Cryptoccal meningitis – the unacceptable consequence of leaving people behind during ART scale up

Editor’s notes: Cryptococcal meningitis is a severe disease that occurs in people with advanced immune suppression.  Its occurrence is an indicator that an HIV treatment programme is not working well, as it is rare in people whose CD4 count is above 100 cells per microlitre.  Rajasingham and colleagues have tried to estimate the current burden of disease.  This is not straightforward, as the number and proportion of people with advanced HIV disease is changing with the increasing scale up of antiretroviral therapy and earlier HIV diagnosis.  Nonetheless, severe immune suppression still occurs in those whose HIV infection remains undiagnosed or is diagnosed too late; among those who are not started on effective ARVs promptly and among those in whom ART fails and who are not managed effectively by the ART treatment programme.  The authors estimate that there could be more than 180 000 deaths from cryptococcal meningitis with the large majority (136 000) in Africa.  This makes Cryptococcus responsible for more than 15% of HIV-related deaths, second only to tuberculosis as a documented cause.  The authors emphasize the need for earlier diagnosis of HIV and better linkage to quality care programmes.  In the meantime, there are also advances in the screening, prophylaxis and treatment of Cryptococcus itself, which require investment in laboratory services and affordable medicines that can save lives until the effects of good ART improves the immune status.

Cassim and colleagues have developed a novel approach to costing different approaches to the roll out of technology for screening for cryptococcal antigen in the blood of people with advanced HIV infection.  Depending on the numbers of samples to be tested in the laboratory, a mix of single use lateral flow assays and automated enzyme immunoassays makes most sense.  The aim is to allow the more cost-effective high-volume sites to subsidize the low volume sites in order to ensure that as many people living with advanced HIV infection as possible can be screened.

Global burden of disease of HIV-associated cryptococcal meningitis: an updated analysis

Rajasingham R, Smith RM, Park BJ, Jarvis JN, Govender NP, Chiller TM, Denning DW, Loyse A, Boulware DR. Lancet Infect Dis. 2017 Aug;17(8):873-881. doi: 10.1016/S1473-3099(17)30243-8. Epub 2017 May 5.

Background: Cryptococcus is the most common cause of meningitis in adults living with HIV in sub-Saharan Africa. Global burden estimates are crucial to guide prevention strategies and to determine treatment needs, and we aimed to provide an updated estimate of global incidence of HIV-associated cryptococcal disease.

Methods: We used 2014 Joint UN Programme on HIV and AIDS estimates of adults (aged >15 years) with HIV and antiretroviral therapy (ART) coverage. Estimates of CD4 less than 100 cells per μL, virological failure incidence, and loss to follow-up were from published multinational cohorts in low-income and middle-income countries. We calculated those at risk for cryptococcal infection, specifically those with CD4 less than 100 cells/μL not on ART, and those with CD4 less than 100 cells per μL on ART but lost to follow-up or with virological failure. Cryptococcal antigenaemia prevalence by country was derived from 46 studies globally. Based on cryptococcal antigenaemia prevalence in each country and region, we estimated the annual numbers of people who are developing and dying from cryptococcal meningitis.

Findings: We estimated an average global cryptococcal antigenaemia prevalence of 6·0% (95% CI 5·8-6·2) among people with a CD4 cell count of less than 100 cells per μL, with 278 000 (95% CI 195 500-340 600) people positive for cryptococcal antigen globally and 223 100 (95% CI 150 600-282 400) incident cases of cryptococcal meningitis globally in 2014. Sub-Saharan Africa accounted for 73% of the estimated cryptococcal meningitis cases in 2014 (162 500 cases [95% CI 113 600-193 900]). Annual global deaths from cryptococcal meningitis were estimated at 181 100 (95% CI 119 400-234 300), with 135 900 (75%; [95% CI 93 900-163 900]) deaths in sub-Saharan Africa. Globally, cryptococcal meningitis was responsible for 15% of AIDS-related deaths (95% CI 10-19).

Interpretation: Our analysis highlights the substantial ongoing burden of HIV-associated cryptococcal disease, primarily in sub-Saharan Africa. Cryptococcal meningitis is a metric of HIV treatment programme failure; timely HIV testing and rapid linkage to care remain an urgent priority.

