Thomas L Patterson

• University of California, San Diego

Safe injection self-efficacy (SISE) is negatively associated with injection risk behaviors among people who inject drugs (PWID) but has not been examined in differing risk environments. We compared responses to a validated SISE scale between PWID in San Diego, California and Tijuana, Mexico, and examine correlates of SISE among PWID in Tijuana. PWI...

Introduction Despite the increasing availability of new psychoactive substances (hereafter referred to as “salts”) in Eastern Europe and Central Asia, there is a dearth of epidemiological data on the relationship between injecting “salts” and HIV risk behaviours. This is particularly relevant in settings where injection drug use accounts for a subs...

Background Safe injection self-efficacy (SISE) is negatively associated with injection risk behaviors among people who inject drugs (PWID) but has not been examined in differing risk environments. We compared responses to a validated SISE scale between PWID in San Diego, California and Tijuana, Mexico, and examine correlates of SISE among PWID in T...

Background Significant disparities continue to exist in the HIV care continuum, whereby Hispanic and Black people living with HIV (PLWH) are less likely to achieve viral suppression compared to their White counterparts. Studies have shown that intervention approaches that involve peer navigation may play an important role in supporting patients to...

Introduction Dementia is a progressive and debilitating disease, and people living with HIV (PLWH) often develop dementia much earlier than those not living with HIV. We estimated the incidence and prevalence of dementia and identified its key risk factors in a cohort of PLWH in British Columbia, Canada. Methods This retrospective cohort study use...

Background Women who inject drugs in Ukraine are disproportionately burdened by HIV. To help address the needs of this population, a greater understanding of how interventions may uniquely benefit women who inject drugs is needed. Methods Data come from a randomized controlled trial of a social network intervention targeting people who inject drug...

The Family Resource Scale (FRS) is a three-factor financial vulnerability (FV) measure. FV may impact HIV transmission risks. Cross-sectional data from 279 people who inject drugs (PWID) in Kyrgyzstan surveyed April–October 2021 was used to validate the FRS and estimate associations between FV on past 6-month injection and sexual HIV risk outcomes....

Background We evaluated the impact of a brief, peer-led intervention on COVID-19 vaccination among people who inject drugs (PWID) presenting at syringe services program (SSP) locations in San Diego County, California. Methods Between March and July 2022, PWID aged ≥18 years old without recent voluntary COVID-19 testing who were not up to date on C...

Background: In North America, overdose rates have steeply risen over the past five years, largely due to the ubiquity of illicitly manufactured fentanyls in the drug supply. Drug checking services (DCS) represent a promising harm reduction strategy and characterizing experiences of use and interest among people who inject drugs (PWID) is a priorit...

Objectives: Non-adherence to antipsychotics is the greatest obstacle to treating schizophrenia. We assessed the economic and clinical impacts of adherence to antipsychotics among people living with HIV/AIDS (PLWH) and schizophrenia in British Columbia, Canada. Design and setting: A population-based cohort study in British Columbia, Canada. Meth...

Background: People who inject drugs (PWID) have low rates of COVID-19 testing yet are vulnerable to severe disease. In partnership with a mobile syringe service program (SSP) in San Diego County, CA, we developed the evidence-, community-, and Social Cognitive Theory-informed "LinkUP" intervention (tailored education, motivational interviewing, pr...

Background and hypothesis: Automated language analysis is becoming an increasingly popular tool in clinical research involving individuals with mental health disorders. Previous work has largely focused on using high-dimensional language features to develop diagnostic and prognostic models, but less work has been done to use linguistic output to a...

HIV transmission in Ukraine is driven in part by unsafe injection drug use and sexual risk behaviors among people who inject drugs. We performed a random-intercept latent transition analysis on responses to 9 binary injection drug use and sexual behavior items from 1195 people who inject drugs with negative HIV status enrolled in a clustered random...

Background: Due to the persistence of COVID-19, it remains important to measure and examine potential barriers to COVID-19 prevention and treatment to avert additional loss of life, particularly among stigmatized populations, such as people who inject drugs (PWID), who are at high risk for contracting and spreading SARS-CoV-2. We assessed the psyc...

