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Evaluation of the POP-UP programme: a multicomponent model of care for people living with HIV with homelessness or unstable housing

Imbert, Elizabetha; Hickey, Matthew D.a; Clemenzi-Allen, Angeloa,b; Lynch, Elizabetha; Friend, Johna; Kelley, Jackelyna; Conte, Madellenac; Das, Doyeld; Rosario, Jan Bing Dela; Collins, Erina; Oskarsson, Jona; Hicks, Mary Lawrencea; Riley, Elise D.a; Havlir, Diane V.a; Gandhi, Monicaa

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doi: 10.1097/QAD.0000000000002843
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Homelessness and unstable housing (HUH) represent a major barrier to realizing the full benefits of antiretroviral therapy (ART) for people with HIV (PWH) [1], threatening targets for Ending the HIV epidemic initiatives [2]. PWH-HUH are significantly less likely to achieve viral suppression than people with stable housing, even among those accessing HIV care [1,3–5]. In San Francisco, only 33% of people experiencing homelessness were virally suppressed in 2018 [6], compared with 75% of those who were housed, and viral suppression rates decrease with increasing housing instability [4]. Furthermore, people homeless at HIV diagnosis have a 27-fold higher odds of death compared with those with housing in San Francisco [7].

Affordable housing is ultimately needed to achieve the goals of the Ending the HIV Epidemic Initiative [3]. Although ongoing efforts are needed to address this key structural barrier, there is an immediate need to address health needs of PWH-HUH at the clinic-level.

PWH-HUH face a number of individual-level and structural barriers to engagement in care [8,9]. Multiple interventions have demonstrated some success in mitigating barriers to care for this vulnerable population, including enhanced contact [10], peer navigation [11], case management [12] and specialized provider training to reduce stigma and address substance use and psychiatric comorbidities [13,14]. Still others cite unstable housing as one potential reason for the lack of a significant intervention effect [15]. These interventions have had limited impact on viral suppression when enacted in isolation. Multicomponent low-barrier care models may be more effective in addressing disparate barriers, although studies to understand implementation and efficacy of such programmes are needed [16–18].

In January 2019, we launched POP-UP (Positive-health On-site Program for Unstably-housed Populations), a no-appointment low-threshold, multicomponent model of care to address barriers to care and improve viral suppression for PWH-HUH with viremia. We describe the POP-UP clinic model and report initial care outcomes.

Materials and methods

Study setting, design and participants

POP-UP is based at the Ward 86 HIV clinic at San Francisco General Hospital. Ward 86 is funded by the San Francisco Department of Public Health (SFDPH) and the Ryan White Care programme and serves 2500 publicly insured or uninsured patients, one-third of whom experience homelessness or unstable housing [4]. Ward 86 patients are eligible to receive care in POP UP if they meet all of the following criteria: HIV viral load more than 200 copies/ml or are off ART, HUH, at least one missed primary care appointment and at least two drop-in visits to Ward 86 over prior 12 months. For this analysis, we included Ward 86 patients who met enrolment criteria and enrolled in POP-UP from January 2019 to February 2020.

POP-UP recruitment and enrolment

At POP-UP inception, Ward 86 patients eligible for POP-UP were identified through a combination of SFDPH surveillance data and electronic medical record review. In addition, Ward 86 providers and a linkage-to-care programme at the SFDPH referred patients who met eligibility criteria. Prior research shows that services like those included in POP-UP improve HIV outcomes. We therefore considered withholding POP-UP services from eligible patients as unethical, and randomization was not conducted. After assessing referral eligibility, POP-UP staff contacted the primary care team and the SFDPH HIV linkage-to-care navigator to determine the best way to navigate patients to Ward 86 for POP-UP enrolment once referred.

POP-UP intervention

POP-UP includes low-threshold primary care services without the need for scheduled appointments; financial incentives; and enhanced outreach with patient navigation and case management [18]. The POP-UP clinical team includes three Ward 86 MDs and a nurse practitioner who are HIV specialists; a nurse; a social worker; the clinic pharmacist and pharmacy technician; and a linkage-to-care navigator, all of whom meet for a weekly case conference to conduct panel management.

Low-threshold comprehensive primary care

POP-UP is open for drop-in visits on weekday afternoons to access medical, social and pharmacy services without an appointment. Medical services include same-day restart of ART, substance use treatment, including buprenorphine, comprehensive primary health services and onsite laboratory services. A psychiatrist is available for phone consultation by the medical provider. Social services include care coordination, referral to case management, referrals for emergency and permanent housing and assistance with access to public insurance coverage. Medications can be delivered to the clinic, allowing patients to pick up medications directly from clinic.

Incentivized care

We provide financial incentives in the form of grocery store gift cards: $10 once a week for a visit with a provider or social worker; $10 for laboratory draws when needed; and $25 every 3 months for achieving or maintaining an HIV viral load less than 200 copies/ml.

