Barriers to effective care: Specialty drug treatment in Philadelphia.

INTRODUCTION: In Philadelphia, the poorest big city in the United States, an estimated 60,000 people misuse opioids and more than 3500 have died of overdose in the past three years. In 2019, fentanyl was detected in 76% of drug-related deaths and 94% of opioid-involved deaths. While much attention has been directed at the public face of the city's drug problem, more than 75% of drug deaths in 2017 took place in a private residence. METHOD: Based on qualitative research to understand the vulnerabilities of this hidden population of drug users, we interviewed kin of 35 people who had died of opioid overdose in 2017 to learn whether their loved one had interacted with any social services or harm-reduction interventions. RESULTS: In our demographically and geographically representative sample of decedents, we found that while most had received treatment at least once, many faced barriers to getting treatment when they needed it, including barriers related to stigma, structural racism, gender inequities, bureaucracy, insurance requirements, and cost. CONCLUSION: We argue that these barriers place an undue burden on people with substance use disorder and their kin during particularly fraught moments of heightened vulnerability. The failure of state and federal policies, practices, and infrastructure to address these barriers, and the failure to require that evidence-based care be provided during treatment have deleterious effects on people affected by the opioid epidemic in the United States.

Predicting the impact of placing an overdose prevention site in Philadelphia: a mathematical modeling approach.

BACKGROUND: Fatal overdoses from opioid use and substance disorders are increasing at an alarming rate. One proposed harm reduction strategy for reducing overdose fatalities is to place overdose prevention sites-commonly known as safe injection facilities-in proximity of locations with the highest rates of overdose. As urban centers in the USA are tackling legal hurdles and community skepticism around the introduction and location of these sites, it becomes increasingly important to assess the magnitude of the effect that these services might have on public health. METHODS: We developed a mathematical model to describe the movement of people who used opioids to an overdose prevention site in order to understand the impact that the facility would have on overdoses, fatalities, and user education and treatment/recovery. The discrete-time, stochastic model is able to describe a range of user behaviors, including the effects from how far they need to travel to the site. We calibrated the model to overdose data from Philadelphia and ran simulations to describe the effect of placing a site in the Kensington neighborhood. RESULTS: In Philadelphia, which has a non-uniform racial population distribution, choice of site placement can determine which demographic groups are most helped. In our simulations, placement of the site in the Kensington neighborhood resulted in White opioid users being more likely to benefit from the site's services. Overdoses that occur onsite can be reversed. Our results predict that for every 30 stations in the overdose prevention site, 6 per year of these would have resulted in fatalities if they had occurred outside of the overdose prevention site. Additionally, we estimate that fatalities will decrease further when referrals from the OPS to treatment are considered. CONCLUSIONS: Mathematical modeling was used to predict the impact of placing an overdose prevention site in the Kensington neighborhood of Philadelphia. To fully understand the impact of site placement, both direct and indirect effects must be included in the analysis. Introducing more than one site and distributing sites equally across neighborhoods with different racial and demographic characteristics would have the broadest public health impact. Cities and locales can use mathematical modeling to help quantify the predicted impact of placing an overdose prevention site in a particular location.

Association between discharges against medical advice and readmission in patients treated for drug injection-related skin and soft tissue infections.

BACKGROUND: The prevalence of injection drug use (IDU)-related skin and soft tissue infections (SSTI) in Philadelphia has been steadily increasing since 2013. Patients seeking treatment for these infections are more likely to be discharged against medical advice (AMA), increasing the likelihood that they will end antibiotic treatment prematurely and require additional medical interventions. METHODS: The research team performed a nested case-control study using the Pennsylvania Health Care Cost Containment Council database for Philadelphia residents hospitalized for SSTI and substance use-related diagnoses between 2013 and 2018. The primary outcome was readmission in the same or following quarter. The study examined the impact of discharge AMA on readmission along with clinical characteristics including diagnoses for anxiety, bipolar disorder, depression, schizophrenia, diabetes, and polydrug use. RESULTS: There were 8265 hospitalizations for IDU-related SSTI and 316 (6%) were readmitted to the hospital at least once in the same or following quarter. In total, 23.4% of cases and 13% of controls left AMA. In the final multivariable regression model, AMA discharge (AOR 2.04, 95% CI 1.46-2.86), anxiety (AOR 1.44, 95% CI 1.01-2.05), diabetes (AOR 2.02, 95% CI 1.46-2.81), and polydrug use (AOR 2.11, 95% CI 1.52-2.92) were associated with higher odds of readmission. CONCLUSIONS: Our study demonstrates that readmissions for IDU-related SSTI are associated with recent discharge AMA. As IDU-related SSTI and polydrug use continue to rise, premature antibiotic treatment completion will impact more people, leading to worse health outcomes and additional strain on the health care system.

