Medicine (St Vincent's) - Research Publications

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    Spread of activation and interaction between channels with multi-channel optogenetic stimulation in the mouse cochlea
    Azees, AA ; Thompson, AC ; Thomas, R ; Zhou, J ; Ruther, P ; Wise, AK ; Ajay, EA ; Garrett, DJ ; Quigley, A ; Fallon, JB ; Richardson, RT (ELSEVIER, 2023-12)
    For individuals with severe to profound hearing loss resulting from irreversibly damaged hair cells, cochlear implants can be used to restore hearing by delivering electrical stimulation directly to the spiral ganglion neurons. However, current spread lowers the spatial resolution of neural activation. Since light can be easily confined, optogenetics is a technique that has the potential to improve the precision of neural activation, whereby visible light is used to stimulate neurons that are modified with light-sensitive opsins. This study compares the spread of neural activity across the inferior colliculus of the auditory midbrain during electrical and optical stimulation in the cochlea of acutely deafened mice with opsin-modified spiral ganglion neurons (H134R variant of the channelrhodopsin-2). Monopolar electrical stimulation was delivered via each of four 0.2 mm wide platinum electrode rings at 0.6 mm centre-to-centre spacing, whereas 453 nm wavelength light was delivered via each of five 0.22 × 0.27 mm micro-light emitting diodes (LEDs) at 0.52 mm centre-to-centre spacing. Channel interactions were also quantified by threshold changes during simultaneous stimulation by pairs of electrodes or micro-LEDs at different distances between the electrodes (0.6, 1.2 and 1.8 mm) or micro-LEDs (0.52, 1.04, 1.56 and 2.08 mm). The spread of activation resulting from single channel optical stimulation was approximately half that of monopolar electrical stimulation as measured at two levels of discrimination above threshold (p<0.001), whereas there was no significant difference between optical stimulation in opsin-modified deafened mice and pure tone acoustic stimulation in normal-hearing mice. During simultaneous micro-LED stimulation, there were minimal channel interactions for all micro-LED spacings tested. For neighbouring micro-LEDs/electrodes, the relative influence on threshold was 13-fold less for optical stimulation compared electrical stimulation (p<0.05). The outcomes of this study show that the higher spatial precision of optogenetic stimulation results in reduced channel interaction compared to electrical stimulation, which could increase the number of independent channels in a cochlear implant. Increased spatial resolution and the ability to activate more than one channel simultaneously could lead to better speech perception in cochlear implant recipients.
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    Point-of-care HCV RNA testing improves hepatitis C testing rates and allows rapid treatment initiation among people who inject drugs attending a medically supervised injecting facility.
    MacIsaac, MB ; Whitton, B ; Anderson, J ; Cogger, S ; Vella-Horne, D ; Penn, M ; Weeks, T ; Elmore, K ; Pemberton, D ; Winter, RJ ; Papaluca, T ; Howell, J ; Hellard, M ; Stoové, M ; Wilson, D ; Pedrana, A ; Doyle, JS ; Clark, N ; Holmes, JA ; Thompson, AJ (Elsevier BV, 2024-01-27)
    BACKGROUND: To achieve hepatitis C virus (HCV) elimination targets, simplified care engaging people who inject drugs is required. We evaluated whether fingerstick HCV RNA point-of-care testing (PoCT) increased the proportion of clients attending a supervised injecting facility who were tested for hepatitis C. METHODS: Prospective single-arm study with recruitment between 9 November 2020 and 28 January 2021 and follow-up to 31 July 2021. Clients attending the supervised injecting facility were offered HCV RNA testing using the Xpert® HCV Viral Load Fingerstick (Cepheid, Sunnyvale, CA) PoCT. Participants with a positive HCV RNA test were prescribed direct acting antiviral (DAA) therapy. The primary endpoint was the proportion of clients who engaged in HCV RNA PoCT, compared to a historical comparator group when venepuncture-based hepatitis C testing was standard of care. RESULTS: Among 1618 clients who attended the supervised injecting facility during the study period, 228 (14%) engaged in PoCT. This was significantly higher than that observed in the historical comparator group (61/1,775, 3%; p < 0.001). Sixty-five (28%) participants were HCV RNA positive, with 40/65 (62%) receiving their result on the same day as testing. Sixty-one (94%) HCV RNA positive participants were commenced on DAA therapy; 14/61 (23%) started treatment on the same day as diagnosis. There was no difference in the proportion of HCV RNA positive participants commenced on treatment with DAA therapy when compared to the historical comparator group (61/65, 94% vs 22/26, 85%; p = 0.153). However, the median time to treatment initiation was significantly shorter in the PoCT cohort (2 days (IQR 1-20) vs 41 days (IQR 22-76), p < 0.001). Among participants who commenced treatment and had complete follow-up data available, 27/36 (75%) achieved hepatitis C cure. CONCLUSIONS: HCV RNA PoCT led to a significantly higher proportion of clients attending a supervised injecting facility engaging in hepatitis C testing, whilst also reducing the time to treatment initiation.
