Correlation between National Peak HIV Prevalence and Concurrency, STI Treatment Capability, Condom Use and Circumcision: An Ecological Study

Background: The extent of the differential spread of HIV around the world remains incompletely explained. This paper examines the extent to which five explanatory variables (circumcision prevalence, condom usage, STI treatment coverage, number of sex partners, partner concurrency) are correlated with peak HIV prevalence rates at a country level. Methods: We performed linear regression analysis to measure the association between each of the independent variables and the national peak HIV prevalence rates for 15 - 49 years old. Results: Our analysis shows a strong positive association between peak HIV prevalence and the prevalence of partner concurrency (rho = 0.853;P = 0.001). There was no association between peak HIV prevalence and circumcision prevalence (rho = 0.118;P = 0.161), condom usage (rho = 0.048;P = 0.794), STI treatment coverage (rho = 0.143;P = 0.136) and number of sex partners (rho = 0.134;P = 0.298) at a global level. There was however a strong negative association between peak HIV prevalence and circumcision prevalence when the analysis was limited to countries within sub Saharan Africa (rho = -0.659;P = 0.000). Sub Saharan Africa had the second and third highest circumcision rates in the world when the circumcision prevalence thresholds were set at 80% and 20% respectively. Conclusions: Differences in the prevalence of circumcision likely influence differential peak HIV prevalence within sub Saharan Africa but are implausible causes for the higher HIV prevalence in this region. The close association found between concurrency and HIV prevalence requires replication in further studies.

Development of a risk score to guide targeted hepatitis C testing among human immunodeficiency virus patients in Cambodia

BACKGROUND The World Health Organization recommends testing all human immunodeficiency virus(HIV)patients for hepatitis C virus(HCV).In resource-constrained contexts with low-to-intermediate HCV prevalence among HIV patients,as in Cambodia,targeted testing is,in the short-term,potentially more feasible and cost-effective.AIM To develop a clinical prediction score(CPS)to risk-stratify HIV patients for HCV coinfection(HCV RNA detected),and derive a decision rule to guide prioritization of HCV testing in settings where‘testing all’is not feasible or unaffordable in the short term.METHODS We used data of a cross-sectional HCV diagnostic study in the HIV cohort of Sihanouk Hospital Center of Hope in Phnom Penh.Key populations were very rare in this cohort.Score development relied on the Spiegelhalter and Knill-Jones method.Predictors with an adjusted likelihood ratio≥1.5 or≤0.67 were retained,transformed to natural logarithms,and rounded to integers as score items.CPS performance was evaluated by the area-under-the-ROC curve(AUROC)with 95% confidence intervals(CI),and diagnostic accuracy at the different cut-offs.For the decision rule,HCV coinfection probability≥1% was agreed as test-threshold.RESULTS Among the 3045 enrolled HIV patients,106 had an HCV coinfection.Of the 11 candidate predictors(from history-taking,laboratory testing),seven had an adjusted likelihood ratio≥1.5 or≤0.67:≥50 years(+1 point),diabetes mellitus(+1),partner/household member with liver disease(+1),generalized pruritus(+1),platelets<200×10^(9)/L(+1),aspartate transaminase(AST)<30 IU/L(-1),AST-to-platelet ratio index(APRI)≥0.45(+1),and APRI<0.45(-1).The AUROC was 0.84(95%CI:0.80-0.89),indicating good discrimination of HCV/HIV coinfection and HIV mono-infection.The CPS result≥0 best fits the test-threshold(negative predictive value:99.2%,95%CI:98.8-99.6).Applying this threshold,30%(n=926)would be tested.Sixteen coinfections(15%)would have been missed,none with advanced fibrosis.CONCLUSION The CPS performed well in the derivation cohort,and bears potential for other contexts of low-to-intermediate prevalence and little onward risk of transmission(i.e.cohorts without major risk factors as injecting drug use,men having sex with men),and where available resources do not allow to test all HIV patients as recommended by WHO.However,the score requires external validation in other patient cohorts before any wider use can be considered.