Increasing presence of xylazine in heroin and/or fentanyl deaths, Philadelphia, Pennsylvania, 2010-2019.

Reports from active drug users state that xylazine, the veterinary tranquilliser, has been increasing in the illicit drug supply in Philadelphia. To describe trends and characteristics of unintentional deaths from heroin and/or fentanyl overdose with xylazine detections occurring in Philadelphia, Pennsylvania, the Philadelphia Department of Public Health analysed data on deaths from unintentional heroin and/or fentanyl overdose from the Philadelphia Medical Examiner's Office over a 10-year period (2010-2019). Xylazine went from being detected in less than 2% cases of fatal heroin and/or fentanyl overdose between 2010 and 2015 to 262 (31%) of the 858 fatal heroin and/or fentanyl overdose cases in 2019. Currently, information is limited on the presence of xylazine in continental United States. Xylazine's association with adverse outcomes in other locations indicates that potential health consequences should also be monitored in the USA. Whenever possible, jurisdictions should consistently test for xylazine.

Adherence to buprenorphine: An analysis of prescription drug monitoring program data.

BACKGROUND: Although buprenorphine is an evidence-based treatment for opioid use disorder (OUD), many individuals discontinue treatment soon after starting. This study assesses predictors of buprenorphine adherence using Prescription Drug Monitoring Program (PDMP) data. METHODS: PDMP data for Philadelphia, Pennsylvania were used to measure 180-day adherence to buprenorphine among new initiates. Adherence was classified using percent days covered (PDC), and new initiates with PDC ≥ 0.80 were classified as adherent. Multivariable logistic regression was conducted to determine factors associated with buprenorphine adherence. RESULTS: Between January 2017 and December 2018, 10,669 Philadelphia residents initiated buprenorphine and 26.6 % remained adherent after 180 days. Demographic factors associated with greater odds of adherence included age category and female sex (aOR: 1.37; 95 % CI: 1.25-1.50). Those filling an opioid prescription, other than buprenorphine, during the follow-up period had lower odds of adherence than those who did not fill an opioid prescription (aOR: 0.62; 95 % CI: 0.50-0.77). Odds of adherence was greater for those on the film formulation (aOR: 1.37; 95 % CI: 1.25-1.50) than the tablet formulation. Those filling medium (aOR: 1.76; 95 % CI: 1.55-2.00) and high dose (aOR: 5.11; 95 % CI: 4.30-6.17) buprenorphine prescriptions had higher odds of adherence than those filling low dose prescriptions. CONCLUSIONS: Individual demographics, receipt of an opioid prescription, buprenorphine formulation, and buprenorphine dose were all associated with adherence to buprenorphine. Ongoing strategies to address OUD need to prioritize increasing retention in long-term evidence-based buprenorphine treatment while also encouraging providers to regularly consult the PDMP to ensure patient compliance.

Susceptibility to Hepatitis A and B Virus Among Clients at a Syringe Services Program in Philadelphia, 2018.