Introduction: We studied characteristics of COVID-19 vaccination uptake among people who inject drugs (PWID). Methods: Participants aged ≥18 years who injected drugs ≤1 month ago were recruited into a community-based cohort from October 2020 to September 2021 in San Diego, California Poisson regression identified correlates of having had ≥1 COVI...

Background People who inject drugs (PWID) have low rates of COVID-19 testing and vaccination and are vulnerable to severe disease. We partnered with a local, community-based syringe service program (SSP) in San Diego County, CA, to develop the single-session theory- and evidence-informed “LinkUP” intervention to increase COVID-19 testing and vaccin...

There is considerable variability in neurocognitive functioning within schizophrenia-spectrum disorders, and neurocognitive performance ranges from severe global impairment to normative performance. Few investigations of neurocognitive clusters have considered the degree to which deterioration relative to premorbid neurocognitive abilities is relat...

Background Along the Mexico-US border, illicitly manufactured fentanyls (fentanyl) have been detected in other illicit drugs, including street opioid formulations known as ‘china white.’ We studied correlates of recent overdose among people who inject drugs (PWID), focusing on the risk of knowlingly or unknowingly using fentanyl in china white. Me...

Background and Hypothesis:Automated language analysis is becoming an increasingly popular tool in clinical research involving individuals with mental health disorders. Previous work has largely focused on using high-dimensional language features to develop diagnostic and prognostic models, but less work has been done to use linguistic output to ass...

In a study of female sex workers (FSW) servicing truck driver clients in Mexican border cities, we evaluated differences in HIV/STI risk behaviors by workplace. Cross-sectional study of FSW servicing truck drivers in Mexico: 100 from Nuevo Laredo (U.S. border); 100 from Ciudad Hidalgo (Guatemalan border). Main outcome was unstable workplace, define...

Background In Kyrgyzstan and other Eastern European and Central Asian countries, injection drug use and HIV-related intersectional stigma undermines HIV prevention efforts, fueling a rapidly expanding HIV epidemic. The Kyrgyzstan InterSectional Stigma (KISS) Injection Drug Use Cohort is the first study designed to assess the impact of drug use, met...

People who inject drugs (PWID) are vulnerable to SARS-CoV-2 infection. We examined correlates of COVID-19 testing among PWID in the U.S.-Mexico border region and described encounters with services or venues representing potential opportunities (i.e., "touchpoints") where COVID-19 testing could have been offered. Between October, 2020 and September,...

Purpose This study aimed at determining to what extent sexual minority status modifies the association between HIV risk behavior and prevalent mood or anxiety disorder diagnosis in British Columbia (BC), Canada, using a population-based survey. Methods This analysis was based on the cross-sectional 2013–2014 Canadian Community Health Survey. The s...

Background People who inject drugs may be at elevated SARS-CoV-2 risk due to their living conditions and/or exposures when seeking or using drugs. No study to date has reported upon risk factors for SARS-CoV-2 infection among people who inject drugs. Methods and findings Between October, 2020 and June, 2021, participants aged ≥18 years from San Di...

Background: People who inject drugs (PWID) are vulnerable to acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We examined correlates of coronavirus disease 2019 (COVID-19) vaccine hesitancy among PWID in the US-Mexico border region, of whom only 7.6% had received ≥ 1 COVID-19 vaccine dose by September 2021. Methods: Betwee...

Tijuana, Mexico, has a concentrated HIV epidemic among overlapping key populations (KPs) including people who inject drugs (PWID), female sex workers (FSW), their male clients, and men who have sex with men (MSM). We developed a dynamic HIV transmission model among these KPs to determine the extent to which their unmet prevention and treatment need...

Background: People who inject drugs (PWID) are vulnerable to acquiring SARS-CoV-2 but their barriers to COVID-19 vaccination are under-studied. We examined correlates of COVID-19 vaccine hesitancy among PWID in the U.S.-Mexico border region, of whom only 7.6% had received ≥one COVID-19 vaccine dose by September, 2021. Methods: Between October, 2020...

Introduction Performance-based assessments of social skills have detected impairments in people with severe mental illness and are correlated with functional outcomes in people with schizophrenia and bipolar disorder. The most common of these assessments, the Social Skills Performance Assessment (SSPA), has two communication scenarios and items mea...

