Regional differences in rates of HIV-1 viral load monitoring in Canada: Insights and implications for antiretroviral care in high income countries

A systematic review of the geospatial barriers to antiretroviral initiation, adherence and viral suppression among people living with HIV

Background With the emergence of antiretroviral therapy (ART), Treatment as Prevention (TasP) has become the cornerstone of both HIV clinical care and HIV prevention. However, despite the efficacy of treatment-based programs and policies, structural barriers to ART initiation, adherence and viral suppression have the potential to reduce TasP effectiveness. These barriers have been studied using Geographic Information Systems (GIS). While previous reviews have examined the use of GIS for HIV testing - an essential antecedent to clinical care - to date, no reviews have summarised the research with respect to other ART-related outcomes.

METHODS

Therefore, the present review leveraged the PubMed database to identify studies that leveraged GIS to examine the barriers to ART initiation, adherence and viral suppression, with the overall goal of understanding how GIS has been used (and might continue to be used) to better study TasP outcomes. Joanna Briggs Institute criteria were used for the critical appraisal of included studies.

RESULTS

In total, 33 relevant studies were identified, excluding those not utilising explicit GIS methodology or not examining TasP-related outcomes.

CONCLUSIONS

Findings highlight geospatial variation in ART success and inequitable distribution of HIV care in racially segregated, economically disadvantaged, and, by some accounts, increasingly rural areas - particularly in the United States. Furthermore, this review highlights the utility and current limitations of using GIS to monitor health outcomes related to ART and the need for careful planning of resources with respect to the geospatial movement and location of people living with HIV (PLWH).

Geographic variation in the costs of medical care for people living with HIV in British Columbia, Canada

Background

Regional variation in medical care costs can indicate heterogeneity in clinical practice, inequities in access, or inefficiencies in service delivery. We aimed to estimate regional variation in medical costs for people living with HIV (PLHIV), adjusting for demographics and case-mix.

Methods

We conducted a retrospective cohort study using linked health administrative databases of PLHIV, from 2010 to 2014, in British Columbia (BC), Canada. Quarterly health care costs (2018 CAD) were derived from inpatient, outpatient, prescription drugs, antiretroviral therapy (ART), and HIV diagnostics. We used a two-part model with a logit link for the probability of incurring costs, and a log link and gamma distribution for observations with positive costs. We also estimated quarterly utilization rates for hospitalization-, physician billing- and prescription drug-days. Primary variables were indicators of individuals’ Health Service Delivery Area (HSDA). We adjusted cost and utilization estimates for demographic characteristics, HIV-disease progression, and comorbidities.

Results

Our cohort included 9577 PLHIV (median age 45.5 years, 80% male). Adjusted total quarterly costs for all 16 HSDAs were within 20% of the provincial mean, 8/16 for hospitalization costs, 16/16 for physician billing costs and 10/16 for prescription drug costs. Northern Interior and Northeast HSDAs had 38 and 44% lower quarterly non-ART prescription drug costs, and 2 and 5% higher quarterly inpatient costs, respectively.

Conclusions

We observed limited variation in medical care costs and utilization among PLHIV in BC. However, lower levels of outpatient care and higher levels of inpatient care indicate possible barriers to accessing care among PLHIV in the most rural regions of the province.

Electronic supplementary material

The online version of this article (10.1186/s12913-019-4391-8) contains supplementary material, which is available to authorized users.

Is there a rural/urban gap in the quality of HIV care for treatment-naïve HIV-positive individuals initiating antiretroviral therapy in British Columbia?

Rurally located people living with HIV (PLWH) face unique challenges associated with remoteness that may negatively affect their HIV care outcomes. The Programmatic Compliance Score (PCS) has been used previously as a quality of care metric, and is predictive of mortality for treatment-naïve individuals initiating combination antiretroviral therapy (cART). This study looked at whether the rurality of PLWH impacted their PCS. PCS was calculated for PLWH (≥19 years old) initiating cART in British Columbia between 2000 and 2013. Rurality was determined at the time of cART initiation using two methodologies: (1) a categorical postal code method; and (2) the General Practice Rurality Index (GPRI), a score representing an individual's degree of rurality. Ordinal logistic regression modeling was used to assess the relationship between rurality and PCS. Among 4616 PLWH with an evaluable PCS, 176 were classified as rural and 3512 as urban (928 had an unknown postal code). After adjusting for age, sex, hepatitis C status, Indigenous ancestry, and year of cART initiation, categorical rurality was not associated with a worse PCS (adjusted odds ratio (AOR) 1.04; 95% CI: 0.77-1.39). However, an increasing degree of rurality was associated with a worse PCS (AOR (per 10 increase in GPRI) 1.13; 95% CI: 1.06-1.20). Given that a poor PCS has been shown to be predictive of all-cause mortality for individuals initiating cART, strategies to improve access to HIV care for rural individuals should be evaluated.

