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result(s) for
"Burchell, Martin"
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De-identified Bayesian personal identity matching for privacy-preserving record linkage despite errors: development and validation
2023
Background
Epidemiological research may require linkage of information from multiple organizations. This can bring two problems: (1) the information governance desirability of linkage without sharing direct identifiers, and (2) a requirement to link databases without a common person-unique identifier.
Methods
We develop a Bayesian matching technique to solve both. We provide an open-source software implementation capable of de-identified probabilistic matching despite discrepancies, via fuzzy representations and complete mismatches, plus de-identified deterministic matching if required. We validate the technique by testing linkage between multiple medical records systems in a UK National Health Service Trust, examining the effects of decision thresholds on linkage accuracy. We report demographic factors associated with correct linkage.
Results
The system supports dates of birth (DOBs), forenames, surnames, three-state gender, and UK postcodes. Fuzzy representations are supported for all except gender, and there is support for additional transformations, such as accent misrepresentation, variation for multi-part surnames, and name re-ordering. Calculated log odds predicted a proband’s presence in the sample database with an area under the receiver operating curve of 0.997–0.999 for non-self database comparisons. Log odds were converted to a decision via a consideration threshold
θ
and a leader advantage threshold
δ
. Defaults were chosen to penalize misidentification 20-fold versus linkage failure. By default, complete DOB mismatches were disallowed for computational efficiency. At these settings, for non-self database comparisons, the mean probability of a proband being correctly declared to be in the sample was 0.965 (range 0.931–0.994), and the misidentification rate was 0.00249 (range 0.00123–0.00429). Correct linkage was positively associated with male gender, Black or mixed ethnicity, and the presence of diagnostic codes for severe mental illnesses or other mental disorders, and negatively associated with birth year, unknown ethnicity, residential area deprivation, and presence of a pseudopostcode (e.g. indicating homelessness). Accuracy rates would be improved further if person-unique identifiers were also used, as supported by the software. Our two largest databases were linked in 44 min via an interpreted programming language.
Conclusions
Fully de-identified matching with high accuracy is feasible without a person-unique identifier and appropriate software is freely available.
Journal Article
Closing the Gap: Increases in Life Expectancy among Treated HIV-Positive Individuals in the United States and Canada
by
Althoff, Keri N.
,
Justice, Amy
,
Gebo, Kelly A.
in
Acquired immune deficiency syndrome
,
Adult
,
Adults
2013
Combination antiretroviral therapy (ART) has significantly increased survival among HIV-positive adults in the United States (U.S.) and Canada, but gains in life expectancy for this region have not been well characterized. We aim to estimate temporal changes in life expectancy among HIV-positive adults on ART from 2000-2007 in the U.S. and Canada.
Participants were from the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD), aged ≥20 years and on ART. Mortality rates were calculated using participants' person-time from January 1, 2000 or ART initiation until death, loss to follow-up, or administrative censoring December 31, 2007. Life expectancy at age 20, defined as the average number of additional years that a person of a specific age will live, provided the current age-specific mortality rates remain constant, was estimated using abridged life tables.
The crude mortality rate was 19.8/1,000 person-years, among 22,937 individuals contributing 82,022 person-years and 1,622 deaths. Life expectancy increased from 36.1 [standard error (SE) 0.5] to 51.4 [SE 0.5] years from 2000-2002 to 2006-2007. Men and women had comparable life expectancies in all periods except the last (2006-2007). Life expectancy was lower for individuals with a history of injection drug use, non-whites, and in patients with baseline CD4 counts <350 cells/mm(3).
A 20-year-old HIV-positive adult on ART in the U.S. or Canada is expected to live into their early 70 s, a life expectancy approaching that of the general population. Differences by sex, race, HIV transmission risk group, and CD4 count remain.
