Atherosclerotic cardiovascular disease thresholds for statin initiation among people living with HIV in Thailand: A cost-effectiveness analysis.

BACKGROUND: People living with HIV (PLHIV) have an elevated risk of atherosclerotic cardiovascular disease (ASCVD) compared to their uninfected peers. Expanding statin use may help alleviate this burden. We evaluated the cost-effectiveness of reducing the recommend statin initiation threshold for primary ASCVD prevention among PLHIV in Thailand. METHODS: Our decision analytic microsimulation model randomly selected (with replacement) individuals from the TREAT Asia HIV Observational Database (data collected between 1/January/2013 and 1/September/2019). Direct medical costs and quality-adjusted life-years were assigned in annual cycles over a lifetime horizon and discounted at 3% per year. We assumed the Thai healthcare sector perspective. The study population included PLHIV aged 35-75 years, without ASCVD, and receiving antiretroviral therapy. Statin initiation thresholds evaluated were 10-year ASCVD risk ≥10% (control), ≥7.5% and ≥5%. RESULTS: A statin initiation threshold of ASCVD risk ≥7.5% resulted in accumulation of 0.015 additional quality-adjusted life-years compared with an ASCVD risk threshold ≥10%, at an extra cost of 3,539 Baht ($US113), giving an incremental cost-effectiveness ratio of 239,000 Baht ($US7,670)/quality-adjusted life-year gained. The incremental cost-effectiveness ratio comparing ASCVD risk ≥5% to ≥7.5% was 349,000 Baht ($US11,200)/quality-adjusted life-year gained. At a willingness-to-pay threshold of 160,000 Baht ($US5,135)/quality-adjusted life-year gained, a 30.8% reduction in the average cost of low/moderate statin therapy led to the ASCVD risk threshold ≥7.5% becoming cost-effective compared with current practice. CONCLUSIONS: Reducing the recommended 10-year ASCVD risk threshold for statin initiation among PLHIV in Thailand would not currently be cost-effective. However, a lower threshold could become cost-effective with greater preference for cheaper statins.

Cost-effectiveness of statins for primary prevention of atherosclerotic cardiovascular disease among people living with HIV in the United States.

BACKGROUND: Expanding statin use may help to alleviate the excess burden of atherosclerotic cardiovascular disease in people living with HIV (PLHIV). Pravastatin and pitavastatin are preferred agents due to their lack of substantial interaction with antiretroviral therapy. We aimed to evaluate the cost-effectiveness of pravastatin and pitavastatin for the primary prevention of atherosclerotic cardiovascular disease among PLHIV in the United States. METHODS: We developed a microsimulation model that randomly selected (with replacement) individuals from the Data-collection on Adverse Effects of Anti-HIV Drugs study with follow-up between 2013 and 2016. Our study population was PLHIV aged 40 to 75 years, stable on antiretroviral therapy, and not currently using lipid-lowering therapy. Direct medical costs and quality-adjusted life-years (QALYs) were assigned in annual cycles and discounted at 3% per year. We assumed a willingness-to-pay threshold of $100,000/QALY gained. The interventions assessed were as follows: (1) treating no one with statins; (2) treating everyone with generic pravastatin 40 mg/day (drug cost $236/year) and (3) treating everyone with branded pitavastatin 4 mg/day (drug cost $2,828/year). The model simulated each individual's probability of experiencing atherosclerotic cardiovascular disease over 20 years. RESULTS: Persons receiving pravastatin accrued 0.024 additional QALYs compared with those not receiving a statin, at an incremental cost of $1338, giving an incremental cost-effectiveness ratio of $56,000/QALY gained. Individuals receiving pitavastatin accumulated 0.013 additional QALYs compared with those using pravastatin, at an additional cost of $18,251, giving an incremental cost-effectiveness ratio of $1,444,000/QALY gained. These findings were most sensitive to the pill burden associated with daily statin administration, statin costs, statin efficacy and baseline atherosclerotic cardiovascular disease risk. In probabilistic sensitivity analysis, no statin was optimal in 5.2% of simulations, pravastatin was optimal in 94.8% of simulations and pitavastatin was never optimal. CONCLUSIONS: Pravastatin was projected to be cost-effective compared with no statin. With substantial price reduction, pitavastatin may be cost-effective compared with pravastatin. These findings bode well for the expanded use of statins among PLHIV in the United States. To gain greater confidence in our conclusions it is important to generate strong, HIV-specific estimates on the efficacy of statins and the quality-of-life burden associated with taking an additional daily pill.

