Economic analysis of rapid multiplex polymerase chain reaction testing for meningitis/encephalitis in adult patients.

PURPOSE: Many patients with suspected meningitis do not require hospitalization yet are admitted, often resulting in unnecessary care and additional cost. We assessed the possible economic impact of a rapid multiplex test for suspected adult community-acquired meningitis/encephalitis. METHODS: A model simulated diagnosis, clinical decisions, resource use/costs of standard of care (SOC) and two cerebrospinal fluid (CSF) testing strategies using the FDA-cleared BioFire® FilmArray® System (FA) which provides results in approximately one hour. RESULTS: Pathogens detected by FA caused approximately 74% of cases, 97% of which would be accurately diagnosed with FA. False positives and false negatives more often led to extended/unnecessary admission than inappropriate discharge/missed admission. Mean cost per case ranged from 16829 to 20791. A strategy of testing all suspected cases yielded greater savings (2213/case) than testing only those with abnormal CSF (812/case) and both were less expensive than SOC. CONCLUSION: This economic analysis demonstrates that FA can inform more appropriate clinician decisions resulting in cost savings with greater economic benefits achievable with syndromic testing of all cases, rather than SOC or targeted syndromic testing.

Efficacy of Infliximab, Abatacept, and Cenicriviroc for the Treatment of Adults Hospitalized with COVID-19 Pneumonia.

A randomized, double-blind, placebo-controlled clinical trial was conducted to investigate the efficacy of infliximab, abatacept, and cenicriviroc in treating patients hospitalized with COVID-19. The patient's clinical status was assessed daily on an 8-point ordinal scale. We evaluated the totality of evidence on the efficacy of the 3 immunomodulators by considering all possible changes in the clinical status of each patient over time. We demonstrated that infliximab accelerated improvement and reduced deterioration of clinical status when added to standard of care. There was also evidence for the benefit of abatacept. There was no evidence for the benefit of cenicriviroc.

Abatacept for Treatment of Adults Hospitalized with Moderate or Severe Covid-19.

Background: We investigated whether abatacept, a selective costimulation modulator, provides additional benefit when added to standard-of-care for patients hospitalized with Covid-19. Methods: We conducted a master protocol to investigate immunomodulators for potential benefit treating patients hospitalized with Covid-19 and report results for abatacept. Intravenous abatacept (one-time dose 10 mg/kg, maximum dose 1000 mg) plus standard of care (SOC) was compared with shared placebo plus SOC. Primary outcome was time-to-recovery by day 28. Key secondary endpoints included 28-day mortality. Results: Between October 16, 2020 and December 31, 2021, a total of 1019 participants received study treatment (509 abatacept; 510 shared placebo), constituting the modified intention-to-treat cohort. Participants had a mean age 54.8 (SD 14.6) years, 60.5% were male, 44.2% Hispanic/Latino and 13.7% Black. No statistically significant difference for the primary endpoint of time-to-recovery was found with a recovery-rate-ratio of 1.14 (95% CI 1.00-1.29; p=0.057) compared with placebo. We observed a substantial improvement in 28-day all-cause mortality with abatacept versus placebo (11.0% vs. 15.1%; odds ratio [OR] 0.62 [95% CI 0.41- 0.94]), leading to 38% lower odds of dying. Improvement in mortality occurred for participants requiring oxygen/noninvasive ventilation at randomization. Subgroup analysis identified the strongest effect in those with baseline C-reactive protein >75mg/L. We found no statistically significant differences in adverse events, with safety composite index slightly favoring abatacept. Rates of secondary infections were similar (16.1% for abatacept; 14.3% for placebo). Conclusions: Addition of single-dose intravenous abatacept to standard-of-care demonstrated no statistically significant change in time-to-recovery, but improved 28-day mortality. Trial registration: ClinicalTrials.gov ( NCT04593940 ).

Infliximab for Treatment of Adults Hospitalized with Moderate or Severe Covid-19.

