Papers by Babette Brumback
Critical Care Medicine, 2020
Annals of Surgery, 2020
OBJECTIVE To characterize endothelial function, inflammation, and immunosuppression in surgical p... more OBJECTIVE To characterize endothelial function, inflammation, and immunosuppression in surgical patients with distinct clinical trajectories of AKI and to determine the impact of persistent kidney injury and renal non-recovery on clinical outcomes, resource utilization, and long-term disability and survival. SUMMARY OF BACKGROUND DATA AKI is associated with increased healthcare costs and mortality. Trajectories that account for duration and recovery of AKI have not been described for sepsis patients, who are uniquely vulnerable to renal dysfunction. METHODS This prospective observational study included 239 sepsis patients admitted and enrolled between January 2015 and July 2017. Kidney Disease: Improving Global Outcomes (KDIGO) and Acute Disease Quality Initiative (ADQI) criteria were used to classify subjects as having no AKI, rapidly reversed AKI, persistent AKI with renal recovery, or persistent AKI without renal recovery. Serial biomarker profiles, clinical outcomes, resource utilization, and long-term physical performance status and survival were compared among AKI trajectories. RESULTS Sixty-two percent of the study population developed AKI. Only one-third of AKI episodes rapidly reversed within 48 hours; the remaining had persistent AKI, among which 57% did not have renal recovery by discharge. One-year survival and proportion of subjects fully active 1 year after sepsis was lowest among patients with persistent AKI compared with other groups. Long-term mortality hazard rates were 5-fold higher for persistent AKI without renal recovery compared with no AKI. CONCLUSIONS Among critically ill surgical sepsis patients, persistent AKI and the absence of renal recovery are associated with distinct early and sustained immunologic and endothelial biomarker signatures and decreased long-term physical function and survival.
Journal of Palliative Medicine, 2017
Purpose of report: Understanding the impact of palliative care interventions on intensive care un... more Purpose of report: Understanding the impact of palliative care interventions on intensive care unit (ICU) costs and utilization is critical for demonstrating the value of palliative care. Performing these economic assessments, however, can be challenging. The purpose of this special report is to highlight and discuss important considerations when assessing ICU utilization and costs from the hospital perspective, with the goal of providing recommendations on methods to consider for future analyses. Findings: ICU length of stay (LOS) and associated costs of care are common and important outcome measures, but must be analyzed properly to yield valid conclusions. There is significant variation in costs by day of stay in the ICU with only modest differences between an ICU day at the end of a stay and the first day on the acute care floor; this variation must be appropriately accounted for analytically. Furthermore, reporting direct variable costs, in addition to total ICU costs, is needed to understand short-term and long-term impact of a reduction in LOS. Importantly, incentives for the hospital to realize savings vary depending on reimbursement policies. Summary: ICU utilization and costs are common outcomes in studies evaluating palliative care interventions. Accurate estimation and interpretation are key to understanding the economic implications of palliative care interventions.
Substance Use & Misuse, 2021
Among people living with HIV (PLWH), alcohol use can have negative impacts beyond HIVrelated outc... more Among people living with HIV (PLWH), alcohol use can have negative impacts beyond HIVrelated outcomes. The objectives of this study are to identify the most common alcohol-related consequences among PLWH in Florida and describe factors associated with experiencing more alcohol-related consequences. Data were collected from PLWH in the Florida Cohort study who drank at least monthly in the past year (n=397). Self-reported consequences were assessed by the 15-item Short Inventory of Problems Revised (SIP-2R). Nonparametric tests and a generalized estimating equation model with inverse probability of exposure weighting were used to evaluate associations between the total SIP-2R score and socio-demographics, mental health, and substance use while controlling for alcohol use. Over half (56%) endorsed at least one consequence and 29% endorsed 5 or more consequences. The most common consequences were doing something they regretted and taking foolish risks (both endorsed by 37% of participants), both in the impulse control domain. After controlling for alcohol use and other covariates, homelessness and injection drug use remained significantly associated with greater SIP-2R scores. PLWH who are experiencing homelessness or injecting drugs could benefit from receiving additional screening for alcohol-related consequences if they report any alcohol use.