Abstract access [1]

Estimating the cost-per-result of a national reflexed cryptococcal antigenaemia screening program: Forecasting the impact of potential HIV guideline changes and treatment goals

Cassim N, Coetzee LM, Schnippel K, Glencross DK. PLoS One. 2017 Aug 22;12(8):e0182154. doi: 10.1371/journal.pone.0182154. eCollection 2017.

Introduction: During 2016, the National Health Laboratory Service (NHLS) introduced laboratory-based reflexed Cryptococcal antigen (CrAg) screening to detect early Cryptococcal disease in immunosuppressed HIV+ patients with a confirmed CD4 count of 100 cells/μl or less.

Objective: The aim of this study was to assess cost-per-result of a national screening program across different tiers of laboratory service, with variable daily CrAg test volumes. The impact of potential ART treatment guideline and treatment target changes on CrAg volumes, platform choice and laboratory workflow are considered.

Methods: CD4 data (with counts ≤ 100 cells/μl) from the fiscal year 2015/16 were extracted from the NHLS Corporate Date Warehouse and used to project anticipated daily CrAg testing volumes with appropriately-matched CrAg testing platforms allocated at each of 52 NHLS CD4 laboratories. A cost-per-result was calculated for four scenarios, including the existing service status quo (Scenario-I), and three other settings (as Scenarios II-IV) which were based on information from recent antiretroviral (ART) guidelines, District Health Information System (DHIS) data and UNAIDS 90/90/90 HIV/AIDS treatment targets. Scenario-II forecast CD4 testing offered only to new ART initiates recorded at DHIS. Scenario-III projected all patients notified as HIV+, but not yet on ART (recorded at DHIS) and Scenario-IV forecast CrAg screening in 90% of estimated HIV+ patients across South Africa (also DHIS). Stata was used to assess daily CrAg volumes at the 5th, 10th, 25th, 50th, 75th, 90th and 95th percentiles across 52 CD4-laboratories. Daily volumes were used to determine technical effort/ operator staff costs (% full time equivalent) and cost-per-result for all scenarios.

Results: Daily volumes ranged between 3 and 64 samples for Scenario-I at the 5th and 95th percentile. Similarly, daily volumes ranges of 1-12, 2-45 and 5-100 CrAg-directed samples were noted for Scenario's II, III and IV respectively. A cut-off of 30 CrAg tests per day defined use of either LFA or EIA platform. LFA cost-per-result ranged from $8.24 to $5.44 and EIA cost-per-result between $5.58 and $4.88 across the range of test volumes. The technical effort across scenarios ranged from 3.2-27.6% depending on test volumes and platform used.

Conclusion: The study reported the impact of programmatic testing requirements on varying CrAg test volumes that subsequently influenced choice of testing platform, laboratory workflow and cost-per-result. A novel percentiles approach is described that enables an overview of the cost-per-result across a national program. This approach facilitates cross-subsidisation of more expensive lower volume sites with cost-efficient, more centralized higher volume laboratories, mitigating against the risk of costing tests at a single site.

Abstract [2]  Full-text [free] access [3]

Comorbidity [5], HIV [6], HIV modelling [7], HIV Treatment [8]
Africa [9], Asia [10], Europe [11], Latin America [12], Northern America [13]
Argentina [14], Benin [15], Brazil [16], Cambodia [17], Cameroon [18], Canada [19], Colombia [20], Côte d'Ivoire [21], Democratic Republic of the Congo [22], Ethiopia [23], Gabon [24], Germany [25], Ghana [26], Guinea Conakry [27], India [28], Indonesia [29], Kenya [30], Lesotho [31], Malawi [32], Mali [33], Mozambique [34], Namibia [35], Nigeria [36], Peru [37], Rwanda [38], South Africa [39], Thailand [40], Togo [41], Uganda [42], United Kingdom of Great Britain and Northern Ireland [43], United Republic of Tanzania [44], United States of America [45], Viet Nam [46], Zimbabwe [47]
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