of 930 children, 142 produced sputum and GLA was obtained from 788 non-sputum producers. Culture-positive tuberculosis was identified in 58 (6·2%) of 930 children: ten from sputum producers and 48 from GLA of non-sputum producers. The sensitivity and specificity of the Xpert MTB/RIF assay were similar: sensitivity was 68·8% (95% CI 53·6-80·9) for GLA versus 90·0% (54·1-99·5; p=0·1649) for sputum samples; specificity was 99·3% (98·3-99·8) for GLA and 98·5% (94·1-99·7; p=0·2871) for sputum samples. The Xpert MTB/RIF assay detected an extra 28 tuberculosis cases compared with smear microscopy and was significantly more sensitive than smear microscopy for both sputum (90·0% [54·1-99·5] vs 30·0% [8·1-64·6], p=0·01) and GLA (68·8% [53·6-80·9] vs 25·0% [14·1-40·0], p<0·0001). The assay load did not differ significantly by sample type (p=0·791). 22 children were infected with HIV and tuberculosis and significant differences in assay performance could not be detected when stratifying by HIV status for either sample type. The Xpert MTB/RIF assay detected rifampicin resistance in three GLA samples: two confirmed as MDR tuberculosis and one false positive.

INTERPRETATION

Analyses of GLA samples with the Xpert MTB/RIF assay is a sensitive and specific method for rapid diagnosis of pulmonary tuberculosis in children who cannot produce sputum. The single site nature of our study invites caution.

FUNDING

European Commission, European Developing Countries Clinical Trials Partnership, and UBS Optimus Foundation.

Evaluation of the burden of unsuspected pulmonary tuberculosis and co-morbidity with non-communicable diseases in sputum producing adult inpatients

BACKGROUND

A high burden of tuberculosis (TB) occurs in sub-Saharan African countries and many cases of active TB and drug-resistant TB remain undiagnosed. Tertiary care hospitals provide an opportunity to study TB co-morbidity with non-communicable and other communicable diseases (NCDs/CDs). We evaluated the burden of undiagnosed pulmonary TB and multi-drug resistant TB in adult inpatients, regardless of their primary admission diagnosis, in a tertiary referral centre.

METHODOLOGY/PRINCIPAL FINDINGS

In this prospective study, newly admitted adult inpatients able to produce sputum at the University Teaching Hospital, Lusaka, Zambia, were screened for pulmonary TB using fluorescent smear microscopy and automated liquid culture. The burden of pulmonary TB, unsuspected TB, TB co-morbidity with NCDs and CDs was determined. Sputum was analysed from 900 inpatients (70.6% HIV infected) 277 (30.8%) non-TB suspects, 286 (31.8%) TB suspects and 337 (37.4%) were already receiving TB treatment. 202/900 (22.4%) of patients had culture confirmed TB. TB co-morbidity was detected in 20/275 (7.3%) NCD patients, significantly associated with diabetes (P = 0.006, OR 6.571, 95%CI: 1.706-25.3). 27/202 (13.4%) TB cases were unsuspected. There were 18 confirmed cases of MDR-TB, 5 of which were unsuspected.

CONCLUSIONS/SIGNIFICANCE

A large burden of unsuspected pulmonary TB co-morbidity exists in inpatients with NCDs and other CDs. Pro-active sputum screening of all inpatients in tertiary referral centres in high TB endemic countries is recommended. The scale of the problem of undiagnosed MDR-TB in inpatients requires further study.

Evaluation of the Xpert MTB/RIF assay at a tertiary care referral hospital in a setting where tuberculosis and HIV infection are highly endemic

BACKGROUND. There were 1.45 million deaths from tuberculosis in 2011. A substantial proportion of active pulmonary tuberculosis cases in countries where tuberculosis, human immunodeficiency virus (HIV) infection, and AIDS are highly endemic remain undiagnosed because of the reliance on sputum-smear microscopy. This study evaluated the performance of the Xpert MTB/RIF assay at a tertiary care referral center in Zambia, a country where the burden of tuberculosis and HIV infection is high. METHODS. A total of 881 adult inpatients admitted to University Teaching Hospital in Lusaka who were able to produce sputum were enrolled and analyzed in the study, irrespective of admission diagnosis. Sputum specimens were analyzed by fluorescence smear microscopy, the Xpert MTB/RIF assay, mycobacterial growth indicator tube (MGIT) culture,and MGIT drug-susceptibility testing. The sensitivity and specificity of the Xpert MTB/RIF assay were evaluated using culture as the gold standard. RESULTS. Culture-confirmed tuberculosis was found in 201 of 881 patients (22.8%). The specificity of the Xpert MTB/RIF assay was 95.0% (95% confidence interval [CI], 92.4%–96.8%),and the sensitivity was 86.1% (95% CI, 80.3%–90.4%). In sputum smear–negative, culture-positive cases, the assay was 74.7% sensitive (95% CI, 64.6%–82.8%), identifying 71 additional tuberculosis cases that were not detected by smear microscopy.A total of 18 of 111 patients with tuberculosis who were tested (16.2%) had multidrug-resistant (MDR) tuberculosis.The sensitivity and specificity of the Xpert MTB/RIF assay for detecting culture-confirmed, rifampicin-resistant tuberculosis was 81.3% (95% CI, 53.7%–95.0%) and 97.5% (95% CI,90.4%–99.6%), respectively. CONCLUSIONS. The Xpert MTB/RIF assay performs better than smear microscopy in an inpatient setting in a country where tuberculosis and HIV infection are highly endemic. Assessment of its usefulness and cost-effectiveness for increased detection of tuberculosis cases missed by sputum smear and for concomitant screening for MDR tuberculosis among adult inpatients attending tertiary care referral centers in other countries with a high burden of tuberculosis and HIV infection is warranted [corrected].