Journal Article
Understanding COVID-19 Vaccine Confidence in People Living with HIV: A pan-Canadian Survey
by
Habanyama, Muluba
,
Margolese, Shari
,
Godin, Guy-Henri
in
Acceptability
,
Advisory committees
,
Altruism
2023
Understanding the roots of Covid-19 vaccine hesitancy in at-risk groups, such as persons living with HIV (PLWH), is of utmost importance. We developed a modified Vaccine Hesitancy Scale (VHS) questionnaire using items from the National Advisory Committee on Immunization Acceptability Matrix. To examine factors associated with receiving COVID-19 vaccine and the link between vaccine attitudes and beliefs with vaccine behavior, PLWH were recruited via social media and community-based organizations (February-May 2022). Descriptive statistics were used to summarize results. Total VHS score was generated by adding Likert scale scores and linear regression models used to compare results between participants who received or did not receive COVID-19 vaccines. Logistic regression models were used to identify factors associated with vaccine uptake. A total of 246 PLWH indicated whether they received a COVID-19 vaccine. 89% received ≥ 1 dose. Mean total VHS(SD) for persons having received ≥ 1 COVID-19 vaccine was 17.8(6.2) vs. 35.4(9.4) for participants not having received any COVID-19 vaccine. Persons who received ≥ 1 dose were significantly older than those who had not received any (48.4 ± 13.8 vs. 34.0 ± 7.7 years, p < 0.0001). The majority of participants considered COVID-19 vaccination important for their health(81.3%) and the health of others(84.4%). Multivariate logistic regression revealed the odds of taking ≥ 1dose were increased 2.4-fold [95% CI 1.6, 3.5] with each increase in age of 10 years (p < 0.0001). Sex and ethnicity were not different between groups. In conclusion, PLWH accept COVID-19 vaccines for both altruistic and individual reasons. With evolving recommendations and increasing numbers of booster vaccines, we must re-examine the needs of PLWH regularly.
Journal Article
Extracellular vesicles with altered tetraspanin CD9 and CD151 levels confer increased prostate cell motility and invasion
2018
To facilitate intercellular communication, cells release nano-sized, extracellular vesicles (EVs) to transfer biological cargo to both local and distant sites. EVs are enriched in tetraspanins, two of which (CD9 and CD151) have altered expression patterns in many solid tumours, including prostate cancer, as they advance toward metastasis. We aimed to determine whether EVs from prostate cells with altered CD9 and CD151 expression could influence cellular behaviour and increase the metastatic capabilities of non-tumourigenic prostate cells. EVs were isolated by ultrafiltration and characterised for their tetraspanin expression and size distribution. iTRAQ was used to identify differences between RWPE1 and tetraspanin-modified RWPE1 EV proteomes, showing an enrichment in protein degradation pathways. Addition of EVs from RWPE1 cells with reduced CD9 or increased CD151 abundance resulted in increased invasion of RWPE1 cells, and increased migration in the case of high CD151 abundance. We have been able to show that alteration of CD9 and CD151 on prostate cells alters the proteome of their resultant EVs, and that these EVs can enhance the migratory and invasive capabilities of a non-tumourigenic prostate cellular population. This work suggests that cellular tetraspanin levels can alter EVs, potentially acting as a driver of metastasis in prostate cancer.
Journal Article
Incidence of AIDS-Defining Opportunistic Infections in a Multicohort Analysis of HIV-infected Persons in the United States and Canada, 2000–2010
by
Jing, Yuezhou
,
Althoff, Keri N.
,
Burkholder, Greer
in
Adult
,
AIDS-Related Opportunistic Infections - epidemiology
,
Canada - epidemiology
2016
Background. There are few recent data on the rates of AIDS-defining opportunistic infections (OIs) among human immuno-deficiency virus (HlV)-infected patients in care in the United States and Canada. Methods. We studied HIV-infected participants in 16 cohorts in the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) during 2000-2010. After excluding 16 737 (21%) with any AIDS-defining clinical events documented before NA-ACCORD enrollment, we analyzed incident OIs among the remaining 63 541 persons, most of whom received antiretroviral therapy during the observation. We calculated incidence rates per 100 person-years of observation (hereafter, \"person-years\") with 95% confidence intervals (CIs) for the first occurrence of any OI and select individual OIs during 2000–2003, 2004–2007, and 2008–2010. Results. A total of 63 541 persons contributed 261 573 person-years, of whom 5836 (9%) developed at least 1 OI. The incidence rate of any first OI decreased over the 3 observation periods, with 3.0 cases, 2.4 cases, and 1.5 cases per 100 person-years of observation during 2000–2003, 2004–2007, and 2008–2010, respectively (Ptrend<.001); the rates of most individual OIs decreased as well. During 2008–2010, the leading OIs included Pneumocystis jiroveci pneumonia, esophageal candidiasis, and disseminated Mycobacterium avium complex or Mycobacterium kansasii infection. Conclusions. For HIV-infected persons in care during 2000–2010, rates of first OI were relatively low and generally declined over this time.
Journal Article
Hiring, training, and supporting Peer Research Associates: Operationalizing community-based research principles within epidemiological studies by, with, and for women living with HIV
by
Carter, Allison
,
de Pokomandy, Alexandra
,
Kaida, Angela
in
Acquired immune deficiency syndrome
,
AIDS
,
Best practice
2019
Background
A community-based research (CBR) approach is critical to redressing the exclusion of women—particularly, traditionally marginalized women including those who use substances—from HIV research participation and benefit. However, few studies have articulated their process of involving and engaging peers, particularly within large-scale cohort studies of women living with HIV where gender, cultural and linguistic diversity, HIV stigma, substance use experience, and power inequities must be navigated.