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    Baseline serum HBV RNA is associated with the risk of hepatitis flare after stopping nucleoside analog therapy in HBeAg-negative participants
    Thompson, AJ ; Jackson, K ; Bonanzinga, S ; Hall, SAL ; Hume, S ; Burns, GS ; Sundararajan, V ; Ratnam, D ; Levy, MT ; Lubel, J ; Nicoll, AJ ; Strasser, SI ; Sievert, W ; Desmond, PV ; Ngu, MC ; Sinclair, M ; Meredith, C ; Matthews, G ; Revill, PA ; Littlejohn, M ; Bowden, DS ; Canchola, JA ; Torres, J ; Siew, P ; Lau, J ; La Brot, B ; Kuchta, A ; Visvanathan, K (LIPPINCOTT WILLIAMS & WILKINS, 2023-08)
    BACKGROUND AND AIMS: HBV RNA in peripheral blood reflects HBV cccDNA transcriptional activity and may predict clinical outcomes. The prospective Melbourne HBV-STOP trial studied nucleot(s)ide analog discontinuation in HBeAg-negative non-cirrhotic participants with long-term virological suppression. Ninety-six weeks after stopping treatment, the proportion of participants with virological relapse (HBV DNA > 2000 IU/mL), biochemical relapse (ALT > 2 × ULN and HBV DNA > 2000 IU/mL), or hepatitis flare (ALT > 5 × ULN and HBV DNA > 2000 IU/mL) was 89%, 58%, and 38%, respectively. We evaluated the ability of serum HBV RNA levels to predict these outcomes. APPROACH RESULTS: HBV RNA levels were measured using the Roche cobas 6800/8800 HBV RNA Investigational Assay. Sixty-five participants had baseline and longitudinal off-treatment specimens available for RNA testing. HBV RNA was detectable at baseline in 25% of participants and was associated with a higher risk of biochemical relapse (81% vs. 51%, p value 0.04) and hepatitis flare (63% vs. 31%, p value 0.04). Participants who had undetectable serum HBV RNA as well as HBsAg ≤ 100 IU/mL at baseline were less likely to experience virological relapse (4 of 9, 44%) than participants with detectable HBV RNA and HBsAg level > 100 IU/mL (15/15, 100%; p value 0.0009). Off-treatment levels of HBV RNA were correlated with HBV DNA and were associated with the risk of hepatitis flare. CONCLUSIONS: Serum HBV RNA may be a useful biomarker for guiding clinical decision-making before stopping nucleot(s)ide analog therapy. Baseline HBV RNA and HBsAg levels are associated with the risk of clinical relapse, hepatitis flare, and disease remission off-treatment.