Statins for atherosclerotic cardiovascular disease prevention in people living with HIV in Thailand: a cost-effectiveness analysis.

INTRODUCTION: People living with HIV (PLHIV) have an elevated risk of atherosclerotic cardiovascular disease (CVD) compared to their HIV-negative peers. Expanding statin use may help alleviate this burden. However, the choice of statin in the context of antiretroviral therapy is challenging. Pravastatin and pitavastatin improve cholesterol levels in PLHIV without interacting substantially with antiretroviral therapy. They are also more expensive than most statins. We evaluated the cost-effectiveness of pravastatin and pitavastatin for the primary prevention of CVD among PLHIV in Thailand who are not currently using lipid-lowering therapy. METHODS: We developed a discrete-state microsimulation model that randomly selected (with replacement) individuals from the TREAT Asia HIV Observational Database cohort who were aged 40 to 75 years, receiving antiretroviral therapy in Thailand, and not using lipid-lowering therapy. The model simulated each individual's probability of experiencing CVD. We evaluated: (1) treating no one with statins; (2) treating everyone with pravastatin 20mg/day (drug cost 7568 Thai Baht ($US243)/year) and (3) treating everyone with pitavastatin 2 mg/day (drug cost 8182 Baht ($US263)/year). Direct medical costs and quality-adjusted life-years (QALYs) were assigned in annual cycles over a 20-year time horizon and discounted at 3% per year. We assumed the Thai healthcare sector perspective. RESULTS: Pravastatin was estimated to be less effective and less cost-effective than pitavastatin and was therefore dominated (extended) by pitavastatin. Patients receiving pitavastatin accumulated 0.042 additional QALYs compared with those not using a statin, at an extra cost of 96,442 Baht ($US3095), giving an incremental cost-effectiveness ratio of 2,300,000 Baht ($US73,812)/QALY gained. These findings were sensitive to statin costs and statin efficacy, pill burden, and targeting of PLHIV based on CVD risk. At a willingness-to-pay threshold of 160,000 Baht ($US5135)/QALY gained, we estimated that pravastatin would become cost-effective at an annual cost of 415 Baht ($US13.30)/year and pitavastatin would become cost-effective at an annual cost of 600 Baht ($US19.30)/year. CONCLUSIONS: Neither pravastatin nor pitavastatin were projected to be cost-effective for the primary prevention of CVD among PLHIV in Thailand who are not currently using lipid-lowering therapy. We do not recommend expanding current use of these drugs among PLHIV in Thailand without substantial price reduction.

Funding antiretroviral treatment for HIV-positive temporary residents in Australia prevents transmission and is inexpensive.

Background The aim of this study is to estimate the reduction in new HIV infections and resultant cost outcomes of providing antiretroviral treatment (ART) through Australia's 'universal access' health scheme to all temporary residents with HIV infection living legally in Australia, but currently deemed ineligible to access subsidised ART via this scheme. METHODS: A mathematical model to estimate the number of new HIV infections averted and the associated lifetime costs over 5 years if all HIV-positive temporary residents in Australia had access to ART and subsidised medical care was developed. Input data came from a cohort of 180 HIV-positive temporary residents living in Australia who are receiving free ART donated by pharmaceutical companies for up to 4 years. RESULTS: Expanding ART access to an estimated total 450 HIV+ temporary residents in Australia for 5 years could avert 80 new infections. The model estimated the total median discounted (5%) cost for ART and associated care to be A$36million, while the total savings in lifetime-discounted costs for the new infections averted was A$22million. CONCLUSIONS: It is estimated that expanded access to ART for all HIV-positive temporary residents in Australia will substantially reduce HIV transmission to their sexual partners at little additional cost. In the context of Australia's National HIV strategy and Australia's endorsement of global goals to provide universal access to ART for all people with HIV, this is an important measure to remove inequities in the provision of HIV-related treatment and care.