Methods
Through our work on the Canadian HIV Women’s Sexual and Reproductive Health Cohort Study (CHIWOS), Canada’s largest community-collaborative longitudinal cohort of women living with HIV (
n
= 1422), we developed a comprehensive, regionally tailored approach for hiring, training, and supporting women living with HIV as Peer Research Associates (PRAs). To reflect the diversity of women with HIV in Canada, we initially hired 37 PRAs from British Columbia, Ontario, and Quebec, prioritizing women historically under-represented in research, including women who use or have used illicit drugs, and women living with HIV of other social identities including Indigenous, racialized, LGBTQ2S, and sex work communities, noting important points of intersection between these groups.
Results
Building on PRAs’ lived experience, research capacity was supported through a comprehensive, multi-phase, and evidence-based experiential training curriculum, with mentorship and support opportunities provided at various stages of the study. Challenges included the following: being responsive to PRAs’ diversity; ensuring PRAs’ health, well-being, safety, and confidentiality; supporting PRAs to navigate shifting roles in their community; and ensuring sufficient time and resources for the translation of materials between English and French. Opportunities included the following: mutual capacity building of PRAs and researchers; community-informed approaches to study the processes and challenges; enhanced recruitment of harder-to-reach populations; and stronger community partnerships facilitating advocacy and action on findings.
Conclusions
Community-collaborative studies are key to increasing the relevance and impact potential of research. For women living with HIV to participate in and benefit from HIV research, studies must foster inclusive, flexible, safe, and reciprocal approaches to PRA engagement, employment, and training tailored to regional contexts and women’s lives. Recommendations for best practice are offered.
Journal Article
High prevalence of abnormal menstruation among women living with HIV in Canada
by
de Pokomandy, Alexandra
,
Caddy, Sheila
,
Kaida, Angela
in
Acquired immune deficiency syndrome
,
Adolescent
,
Adult
2019
To measure the prevalence and correlates of abnormal menstruation among women living with HIV (WLWH) in Canada.
We used cross-sectional questionnaire data from the community-based Canadian HIV Women's Sexual and Reproductive Health Cohort Study (CHIWOS), which enrolled WLWH aged ≥16 from British Columbia (BC), Ontario, and Quebec. For this analysis, we excluded women >45 years, who had primary amenorrhea, were pregnant, on hormonal contraception, or who reported history of endometrial cancer, last menstrual period >12 months ago, or premature ovarian failure. The primary outcome was abnormal menstruation (Yes vs No) based on responses to five questions about menstrual regularity, frequency, volume, duration, and intermenstrual bleeding in the six months prior to interview. An exploratory multivariable logistic regression analysis examined independent correlates of abnormal menstruation.
Of 1422 women enrolled, 521 (37%) met eligibility criteria. Overall, 55.9% (95% CI:52%-60%) reported abnormal menstruation. In adjusted analyses, abnormal menstruation was associated with having a biologic sister/mother who entered menopause before age 40 (AOR 5.01, 95%CI 1.39-18.03), Hepatitis B co-infection (AOR 6.97, 95%CI 1.52-31.88), current smoking (AOR 1.69, 95%CI 1.55-3.41); and currently taking antiretroviral therapy (ART) (AOR 2.36, 95%CI 1.25-4.45) compared to being ART-naïve. Women in BC had higher adjusted odds of abnormal menstruation (AOR 2.95, 95%CI 1.61-5.39), relative to women in Ontario and Quebec.
Over half of WLWH in this analysis had abnormal menstruation. Correlates of abnormal menstruation include genetic, socio-behavioural factors (province of residence, smoking), Hepatitis B co-infection, and current ART use.
Journal Article
Trends and Disparities in Antiretroviral Therapy Initiation and Virologic Suppression Among Newly Treatment-Eligible HIV-Infected Individuals in North America, 2001–2009
2013
Background. Since the mid-1990s, effective antiretroviral therapy (ART) regimens have improved in potency, tolerability, ease of use, and class diversity. We sought to examine trends in treatment initiation and resulting human immunodeficiency virus (HIV) virologic suppression in North America between 2001 and 2009, and demographic and geographic disparities in these outcomes. Methods. We analyzed data on HIV-infected individuals newly clinically eligible for ART (ie, first reported CD4 + count <350 cells/μL or AIDS-defining illness, based on treatment guidelines during the study period) from 17 North American AIDS Cohort Collaboration on Research and Design cohorts. Outcomes included timely ART initiation (within 6 months of eligibility) and virologic suppression (≤500 copies/mL, within 1 year). We examined time trends and considered differences by geographic location, age, sex, transmission risk, race/ethnicity, CD4 + count, and viral load, and documented psychosocial barriers to ART initiation, including non—injection drug abuse, alcohol abuse, and mental illness. Results. Among 10 692 HIV-infected individuals, the cumulative incidence of 6-month ART initiation increased from 51% in 2001 to 72% in 2009 (P trend < .001). The cumulative incidence of 1-year virologic suppression increased from 55% to 81%, and among ART initiators, from 84% to 93% (both P trend < .001). A greater number of psychosocial barriers were associated with decreased ART initiation, but not virologic suppression once ART was initiated. We found significant heterogeneity by state or province of residence (P < .001). Conclusions. In the last decade, timely ART initiation and virologic suppression have greatly improved in North America concurrent with the development of better-tolerated and more potent regimens, but significant barriers to treatment uptake remain, both at the individual level and systemwide.