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    Assessment of the cobas® HBV RNA investigational assay in the setting of nucleoside analog therapy cessation
    Jackson, K ; Bonanzinga, S ; Edwards, R ; Visvanathan, K ; Li, X ; Hall, S ; Kuchta, A ; Canchola, JA ; Thompson, AJ (WILEY, 2022-12)
    HBV RNA is used as a marker of cccDNA transcription and is applicable in the setting of nucleos(t)ide analog (NA) treatment, which suppresses HBV DNA. Traditional assays for quantification of HBV RNA rely on labor-intensive 3'RACE assays targeting the polyA tail. In this study, the high-throughput Roche cobas®HBV RNA investigational assay was assessed on the Roche cobas® 6800 automated platform. Of 969 samples collected for a NA treatment cessation trial, and tested on the cobas assay, 249 were analyzed for sensitivity, reproducibility, sample type applicability, and results were compared to a RACE-based assay. Results of 97 paired serum and plasma samples demonstrated an excellent correlation of 0.98. However, 14.5% of plasma samples yielded detectable (below the limit of quantification) results, when the paired serum was undetectable, and plasma was shown to yield a statistically significant (p < 0.001) greater mean 0.119 log10 copies/ml. Quantification of 152 samples showed good correlation (0.91) between the cobas and RACE assays. The cobas assay demonstrated superior lower limit of quantification, 10 copies/ml, which resulted in detection of 13.2% more samples than the RACE assay. Reproducibility and linear range of the automated assay were also confirmed. The Roche cobas assay for HBV RNA is sensitive and highly recommended.
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    Clinical outcomes amongst elderly patients with inflammatory bowel disease
    Sivanathan, V ; Basnayake, C ; Connell, W ; Wright, E ; Ding, JN ; Niewadomski, O ; Stanley, A ; Wilson-O'Brien, A ; Fry, S ; Samyue, T ; Lust, M ; Flanagan, E ; Thompson, AJ ; Kamm, MA (WILEY, 2023-10)
    BACKGROUNDS AND AIMS: Inflammatory bowel disease (IBD) affects a growing cohort of elderly patients. Our aim was to compare the quality of care received by elderly patients with IBD with a nonelderly adult IBD population using clinical markers including steroid-free clinical remission. METHOD: Retrospective audit of all consecutive patients attending a specialist IBD centre over a 1-year period aged >60 (elderly cohort [EC]) and 50 consecutive patients aged 30-45 years (control cohort [CC]). A follow-up survey was completed assessing current symptoms and perceptions of care. RESULTS: One hundred thirty-nine patients were evaluated (89 EC, 50 CC). Steroid-free clinical remission was observed less commonly in the EC (58, 64%) compared with the CC (40, 80%) (P < 0.05). Biologics such as infliximab (15% EC vs 36% CC; P < 0.01) and adalimumab (14% EC vs 30% CC; P = 0.02) were used less frequently in the EC, whilst vedolizumab (6% EC vs 6% CC; P = 1) and ustekinumab (3% EC vs 2% CC; P = 1) were used at a similar frequency. Patients in the EC were less likely to have specialist IBD nursing contact (P < 0.01), smoking screening (P < 0.011) or influenza vaccinations (P < 0.006). IBD nurse contact was associated with significantly greater provision of the preventative care measures. CONCLUSION: Elderly patients with IBD were less likely to experience steroid-free clinical remission or be prescribed biologics. Elderly patients were less likely to receive education with respect to preventative medicine. The models of care for the elderly need re-evaluation and greater incorporation with the multidisciplinary IBD team.
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    The impact of point-of-care hepatitis C testing in needle and syringe exchange programs on linkage to care and treatment uptake among people who inject drugs: An Australian pilot study
    Howell, J ; Traeger, MW ; Williams, B ; Layton, C ; Doyle, JS ; Latham, N ; Draper, B ; Bramwell, F ; Membrey, D ; McPherson, M ; Roney, J ; Stoove, M ; Thompson, AJ ; Hellard, ME ; Pedrana, A (WILEY, 2022-05)
    Point-of-care (POC) diagnostics overcome barriers to conventional hepatitis C (HCV) testing in people who inject drugs. This study assessed impact on hepatitis C treatment uptake of POC HCV testing in needle and syringe exchange programs (NSPs). Rapid EC was a single-arm interventional pilot study of HCV POC testing conducted in three inner-city community clinics with NSPs. Twelve months after the POC testing, a retrospective medical record and Pharmaceutical Benefits Scheme audit was performed to determine the number of HCV RNA-positive participants who were prescribed HCV treatment. 70 HCV RNA-positive Rapid EC study participants were included. 44 (63%) were prescribed DAAs; 26 (59%) completed treatment and 15 (34%) had SVR testing, all of whom were cured. Age ≥ 40 years (aOR 3.45, 95% CI 1.10-11.05, p = .03) and secondary school education (aOR 5.8, 95% CI 1.54-21.80, p = .009) had higher likelihood of being prescribed DAAs, whereas homelessness was inversely associated with prescription of DAAs (aOR 0.30, 95% CI 0.09-1.04, p = .057). Median time to receive a DAA script from date of diagnosis was seven days (IQR 0 to 14 days), and time to filling the DAA prescription was 2 days (IQR 0-12 days). In conclusion, provision of POC testing through NSPs was effective for linking new clients to HCV treatment and reduced the time to treatment. Further studies are needed to define the most cost-effective use of POC testing in models of care for people who inject drugs to increase HCV treatment uptake.
