Publications by authors named "G M Chambers"

362 Publications

Evaluating the prevention benefit of HCV treatment: Modelling the SToP-C treatment as prevention study in prisons.

Hepatology 2021 Jun 9. Epub 2021 Jun 9.

Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.

Background & Aims: Between 2014-2019, the SToP-C trial observed a halving in HCV incidence in four Australian prisons following scale-up of direct-acting antiviral (DAA) therapy. However, the contribution of HCV treatment to this decline is unclear due to the study not having a control group. We used modelling to consider this question.

Approach & Results: We parameterised and calibrated a dynamic model of HCV transmission in prisons to data from each SToP-C prison on incarceration dynamics, injecting drug use, HCV prevalence trends among prison entrants, baseline HCV incidence before treatment scale-up, and subsequent HCV treatment scale-up. The model projected the decrease in HCV incidence resulting from increases in HCV treatment and other effects. We assessed whether the model agreed better with observed reductions in HCV incidence overall and by prison if we included HCV treatment scale-up, and its prevention benefits, or did not. The model estimated how much of the observed decrease in HCV incidence was due to HCV treatment in prison. The model projected a decrease in HCV incidence of 48.5% (95% uncertainty interval [UI] 41.9-54.1%) following treatment scale-up across the four prisons, agreeing with the observed HCV incidence decrease (47.6%, 95% confidence interval 23.4-64.2%) from the SToP-C trial. Without any in-prison HCV treatment, the model indicated that incidence would have decreased by 7.2% (95%UI -0.3-13.6%). This suggests 85.1% (95%UI 72.6-100.6%) of the observed halving in incidence was from HCV treatment scale-up, with the remainder from observed decreases in HCV prevalence among prison entrants (14.9%; 95%UI -0.6-27.4%).

Conclusions: Our results demonstrate the prevention benefits of scaling up HCV treatment in prison settings. Prison-based DAA scale-up should be an important component of HCV elimination strategies.
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http://dx.doi.org/10.1002/hep.32002DOI Listing
June 2021

The clinical performance and cost-effectiveness of two psychosocial assessment models in maternity care: The Perinatal Integrated Psychosocial Assessment study.

Women Birth 2021 Jun 4. Epub 2021 Jun 4.

Perinatal and Women's Mental Health Unit, St John of God Health Care, 23 Grantham St, Burwood NSW 2134, Australia; School of Psychiatry, University of New South Wales, Sydney, NSW 2052, Australia; Royal Hospital for Women, Sydney, Barker Street, Randwick, NSW 2031, Australia. Electronic address:

Problem: Although perinatal universal depression and psychosocial assessment is recommended in Australia, its clinical performance and cost-effectiveness remain uncertain.

Aim: To compare the performance and cost-effectiveness of two models of psychosocial assessment: Usual-Care and Perinatal Integrated Psychosocial Assessment (PIPA).

Methods: Women attending their first antenatal visit were prospectively recruited to this cohort study. Endorsement of significant depressive symptoms or psychosocial risk generated an 'at-risk' flag identifying those needing referral to the Triage Committee. Based on its detailed algorithm, a higher threshold of risk was required to trigger the 'at-risk' flag for PIPA than for Usual-Care. Each model's performance was evaluated using the midwife's agreement with the 'at-risk' flag as the reference standard. Cost-effectiveness was limited to the identification of True Positive and False Positive cases. Staffing costs associated with administering each screening model were quantified using a bottom-up time-in-motion approach.

Findings: Both models performed well at identifying 'at-risk' women (sensitivity: Usual-Care 0.82 versus PIPA 0.78). However, the PIPA model was more effective at eliminating False Positives and correctly identifying 'at-risk' women (Positive Predictive Value: PIPA 0.69 versus Usual Care 0.41). PIPA was associated with small incremental savings for both True Positives detected and False Positives averted.

Discussion: Overall PIPA performed better than Usual-Care as a psychosocial screening model and was a cost-saving and relatively effective approach for detecting True Positives and averting False Positives. These initial findings warrant evaluation of longer-term costs and outcomes of women identified by the models as 'at-risk' and 'not at-risk' of perinatal psychosocial morbidity.
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http://dx.doi.org/10.1016/j.wombi.2021.05.007DOI Listing
June 2021

Evaluation of hepatitis C treatment-as-prevention within Australian prisons (SToP-C): a prospective cohort study.