Estimation of state occupancy probabilities in multistate models with dependent intermittent observation, with application to HIV viral rebounds

In follow-up studies on chronic disease cohorts, individuals are often observed at irregular visit times that may be related to their previous disease history and other factors. This can produce bias in standard methods of estimation. Working in the context of multistate models, we consider a method of nonparametric estimation for state occupancy probabilities that adjusts for dependent follow-up through the use of inverse-intensity-of-visit weighted estimating functions and smoothing. The methodology is applied to the estimation of viral rebound probabilities in the Canadian Observational Cohort on HIV-positive persons. Copyright © 2016 John Wiley & Sons, Ltd.

Use of Dried Plasma Spots for HIV-1 Viral Load Determination and Drug Resistance Genotyping in Mexican Patients

Monitoring antiretroviral therapy using measurements of viral load (VL) and the genotyping of resistance mutations is not routinely performed in low- to middle-income countries because of the high costs of the commercial assays that are used. The analysis of dried plasma spot (DPS) samples on filter paper may represent an alternative for resource-limited settings. Therefore, we evaluated the usefulness of analyzing DPS samples to determine VL and identify drug resistance mutations (DRM) in a group of HIV-1 patients. The VL was measured from 22 paired plasma and DPS samples. In these samples, the average VL was 4.7 log₁₀ copies/mL in liquid plasma and 4.1 log₁₀ copies/mL in DPS, with a correlation coefficient of R = 0.83. A 1.1 kb fragment of HIV pol could be amplified in 14/22 (63.6%) of the DPS samples and the same value was amplified in plasma samples. A collection of ten paired DPS and liquid plasma samples was evaluated for the presence of DRM; an excellent correlation was found in the identification of DRM between the paired samples. All HIV-1 pol sequences that were obtained corresponded to HIV subtype B. The analysis of DPS samples offers an attractive alternative for monitoring ARV therapy in resource-limited settings.

Factors associated with the frequency of monitoring of liver enzymes, renal function and lipid laboratory markers among individuals initiating combination antiretroviral therapy: a cohort study

Background

As the average age of the HIV-positive population increases, there is increasing need to monitor patients for the development of comorbidities as well as for drug toxicities.

Methods

We examined factors associated with the frequency of measurement of liver enzymes, renal function tests, and lipid levels among participants of the Canadian Observational Cohort (CANOC) collaboration which follows people who initiated HIV antiretroviral therapy in 2000 or later. We used zero-inflated negative binomial regression models to examine the associations of demographic and clinical characteristics with the rates of measurement during follow-up. Generalized estimating equations with a logit link were used to examine factors associated with gaps of 12 months or more between measurements.

Results

Electronic laboratory data were available for 3940 of 7718 CANOC participants. The median duration of electronic follow-up was 3.5 years. The median (interquartile) rates of tests per year were 2.76 (1.60, 3.73), 2.55 (1.44, 3.38) and 1.42 (0.50, 2.52) for liver, renal and lipid parameters, respectively. In multivariable zero-inflated negative binomial regression models, individuals infected through injection drug use (IDU) were significantly less likely to have any measurements. Among participants with at least one measurement, rates of measurement of liver, renal and lipid tests were significantly lower for younger individuals and Aboriginal Peoples. Hepatitis C co-infected individuals with a history of IDU had lower rates of measurement and were at greater risk of having 12 month gaps between measurements.

Conclusions

Hepatitis C co-infected participants infected through IDU were at increased risk of gaps in testing, despite publicly funded health care and increased risk of comorbid conditions. This should be taken into consideration in analyses examining factors associated with outcomes based on laboratory parameters.

HIV viral load: a concept analysis and critique

In this article, we examine the concept of HIV viral load and how it has evolved over time (1995-2013) in the field of HIV/AIDS. Although the term viral load is used extensively in this field, few efforts have been directed toward the conceptualization of HIV viral load, which is often left unquestioned, undertheorized, and portrayed as a neutral and objective laboratory value that has remained relatively stable over time--with the exception of progressive advancements in technology, techniques, and sensitivity. The purpose of this article is to apply the evolutionary concept analysis method developed by Rodgers (1989, 2000a) to the concept of HIV viral load. To set the stage, we establish the need for a concept analysis of HIV viral load and provide an overview of the evolutionary view. Then, drawing on the steps proposed by Rodgers (2000a), we outline the process of data collection, management, and analysis. We then offer an in-depth discussion of the findings (attributes, antecedents, and consequences) informed by Wuest's (2000) critical approach to concept analysis. We conclude by highlighting the implications of this analysis for clinical practice, research, and theory.