Background: Immune dysregulation contributes to poorer outcomes in severe Covid-19. Immunomodulators targeting various pathways have improved outcomes. We investigated whether infliximab provides benefit over standard of care. Methods: We conducted a master protocol investigating immunomodulators for potential benefit in treatment of participants hospitalized with Covid-19 pneumonia. We report results for infliximab (single dose infusion) versus shared placebo both with standard of care. Primary outcome was time to recovery by day 29 (28 days after randomization). Key secondary endpoints included 14-day clinical status and 28-day mortality. Results: A total of 1033 participants received study drug (517 infliximab, 516 placebo). Mean age was 54.8 years, 60.3% were male, 48.6% Hispanic or Latino, and 14% Black. No statistically significant difference in the primary endpoint was seen with infliximab compared with placebo (recovery rate ratio 1.13, 95% CI 0.99-1.29; p=0.063). Median (IQR) time to recovery was 8 days (7, 9) for infliximab and 9 days (8, 10) for placebo. Participants assigned to infliximab were more likely to have an improved clinical status at day 14 (OR 1.32, 95% CI 1.05-1.66). Twenty-eight-day mortality was 10.1% with infliximab versus 14.5% with placebo, with 41% lower odds of dying in those receiving infliximab (OR 0.59, 95% CI 0.39-0.90). No differences in risk of serious adverse events including secondary infections. Conclusions: Infliximab did not demonstrate statistically significant improvement in time to recovery. It was associated with improved 14-day clinical status and substantial reduction in 28- day mortality compared with standard of care. Trial registration: ClinicalTrials.gov ( NCT04593940 ).

Economic analysis of rapid multiplex polymerase chain reaction testing for meningitis/encephalitis in pediatric patients.

AIM: We assessed the possible economic impact of a rapid test in pediatric patients with suspected community-acquired meningitis/encephalitis. MATERIALS & METHODS: Modeling simulated diagnosis, clinical decisions, resource use/costs of standard of care (SOC) and two cerebrospinal fluid testing strategies using FilmArray® (FA), a US FDA-cleared system that provides results in approximately 1 h. RESULTS: Pathogens detected by FA caused approximately 75% of cases, 97% of which would be accurately diagnosed with FA.  Mean cost/case ranged from $17,599 to $22,025.  Syndromic testing is less expensive than SOC. Testing all suspected cases yielded greater savings ($3481/case) than testing only those with abnormal cerebrospinal fluid ($2157/case). CONCLUSION: Greater economic benefits are achievable with syndromic testing of all cases, rather than SOC or targeted syndromic testing.

Cardiovascular and cerebrovascular events in patients treated for human immunodeficiency virus infection.

BACKGROUND: Metabolic abnormalities associated with human immunodeficiency virus (HIV) infection, including dysglycemia and hyperlipidemia, are increasingly prevalent, and there is concern about the possibility of an association with accelerated cardiovascular and cerebrovascular disease. METHODS: We conducted a retrospective study of the risk of cardiovascular and cerebrovascular disease among the 36,766 patients who received care for HIV infection at Veterans Affairs facilities between January 1993 and June 2001. RESULTS: For antiretroviral therapy, 70.2 percent of the patients received nucleoside analogues, 41.6 percent received protease inhibitors, and 25.6 percent received nonnucleoside reverse-transcriptase inhibitors for a median of 17 months, 16 months, and 9 months, respectively. Approximately 1000 patients received combination therapy with a protease inhibitor for at least 48 months, and approximately 1000 patients received combination therapy with a nonnucleoside reverse-transcriptase inhibitor for at least 24 months. Between 1995 and 2001, the rate of admissions for cardiovascular or cerebrovascular disease decreased from 1.7 to 0.9 per 100 patient-years, and the rate of death from any cause decreased from 21.3 to 5.0 deaths per 100 patient-years. Patient-level regression analyses indicated that there was no relation between the use of nucleoside analogues, protease inhibitors, or nonnucleoside reverse-transcriptase inhibitors and the hazard of cardiovascular or cerebrovascular events, but the use of antiretroviral drugs was associated with a decreased hazard of death from any cause. CONCLUSIONS: Use of newer therapies for HIV was associated with a large benefit in terms of mortality that was not diminished by any increase in the rate of cardiovascular or cerebrovascular events or related mortality. Fear of accelerated vascular disease need not compromise antiretroviral therapy over the short term. However, prolonged survival among HIV infected patients means that longer-term observation and analysis are required.

A model for a smallpox-vaccination policy.