Lancet Gastroenterol Hepatol 2021 Jul 7;6(7):533-546. Epub 2021 May 7.

The Kirby Institute, UNSW Sydney, Sydney, NSW, Australia. Electronic address:

Background: Limited empirical evidence exists for the effectiveness of hepatitis C virus (HCV) treatment-as-prevention. The Surveillance and Treatment of Prisoners with hepatitis C (SToP-C) study aimed to assess the effect of HCV treatment-as-prevention in the prison setting.

Methods: SToP-C was a prospective study, including a before-and-after analysis, within a cohort of people incarcerated in two maximum-security prisons (male) and two medium-security prisons (one male, one female) in New South Wales, Australia. All prison inmates aged at least 18 years were eligible for enrolment. After HCV testing, participants were monitored for risk behaviours and HCV infection, among three sub-populations: uninfected (HCV antibody-negative); previously infected (HCV antibody-positive, HCV RNA-negative); and infected (HCV antibody and HCV RNA-positive). Uninfected participants were followed up every 3-6 months to detect HCV primary infection and previously infected participants were followed up every 3-6 months to detect re-infection. Participants with HCV infection were assessed for treatment, initially standard-of-care treatment (administered by prison health services) from 2014 to mid-2017, then direct-acting antiviral (DAA) treatment scale-up from mid-2017 onwards (12 weeks of sofosbuvir plus velpatasvir, administered through SToP-C). Participants were followed up until study closure in November, 2019. The primary study outcome was HCV incidence before and after DAA treatment scale-up among participants at risk of HCV primary infection or re-infection. This study is registered with ClinicalTrials.gov, NCT02064049.

Findings: Between Oct 30, 2014, and Sept 30, 2019, 3691 participants were enrolled in the SToP-C study. 719 (19%) participants had detectable HCV RNA, 2240 (61%) were at risk of primary HCV infection, and 725 (20%) were at risk of re-infection at baseline. DAA treatment was initiated in 349 (70%) of 499 eligible participants during the treatment scale-up period. The HCV incidence analysis comprised 1643 participants at risk of HCV infection or re-infection during longitudinal follow-up (median age 33 years [IQR 27-42]; 1350 [82%] male). 487 (30%) of 1643 participants reported injecting drugs in prison. HCV incidence decreased from 8·31 per 100 person-years in the pre-treatment scale-up period to 4·35 per 100 person-years in the post-treatment scale-up period (incidence rate ratio [IRR] 0·52 [95% CI 0·36-0·78]; p=0·0007). The incidence of primary infection decreased from 6·64 per 100 person-years in the pre-treatment scale-up period to 2·85 per 100 person-years in the post-treatment scale-up period (IRR 0·43 [95% CI 0·25-0·74]; p=0·0019), whereas the incidence of re-infection decreased from 12·36 per 100 person-years to 7·27 per 100 person-years (0·59 [0·35-1·00]; p=0·050). Among participants reporting injecting drugs during their current imprisonment, the incidence of primary infection decreased from 39·08 per 100 person-years in the pre-treatment scale-up period to 14·03 per 100 person-years in the post-treatment scale-up period (IRR 0·36 [95% CI 0·16-0·80]; p=0·0091), and the incidence of re-infection decreased from 15·26 per 100 person-years to 9·34 per 100 person-years (0·61 [0·34-1·09]; p=0·093). The adjusted analysis (adjusted for age, Indigenous Australian ethnicity, duration of stay in prison, previous imprisonment, injecting drug use status, and prison site) indicated a significant reduction in the risk of HCV infection between the pre-DAA treatment scale-up and post-DAA treatment scale-up periods (adjusted hazard ratio 0·50 [95% CI 0·33-0·76]; p=0·0014).

Interpretation: DAA treatment scale-up was associated with reduced HCV incidence in prison, indicative of a beneficial effect of HCV treatment-as-prevention in this setting. These findings support broad DAA treatment scale-up within incarcerated populations.

Funding: Australian National Health and Medical Research Council Partnership Project Grant and Gilead Sciences.
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http://dx.doi.org/10.1016/S2468-1253(21)00077-7DOI Listing
July 2021

International Committee for Monitoring Assisted Reproductive Technologies (ICMART): world report on assisted reproductive technologies, 2013.

Fertil Steril 2021 Apr 26. Epub 2021 Apr 26.

Equal3 Fertility, Cupertino; Stanford University School of Medicine, Palo Alto; and University of California School of Medicine, San Francisco, California.