Impulsivity is a trait characteristic that is associated with sexual risk behavior. We examined correlates of impulsivity among 602 female sex workers (FSWs) enrolled in a sexual risk reduction intervention in Mexico (2016–2020). Impulsivity was positively associated with condomless sex with clients. Higher levels of impulsivity were associated wit...

Background People who inject drugs may be at elevated SARS-CoV-2 risk due to their living conditions and/or exposures when seeking or using drugs. No study to date has reported upon risk factors for SARS-CoV-2 infection among people who inject drugs or sex workers. Methods and Findings Between October, 2020 and June, 2021, participants aged ≥18 ye...

Background: Mediated and moderated processes that lead to intervention efficacy may underlie results of trials ruled as non- efficacious. The overall purpose of this study was to examine such processes to explain the findings of one of the largest, rigorously conducted behavioral intervention randomized controlled trials, EXPLORE. Methods: 4,295...

Background Efforts to increase HIV testing, diagnosis and care are critical to curbing HIV epidemics among cisgender men who have sex with men (MSM) and transgender women (TW) in low‐ and middle‐income countries (LMIC). We compared the effectiveness of respondent‐driven sampling (RDS) and venue‐based sampling (VBS) for identifying previously undiag...

Background A remarkable reduction in AIDS-related mortality has been achieved through the widespread use of triple combination antiretroviral therapy, considerably increasing the life expectancy of people living with HIV (PLWH). However, these survival gains are now at risk in North America due to an unprecedented public health emergency: the deadl...

Shame may increase HIV risk among stigmatized populations. The Personal Feelings Questionnaire–2 (PFQ-2) measures shame, but has not been validated in Spanish-speaking or nonclinical stigmatized populations disproportionately affected by HIV in resource-limited settings. We examined the psychometric properties of the Spanish-translated PFQ-2 shame...

Mobile phone technology may help sustain reductions in HIV/STI transmission risk behaviors among female sex workers (FSWs). We examined the efficacy of a text messaging intervention designed to maintain behavioral improvements in safer sex practices among 602 FSWs in Tijuana and Ciudad Juarez, Mexico. We hypothesized that FSWs who received brief ri...

Decriminalization of sex work is increasingly promoted as a structural measure to improve the health of vulnerable groups. In México, sex work is not illegal, but knowledge of policies’ street-level impact is limited. This study describes typologies of police violence against female sex workers who inject drugs (FSWID), identifying risk and protect...

OBJECTIVE To characterize recent HIV infections among newly diagnosed men who have sex with men and transgender women in Tijuana. METHODS Limiting Antigen (LAg)-Avidity testing was performed to detect recent HIV infection within a cohort of newly-diagnosed men who have sex with men and transgender women in Tijuana. Logistic regression was used to...

This paper evaluates correlates of trichomoniasis among female sex workers who inject drugs (FSWIDs) in two Mexico-US border cities. HIV-negative FSWIDs aged 18 years or older were enrolled in a study between 2008 and 2010 in Tijuana and Ciudad Juarez (Cd.), Mexico. All participants underwent a baseline interviewer-administered survey and did a rap...

The Personal Feelings Questionnaire-2 (PFQ-2) was developed as a measure of shame among college students but has not been validated within stigmatized populations for whom shame may increase risk for HIV and other sexually transmitted infections. We examined the psychometric properties of the Spanish-translated 10-item PFQ-2 shame subscale in a sam...

Background This study examined whether biological mechanisms linking dementia caregiving with an increased risk of coronary heart disease can be modified by psychosocial interventions and which caregivers might benefit the most from an intervention. Methods Spousal dementia caregivers were randomized to 12-week treatment with either a behavioral a...

Methamphetamine use, sexual relationship power (SRP), and partner violence (PV) are associated with increased risk of sexually transmitted infections (STIs) among women. The objective of our study was to examine the association of recent PV and SRP on STIs by partner type among HIV-negative, heterosexual women who use methamphetamine in San Diego,...

To assess the potential for decreased condom use as pre-exposure prophylaxis (PrEP) is scaled-up in Latin America, we examined HIV prevention method preferences (neither PrEP nor condoms, condoms only, PrEP only, or PrEP with condoms) within 1302 sexual partnerships reported by 397 HIV-negative men who have sex with men (MSM) and transgender women...