Estimation and assessment of markov multistate models with intermittent observations on individuals

Multistate models provide important methods of analysis for many life history processes, and this is an area where John Klein made numerous contributions. When individuals in a study group are observed continuously so that all transitions between states, and their times, are known, estimation and model checking is fairly straightforward. However, individuals in many studies are observed intermittently, and only the states occupied at the observation times are known. We review methods of estimation and assessment for Markov models in this situation. Numerical studies that show the effects of inter-observation times are provided, and new methods for assessing fit are given. An illustration involving viral load dynamics for HIV-positive persons is presented.

Predictors of unstructured antiretroviral treatment interruption and resumption among HIV-positive individuals in Canada

OBJECTIVES

Sustained optimal use of combination antiretroviral therapy (cART) has been shown to decrease morbidity, mortality and HIV transmission. However, incomplete adherence and treatment interruption (TI) remain challenges to the full realization of the promise of cART. We estimated trends and predictors of treatment interruption and resumption among individuals in the Canadian Observational Cohort (CANOC) collaboration.

METHODS

cART-naïve individuals ≥ 18 years of age who initiated cART between 2000 and 2011 were included in the study. We defined TIs as ≥ 90 consecutive days off cART. We used descriptive analyses to study TI trends over time and Cox regression to identify factors predicting time to first TI and time to treatment resumption after a first TI.

RESULTS

A total of 7633 participants were eligible for inclusion in the study, of whom 1860 (24.5%) experienced a TI. The prevalence of TI in the first calendar year of cART decreased by half over the study period. Our analyses highlighted a higher risk of TI among women [adjusted hazard ratio (aHR) 1.59; 95% confidence interval (CI) 1.33-1.92], younger individuals (aHR 1.27; 95% CI 1.15-1.37 per decade increase), earlier treatment initiators (CD4 count ≥ 350 vs. <200 cells/μL: aHR 1.46; 95% CI 1.17-1.81), Aboriginal participants (aHR 1.67; 95% CI 1.27-2.20), injecting drug users (aHR 1.43; 95% CI 1.09-1.89) and users of zidovudine vs. tenofovir in the initial cART regimen (aHR 2.47; 95% CI 1.92-3.20). Conversely, factors predicting treatment resumption were male sex, older age, and a CD4 cell count <200 cells/μL at cART initiation.

CONCLUSIONS

Despite significant improvements in cART since its advent, our results demonstrate that TIs remain relatively prevalent. Strategies to support continuous HIV treatment are needed to maximize the benefits of cART.

Trends and disparities in antiretroviral therapy initiation and virologic suppression among newly treatment-eligible HIV-infected individuals in North America, 2001-2009

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 (Ptrend<.001). The cumulative incidence of 1-year virologic suppression increased from 55% to 81%, and among ART initiators, from 84% to 93% (both Ptrend<.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.

Frequency of HIV-1 viral load monitoring of patients initially successfully treated with combination antiretroviral therapy

Background

Although considered an essential tool for monitoring the effect of combination antiretroviral treatment (CART), HIV-1 RNA (viral load, VL) testing is greatly influenced by cost and availability of resources.

Objectives

To examine whether HIV infected patients who were initially successfully treated with CART have less frequent monitoring of VL over time and whether CART failure and other HIV-disease and sociodemographic characteristics are associated with less frequent VL testing.

Methods

The study included patients who started CART in the period 1999–2004, were older than 18 years, CART naive, had two consecutive viral load measurements of <400 copies/ml after 5 months of treatment and had continuous CART during the first 15 months. The time between two consecutive visits (days) was the outcome and associated factors were assessed using linear mixed models.

Results

We analyzed a total of 128 patients with 1683 visits through December 2009. CART failure was observed in 31 (24%) patients. When adjusted for the follow-up time, the mean interval between two consecutive VL tests taken in patients before CART failure (155.2 days) was almost identical to the interval taken in patients who did not fail CART (155.3 days). On multivariable analysis, we found that the adjusted estimated time between visits was 150.9 days before 2003 and 177.6 in 2008/2009. A longer time between visits was observed in seafarers compared to non-seafarers; the mean difference was 30.7 days (95% CI, 14.0 to 47.4; p<0.001); and in individuals who lived more than 160 kilometers from the HIV treatment center (mean difference, 16 days, p = 0.010).

Conclusions

Less frequent monitoring of VL became common in recent years and was not associated with failure. We identified seafarers as a population with special needs for CART monitoring and delivery.