The contribution of alcohol use disorder to decompensated cirrhosis among people with hepatitis C: An international study.

BACKGROUND & AIMS: The advent of direct-acting antivirals (DAAs) has led to ambitious targets for hepatitis C virus (HCV) elimination. However, in the context of alcohol use disorder the ability of DAAs to achieve these targets may be compromised. The aim of this study was to evaluate the contribution of alcohol use disorder to HCV-related decompensated cirrhosis in three settings. METHODS: HCV notifications from British Columbia, Canada; New South Wales, Australia, and Scotland (1995-2011/2012/2013, respectively) were linked to hospital admissions (2001-2012/2013/2014, respectively). Alcohol use disorder was defined as non-liver-related hospitalisation due to alcohol use. Age-standardised decompensated cirrhosis incidence rates were plotted, associated factors were assessed using Cox regression, and alcohol use disorder-associated population attributable fractions (PAFs) were computed. RESULTS: Among 58,487, 84,529, and 31,924 people with HCV in British Columbia, New South Wales, and Scotland, 2,689 (4.6%), 3,169 (3.7%), and 1,375 (4.3%) had a decompensated cirrhosis diagnosis, and 28%, 32%, and 50% of those with decompensated cirrhosis had an alcohol use disorder, respectively. Age-standardised decompensated cirrhosis incidence rates were considerably higher in people with alcohol use disorder in New South Wales and Scotland. Decompensated cirrhosis was independently associated with alcohol use disorder in British Columbia (aHR 1.92; 95% CI 1.76-2.10), New South Wales (aHR 3.68; 95% CI 3.38-4.00) and Scotland (aHR 3.88; 95% CI 3.42-4.40). The PAFs of decompensated cirrhosis-related to alcohol use disorder were 13%, 25%, and 40% in British Columbia, New South Wales and Scotland, respectively. CONCLUSIONS: Alcohol use disorder was a major contributor to HCV liver disease burden in all settings, more distinctly in Scotland. The extent to which alcohol use would compromise the individual and population-level benefits of DAA therapy needs to be closely monitored. Countries, where appropriate, must develop strategies combining promotion of DAA treatment uptake with management of alcohol use disorders, if World Health Organization 2030 HCV mortality reduction targets are going to be achieved. LAY SUMMARY: The burden of liver disease has been rising among people with hepatitis C globally. The recent introduction of highly effective medicines against hepatitis C (called direct-acting antivirals or DAAs) has brought renewed optimism to the sector. DAA scale-up could eliminate hepatitis C as a public health threat in the coming decades. However, our findings show heavy alcohol use is a major risk factor for liver disease among people with hepatitis C. If continued, heavy alcohol use could compromise the benefits of new antiviral treatments at the individual- and population-level. To tackle hepatitis C as a public health threat, where needed, DAA therapy should be combined with management of heavy alcohol use.

Hepatitis C testing and re-testing among people attending sexual health services in Australia, and hepatitis C incidence among people with human immunodeficiency virus: analysis of national sentinel surveillance data.