Enhanced outreach

A patient navigator assists with finding and linking patients to care or other services including benefit services, Medicaid enrolment and medical appointments. Our nurse coordinates with care providers in the community to perform wellness checks and assist with medication adherence. There is a dedicated POP-UP phone that accepts text messages.

Study measurements

We conducted chart review to obtain demographic information, documentation of a substance use disorder or mental health disorder based on ICD-10 codes and diagnoses listed in clinic notes, housing status, CD4+ cell count and HIV viral load at the time of POP-UP enrolment. We abstracted subsequent clinic visit data and HIV viral load data from the electronic health record.


Our primary outcome was cumulative incidence of viral suppression (HIV RNA < 200 copies/ml) assessed 6 months post-enrolment. Secondary outcomes included the proportion of patients restarting ART within 7 days of POP-UP enrolment, early engagement (proportion returning for a second visit within 1 month and 3 months) and sustained engagement (proportion with a visit during both the first 3 months and the second 3 months over the first 6 months of follow-up). Viral suppression, ART initiation and early engagement outcomes were assessed using Kaplan--Meier, censoring at date of programme unenrolment due to death, moving out of San Francisco, suspension from the programme or transfer to another clinic/provider, or the last date of the analysis (29 February 2020).


From January 2019 to February 2020, 192 patients were referred to POP-UP, of whom 152 met eligibility criteria and 75 were enrolled (Fig. 1). Nearly half of those who were eligible were referred from electronic medical record surveillance data (49%). Additional referral sources of enrolled patients included primary care providers (29%); urgent care providers (25%); and Positive Health Access to Services and Treatment (PHAST), a rapid response team at Ward 86 that champions HIV testing and linkage-to-care (5%). Out of the 77 who were not enrolled, 67 have not been reached, eight preferred to stay with their primary care physician and two were later enrolled after the follow-up period described in this analysis.

Fig. 1:
Flowchart of POP-UP clinic referrals, January 2019--February 2020.

Demographics and clinical characteristics

Table 1 summarizes the baseline characteristics of the first 75 patients enrolled in POP-UP. Overall, two-thirds were aged 50 years or younger, and 55% were nonwhite. The majority were cisgender men; 9% cisgender women; and 5% trans-women or gender nonbinary. In terms of housing status, 51% were street homeless at enrolment. All enrolled patients had a documented substance use disorder, 91% with methamphetamines and 15% with opiates. Three quarters (77%) had a mental health diagnosis and 51% had a depressive disorder. At baseline, 40% of those enrolled had a CD4+ cell count less than 200 copies/ml. All patients were either virally unsuppressed at baseline or reported being off ART with no viral load measured; 17 (23%) of patients had at least one HIV viral load less than 200 copies/ml in the 12 months prior to enrolment; however, none were suppressed at the baseline visit.

Table 1 - Participant characteristics.
Enrolled (n = 75)
n %
Referral source
 Urgent care 19 25%
 Primary care team 22 29%
 PHAST team 12 16%
 LINCS 2 3%
 Surveillance data 19 25%
 Other 4 5%
Age (years)
 18–35 21 28%
 35–50 29 39%
 >50 25 33%
 Cisgender man 64 85%
 Cisgender woman 7 9%
 Transgender woman 1 1%
 Nonbinary/gender nonconforming 3 4%
 Black/African–American 26 35%
 White 34 45%
 Hispanic/Latinx 7 9%
 Asian/Pacific Islander 0 0%
 American Indian/Native American 5 7%
 Other 3 4%
Housing status at enrolment
 Single room occupancy 5 7%
 Transitional housing 9 12%
 Treatment programme 2 3%
 Couch surfing 11 15%
 Shelter 10 13%
 Street 38 51%
Baseline CD4+ cell count (cells/μl)
 <200 30 40%
 200–349 20 27%
 350–499 16 21%
 ≥500 12 16%
 Substance use disorder (any) 75 100%
 Methamphetamine 68 91%
 Cocaine 8 11%
 Opioids 11 15%
 Alcohol 7 9%
 Mental health disorder (any) 58 77%
 Psychotic disorder 12 16%
 Bipolar disorder 11 15%
 Depressive disorder 38 51%
 Anxiety disorder 14 19%


The cumulative incidence of restarting ART within 7 days of enrolment was 79% [95% confidence interval (95% CI) 69–87]. The cumulative incidence of returning for a visit (with either a POP-UP provider or a social worker) within 1 month was 68% (95% CI 57–78) and, within 3 months, was 91% (95% CI 83–96). Overall, 86% of the 49 patients with at least 6 months of follow-up had visits in both the first and second quarters. During the first 6 months following enrolment, the mean financial incentive per month per patient was $15.98 (SD = 18.22). Cumulative incidence of viral suppression by 6 months among the entire cohort (n = 75) was 55% (95% CI 43–68). Among the 41 who attained viral suppression, eight subsequently had viral rebound at least 200 copies/ml by 6 months. Among the eight, five resuppressed to less than 200 copies/ml a second time and three remained at least 200 copies/ml at 6 months. Sixteen patients (21%) were disenrolled from the programme (five died, three transferred back to their primary care provider, three moved, three suspended for violent behaviour, one went to prison, and one institutionalized in a long-term care facility).