BACKGROUND: The new reality of biologic terrorism and warfare has ignited a debate about whether to reintroduce smallpox vaccination. METHODS: We developed scenarios of smallpox attacks and built a stochastic model of outcomes under various control policies. We conducted a systematic literature review and estimated model parameters on the basis of European and North American outbreaks since World War II. We assessed the trade-offs between vaccine-related harms and benefits. RESULTS: Nations or terrorists possessing a smallpox weapon could feasibly mount attacks that vary with respect to tactical complexity and target size, and patterns of spread can be expected to vary according to whether index patients are hospitalized early. For acceptable results, vaccination of contacts must be accompanied by effective isolation. Vaccination of contacts plus isolation is expected to result in 7 deaths (from vaccine or smallpox) in a scenario involving the release of variola virus from a laboratory, 19 deaths in a human-vector scenario, 300 deaths in a building-attack scenario, 2735 deaths in a scenario involving a low-impact airport attack, and 54,729 deaths in a scenario involving a high-impact airport attack. Immediate vaccination of the public in an attacked region would provide little additional benefit. Prior vaccination of health care workers, who would be disproportionately affected, would save lives in large local or national attacks but would cause 25 deaths nationally. Prior vaccination of health care workers and the public would save lives in a national attack but would cause 482 deaths nationally. The expected net benefits of vaccination depend on the assessed probability of an attack. Prior vaccination of health care workers would be expected to save lives if the probability of a building attack exceeded 0.22 or if the probability of a high-impact airport attack exceeded 0.002. The probability would have to be much higher to make vaccination of the public life-saving. CONCLUSIONS: The analysis favors prior vaccination of health care workers unless the likelihood of any attack is very low, but it favors vaccination of the public only if the likelihood of a national attack or of multiple attacks is high.

Participation in research and access to experimental treatments by HIV-infected patients.

BACKGROUND: Although there is concern that minority groups and women are underrepresented in research involving patients with human immunodeficiency virus (HIV) infection, the available data are inconclusive. METHODS: We used nationally representative data from the HIV Cost and Services Utilization Study to determine the characteristics of the participants and nonparticipants in trials of medications for HIV infection and whether or not patients had access to experimental treatments. A probability sample of 2864 persons, representing all 231,400 adults with known HIV infection who are cared for in the contiguous United States, were interviewed on three occasions between 1996 and 1998. They were asked about participation in clinical research studies of medications and past receipt of experimental medications for HIV. RESULTS: We estimate that 14 percent of adults receiving care for HIV infection participated in a medication trial or study; 24 percent had received experimental medications; and 8 percent had tried and failed to obtain experimental treatments. According to multivariate models, non-Hispanic blacks and Hispanics were less likely to be participating in trials than non-Hispanic whites (odds ratio for participation among non-Hispanic blacks, 0.50 [95 percent confidence interval, 0.28 to 0.91]; odds ratio among Hispanics, 0.58 [95 percent confidence interval, 0.37 to 0.93]) and to have received experimental medications (odds ratios, 0.41 [95 percent confidence interval, 0.32 to 0.54] and 0.56 [95 percent confidence interval, 0.41 to 0.78], respectively). Patients who were cared for in private health maintenance organizations were less likely to participate in trials than those with fee-for-service insurance (odds ratio, 0.43 [95 percent confidence interval, 0.21 to 0.88]). Women were not underrepresented in research trials and had a similar likelihood of receiving experimental treatments. CONCLUSIONS: Among patients with HIV infection, participation in research trials and access to experimental treatment is influenced by race or ethnic group and type of health insurance.

HIV testing of at risk patients in a large integrated health care system.

OBJECTIVE: Early identification of HIV infection is critical for patients to receive life-prolonging treatment and risk-reduction counseling. Understanding HIV screening practices and barriers to HIV testing is an important prelude to designing successful HIV screening programs. Our objective was to evaluate current practice patterns for identification of HIV. METHODS: We used a retrospective cohort analysis of 13,991 at-risk patients seen at 4 large Department of Veterans Affairs (VA) health-care systems. We also reviewed 1,100 medical records of tested patients. We assessed HIV testing rates among at-risk patients, the rationale for HIV testing, and predictors of HIV testing and of HIV infection. RESULTS: Of the 13,991 patients at risk for HIV, only 36% had been HIV-tested. The prevalence of HIV ranged from 1% to 20% among tested patients at the 4 sites. Approximately 90% of patients who were tested had a documented reason for testing. CONCLUSION: One-half to two-thirds of patients at risk for HIV had not been tested within our selected VA sites. Among tested patients, the rationale for HIV testing was well documented. Further testing of at-risk patients could clearly benefit patients who have unidentified HIV infection by providing earlier access to life-prolonging therapy.

Prevalence of HIV infection among inpatients and outpatients in Department of Veterans Affairs health care systems: implications for screening programs for HIV.