BACKGROUND: Direct acting antivirals are expected to drastically reduce the burden of hepatitis C virus (HCV) in people living with Human Immunodeficiency Virus (HIV). However, rates of HCV testing, re-testing and incident infection in this group remain uncertain in Australia. We assessed trends in HCV testing, re-testing and incident infection among HIV-positive individuals, and evaluated factors associated with HCV re-testing and incident infection. METHODS: The study population consisted of HIV-positive individuals who visited a sexual health service involved in the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance (ACCESS) between 2007 and 2015. Poisson regression was used to assess trends and to evaluate factors associated with HCV re-testing and incident HCV infection. RESULTS: There were 9227 HIV-positive individuals included in our testing rate analysis. Of 3799 HIV-positive/HCV-negative people that attended an ACCESS sexual health service more than once, 2079 (54.7%) were re-tested for HCV and were therefore eligible for our incidence analysis. The rate of HCV testing increased from 17.1 to 51.4 tests per 100 patient years between 2007 and 2015 (p for trend <0.01). Over the same period, HCV re-testing rates increased from 23.9 to 79.7 tests per 100 person years (p for trend <0.01). A clear increase in testing and re-testing began after 2011. Patients who identified as men who have sex with men and those with a history of injecting drug use experienced high rates of HCV re-testing over the course of the study period. Among those who re-tested, 157 incident HCV infections occurred at a rate of 2.5 events per 100 person years. Between 2007 and 2009, 2010-2011, 2012-2013 and 2014-2015, rates of incident HCV were 0.8, 1.5, 3.9 and 2.7 events per 100 person years, respectively (p for trend <0.01). Incident HCV was strongly associated with a history of injecting drug use. CONCLUSIONS: High rates of HCV testing and re-testing among HIV-positive individuals in Australia will assist strategies to achieve HCV elimination through rapid treatment scale up. Continued monitoring of HCV incidence in this population is essential for guiding both HCV prevention and treatment strategies.

Attrition and Mortality of Children Receiving Antiretroviral Treatment through the Universal Coverage Health Program in Thailand.

OBJECTIVE: To assess mortality and loss to follow-up of children with HIV infection who started antiretroviral therapy (ART) through the Universal Coverage Health Program (UC) in Thailand. STUDY DESIGN: Children with HIV infection who initiated ART at age <15 years through the UC between 2008 and 2013 were included in the analysis. Death was ascertained through linkage with the National Death Registry. A competing-risks method was used to calculate subdistribution hazard ratios (SHRs) of predictors for loss to follow-up. Death was considered a competing risk. Cox proportional hazards models were used to assess predictors of mortality. RESULTS: A total of 4618 children from 497 hospitals in Thailand were included in the study. Median age at ART initiation was 9 years (IQR, 6-12 years), and the median duration of tracking was 4.1 years (a total of 18 817 person-years). Three hundred and ninety-five children (9%) died, for a mortality rate of 2.1 (95% CI, 1.9-2.3) per 100 person-years, and 525 children (11%) were lost to follow-up, for a lost to follow-up rate of 2.9 (95% CI, 2.7-3.2) per 100 person-years. The cumulative incidence of loss to follow-up increased from 4% at 1 year to 8.8% at 3 years. Children who started ART at age ≥12 years were at the greatest risk of loss to follow-up. The probability of death was 3.2% at 6 months and 6.4% at 3 years. Age ≥12 years at ART initiation, lower baseline CD4%, advanced HIV staging, and loss to follow-up were associated with mortality. CONCLUSION: The Thai national HIV treatment program has been very effective in treating children with HIV infection, with low mortality and modest rates of loss to follow-up.

First-Line Antiretroviral Treatment Outcomes and Durability in HIV-Infected Children Treated Through the Universal Coverage Health Program in Thailand.

BACKGROUND: We assessed the treatment outcomes on first-line antiretroviral therapy (ART), and factors associated with switching regimen in HIV-infected children treated through the universal coverage health program (UC) in Thailand. METHODS: Children aged <15 years at ART initiation who had been receiving ART for at least 6 months between 2008 and 2014 through UC were included in the analysis. The Kaplan-Meier method was used to estimate immunological recovery (IMR), immunological failure, and virological failure (VF). Cox models were used to assess predictors of IMR and VF. Competing risk models were used to assess factors associated with switching to a second-line regimen, with death considered as a competing risk. RESULTS: A total of 4120 children initiated ART at a median (interquartile range) age of 9.3 (5.8-12.0) years. The median duration of ART was 3.7 years with 17,950 person-years of follow-up. Two thousand eight hundred five children achieved IMR, and the probability of IMR increased to 76% by 3 years after ART initiation. Among 1054 children switched to second-line regimens, 84% had VF and 19% had immunological failure. The cumulative rate of switching regimen increased from 4% to 20% from 1 to 3 years after treatment. Children aged ≥12 years at ART initiation, starting with nonnucleoside reverse-transcriptase inhibitors, and baseline CD4% <10% had an increased risk of switching to second-line regimens. CONCLUSIONS: Children receiving ART through UC had good treatment outcomes, although a fifth required switching regimen by 3 years. Earlier treatment initiation and avoiding nonnucleoside reverse-transcriptase inhibitor first-line regimens in high-risk children may prevent treatment failure.