Objective: To report the utilization, effectiveness, and safety of practices in assisted reproductive technology (ART) globally in 2013 and assess global trends over time.

Design: Retrospective, cross-sectional survey on the utilization, effectiveness, and safety of ART procedures performed globally during 2013.

Setting: Seventy-five countries and 2,639 ART clinics.

Patient(s): Women and men undergoing ART procedures.

Intervention(s): All ART.

Main Outcome Measure(s): The ART cycles and outcomes on country-by-country, regional, and global levels. Aggregate country data were processed and analyzed based on methods developed by the International Committee for Monitoring Assisted Reproductive Technology (ICMART).

Result(s): A total of 1,858,500 ART cycles were conducted for the treatment year 2013 across 2,639 clinics in 75 participating countries with a global participation rate of 73.6%. Reported and estimated data suggest 1,160,474 embryo transfers (ETs) were performed resulting in >344,317 babies. From 2012 to 2013, the number of reported aspiration and frozen ET cycles increased by 3% and 16.4%, respectively. The proportion of women aged >40 years undergoing nondonor ART increased from 25.2% in 2012 to 26.3% in 2013. As a percentage of nondonor aspiration cycles, intracytoplasmic sperm injection (ICSI) was similar to results for 2012. The in vitro fertilization (IVF)/ICSI combined delivery rates per fresh aspiration and frozen ET cycles were 24.2% and 22.8%, respectively. In fresh nondonor cycles, single ET increased from 33.7% in 2012 to 36.5% in 2013, whereas the average number of transferred embryos was 1.81-again with wide country variation. The rate of twin deliveries after fresh nondonor transfers was 17.9%; the triplet rate was 0.7%. In frozen ET cycles performed in 2013, single ET was used in 57.6%, with an average of 1.49 embryos transferred and twin and triplet rates of 10.8% and 0.4%, respectively. The cumulative delivery rate per aspiration was 30.4%, similar to that in 2012. Perinatal mortality rate per 1,000 births was 22.2% after fresh IVF/ICSI and 16.8% after frozen ET. The data presented depended on the quality and completeness of the data submitted by individual countries. This report covers approximately two-thirds of world ART activity. Continued efforts to improve the quality and consistency of reporting ART data by registries are still needed.

Conclusion(s): Reported ART cycles, effectiveness, and safety increased between 2012 and 2013 with adoption of a better method for estimating unreported cycles.
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http://dx.doi.org/10.1016/j.fertnstert.2021.03.039DOI Listing
April 2021

Population data and genetic characteristics of 12 X-STR loci using the Investigator® Argus X-12 Quality Sensor kit for the Kedayan population of Borneo in Malaysia.

Int J Legal Med 2021 Jul 30;135(4):1433-1435. Epub 2021 Mar 30.

Forensic Science Programme, School of Health Sciences, Universiti Sains Malaysia, Health Campus, 16150, Kubang Kerian, Kelantan, Malaysia.

DNA profiling of X-chromosomal short tandem repeats (X-STR) has exceptional value in criminal investigations, especially for complex kinship and incest cases. In this study, Investigator® Argus X-12 Quality Sensor (QS) kits were successfully used to characterize 12 X-STR loci in 199 unrelated healthy Kedayan individuals living in Sabah and Sarawak, Malaysia. The LG1 haplogroup (DXS8378 - DXS10135 - DXS10148) has the largest HD (0.9799) as compared with all other closely linked haplotype groups examined (LG2; DXS7132-DXS10074-DXS10079, LG3; DXS10103-DXS10101-HPRTB and LG4; DXS10134-DXS7423-DXS10146). Data from statistical analysis showed that high combined of PD, PD, MEC_, MEC_, MEC_, and MEC_ values (0.999999994405922, 0.99999999999999, 0.999990463834938, 0.999999975914808, 0.999999975985006, and 0.999996491927194, respectively) in the Kedayan. In a two-dimensional scaling (MDS) plot and dendrogram constructed using allele frequencies at the 12 X-STR loci, Kedayan appear to be most closely related to their other Austronesian populations including the Malays and Filipinos as compared with other reference population groups. Findings from the present study thus demonstrate high genetic variability across the 12 tested X-STR loci and can be used for population studies and forensic applications.
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http://dx.doi.org/10.1007/s00414-021-02577-0DOI Listing
July 2021