Journal Article
Renal artery sympathetic denervation: observations from the UK experience
by
Hameed, Awais
,
Lobo, Melvin D.
,
Mather, Adam N.
in
Aged
,
Antihypertensive Agents - therapeutic use
,
Blood Pressure - drug effects
2016
Background
Renal denervation (RDN) may lower blood pressure (BP); however, it is unclear whether medication changes may be confounding results. Furthermore, limited data exist on pattern of ambulatory blood pressure (ABP) response—particularly in those prescribed aldosterone antagonists at the time of RDN.
Methods
We examined all patients treated with RDN for treatment-resistant hypertension in 18 UK centres.
Results
Results from 253 patients treated with five technologies are shown. Pre-procedural mean office BP (OBP) was 185/102 mmHg (SD 26/19;
n
= 253) and mean daytime ABP was 170/98 mmHg (SD 22/16;
n
= 186). Median number of antihypertensive drugs was 5.0: 96 % ACEi/ARB; 86 % thiazide/loop diuretic and 55 % aldosterone antagonist. OBP, available in 90 % at 11 months follow-up, was 163/93 mmHg (reduction of 22/9 mmHg). ABP, available in 70 % at 8.5 months follow-up, was 158/91 mmHg (fall of 12/7 mmHg). Mean drug changes post RDN were: 0.36 drugs added, 0.91 withdrawn. Dose changes appeared neutral. Quartile analysis by starting ABP showed mean reductions in systolic ABP after RDN of: 0.4; 6.5; 14.5 and 22.1 mmHg, respectively (
p
< 0.001 for trend). Use of aldosterone antagonist did not predict response (
p
> 0.2).
Conclusion
In 253 patients treated with RDN, office BP fell by 22/9 mmHg. Ambulatory BP fell by 12/7 mmHg, though little response was seen in the lowermost quartile of starting blood pressure. Fall in BP was not explained by medication changes and aldosterone antagonist use did not affect response.
Journal Article
High Throughput Mutagenesis for Identification of Residues Regulating Human Prostacyclin (hIP) Receptor Expression and Function
by
Rosethorne, Elizabeth M.
,
Marelli, Anthony
,
Burchell, Lynn
in
Abnormalities
,
Amino Acids - genetics
,
Arteriosclerosis
2014
The human prostacyclin receptor (hIP receptor) is a seven-transmembrane G protein-coupled receptor (GPCR) that plays a critical role in vascular smooth muscle relaxation and platelet aggregation. hIP receptor dysfunction has been implicated in numerous cardiovascular abnormalities, including myocardial infarction, hypertension, thrombosis and atherosclerosis. Genomic sequencing has discovered several genetic variations in the PTGIR gene coding for hIP receptor, however, its structure-function relationship has not been sufficiently explored. Here we set out to investigate the applicability of high throughput random mutagenesis to study the structure-function relationship of hIP receptor. While chemical mutagenesis was not suitable to generate a mutagenesis library with sufficient coverage, our data demonstrate error-prone PCR (epPCR) mediated mutagenesis as a valuable method for the unbiased screening of residues regulating hIP receptor function and expression. Here we describe the generation and functional characterization of an epPCR derived mutagenesis library compromising >4000 mutants of the hIP receptor. We introduce next generation sequencing as a useful tool to validate the quality of mutagenesis libraries by providing information about the coverage, mutation rate and mutational bias. We identified 18 mutants of the hIP receptor that were expressed at the cell surface, but demonstrated impaired receptor function. A total of 38 non-synonymous mutations were identified within the coding region of the hIP receptor, mapping to 36 distinct residues, including several mutations previously reported to affect the signaling of the hIP receptor. Thus, our data demonstrates epPCR mediated random mutagenesis as a valuable and practical method to study the structure-function relationship of GPCRs.
Journal Article