Background: Stigma toward sexual and gender minorities is an important structural driver of HIV epidemics among men who have sex with men (MSM) and transgender women (TW) globally. Sex-seeking websites and apps are popular among MSM and TW. Interventions delivered via Web-based sex-seeking platforms may be particularly effective for engaging MSM an...

Using data from the Comparison of Outcomes and Service Utilization Trends (COAST) study we examined factors associated with mood disorder diagnosis (MDD) among people living with HIV (PLHIV) and HIV-negative individuals in British Columbia, Canada. MDD cases were identified between 1998 and 2012 using International Classification of Disease 9 and 1...

Background Given the slow uptake of PrEP among cisgender men who have sex with men (MSM) in high-income countries, efforts to roll-out PrEP in low- and middle-income countries (LMIC) should address barriers to PrEP use to facilitate its more rapid uptake. To inform PrEP programs in LMIC, we examined patterns of perceived barriers to PrEP use among...

Objective Our primary objective was to examine the syndemic effect of HIV/HCV co-infection and mental health disorders (MHD) on the acute care hospitalization rate among people living with HIV (PLW-HIV) in British Columbia, Canada. Secondarily, we aimed to characterize the longitudinal trends in the aforementioned rate, while controlling for the ef...

Understanding the relationship between cognitive and behavioral processes and long-term behavior change is critical to developing behavior change maintenance interventions. We examined the relationship between cognitive and behavioral safer sex maintenance strategies and condomless vaginal/anal sex with clients among female sex workers (FSWs) in Me...

Stigma toward sexual and gender minorities is an important structural driver of HIV epidemics among men who have sex with men (MSM) and transgender women (TW) globally. Sex-seeking websites and applications are popular among MSM and TW. Interventions that harness these online platforms may be particularly effective for engaging MSM and TW in HIV pr...

Stressors that arise in parenting are likely to have an adverse impact on the psychological well-being of female sex workers (FSWs), particularly in low- to middle-income countries (LMIC). This study examined the association between maternal role strain and depressive symptoms among 426 FSW mothers with dependent-age children (aged < 18 years) in T...

Globally, punitive drug law enforcement drives human rights violations. Drug control tactics, such as syringe confiscation and drug-related arrests, also cascade into health harms among people who use drugs. The role of police officer characteristics in shaping such enforcement and measures to reform police practices remains underexamined. We evalu...

Female sex workers (FSWs) experience syndemic factors (e.g., polydrug use, hazardous alcohol consumption, client-perpetrated violence, depression, and sexually transmitted infections) that often heighten vulnerability to HIV and limit healthcare utilization. We hypothesized that syndemic factors will limit FSWs' uptake of pre-exposure prophylaxis (...

This study examined service provider perceptions of feasibility and acceptability of implementing evidence-based practices for preventing HIV/AIDS and STIs in female sex workers (FSWs) in Mexico. Semi-structured interviews were conducted with 124 directors, supervisors, and counselors from 12 reproductive health clinics located throughout Mexico pa...

Schizophrenia is a severe mental illness with important implications for morbidity and mortality. This population-based cohort study examined the impact of schizophrenia diagnoses on all-cause mortality among a sample of people living with HIV (PLHIV) and a 10% random sample of individuals living without HIV (HIV-) in British Columbia (BC), through...

Objective: Older adults are among the most frequent users of emergency departments (EDs). Non-specific symptoms such as fatigue and widespread pain are among the most common symptoms in patients admitted at the ED. Interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) are inflammation biomarkers associated with chronic stress (i.e., dementi...

Background Cannabis use, anxiety, and depression are common among gay, bisexual, and other men who have sex with men (gbMSM) and some report using cannabis to manage mental health symptoms. Methods Sexually-active gbMSM aged ≥16 years were recruited into a longitudinal cohort through respondent-driven sampling and completed study visits every six...

Objective: To identify correlates of HIV/STI prevalence among 13 cities with varying sizes of female sex worker (FSW) populations and municipal characteristics in Mexico. Materials and methods: FSWs underwent interviews and testing for HIV, syphilis, gonorrhea and chlamydia. Logistic regression explored variations in HIV/STI prevalence. Results...