Comprehensiveness of HIV care provided at global HIV treatment sites in the IeDEA consortium: 2009 and 2014.

INTRODUCTION: An important determinant of the effectiveness of HIV treatment programs is the capacity of sites to implement recommended services and identify systematic changes needed to ensure that invested resources translate into improved patient outcomes. We conducted a survey in 2014 of HIV care and treatment sites in the seven regions of the International epidemiologic Database to Evaluate AIDS (IeDEA) Consortium to evaluate facility characteristics, HIV prevention, care and treatment services provided, laboratory capacity, and trends in the comprehensiveness of care compared to data obtained in the 2009 baseline survey. METHODS: Clinical staff from 262 treatment sites in 45 countries in IeDEA completed a site survey from September 2014 to January 2015, including Asia-Pacific with Australia (n = 50), Latin America and the Caribbean (n = 11), North America (n = 45), Central Africa (n = 17), East Africa (n = 36), Southern Africa (n = 87), and West Africa (n = 16). For the 55 sites with complete data from both the 2009 and 2014 survey, we evaluated change in comprehensiveness of care. RESULTS: The majority of the 262 sites (61%) offered seven essential services (ART adherence, nutritional support, PMTCT, CD4+ cell count testing, tuberculosis screening, HIV prevention, and outreach). Sites that were publicly funded (64%), cared for adults and children (68%), low or middle Human Development Index (HDI) rank (68%, 68%), and received PEPFAR support (71%) were most often fully comprehensive. CD4+ cell count testing was universally available (98%) but only 62% of clinics offered it onsite. Approximately two-thirds (69%) of sites reported routine viral load testing (44-100%), with 39% having it onsite. Laboratory capacity to monitor antiretroviral-related toxicity and diagnose opportunistic infections varied widely by testing modality and region. In the subgroup of 55 sites with two surveys, comprehensiveness of services provided significantly increased across all regions from 2009 to 2014 (5.7 to 6.5, p < 0.001). CONCLUSION: The availability of viral load monitoring remains suboptimal and should be a focus for site capacity, particularly in East and Southern Africa, where the majority of those initiating on ART reside. However, the comprehensiveness of care provided increased over the past 5 years and was related to type of funding received (publicly funded and PEPFAR supported).

Testing commercial sex workers for sexually transmitted infections in Victoria, Australia: an evaluation of the impact of reducing the frequency of testing.

BACKGROUND: The frequency of testing sex workers for sexually transmitted infections (STIs) in Victoria, Australia, was changed from monthly to quarterly on 6 October 2012. Our aim was to determine the impact of this change to the clients seen at the Melbourne Sexual Health Centre (MHSC). METHODS: Computerised medical records of all clients attending at MHSC from 7 October 2011 to 7 October 2013 were analysed. RESULTS: Comparing between the monthly and quarterly testing periods, the number of consultations at MSHC with female sex workers (FSW) halved from 6146 to 3453 (p<0.001) and the consultation time spent on FSW reduced by 40.6% (1942 h to 1153 h). More heterosexual men (p<0.001), and women (p<0.001) were seen in the quarterly testing period. The number of STIs diagnosed in the clinic increased from 2243 to 2589 from the monthly to quarterly period, respectively [15.4% increase (p<0.001)]. Up to AU$247,000 was saved on FSW testing after the shift to quarterly testing. CONCLUSIONS: The change to STIs screening frequency for sex workers from monthly to quarterly resulted in a 15% increase in STI diagnoses in the clinic and approximate a quarter of a million dollars was diverted from FSW testing to other clients. Overall the change in frequency is likely to have had a beneficial effect on STI control in Victoria.

Herd immunity effect of the HPV vaccination program in Australia under different assumptions regarding natural immunity against re-infection.