OBJECTIVES: Although many people who use drugs meet criteria for vaccination against hepatitis A virus (HAV) and hepatitis B virus (HBV), estimates of susceptibility (ie, lack of immunity) are not well established. This study sought to identify the prevalence of and characteristics associated with HAV and HBV susceptibility among people who use drugs attending an urban syringe services program. METHODS: We initiated this seroprevalence study in 2018 among 438 clients of a syringe services program who met study criteria, including provision of a blood specimen and a self-reported history of drug use. We assessed HAV and HBV susceptibility and infection via serological testing. We examined associations between participant characteristics and serology status by using descriptive statistics and multivariable logistic regression models. RESULTS: Of the initial 438 clients identified, 353 (80.6%) met study criteria. Of 352 participants with conclusive HAV test results, 48.6% (n = 171) were HAV susceptible; of 337 participants with conclusive HBV test results, 32.6% (n = 110) were HBV susceptible, 24.3% (n = 82) showed evidence of past or present HBV infection, and 43.0% (n = 145) had vaccine-derived immunity. Compared with participants born before 1970, participants born during 1980-1989 had 5.90 (95% CI, 2.42-14.40) times the odds of HAV susceptibility and 0.18 (95% CI, 0.06-0.53) times the odds of HBV susceptibility, and participants born during 1990-1999 had 6.31 (95% CI, 2.34-17.00) times the odds of HAV susceptibility. Decreased odds of HAV susceptibility were associated with homelessness (adjusted odds ratio = 0.48; 95% CI, 0.28-0.82). CONCLUSION: Despite applicable HAV and HBV vaccination recommendations, substantial gaps exist in HAV and HBV susceptibility among a population of people who use drugs. These findings highlight the need for increased HAV and HBV vaccination efforts among people who use drugs.

Correlates of experiencing and witnessing non-fatal opioid overdoses among individuals accessing harm reduction services in Philadelphia, Pennsylvania.

Background: With the dramatic increase in overdose deaths in the United States, layperson overdose education and naloxone distribution (OEND) programs serve a critical role in preventing opioid overdose fatality. This study examines associations for witnessing an opioid overdose or experiencing a non-fatal opioid overdose to identify new opportunities for expansion of OEND programs. Methods: Cross sectional surveys were administered at the sole needle and syringe exchange program in Philadelphia, PA. Bivariate and multivariable logistic regression analyses were conducted to examine associations for witnessing an opioid overdose or experiencing a non-fatal opioid overdose in the previous 12 months. Results: In total, 370 individuals were identified as using opioids in the previous three months and included in the study. Factors associated with experiencing a non-fatal opioid overdose were unstable housing (aOR: 2.16; 95% CI: 1.12-3.99), recent incarceration (aOR: 2.34; 95% CI: 1.41-3.89), co-use of opioids and benzodiazepines (aOR: 2.04; 95% CI: 1.22-3.41), co-use of heroin and cocaine (aOR: 1.69; 95% CI: 1.04-2.75), drug injection (aOR: 4.25; 95% CI: 1.90-9.54), inpatient detoxification history (aOR: 2.33; 95% CI:1.27-4.43), and witnessing an overdose in the previous 12 months (aOR: 2.51; 95% CI: 1.02-6.13). Factors associated with witnessing an overdose were unstable housing (aOR: 5.14; 95% CI: 2.57-10.28), recent incarceration (aOR: 2.88; 95% CI: 1.24-6.74), and a history of being trained to use naloxone (aOR: 3.39; 95% CI: 1.63-7.04). Discussion: Findings presented here show characteristics of those most likely to witness an overdose or experience a non-fatal overdose who could be served by expansion of OEND programs.

Increased Health and Social Vulnerability Among Hepatitis C Infected Individuals Co-infected with Hepatitis B.

Hepatitis B (HBV) and hepatitis C (HCV) infections contribute significant morbidity in the United States, particularly among those with a history of incarceration, homeless-ness, and/or co-morbid mental illness. Data from the Philadelphia Department of Public Health's viral hepatitis registry were matched at the person-level to the city's shelter, jail, and mental health system datasets (vulnerability datasets), and descriptive statistics were calculated. Between January 2010 and December 2014, 29,807 cases of HCV and 133 cases of HBV/HCV were reported. Fifty-eight percent of HCV cases and 70% of HBV/HCV cases were found in at least one vulnerability dataset. Compared with HCV cases, HBV/HCV cases were more likely to have a mental health diagnosis and history of incarceration, and to have spent more days in jail, and were less likely to be receiving treatment for HCV. Data are needed to describe more adequately the trajectory of HBV/HCV co-infected individuals to improve health service planning and policy.

Beyond the walls: Risk factors for overdose mortality following release from the Philadelphia Department of Prisons.