Within an exceptionally vulnerable population of HUH, viraemic safety-net clinic patients living with HIV, we demonstrate that over half can achieve viral suppression within the first 6 months following enrolment in a low-barrier, high-intensity HIV care programme. Although interventions have demonstrated some success with similar populations, our intervention is the first clinic-based multicomponent care model to specifically focus on PWH-HUH. The Project HOPE study evaluated the effect of incentives and care navigation on viral suppression among PWH on hospital discharge, though only 38% of participants reported any housing instability in the six months prior to enrolment. Among participants in Project HOPE not virally suppressed at baseline, 42% in the incentives-plus-navigation arm achieved viral suppression at 6 months compared to 32% in the usual-treatment arm (RD, 10.2%; 95% CI, 1.4–19.1), a rate of viral suppression lower than that seen in POP-UP. In Project HOPE, participants in the navigation-plus-incentive arm received a median incentive payment of $716 (IQR $495–890) over the 6-month intervention, substantially higher than the mean incentive payment of $16 per month received by patients in POP-UP [11]. The Max Clinic in Seattle is a similar low-barrier, high-intensity HIV primary care clinic that provides multicomponent interventions such as financial incentives, intensive case management, and enhanced outreach to patients not engaged in traditional primary care, 65% of whom were homeless or unstably housed. Six months after enrolment, 51% of patients in the Max clinic attained viral suppression, similar to the results seen in POP-UP [17].

Nearly half of patients eligible for POP-UP could not be reached to offer enrolment, highlighting the challenges of linking this patient population even to low-threshold models of care. Furthermore, participants identified through surveillance data were the least likely to enrol in POP-UP, reflecting the challenges of data-to-care interventions [19]. Provider and staff training on eligibility criteria generated a greater proportion of successful referrals to POP-UP, particularly from primary care and urgent care providers at the clinic.

The cumulative incidence of re-starting ART within 7 days was high at 79%, suggesting acceptability and feasibility of rapid restarts among this population. Although same day ART initiation has been associated with very high rates of subsequent viral suppression [20], patients in our study were all ART-experienced, so POP-UP focuses on restarting ART and addressing known adherence barriers. The high proportion of methamphetamine use (91%) and mental health diagnoses (77%) among those enrolled in POP-UP demonstrate additional challenges to care engagement faced by this patient population, in addition to the structural challenges posed by lack of housing. Despite these individual and structural barriers, we observed early and sustained engagement in the POP-UP programme. A primary limitation of our analysis is that it was not controlled, thus limiting our ability to determine whether increases in viral suppression were due to the POP-UP programme. We also implemented this intervention at a single site, and the generalizability of our results is uncertain.

POP-UP has features that are similar to other low-barrier primary care models [16,17], though it differs in focusing exclusively on patients who are homeless or unstably housed. Low-barrier, high-intensity primary care programmes offering comprehensive services and incentives similar to POP-UP may improve patient outcomes for PWH-HUH in other urban settings. Further research is needed to understand the costs associated with this model of care and how programmes such as POP-UP can expand their reach to include patients not currently accessing care. An expansion of similar programmes, tailored specifically for high-risk populations, may improve HIV outcomes across geographic locations, which could provide a new cornerstone for strategies to end the HIV epidemic.


Elizabeth Imbert, Matthew D. Hickey, Angelo Clemenzi-Allen did substantial contribution to the conception or design of the work; substantial contribution to the acquisition and interpretation of data for the work; drafting the work and revising it critically for important intellectual content.

Elizabeth Lynch, John Friend, Jackelyn Kelley, Madellena Conte, Erin Collins, Jon Oskarsson, Mary Lawrence Hicks, Elise D. Riley, Diane V. Havlir, Monica Gandhi did substantial contribution to the acquisition of data for the work; revising the work critically for important intellectual content.

Doyel Das did substantial contribution to the acquisition of data for the work.

Jan Bing Del Rosario did substantial contribution to the acquisition and analysis of the data for the work.

The ‘Ward 86’ HIV programme in the Division of HIV, ID and Global Medicine received an unrestricted investigator-initiated grant from the Gilead Foundation to support implementation and evaluation of the ’POP-UP’ programme, a clinical programme for PLWH experiencing HUH (Grant # IN-US-985-5691). Gilead had no role in the interpretation or presentation of these results.

This research was supported by an Ending the HIV Epidemic Supplemental grant from the National Institutes of Health to the UCSF-Gladstone Center for AIDS Research (P30 AI027763).

This publication/presentation/grant proposal was made possible with help from an Ending the HIV Epidemic supplement to the UCSF-Gladstone Center for AIDS Research (CFAR), an NIH-funded programme (P30 AI027763).

Elizabeth Imbert and Matthew D. Hickey contributed equally.

Conflicts of interest

There are no conflicts of interest.


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HIV; homelessness and unstable housing; retention in care

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