Innovation in Aging, 2020
As in-hospital sepsis mortality has decreased, more “sepsis survivors” are progressing into poorl... more As in-hospital sepsis mortality has decreased, more “sepsis survivors” are progressing into poorly characterized long-term outcomes. The purpose of this study was to describe the current epidemiology of sepsis in older adults compared to middle-aged and young adults. Design: Prospective longitudinal study with patients categorized into young (≤ 45 years), middle-aged (46-64 years) and older (≥ 65 years) patient groups. 328 sepsis patients were characterized by a) baseline demographics and predisposition factors, b) septic event, c) hospital outcomes and discharge disposition, d) 12-month mortality and e) Zubrod Performance status, physical function and cognitive function at three, six and 12-month follow-up. Follow-up visits were not completed due to death (in 68) and withdrawal of consent (in 32). Compared to young and middle-aged patients, older patients had: 1) significantly more comorbidities at presentation (example chronic renal disease 6% vs 12 % vs 21%), intra-abdominal infe...
Journal of the Pediatric Infectious Diseases Society, 2020
Background Guidelines assume children with chronic lung disease (CLD) who require medical support... more Background Guidelines assume children with chronic lung disease (CLD) who require medical support within 6 months before the second respiratory syncytial virus (RSV) season remains at high risk of severe RSV disease. We determined the number of days since the last treatment (DSL) when the risk of RSV hospitalization among children with CLD becomes equivalent to the risk for those not qualified for immunoprophylaxis. Methods The study cohort was assembled using Medicaid billing records from 1999 to 2010 linked to Florida and Texas birth certificate records. We developed DSL-trend discrete time logistic regression models within a survival analysis framework, adjusting for use of immunoprophylaxis, to compare the hospitalization risk of CLD infants at 4 age points to that of term infants at 1 month of age with siblings. Results The study cohort included 858 830 healthy term and 5562 preterm infants with CLD. Among 1-month-old term infants, the RSV hospitalization risk averaged across a...
Journal of the American Medical Informatics Association, 2019
Objective In the context of patient broad consent for future research uses of their identifiable ... more Objective In the context of patient broad consent for future research uses of their identifiable health record data, we compare the effectiveness of interactive trust-enhanced e-consent, interactive-only e-consent, and standard e-consent (no interactivity, no trust enhancement). Materials and Methods A randomized trial was conducted involving adult participants making a scheduled primary care visit. Participants were randomized into 1 of the 3 e-consent conditions. Primary outcomes were patient-reported satisfaction with and subjective understanding of the e-consent. Secondary outcomes were objective knowledge, perceived voluntariness, trust in medical researchers, consent decision, and time spent using the application. Outcomes were assessed immediately after use of the e-consent and at 1-week follow-up. Results Across all conditions, participants (N = 734) reported moderate-to-high satisfaction with consent (mean 4.3 of 5) and subjective understanding (79.1 of 100). Over 94% agree...
American Journal of Health-System Pharmacy, 2018
Purpose. Construction and validation of a fall risk prediction model specific to inpatients recei... more Purpose. Construction and validation of a fall risk prediction model specific to inpatients receiving fall risk-increasing drugs (FRIDs) are described. Methods. In a retrospective cohort study of 75,036 admissions to 2 hospitals over a designated 22-month period that involved FRID exposure during the first 5 hospital days, factors influencing fall risk were investigated via logistic regression. The resultant risk prediction model was internally validated and its performance compared with that of a model based on Morse Fall Scale (MFS) scores. Results. A total of 220,904 patient-days of FRID exposure were evaluated. The three most commonly administered FRIDs were oxycodone (given on 79,697 patient-days, 36.08%), morphine (52,427, 23.73%) and hydromorphone (42,063, 19.04%). Within the 90th percentile of modeled risk scores, 144 of the 466 documented falls (30.9%) were captured by the developed risk prediction model (unbiased C statistic, 0.69), as compared with 94 falls (20.2%) captured using the MFS model (unbiased C statistic, 0.62). Strong predictors of inpatient falls included a history of falling (odds ratio [OR], 1.99; 95% confidence interval (CI), 1.42-2.80); overestimation of ability to ambulate (OR, 1.53; 95% CI, 1.12-2.09); and "comorbidity predisposition," a composite measure encompassing a history of falling and 11 past diagnoses (OR, 1.60; 95% CI, 1.30-1.97). Conclusion. The proposed risk model for inpatient falls achieved superior predictive performance when compared with the MFS model. All risk factors were operationalized from discrete electronic health record fields, allowing full automation of real-time identification of high-risk patients.