Deterministic dynamic compartmental transmission models (DDCTMs) of human papillomavirus (HPV) transmission have been used in a number of studies to estimate the potential impact of HPV vaccination programs. In most cases, the models were built under the assumption that an individual who cleared HPV infection develops (life-long) natural immunity against re-infection with the same HPV type (this is known as SIR scenario). This assumption was also made by two Australian modelling studies evaluating the impact of the National HPV Vaccination Program to assist in the health-economic assessment of male vaccination. An alternative view denying natural immunity after clearance (SIS scenario) was only presented in one study, although neither scenario has been supported by strong evidence. Some recent findings, however, provide arguments in favour of SIS. We developed HPV transmission models implementing life-time (SIR), limited, and non-existent (SIS) natural immunity. For each model we estimated the herd immunity effect of the ongoing Australian HPV vaccination program and its extension to cover males. Given the Australian setting, we aimed to clarify the extent to which the choice of model structure would influence estimation of this effect. A statistically robust and efficient calibration methodology was applied to ensure credibility of our results. We observed that for non-SIR models the herd immunity effect measured in relative reductions in HPV prevalence in the unvaccinated population was much more pronounced than for the SIR model. For example, with vaccine efficacy of 95% for females and 90% for males, the reductions for HPV-16 were 3% in females and 28% in males for the SIR model, and at least 30% (females) and 60% (males) for non-SIR models. The magnitude of these differences implies that evaluations of the impact of vaccination programs using DDCTMs should incorporate several model structures until our understanding of natural immunity is improved.

Estimating the cost-effectiveness of needle-syringe programs in Australia.

OBJECTIVE: To evaluate the impact and cost-effectiveness of needle-syringe programs (NSPs) with respect to HIV and hepatitis C virus (HCV) infections among Australian injecting drug users (IDUs). DESIGN/METHODS: A health economic analysis was conducted incorporating a mathematical model of HIV and HCV transmission among IDUs. An empirical relationship between syringe availability and receptive syringe sharing (RSS) was assessed. We compared the epidemiological outcomes and costs of NSP coverage (status quo RSS of 15-17%) with scenarios that had no NSPs (RSS of 25-50%). Outcomes included numbers of HIV and HCV infections averted, lifetime health sector costs, and cost per quality-adjusted life year (QALY) gained. Discounting was applied at 3% (sensitivity: 0%, 5%) per annum. RESULTS: We estimated that NSPs reduced incidence of HIV by 34-70% (192-873 cases) and HCV by 15-43% (19 000-77 000 cases) during 2000-2010, leading to 20 000-66 000 QALYs gained. Economic analysis showed that NSP coverage saved A$70-220 million in healthcare costs during 2000-2010 and will save an additional A$340-950 million in future healthcare costs. With NSPs costing A$245 million, the programs are very cost-effective at A$416-8750 per QALY gained. Financial investment in NSPs over 2000-2010 is estimated to be entirely recovered in healthcare cost savings by 2032 with a total future return on investment of $1.3-5.5 for every $1 invested. CONCLUSION: Australia's early introduction and high coverage of NSPs has significantly reduced the prevalence of HIV and HCV among IDUs. NSPs are a cost-effective public health strategy and will result in substantial net cost savings in the future.

Economic evaluation of monitoring virologic responses to antiretroviral therapy in HIV-infected children in resource-limited settings.

OBJECTIVE: Antiretroviral therapy (ART) management for HIV-infected children is critical in many resource-constrained countries. We investigated the cost-effectiveness and cost-utility of different frequencies of monitoring plasma viral load among HIV-positive children initiating ART in a resource-limited setting. DESIGN/METHODS: A stochastic agent-based simulation model was built and directly informed by a cohort of 304 HIV-infected children starting ART in Thailand between 2001 and 2009. The model simulated the expected costs and clinical outcomes over time according to different viral load monitoring frequencies and initiation of second-line therapies when appropriate. RESULTS: The optimal frequency of viral load monitoring was found to be annual, after a single screening at 6 months. Associated costs of viral load monitoring and appropriate ART would approximately triple current treatment costs. Compared with current conditions, a single screening during the first year of ART led to a 58.4% reduction in the total person-years of virological failure with annual monitoring leading to a 76.6% reduction. The incremental cost per quality adjusted life year gained from the optimal monitoring frequency was estimated as US$ 68,084 when including costs of ART and US$ 7224 without ART costs. The estimated cost attributed to preventing 1 year of virological failure was US$ 3393 with ART costs and US$ 359 without ART costs. CONCLUSION: Even infrequent viral load monitoring is likely to provide substantial clinical benefit to HIV-infected children on ART. Viral load monitoring can be considered cost-effective in many resource-limited settings. However, the costs associated with second-line therapies could be a barrier to its economic feasibility.

