School of Clinical Medicine

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    Factors associated with mortality in HIV-infected people in rural and urban South Africa
    (2014) Otwombe, KN; Petzold, M; Modisenyane, T
    Background: Factors associated with mortality in HIV-infected people in sub-Saharan Africa are widely reported. However rural urban disparities and their association with all-cause mortality remain unclear. Furthermore, commonly used classical Cox regression ignores unmeasured variables and frailty. Objective: To incorporate frailty in assessing factors associated with mortality in HIV-infected people in rural and urban South Africa. Design: Using data from a prospective cohort following 6,690 HIV-infected participants from Soweto (urban) and Mpumalanga (rural) enrolled from 2003 to 2010; covariates of mortality were assessed by the integrated nested Laplace approximation method. Results: We enrolled 2,221 (33%) rural and 4,469 (67%) urban participants of whom 1,555 (70%) and 3,480 (78%) were females respectively. Median age (IQR) was 36.4 (31.0 44.1) in rural and 32.7 (28.2 38.1) in the urban participants. The mortality rate per 100 person-years was 11 (9.7 12.5) and 4 (3.6 4.5) in the rural and urban participants, respectively. Compared to those not on HAART, rural participants had a reduced risk of mortality if on HAART for 6 12 (HR: 0.20, 95% CI: 0.10 0.39) and 12 months (HR: 0.10, 95% CI: 0.05 0.18). Relative to those not on HAART, urban participants had a lower risk if on HAART 12 months (HR: 0.35, 95% CI: 0.27 0.46). The frailty variance was significant and 1 in rural participants indicating more heterogeneity. Similarly it was significant but B1 in the urban participants indicating less heterogeneity. Conclusion: The frailty model findings suggest an elevated risk of mortality in rural participants relative to the urban participants potentially due to unmeasured variables that could be biological, socio economic, or healthcare related. Use of robust methods that optimise data and account for unmeasured variables could be helpful in assessing the effect of unknown risk factors thus improving patient management and care in South Africa and elsewhere.
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    Setting ART initiation targets in response to changing guidelines : The importance of addressing both steady-state and backlog
    (2014-06) Martin, C; Naidoo, N P; Venter, W D F; et al.
    Background: Target setting is useful in planning, assessing and improving antiretroviral treatment (ART) programmes. In the past 4 years, the ART initiation environment has been transformed due to the change in eligibility criteria (starting ART at a CD4+ count <350 cells/μl v. <200 cells/μl) and the roll-out of nurse-initiated management of ART. Objective: To describe and illustrate the use of a target-setting model for estimating district-based targets in the era of an expanding ART programme and changing CD4+ count thresholds for ART initiation. Method: Using previously described models and data for annual new HIV infections, we estimated both steady-state need for ART initiation and backlog in a North West Province district, accounting for the shift in eligibility. Comparison of actual v. targeted ART initiations was undertaken. The change in CD4+ count threshold adds a once-off group of newly eligible patients to the pool requiring ART – the backlog. The steady-state remains unchanged as it is determined by the annual rate of new HIV infections in previous years. Results: The steady-state need for the district was 639 initiations/month, and the backlog was ~15 388 patients. After the shift in eligibility in September 2011, the steady-state target was exceeded over several months with some backlog addressed. Of the total backlog for this district, 72% remains to be cleared. Conclusion: South Africa has two pools of patients who need ART: the steady-state of HIV-infected patients entering the programme each year, determined by historical infection rates; and the backlog created by the shift in eligibility. The healthcare system needs to build longterm capacity to meet the steady-state need for ART and additional capacity to address the backlog.