Alan Yeung

• PhD in Statistics
• Research Fellow at Glasgow Caledonian University

Objectives Our aim was to examine mortality trends in the era of antiretroviral therapy, among people who inject drugs (PWID) who are living with HIV. The study objectives were to assess and quantify mortality among PWID diagnosed with HIV over time in Scotland, in the context of a recent outbreak of HIV and rise in drug‐related mortality. Methods...

Background and aims Opioid dependence is associated with an increased risk of suicide. Drug‐related mortality among people with opioid dependence in Scotland has more than tripled since 2010; less is known about changes in suicide risk. We aimed to determine if opioid agonist therapy (OAT) in Scotland is protective against suicide and to measure tr...

Background In the context of an outbreak of HIV among people who inject drugs in Glasgow, Scotland, identified in 2015, our objectives were to: (1) develop epidemiological methods to estimate HIV incidence using data linkage, and (2) examine temporal changes in HIV incidence to inform public health responses. Methods This was a retrospective cohor...

Background Lookback investigations are conducted by blood services when a risk of transmission of infection from a donor to a recipient has been identified. They involve tracing transfusion recipients and offering them testing for the relevant infectious agent. Results are relayed to the recipient to provide reassurance that there has been no trans...

Background To inform global ambitions to end AIDS, evaluation of progress towards HIV incidence reduction require robust methods to measure incidence. Although HIV diagnosis date in routine HIV/AIDS surveillance systems are often used as a surrogate marker for incidence, it can be misleading if acquisition of transmission occurred years before test...

Glasgow, Scotland’s largest city, has been experiencing an HIV outbreak among people who inject drugs (PWID) since 2015. A key focus of the public health response has been to increase HIV testing among those at risk of infection. Our aim was to assess the impact of COVID-19 on HIV testing among PWID in Glasgow. HIV test uptake in the last 12 months...

Background and aims Drug‐related deaths in Scotland more than doubled between 2011 and 2020. To inform policymakers and understand drivers of this increase, we estimated the number of people with opioid dependence aged 15–64 from 2014/15 to 2019/20. Design We fitted a Bayesian multi‐parameter estimation of prevalence (MPEP) model, using adverse ev...

Background There is limited evidence quantifying the risk of severe COVID-19 disease among people with opioid dependence. We examined vaccine uptake and severe disease (admission to critical care or death with COVID-19) among individuals prescribed opioid agonist therapy (OAT). Method A case–control design was used to examine vaccine uptake in tho...

Background: Prescribing of gabapentinoids and Z-drug-hypnotics has increased in the population and among people receiving opioid-agonist treatment (OAT) for opioid dependence. Evidence is mixed on whether co-prescribing of sedatives such as gabapentinoids and Z-drugs during OAT increases risk of drug-related death (DRD). Methods: We conducted a ret...

Background and aims Direct‐acting antiviral (DAA) treatment has an established positive effect on liver outcomes in people with hepatitis C infection; however, there is insufficient evidence regarding its effects on the ‘extra‐hepatic’ outcomes of drug‐related hospitalization and mortality (DRM) among people who inject drugs (PWID). We investigated...

Background: Take-home naloxone (THN) programmes have been associated with reductions in opioid-related mortality. In response to high rates of drug-related deaths in Scotland, the Scottish Government commissioned the 'How to save a life' (HTSAL) mass media campaign to: (1) increase awareness of drug-related deaths and how to respond to an overdose...

Objectives To quantify mortality rates for patients successfully treated for hepatitis C in the era of interferon-free, direct acting antivirals and compare these rates with those of the general population. Design Population based cohort study. Setting British Columbia, Scotland, and England (England cohort consists of patients with cirrhosis onl...

Background: Drug-related death (DRD) rate in Scotland, UK, has increased rapidly to one of the highest in the world. Our aim was to examine the extent to which opioid-agonist therapy (OAT) in Scotland is protective against drug-related mortality and how this effect has varied over time. Methods: We included individuals in Scotland with opioid us...

Background: Risk scores estimating a patient's probability of a hepatocellular carcinoma (HCC) diagnosis are abundant, but are difficult to interpret in isolation. Here, we compared the predicted HCC probability for individuals with cirrhosis and cured hepatitis C to the general population (GP). Methods: All patients with cirrhosis achieving sus...