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    Monitoring quality of care in hepatocellular carcinoma: A modified Delphi consensus
    Maharaj, AD ; Lubel, J ; Lam, E ; Clark, PJ ; Duncan, O ; George, J ; Jeffrey, GP ; Lipton, L ; Liu, H ; McCaughan, G ; Neo, E-L ; Philip, J ; Strasser, S ; Stuart, K ; Thompson, A ; Tibballs, J ; Tu, T ; Wallace, MC ; Wigg, A ; Wood, M ; Zekry, A ; Greenhill, E ; Ioannou, LJ ; Ahlenstiel, G ; Bowers, K ; Clarke, SJ ; Dev, A ; Fink, M ; Goodwin, M ; Karapetis, CS ; Levy, MT ; Muller, K ; O'Beirne, J ; Pryor, D ; Seow, J ; Shackel, N ; Tallis, C ; Butler, N ; Olynyk, JK ; Reed-Cox, K ; Zalcberg, JR ; Roberts, SK (LIPPINCOTT WILLIAMS & WILKINS, 2022-11)
    Although there are several established international guidelines on the management of hepatocellular carcinoma (HCC), there is limited information detailing specific indicators of good quality care. The aim of this study was to develop a core set of quality indicators (QIs) to underpin the management of HCC. We undertook a modified, two-round, Delphi consensus study comprising a working group and experts involved in the management of HCC as well as consumer representatives. QIs were derived from an extensive review of the literature. The role of the participants was to identify the most important and measurable QIs for inclusion in an HCC clinical quality registry. From an initial 94 QIs, 40 were proposed to the participants. Of these, 23 QIs ultimately met the inclusion criteria and were included in the final set. This included (a) nine related to the initial diagnosis and staging, including timing to diagnosis, required baseline clinical and laboratory assessments, prior surveillance for HCC, diagnostic imaging and pathology, tumor staging, and multidisciplinary care; (b) thirteen related to treatment and management, including role of antiviral therapy, timing to treatment, localized ablation and locoregional therapy, surgery, transplantation, systemic therapy, method of response assessment, and supportive care; and (c) one outcome assessment related to surgical mortality. Conclusion: We identified a core set of nationally agreed measurable QIs for the diagnosis, staging, and management of HCC. The adherence to these best practice QIs may lead to system-level improvement in quality of care and, ultimately, improvement in patient outcomes, including survival.
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    The Hidden Epidemic: The Prevalence and Impact of Concurrent Liver Diseases in Patients Undergoing Liver Transplantation in Australia and New Zealand
    Howell, J ; Majumdar, A ; Fink, M ; Byrne, M ; McCaughan, G ; Strasser, SI ; Crawford, M ; Hodgkinson, P ; Stuart, KA ; Tallis, C ; Chen, J ; Wigg, A ; Jones, R ; Jaques, B ; Jeffrey, G ; Adams, L ; Wallace, MC ; Gane, E ; Thompson, A ; Gow, P (LIPPINCOTT WILLIAMS & WILKINS, 2022-08)
    UNLABELLED: Prevalence of concurrent liver diseases among liver transplant recipients and impact on posttransplant outcomes are unknown. METHODS: This retrospective study included adult liver transplants between January 1' 1985' and December 31' 2019' from the Australian and New Zealand Liver and Intestinal Transplant Registry. Up to 4 liver disease causes were recorded for each transplant; concurrent liver diseases were defined as >1 liver disease indication for transplantation, excluding hepatocellular carcinoma. Impact on posttransplant survival was determined using Cox regression. RESULTS: A total of 840 (15%) of 5101 adult liver transplant recipients had concurrent liver diseases. Recipients with concurrent liver diseases were more likely male (78% versus 64%) and older (mean age 52 versus 50 y). A higher proportion of liver transplants for hepatitis B (12% versus 6%), hepatitis C (33% versus 20%), alcohol liver disease (23% versus 13%), and metabolic-associated fatty liver disease (11% versus 8%, all P < 0.001) were identified when all indications were included than with primary diagnosis only. The number and proportion of liver transplants performed for concurrent liver diseases have increased from 8 (6%) during Era 1 (1985-1989) to 302 (20%) during Era 7 (2015-2019; P < 0.001). Concurrent liver diseases were not associated with increased posttransplant mortality (adjusted hazard ratio, 0.98, 95% confidence interval, 0.84-1.14). CONCLUSIONS: Concurrent liver diseases are increasing among adult liver transplant recipients in Australia and New Zealand; however, they do not appear to impact posttransplant survival. Reporting all liver disease causes in the transplant registry reports provides more accurate estimates of liver disease burden.