OBJECTIVES: We sought to determine the prevalence of HIV in both inpatient and outpatient settings in 6 Department of Veterans Affairs (VA) health care sites. METHODS: We collected demographic data and data on comorbid conditions and then conducted blinded, anonymous HIV testing. We conducted a multivariate analysis to determine predictors of HIV infection. RESULTS: We tested 4500 outpatient blood specimens and 4205 inpatient blood specimens; 326 (3.7%) patients tested positive for HIV. Inpatient HIV prevalence ranged from 1.2% to 6.9%; outpatient HIV prevalence ranged from 0.9% to 8.9%. Having a history of hepatitis B or C infection, a sexually transmitted disease, or pneumonia also predicted HIV infection. The prevalence of previously undocumented HIV infection varied from 0.1% to 2.8% among outpatients and from 0.0% to 1.7% among inpatients. CONCLUSIONS: The prevalence of undocumented HIV infection was sufficiently high for routine voluntary screening to be cost effective in each of the 6 sites we evaluated. Many VA health care systems should consider expanded routine voluntary HIV screening.

Non-pharmaceutical public health interventions for pandemic influenza: an evaluation of the evidence base.

BACKGROUND: In an influenza pandemic, the benefit of vaccines and antiviral medications will be constrained by limitations on supplies and effectiveness. Non-pharmaceutical public health interventions will therefore be vital in curtailing disease spread. However, the most comprehensive assessments of the literature to date recognize the generally poor quality of evidence on which to base non-pharmaceutical pandemic planning decisions. In light of the need to prepare for a possible pandemic despite concerns about the poor quality of the literature, combining available evidence with expert opinion about the relative merits of non-pharmaceutical interventions for pandemic influenza may lead to a more informed and widely accepted set of recommendations. We evaluated the evidence base for non-pharmaceutical public health interventions. Then, based on the collective evidence, we identified a set of recommendations for and against interventions that are specific to both the setting in which an intervention may be used and the pandemic phase, and which can be used by policymakers to prepare for a pandemic until scientific evidence can definitively respond to planners' needs. METHODS: Building on reviews of past pandemics and recent historical inquiries, we evaluated the relative merits of non-pharmaceutical interventions by combining available evidence from the literature with qualitative and quantitative expert opinion. Specifically, we reviewed the recent scientific literature regarding the prevention of human-to-human transmission of pandemic influenza, convened a meeting of experts from multiple disciplines, and elicited expert recommendation about the use of non-pharmaceutical public health interventions in a variety of settings (healthcare facilities; community-based institutions; private households) and pandemic phases (no pandemic; no US pandemic; early localized US pandemic; advanced US pandemic). RESULTS: The literature contained a dearth of evidence on the efficacy or effectiveness of most non-pharmaceutical interventions for influenza. In an effort to inform decision-making in the absence of strong scientific evidence, the experts ultimately endorsed hand hygiene and respiratory etiquette, surveillance and case reporting, and rapid viral diagnosis in all settings and during all pandemic phases. They also encouraged patient and provider use of masks and other personal protective equipment as well as voluntary self-isolation of patients during all pandemic phases. Other non-pharmaceutical interventions including mask-use and other personal protective equipment for the general public, school and workplace closures early in an epidemic, and mandatory travel restrictions were rejected as likely to be ineffective, infeasible, or unacceptable to the public. CONCLUSION: The demand for scientific evidence on non-pharmaceutical public health interventions for influenza is pervasive, and present policy recommendations must rely heavily on expert judgment. In the absence of a definitive science base, our assessment of the evidence identified areas for further investigation as well as non-pharmaceutical public health interventions that experts believe are likely to be beneficial, feasible and widely acceptable in an influenza pandemic.

Effect of Procalcitonin Testing on Health-care Utilization and Costs in Critically Ill Patients in the United States.