Text messages may sustain post-counseling gains in behavioral improvements and reduce HIV/STI incidence. However, their effectiveness may depend on the messages' time perspective and characteristics of the individual. We evaluated the impact of time perspective on a text messaging intervention designed to maintain improvements in safer sex practice...

Background Caregivers of a family member with a chronic disability or illness such as dementia are at increased risk for chronic disease. There are many factors that contribute to dementia caregiver vulnerability and these factors can be challenging to assess in clinical settings. Self-rated health (SRH) is an independent measure of survival and ph...

We examined correlates of late and delayed initiation of antiretroviral therapy (ART) in British Columbia, Canada. From December 2013 to December 2015 we recruited treatment-naïve people living with HIV who initiated ART within the previous year. 'Late initiation' was defined as CD4 cell count ≤500 cells/µL at ART initiation and 'delayed initiation...

With the advent of antiretroviral medications, AIDS has transformed from a fatal to a chronic illness. Meanwhile, HIV prevention interventions throughout the world have varied tremendously in both the theories that guide them and the contexts in which they are delivered. Consequently, this chapter (1) selectively reviews approaches to preventing HI...

Objective The overall aim of this paper is to examine effectiveness of an evidence-based intervention in community settings, and the factors associated with effectiveness. Limited research in the area of HIV prevention has focused on evaluating intervention program effectiveness in real-world settings. Methods We implemented an efficacious theory-...

Methamphetamine use poses increased risk for HIV and other sexually transmitted infections. There is robust evidence that methamphetamine use increases sexual risk behavior, like condomless sex, primarily among men who have sex with men but also among heterosexual women and men. Gender differences have been found among women and men who use meth, a...

To assess the potential uptake of HIV pre-exposure prophylaxis (PrEP) products among female sex workers (FSWs) vulnerable to HIV infection, we examined the influence of product attributes on willingness to use products among 271 HIV-negative FSWs in Tijuana and Ciudad Juarez, Mexico (2016–2017). Via five-point Likert scale ratings, participants ind...

Background: Bacterial vaginosis (BV) is the most common cause of vaginitis among women worldwide and is associated with increased susceptibility to sexually transmitted infections (STIs), including HIV. We aimed to determine the impact of the HIV risk environment on BV among female sex workers who inject drugs (FSW-PWIDs) in Tijuana and Ciudad Jua...

Abstract Background To assess the potential acceptability and inform the development of behaviorally-congruent vaginal douche- or gel-based HIV pre-exposure prophylaxis (PrEP) products, we examined vaginal washing and lubrication practices among female sex workers (FSWs) in Tijuana and Ciudad Juarez, two northern Mexico cities bordering the United...

Undiagnosed HIV infection is common among men who have sex with men (MSM) and transgender women (TW) in Latin America. We examined uptake of a partner notification (PN) model among MSM and TW in Tijuana, Mexico. Forty-six HIV-positive MSM/TW enrolled as index patients, and reported 132 MSM/TW sexual partners for PN. Of notified partners (90/132), 3...

Background: Negative symptoms and cognitive impairments predict difficulties in aspects of everyday functioning in schizophrenia, with little research to date attempting to determine if there are threshold levels of impairment required to predict the severity of functional deficits. Methods: People diagnosed with chronic schizophrenia (n = 821)...

Using data from the Comparison of Outcomes and Service Utilization Trends (COAST) study we examined factors associated with mood disorder diagnosis (MDD) among people living with HIV (PLHIV) and HIV-negative individuals in British Columbia, Canada. MDD cases were identified between 1998 and 2012 using International Classification of Disease 9 and 1...

Objectives Schizophrenia and bipolar disorder overlap considerably. Schizophrenia is a primary psychotic disorder, whereas approximately half of people with bipolar disorder will experience psychosis. In this study, we examined the extent to which cognitive and functional impairments are related to the presence and history of psychosis across the t...

Introduction: Among gay, bisexual, and other men who have sex with men (GBM), collinearity between polysubstance use and mental health concerns has obscured their combined effects on HIV risk with multivariable results often highlighting only one or the other. Methods: We used mediation and moderation analyses to examine the effects of polysubst...