BACKGROUND: High overdose mortality after release from state prison systems is well documented; however, little is known about overdose mortality following release from local criminal justice systems (CJS). The purpose of this study was to assess overdose mortality following release from a local CJS in Philadelphia, PA. METHODS: We conducted a retrospective cohort study of individuals released to the community from a local CJS between 2010 and 2016. Incarceration records were linked to overdose fatality data from the Medical Examiner's Office and death certificate records. All-cause, overdose, and non-overdose mortality were examined. RESULTS: Of the 82,780 individuals released between 2010 and 2016, 2,522 (3%) died from any cause, of which 837 (33%) succumbed to overdose. Individuals released from incarceration had higher risk of overdose death compared to the non-incarcerated population (Standardized Mortality Ratio [SMR]: 5.29, 95% CI 4.93-5.65), and risk was greatest during the first two weeks following release (SMR: 36.91, 95% CI: 29.92-43.90). Among released individuals, black, non-Hispanic individuals (Hazard Rate [HR]: 0.17, 95% CI: 0.14-0.19) and Hispanic individuals (HR: 0.41, 95% CI: 0.34-0.50) were at lower risk for overdose than white, non-Hispanic individuals. Individuals released with a serious mental illness (SMI) were at higher risk of overdose (HR: 1.54, 95% CI: 1.27-1.87) than those without a SMI. DISCUSSION: Previously incarcerated individuals are at high risk of overdose death following release from a local CJS, especially in the earliest weeks following release. Prevention measures including behavioral health treatment and referral and take-home naloxone may reduce overdose mortality after release.

Influence of birth origin and risk factor profile on hepatitis B mortality: Philadelphia, PA 2003-2013.

PURPOSE: Chronic hepatitis B virus (HBV) affects specific subpopulations in the United States, including individuals born in HBV-endemic countries and persons engaging in high-risk behaviors. METHODS: The 2003-2013 HBV registry data and surveillance investigations for Philadelphia, PA were matched to death certificate data to examine demographic, risk factor, and cause of death characteristics among HBV-infected populations. Bivariate analysis compared investigated foreign-born (FB) and US-born chronic HBV individuals. Multivariable logistic regression assessed associations between HBV-status, birth origin, demographic information, and liver-related death. RESULTS: Of 773 investigated HBV-infected individuals, 159 were US-born and 614 were FB and of primarily non-Hispanic Asian descent. Behavioral risk factors were more often reported by US-born individuals. HBV-infected FB decedents were twice as likely as US-born decedents to have a liver-related cause of death, whereas HIV/AIDS and drug overdose were more likely causes of death among those born in the United States. CONCLUSIONS: There are two HBV-infected populations in Philadelphia: 1) FB individuals most likely infected at birth or during early childhood and 2) US-born individuals with behaviors suggestive of risk-related HBV acquisition. These findings illustrate the need for both FB and US-born individuals with ongoing risk behaviors to receive routine HBV screening, vaccination if indicated, and medical care for outcomes of chronic HBV infection.

Capture-Recapture: Using Existing Data Sources to Improve Perinatal Hepatitis B Surveillance, Philadelphia, 2008-2014.

OBJECTIVE: The objective of this study was to describe the capture-recapture method used by the Philadelphia Department of Public Health to enhance surveillance of perinatal hepatitis B virus (HBV), report on results and limitations of the process, and determine why some HBV-positive mother-infant pairs were not initially identified by Philadelphia's Perinatal Hepatitis B Prevention Program (PHBPP). METHODS: We performed capture-recapture retrospectively for births in 2008 and 2009 in Philadelphia and prospectively for births from 2010 to 2014 by independently matching annual birth certificate data to PHBPP and HBV surveillance data. We compared the number of HBV-positive mother-infant pairs identified each year to the point estimates and lower-limit estimates calculated by the Centers for Disease Control and Prevention for the Philadelphia PHBPP. RESULTS: Of 156 605 pregnancy outcomes identified between 2008 and 2014, we found 1549 HBV-positive mother-infant pairs. Of 705 pairs that were initially determined, 358 (50.7%) were confirmed to be previously unidentified HBV-positive pairs. Reasons for failing to identify these mother-infant pairs prior to capture-recapture included internal administrative issues (n = 191, 53.4%), HBV testing and reporting issues (n = 92, 25.7%), and being lost to follow-up (n = 75, 20.9%). Each year that capture-recapture was used, the number of pairs identified by the Philadelphia PHBPP exceeded the Centers for Disease Control and Prevention's lower-limit estimates for HBV-positive mother-infant pairs. CONCLUSIONS: Capture-recapture was useful for identifying HBV-positive pregnant women for Philadelphia's PHBPP and for highlighting inadequacies in health department protocols and HBV testing during pregnancy. Other health departments with access to similar data sources and staff members with the necessary technical skills can adapt this method.