BACKGROUND: There is a growing use of procalcitonin (PCT) to facilitate the diagnosis and management of severe sepsis. We investigated the impact of one to two PCT determinations on ICU day 1 on health-care utilization and cost in a large research database. METHODS: A retrospective, propensity score-matched multivariable analysis was performed on the Premier Healthcare Database for patients admitted to the ICU with one to two PCT evaluations on day 1 of ICU admission vs patients who did not have PCT testing. RESULTS: A total of 33,569 PCT-managed patients were compared with 98,543 propensity score-matched non-PCT patients. In multivariable regression analysis, PCT utilization was associated with significantly decreased total length of stay (11.6 days [95% CI, 11.4 to 11.7] vs 12.7 days [95% CI, 12.6 to 12.8]; 95% CI for difference, 1 to 1.3; P < .001) and ICU length of stay (5.1 days [95% CI, 5.1 to 5.2] vs 5.3 days [95% CI, 5.3 to 5.4]; 95% CI for difference, 0.1 to 0.3; P < .03), and lower hospital costs ($30,454 [95% CI, 29,968 to 31,033] vs $33,213 [95% CI, 32,964 to 33,556); 95% CI for difference, 2,159 to 3,321; P < .001). There was significantly less total antibiotic exposure (16.2 days [95% CI, 16.1 to 16.5] vs 16.9 days [95% CI, 16.8 to 17.1]; 95% CI for difference, -0.9 to 0.4; P = .006) in PCT-managed patients. Patients in the PCT group were more likely to be discharged to home (44.1% [95% CI, 43.7 to 44.6] vs 41.3% [95% CI, 41 to 41.6]; 95% CI for difference, 2.3 to 3.3; P = .006). Mortality was not different in an analysis including the 96% of patients who had an independent measure of mortality risk available (19.1% [95% CI, 18.7 to 19.4] vs 19.1% [95% CI, 18.9 to 19.3]; 95% CI for difference, -0.5 to 0.4; P = .93). CONCLUSIONS: Use of PCT testing on the first day of ICU admission was associated with significantly lower hospital and ICU lengths of stay, as well as decreased total, ICU, and pharmacy cost of care. Further elucidation of clinical outcomes requires additional data.

Transmission patterns of smallpox: systematic review of natural outbreaks in Europe and North America since World War II.

BACKGROUND: Because smallpox (variola major) may be used as a biological weapon, we reviewed outbreaks in post-World War II Europe and North America in order to understand smallpox transmission patterns. METHODS: A systematic review was used to identify papers from the National Library of Medicine, Embase, Biosis, Cochrane Library, Defense Technical Information Center, WorldCat, and reference lists of included publications. Two authors reviewed selected papers for smallpox outbreaks. RESULTS: 51 relevant outbreaks were identified from 1,389 publications. The median for the effective first generation reproduction rate (initial R) was 2 (range 0-38). The majority outbreaks were small (less than 5 cases) and contained within one generation. Outbreaks with few hospitalized patients had low initial R values (median of 1) and were prolonged if not initially recognized (median of 3 generations); outbreaks with mostly hospitalized patients had higher initial R values (median 12) and were shorter (median of 3 generations). Index cases with an atypical presentation of smallpox were less likely to have been diagnosed with smallpox; outbreaks in which the index case was not correctly diagnosed were larger (median of 27.5 cases) and longer (median of 3 generations) compared to outbreaks in which the index case was correctly diagnosed (median of 3 cases and 1 generation). CONCLUSION: Patterns of spread during Smallpox outbreaks varied with circumstances, but early detection and implementation of control measures is a most important influence on the magnitude of outbreaks. The majority of outbreaks studied in Europe and North America were controlled within a few generations if detected early.

An HIV collaborative in the VHA: do advanced HIT and one-day sessions change the collaborative experience?

BACKGROUND: Many organizations participate in quality collaboratives, yet the return on investment of the associated time and costs is unclear. METHOD: Semistructured interviews, surveys, and direct observation were used to assess experiences, improvement activities, and costs associated with participation in a year-long modified Institute for Healthcare Improvement-style collaborative designed to improve HIV care within the Veterans Health Administration. All nine sites had access to automated patient registries and semi-automated clinical measure reports; five sites also received computerized clinical reminders. Three one-day learning sessions were conducted. RESULTS: Participants reported that burden was small and value high, although many suggested that more time for peer-to peer learning would have been helpful. Teams averaged five quality improvement activities per site and most reported improvements in HIV care processes. The average annual cost per site was dollars 28,000 but costs varied considerably by site. DISCUSSION: Shortened learning sessions and the incorporation of health information technology can reduce some of the costs and burdens associated with collaboratives, yet peer-to-peer interaction and local organizational factors remain important to ensuring perceived effectiveness of collaboratives.

Creating a crosswalk to estimate AIDS Clinical Trials Group quality of life scores in a nationally representative sample of persons in care for HIV in the United States.