Compared to HIV research on men who have sex with men, less is known about the risks and vulnerabilities for HIV among Male to Female (MTF) transgender persons, particularly in different geographic regions like Mexico. In Tijuana, Mexico, a border city experiencing a dynamic HIV epidemic, no precedent data exists on the MTF transgender population....

Data for study on correlates of anal sex among MSM in Tijuana, Mexico. (SAV)

Background: North Tijuana, Mexico, along the US border, is home to many individuals at high-risk for transmitting and acquiring HIV. Recently, policy shifts by local government impacted how these individuals were handled by authorities. Here we examined how this affected regional HIV transmission dynamics. Methods: HIV pol sequences and associat...

Objective Caregiving stress is associated with increased risk of cardiovascular disease (CVD). Inability to adequately regulate blood pressure is a possible underlying mechanism explaining this risk. We examined the relationship between length of caregiving and cardiovagal baroreflex sensitivity (cBRS) to better understand the link between caregivi...

Background. North Tijuana, Mexico is home to many individuals at high risk for transmitting and acquiring human immu-nodeficiency virus (HIV). Recently, policy shifts by local government impacted how these individuals were handled by authorities. Here we examined how this affected regional HIV transmission dynamics. Methods. HIV pol sequences and a...

We use data collected from a sample of 400 male clients of female sex workers (FSW) to examine their HIV testing behavior. We present frequencies of HIV testing and used bivariate and multivariable analyses to assess its socio-demographic, behavioral, and psychosocial correlates. We found that the majority (55 %) of male clients of FSW in Tijuana,...

The UCSD Performance-Based Skills Assessment (UPSA) is a performance-based measure of functional capacity. The brief, two-domain (finance and communication ability) version of the assessment (UPSA-B) is now widely used in both clinical research and treatment trials. To date, research has not examined possible demographic-UPSA-B relationships within...

Objective: Elevated blood pressure is a significant public health concern, particularly given its association with cardiovascular disease risk, including stroke. Caring for a loved one with Alzheimer's disease has been associated with physical health morbidity, including higher blood pressure. Engagement in adaptive coping strategies may help prev...

Sexual violence among men who have sex with men (MSM) is prevalent in developing countries and is associated with increased HIV/STI risk. Despite high HIV prevalence (20 %) among MSM in Tijuana, Mexico, little attention has been paid to the occurrence of sexual violence in this high-risk group. The present study used a syndemic conditions framework...

Men’s misogynistic attitudes (i.e., dislike or contempt for women) have been shown to be associated with men’s perpetration of physical/sexual violence against women and poor health outcomes for women. However, these attitudes have rarely been examined for their influence on men’s own health. This article examines the sociodemographic, substance us...

Background: Studies have found that gay, bisexual, and other men who have sex with men (GBM) have higher rates of mental health conditions and substance use than heterosexual men, but are limited by issues of representativeness. Objectives: To determine the prevalence and correlates of mental health disorders among GBM in Metro Vancouver, Canada...

Background Intervention fidelity and participant-level variables, such as negative attitudes towards condoms, are important variables to consider in the successful implementation of evidence-based HIV prevention interventions. Mujer Segura is an intervention that has been shown to be efficacious at reducing condomless sex for female sex workers (FS...

People living with HIV/AIDS (PHA) often concurrently cope with mental health disorders that may greatly influence HIV and other health-related outcomes. The objective of this study was to examine the prevalence and correlates of self-reported mental health disorder diagnosis among a cohort of harder-to-reach HIV-positive individuals in British Colu...

Depressed mood has a complex relationship with self-evaluation of personal competence in multiple populations. The absence of depression may be associated with overestimation of abilities, while mild depression seems to lead to accurate self-assessment. Significant depression may lead to underestimation of functioning. In this study, we expand on o...

This study examined correlates of unprotected vaginal and anal sex (UVA) with male clients among female sex workers (FSWs). Baseline data were gathered from 1089 FSWs recruited from 13 cities across Mexico enrolled in an evidence-based sexual risk reduction intervention. We used generalised estimating equations (GEE) to predict total UVA while cont...