Integrating Routine HCV Testing in Primary Care: Lessons Learned from Five Federally Qualified Health Centers in Philadelphia, Pennsylvania, 2012-2014.

OBJECTIVE: An estimated 2.7-3.9 million Americans are infected with hepatitis C virus (HCV). Despite being the most common blood-borne virus in the United States, routine HCV testing is not commonly practiced. To address this gap, we measured the impact of integrated routine HCV testing on patient care. METHODS: As part of CDC's Hepatitis Testing and Linkage to Care initiative, which promoted viral hepatitis B and hepatitis C screening, posttest counseling, and linkage to care at 34 U.S. sites, National Nursing Centers Consortium integrated a routine opt-out HCV testing and linkage-to-care model at five federally qualified health centers in Philadelphia, Pennsylvania, from October 1, 2012, to June 30, 2014. The model included medical assistant-initiated testing, reflex laboratory-based HCV tests, and electronic health record modifications to prompt, track, and facilitate reimbursement for tests performed on uninsured patients. RESULTS: During the study period, 4,207 unique patients received HCV antibody (anti-HCV) testing, of whom 488 (11.6%) tested anti-HCV positive. Of those testing positive, 433 (88.7%) received a confirmatory HCV RNA test; of these 433 recipients, 313 (72.3%) were diagnosed with current infection (overall prevalence = 7.4%), of which 243 (77.6%) received their HCV RNA-positive results, 184 (58.8%) were referred to an HCV care provider, and 121 (38.7%) were linked to care. The highest rates of current infection were among non-Hispanic white patients (18.1%, 90/496); patients from the Public Health Management Corporation Care Clinic, which treats HIV and HCV patients on-site (14.3%, 200/1,394); and patients aged 50-69 years (10.7%, 189/1,767). CONCLUSION: Our model successfully integrated HCV testing and linkage to care into routine primary care. This study also identified potential successes and barriers that may be experienced by other primary care health centers that are integrating HCV testing.

Varicella Vaccine Effectiveness in Preventing Community Transmission in the 2-Dose Era.

OBJECTIVES: We examined overall and incremental effectiveness of 2-dose varicella vaccination in preventing community transmission of varicella among children aged 4 to 18 years in 2 active surveillance sites. One-dose varicella vaccine effectiveness (VE) was examined in those aged 1 to 18 years. METHODS: From May 2009 through June 2011, varicella cases identified during active surveillance in Antelope Valley, CA and Philadelphia, PA were enrolled into a matched case-control study. Matched controls within 2 years of the patient's age were selected from immunization registries. A standardized questionnaire was administered to participants' parents, and varicella vaccination history was obtained from health care provider, immunization registry, or parent records. We used conditional logistic regression to estimate varicella VE against clinically diagnosed and laboratory-confirmed varicella. RESULTS: A total of 125 clinically diagnosed varicella cases and 408 matched controls were enrolled. Twenty-nine cases were laboratory confirmed. One-dose VE (1-dose versus unvaccinated) was 75.6% (95% confidence interval [CI], 38.7%-90.3%) in preventing any clinically diagnosed varicella and 78.1% (95% CI, 12.7%-94.5%) against moderate or severe, clinically diagnosed disease (≥50 lesions). Among subjects aged ≥4 years, 2-dose VE (2-dose versus unvaccinated) was 93.6% (95% CI, 75.6%-98.3%) against any varicella and 97.9% (95% CI, 83.0%-99.7%) against moderate or severe varicella. Incremental effectiveness (2-dose versus 1-dose) was 87.5% against clinically diagnosed varicella and 97.3% against laboratory-confirmed varicella. CONCLUSIONS: Two-dose varicella vaccination offered better protection against varicella from community transmission among school-aged children compared with 1-dose vaccination.

Failure to Test and Identify Perinatally Infected Children Born to Hepatitis C Virus-Infected Women.