Background and Aims Existing models predicting hepatocellular carcinoma (HCC) occurrence do not account for competing risk events and, thus, may overestimate the probability of HCC. Our goal was to quantify this bias for patients with cirrhosis and cured hepatitis C. Methods We analyzed a nationwide cohort of patients with cirrhosis and cured hepa...

Background COVID-19 has likely affected the delivery of interventions to prevent blood-borne viruses (BBVs) among people who inject drugs (PWID). We examined the impact of the first wave of COVID-19 in Scotland on: 1) needle and syringe provision (NSP), 2) opioid agonist therapy (OAT) and 3) BBV testing. Methods An interrupted time series study de...

Background & Aims The impact of interferon (IFN)-free therapies on the epidemiology of hepatitis C virus (HCV) related hepatocellular carcinoma (HCC) is not well understood at a population level. Our goal was to bridge this evidence gap. Methods This study included all patients in Scotland with chronic HCV and a diagnosis of cirrhosis during 1999-...

Background & aims: Scale-up of highly-effective direct-acting antivirals (DAAs) for hepatitis C virus (HCV) among people who inject drugs (PWID) in Scotland has led to a reduction in prevalence of viraemia in this population. However, the extent of reinfection among those treated with DAAs remains uncertain. We estimated HCV reinfection rates amon...

BACKGROUND Hepatocellular carcinoma (HCC) prediction models can inform clinical decisions about HCC screening provided their predictions are robust. We conducted an external validation of six HCC prediction models for UK patients with cirrhosis and a hepatitis C virus (HCV) virological cure. METHODS Cirrhosis patients with cured HCV were identifie...

Background Drug-related deaths globally are increasing year on year, with the largest proportion of these being opioid-related. The opioid antagonist naloxone distributed for take-home use (‘Take-Home Naloxone (THN)’) has been championed as one method of tackling this public health crisis, however to be effective it must be available at an opioid o...

Background and aims: There has been little empirical evidence to show the 'real world' impact of scaling-up direct-acting antiviral (DAA) treatment among people who inject drugs (PWID) on hepatitis C virus (HCV) viraemia at a population level. We aimed to assess the population impact of rapid DAA scale-up to PWID delivered through community servic...

Objectives To review characteristics of individuals newly diagnosed with HIV following implementation of a national pre-exposure prophylaxis (PrEP) programme (comprehensive PrEP services, delivered in sexual health clinics) to inform future delivery and broader HIV prevention strategies. Methods We extracted data from national HIV databases (July...

Faced with the 2020 SARS-CoV2 epidemic, public health officials have been seeking models that could be used to predict not only the number of new cases but also the levels of hospitalisation, critical care and deaths. In this paper we present a stochastic compartmental model capable of real-time monitoring and forecasting of the pandemic incorporat...

Objective: The aim of this study was to evaluate Scotland's national HIV preexposure prophylaxis (PrEP) programme in relation to PrEP uptake and associated population-level impact on HIV incidence among MSM. Design: A retrospective cohort study within real-world implementation. Methods: Comparison of HIV diagnoses from national surveillance da...

Objective Population-based studies demonstrating the clinical impact of interferon-free direct-acting antiviral (DAA) therapies are lacking. We examined the impact of the introduction of DAAs on HCV-related decompensated cirrhosis (DC) through analysis of population-based data from Scotland. Design Through analysis of national surveillance data (i...

Introduction Hepatitis C virus (HCV) is the second largest contributor to liver disease in the UK, with injecting drug use as the main risk factor among the estimated 200 000 people currently infected. Despite effective prevention interventions, chronic HCV prevalence remains around 40% among people who inject drugs (PWID). New direct-acting antivi...

Background: Novel Psychoactive Substance (NPS) use has increased in recent years and generated significant concern within public health. People who inject drugs (PWID) are at increased risk of blood borne viruses, in particular Hepatitis C virus (HCV). However, little is known about the extent of NPS injecting at a national level and its associati...

Background and aims: In Scotland, Hepatitis B virus (HBV) vaccination for all prisoners was introduced in 1999; here, we examine the impact of this programme among people who inject drugs (PWID) in the community. This study aimed to compare rates of HBV vaccine uptake before and after implementation of the prison programme and to estimate the dete...

Background and aims: In April 2015, the UK government enacted a temporary class drug order (TCDO) on ethylphenidate in response to reported harms associated with its use, in particular an outbreak of infections among people who inject drugs (PWID) in Lothian, Scotland. This study assesses the effect that the TCDO had on reducing the most common in...