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    Real-world monitoring progress towards the elimination of hepatitis C virus in Australia using sentinel surveillance of primary care clinics; an ecological study of hepatitis C virus antibody tests from 2009 to 2019 (vol 150, E7, 2022)
    Lee Wilkinson, A ; Pedrana, A ; Traeger, MW ; Asselin, J ; El-Hayek, C ; Nguyen, L ; Polkinghorne, V ; Doyle, JS ; Thompson, AJ ; Howell, J ; Scott, N ; Dimech, W ; Guy, R ; Hellard, M ; Stoove, M (CAMBRIDGE UNIV PRESS, 2022-03-04)
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    Eliminating hepatitis C in Australia: a novel model of hepatitis C testing and treatment for people who inject drugs at a medically supervised injecting facility
    MacIsaac, MB ; Whitton, B ; Hubble, A ; Cogger, S ; Penn, M ; Weeks, A ; Elmore, K ; Pemberton, D ; Anderson, J ; Howard, R ; McKeever, U ; Papaluca, T ; Hellard, ME ; Stoove, M ; Wilson, D ; Pedrana, A ; Doyle, J ; Clark, N ; Holmes, J ; Thompson, AJ (WILEY, 2023-04-03)
    OBJECTIVE: To evaluate the feasibility of testing and treating people who inject drugs at a supervised injecting facility for hepatitis C virus (HCV) infection. DESIGN: Retrospective cohort study. SETTING, PARTICIPANTS: People who inject drugs who attended the Melbourne supervised injecting facility, 30 June 2018 - 30 June 2020. MAIN OUTCOME MEASURES: Proportion of people tested for hepatitis C; proportions of people positive for anti-HCV antibody and HCV RNA, and of eligible people prescribed direct-acting antiviral (DAA) treatment; sustained virological response twelve weeks or more after treatment completion. RESULTS: Of 4649 people who attended the supervised injecting facility during 2018-20, 321 were tested for hepatitis C (7%); 279 were anti-HCV antibody-positive (87%), of whom 143 (51%) were also HCV RNA-positive. Sixty-four of 321 had previously been treated for hepatitis C (20%), 21 had clinically identified cirrhosis (7%), eight had hepatitis B infections (2%), and four had human immunodeficiency virus infections (1%). In multivariate analyses, people tested for hepatitis C were more likely than untested clients to report psychiatric illness (adjusted odds ratio [aOR], 9.65; 95% confidence interval [CI], 7.26-12.8), not have a fixed address (aOR, 1.59; 95% CI, 1.18-2.14), and to report significant alcohol use (aOR, 1.57; 95% CI, 1.06-2.32). The median number of injecting facility visits was larger for those tested for hepatitis C (101; interquartile range [IQR], 31-236) than for those not tested (20; IQR, 3-90). DAA treatment was prescribed for 126 of 143 HCV RNA-positive clients (88%); 41 of 54 with complete follow-up data were cured (76%). CONCLUSIONS: People who attend supervised injecting facilities can be tested and treated for hepatitis C on site. Models that provide streamlined, convenient hepatitis C care promote engagement with treatment in a group in which the prevalence of hepatitis C is high.