BACKGROUND: Vertical transmission of hepatitis C virus (HCV) is the most common route of pediatric HCV infection. Approximately 5% of children born to HCV-infected mothers develop chronic infection. Recommendations employ risk-based HCV testing of pregnant women, and screening children at a young age. This study assesses testing rates of children born to mothers tested HCV-positive in a major US city with a high burden of HCV infection. METHODS: HCV surveillance data reported to the Philadelphia Department of Public Health are housed in the Hepatitis Registry. Additional tests, including negative results, were retrospectively collected. HCV data were matched with 2011-2013 birth certificates of children aged ≥20 months to identify mothers tested HCV-positive and screened children. The observed perinatal HCV seropositivity rate was compared to the expected rate (5%). RESULTS: A total of 8119 females aged 12-54 years tested HCV-positive and in the Hepatitis Registry. Of these, 500 (5%) had delivered ≥1 child, accounting for 537 (1%) of the 55 623 children born in Philadelphia during the study period. Eighty-four (16%) of these children had HCV testing; 4 (1% of the total) were confirmed cases. Twenty-three additional children are expected to have chronic HCV infection, but were not identified by 20 months of age. CONCLUSIONS: These findings illustrate that a significant number of women giving birth in Philadelphia test positive for HCV and that most of their at-risk children remain untested. To successfully identify all HCV-infected children and integrate them into HCV-specific care, practices for HCV screening of pregnant women and their children should be improved.

Identification and Linkage to Care of HCV-Infected Persons in Five Health Centers - Philadelphia, Pennsylvania, 2012-2014.

Approximately three million persons in the United States are infected with hepatitis C virus (HCV), a blood-borne pathogen that is an increasing cause of liver disease and mortality in the United States. Treatments for HCV are curative, of short duration, and have few associated side effects, increasing the importance of identifying HCV-infected persons. Many persons with HCV infection were infected decades ago, before implementation of prevention measures and most are unaware of their infection, regardless of when it occurred. Most newly diagnosed cases are associated with injection drug use. Persons born during 1945-1965 have a fivefold higher risk of HCV infection than other adults and the highest risk for HCV-related morbidity and mortality. CDC recommends testing for this group, for persons who inject drugs, and others at risk for HCV infection. From October 2012 through July 2014, the National Nursing Centers Consortium (NNCC) carried out a project to integrate routine HCV testing and linkage-to-care in five federally qualified health centers in Philadelphia, PA, that primarily serve homeless persons and public housing residents. During the project period, 4,514 patients across the five centers were tested for HCV. Of these, 595 (13.2%) were HCV-antibody positive and 550 (92.4%) had a confirmatory HCV-RNA test performed. Of those who had a confirmatory HCV-RNA test performed, 390 (70.9%) were identified as having current (i.e., chronic) HCV infection (overall prevalence = 8.6%). Of those currently infected with HCV, 90% were informed of their status, 78% were referred to an HCV care specialist, and 62% went to the referred specialist for care. Replicable system modifications that improved HCV testing and care included enhancements to electronic medical records (EMRs), simplification of HCV testing protocols, and addition of a linkage-to-care coordinator. Findings from this project highlight the need for innovative strategies for HCV testing, care, and treatment, as well as the important role of community health centers in expanding access for patient populations disproportionately affected by HCV infection.

Comparison of risk-based hepatitis C screening and the true seroprevalence in an urban prison system.

Hepatitis C virus (HCV) is the most common blood-borne infection in the USA, though seroprevalence is elevated in certain high-risk groups such as inmates. Correctional facility screening protocols vary from universal testing to opt-in risk-based testing. This project assessed the success of a risk-based HCV screening strategy in the Philadelphia Prison System (PPS) by comparing results from current testing practices during 2011-2012 (Risk-Based Screening Group) to a September 2012 blinded seroprevalence study (Philadelphia Department of Public Health (PDPH) Study Cohort). PPS processed 51,562 inmates in 2011-2012; 2,727 were identified as high-risk and screened for HCV, of whom 57 % tested HCV antibody positive. Twelve percent (n = 154) of the 1,289 inmates in the PDPH Study Cohort were anti-HCV positive. Inmates ≥30 years of age had higher rates of seropositivity in both groups. Since only 5.3 % of the prison population was included in the Risk-Based Screening Group, an additional 4,877 HCV-positive inmates are projected to have not been identified in 2011-2012. Gaps in case identification exist when risk-based testing is utilized by PPS. A more comprehensive screening model such as opt-out universal testing should be considered to identify HCV-positive inmates. Identification of these individuals is an important opportunity to aid underserved high-risk populations and to provide medical care and secondary prevention.