BACKGROUND: Optimizing health-related quality of life (HRQOL) is an increasingly important goal in the treatment of HIV/AIDS. Interpretation of HRQOL scores in clinical trials is enhanced by comparative data. PURPOSE: To estimate AIDS Clinical Trials Group (ACTG) QOL 601-602 questionnaire scale scores for a nationally representative sample of persons in care for HIV. METHOD: The study cohort was from the HIV Cost and Services Utilization Study (HCSUS), a multistage national probability sample. We derived HCSUS HRQOL scale scores from the items shared between the ACTG QOL 601-602 and HCSUS HRQOL questionnaires using regression equations. Cronbach's alpha coefficient was used to estimate the reliability of the multi-item scales in the ACTG QOL 601-602 and HCSUS HRQOL instruments. Correlation Coefficients and R2s of regression models were calculated to determine the concordance of the models. Multiple regression was used to determine if patient characteristics accounted for differences (residuals) between scores observed from the full HCSUS HRQOL instruments and scores predicted using the subset of shared items in ACTG QOL 601-2. RESULTS: Internal consistency reliability estimates were acceptable (>0.70) for all scales in the ACTG QOL 601-602 and HCSUS HRQOL instruments. Correlations between corresponding ACTG QOL 601-602 and HCSUS HRQOL scale scores were high (>0.9). The R2s for predicting HCSUS HRQOL scores from the ACTG QOL 601-602 scales were also high (>0.8). For physical functioning, emotional well-being, and general health perceptions, the predictors of differences (residuals) in observed and predicted HCSUS HRQOL scores were gender and CDC stage of HIV infection (P < .05). CONCLUSION: This study provides normative data from the US HIV/AIDS population for comparison to the ACTG QOL 601-602 questionnaire. Accuracy of estimation is enhanced if done separately by gender and HIV disease stage.

The effect of socioeconomic status on the survival of people receiving care for HIV infection in the United States.

HIV-infected people with low socioeconomic status (SES) and people who are members of a racial or ethnic minority have been found to receive fewer services, including treatment with Highly Active Antiretroviral Therapy (HAART), than others. We examined whether these groups also have worse survival than others and the degree to which service use and antiretroviral medications explain these disparities in a prospective cohort study of a national probability sample of 2,864 adults receiving HIV care. The independent variables were wealth (net accumulated financial assets), annual income, educational attainment, employment status (currently working or not working), race/ethnicity, insurance status, use of services, and use of medications at baseline. The main outcome variable was death between January 1996 and December 2000. The analysis was descriptive and multivariate adjusted Cox proportional hazards regression analysis of survival. By December 2000, 20% (13% from HIV, 7% non-HIV causes) of the sample had died. Those with no accumulated financial assets had an 89% greater risk of death (RR=1.89, 95% CI=1.15-3.13) and those with less than a high school education had a 53% greater risk of death (RR=1.53, 95% CI=1.15-2.04 ) than their counterparts, after adjusting for sociodemographic and clinical variables only. Further adjusting for use of services and antiretroviral treatment diminished, but did not eliminate, the elevated relative risk of death for those with low SES by three of the four measures. The finding of markedly elevated relative risks of death for those with HIV infection and low SES is of particular concern given the disproportionate rates of HIV infection in these groups. Effective interventions are needed to improve outcomes for low SES groups with HIV infection.

HIV laboratory monitoring reliably identifies persons engaged in care.

BACKGROUND: Attendance at biannual medical encounters has been proposed as a minimum national standard for adequate engagement in HIV care. Using data from the HIV Outpatient Study, we analyzed how well dates of HIV-related laboratory testing correlated with attendance at biannual medical encounters. METHODS: HIV Outpatient Study is an open prospective cohort study of HIV-infected patients receiving outpatient care in the United States. The data set included dates for laboratory measurements and medical encounters. We included patients with at least 1 HIV laboratory test (CD4 cell count or plasma HIV RNA viral load) during 2010-2011. An HIV laboratory test was defined as associated with a medical encounter if it occurred within 3 weeks of the encounter. We assessed the predictive value of HIV laboratory tests as a proxy for adequate engagement in clinical care, defined as having had ≥2 HIV laboratory tests within 1 year and performed >90 days apart. RESULTS: A total of 10,321 HIV laboratory tests were recorded from 2909 patients. Adequate engagement in clinical care based on medical encounters was 88.2% and 77.3% when based on laboratory tests. Using HIV laboratory tests to assess engagement had a sensitivity of 85.7%, specificity of 86.0%, and positive and negative predictive values of 97.9% and 44.5%, respectively. Of the 22.7% classified as not engaged in care by the proxy measure, over half (55.5%) were actually engaged. CONCLUSIONS: Using laboratory monitoring reliably classified persons as engaged in care. Of the 22.7% of patients classified as not engaged in care, most were actually engaged.