The epidemiology of hepatitis C in Australia: notifications, treatment uptake and liver transplantations, 1997-2006.

BACKGROUND AND AIM: Regular monitoring of hepatitis C (HCV)-related surveillance data is essential to inform and evaluate strategies to reduce the expanding HCV burden. The aim of this study was to examine trends in the epidemiology and treatment of HCV in Australia. METHODS: We reviewed data about HCV notifications, treatment of HCV infection through the Highly Specialised Drugs (s100) Program, and liver transplants (Australia and New Zealand Liver Transplant Registry) for the period 1997-2006. RESULTS: HCV case notification rates declined by almost 50% between 1999 and 2006, with the greatest reductions between 2001 and 2002 and amongst young adults. For newly acquired HCV cases, 89% were Australian-born and 90% reported injecting drug use as a risk factor for infection. Overall, 30% of liver transplant recipients had HCV-related cirrhosis, but the number and proportion of HCV diagnoses increased between 1997 and 2006. HCV treatment also increased over the review period. However, only 1.4% of the 202,400 people estimated to be living with chronic HCV at the end of 2006 received treatment that year. CONCLUSION: The decline in HCV notifications is consistent with a decline in HCV incidence in Australia. However, the burden of advanced HCV disease continues to expand. To reduce this burden, treatment uptake needs to increase. Consistent and sensitive surveillance mechanisms are required to detect newly acquired cases together with an expansion of surveillance for chronic HCV infections.

Modelling the population-level impact of vaccination on the transmission of human papillomavirus type 16 in Australia.

BACKGROUND: Vaccines are now available to prevent the development of cervical cancer from genital human papillomavirus (HPV) infection. The decision to vaccinate depends on a vaccine's cost-effectiveness. A rigorous cost-effectiveness model for vaccinated individuals is presented in a companion paper; this paper investigates the additional benefits the community might receive from herd immunity. METHODS: A mathematical model was developed to estimate the impact of a prophylactic vaccine on transmission of HPV type 16 in Australia. The model was used to estimate the expected reduction in HPV incidence and prevalence as a result of vaccination, the time required to achieve these reductions, and the coverage required for elimination. The modelled population was stratified according to age, gender, level of sexual activity and HPV infection status using a differential equation formulation. Clinical trials show that the vaccine is highly effective at preventing persistent infection and pre-cancerous lesions. These trials do not, however, provide conclusive evidence that infection is prevented altogether. The possible modes of vaccine action were investigated to see how vaccination might change the conclusions. RESULTS: The model predicts that vaccination of 80% of 12-year-old girls will eventually reduce HPV 16 prevalence by 60-100% in vaccinated and 7-31% in unvaccinated females. If 80% of boys are also vaccinated, reductions will be 74-100% in vaccinated and 86-96% in unvaccinated females. A campaign covering only 12-year-old girls would require 5-7 years to achieve 50% of the eventual reduction. With a catch-up campaign covering 13-26-year-olds, this delay would be reduced to only 2 years. Unrealistically high coverage in both sexes would be required to eliminate HPV 16 from the population. Under pessimistic assumptions about the duration of vaccine-conferred immunity, HPV 16 incidence is predicted to rise in some older age groups. CONCLUSIONS: Mass vaccination with a highly effective vaccine against HPV 16 has the potential to substantially reduce the incidence and prevalence of infection. Catch-up vaccination offers the potential to substantially reduce the delay before the benefits of vaccination are observed. A booster vaccination might be required to prevent an increase in incidence of infection in women over 25 years of age.