BMJ open, 2017
Sepsis is a common, costly and morbid cause of critical illness in trauma and surgical patients. ... more Sepsis is a common, costly and morbid cause of critical illness in trauma and surgical patients. Ongoing advances in sepsis resuscitation and critical care support strategies have led to improved in-hospital mortality. However, these patients now survive to enter state of chronic critical illness (CCI), persistent low-grade organ dysfunction and poor long-term outcomes driven by the persistent inflammation, immunosuppression and catabolism syndrome (PICS). The Sepsis and Critical Illness Research Center (SCIRC) was created to provide a platform by which the prevalence and pathogenesis of CCI and PICS may be understood at a mechanistic level across multiple medical disciplines, leading to the development of novel management strategies and targeted therapies. Here, we describe the design, study cohort and standard operating procedures used in the prospective study of human sepsis at a level 1 trauma centre and tertiary care hospital providing care for over 2600 critically ill patients...
BMC pregnancy and childbirth, Jan 6, 2017
Application of latent variable models in medical research are becoming increasingly popular. A la... more Application of latent variable models in medical research are becoming increasingly popular. A latent trait model is developed to combine rare birth defect outcomes in an index of infant morbidity. This study employed four statewide, retrospective 10-year data sources (1999 to 2009). The study cohort consisted of all female Florida Medicaid enrollees who delivered a live singleton infant during study period. Drug exposure was defined as any exposure to Antiepileptic drugs (AEDs) during pregnancy. Mothers with no AED exposure served as the AED unexposed group for comparison. Four adverse outcomes, birth defect (BD), abnormal condition of new born (ACNB), low birth weight (LBW), and pregnancy and obstetrical complication (PCOC), were examined and combined using a latent trait model to generate an overall severity index. Unidimentionality, local independence, internal homogeneity, and construct validity were evaluated for the combined outcome. The study cohort consisted of 3183 mother-...
Journal of Adolescence, 2005
Predictors of perceived family bonds were examined among homeless young people who initially left... more Predictors of perceived family bonds were examined among homeless young people who initially left home one year earlier. Newly homeless young people aged 12-20 years who had recently left home were recruited in Los Angeles County, United States (n ¼ 201) and Melbourne, Australia (n ¼ 124) and followed longitudinally at 3, 6, and 12 months (follow-up rates ranging from 72% to 86% overall). These homeless young people varied substantially in their bonds to their families. Family bonds at one year were predicted in multivariate regression analyses by having significantly fewer problem behaviours when leaving home and decreasing rates of problem behaviours over the next year. Having more emotional support and more instrumental financial support were also significantly associated with greater family bonds one year later. These results suggest that efforts to reunite families may be a viable intervention strategy for newly homeless young people.
International Journal of Epidemiology, 2002
Following a long history of informal use in path analysis, causal diagrams (graphical causal mode... more Following a long history of informal use in path analysis, causal diagrams (graphical causal models) saw an explosion of theoretical development during the 1990s, 1-3 including elaboration of connections to other methods for causal modelling. The latter connections are especially valuable for those familiar with some but not all methods, as certain background assumptions and sources of bias are more easily seen with certain models, whereas practical statistical procedures may be more easily derived under other models. We provide here a brief overview of graphical causal models, 1-6 the sufficient-component cause (SCC) models of Rothman, 7,8 Ch. 2 the potential-outcome (counterfactual) models now popular in statistics, health, and social sciences, 9-15 and the structural-equations models long established in social sciences. 11-14 We focus on special insights facilitated by each approach, translations among the approaches, and the level of detail specified by each approach. Graphical models The following is a brief summary of terms and concepts of causal graph theory; see Greenland et al. 4 and Robins 5 for more detailed explanations. Figure 1 provides the graphs used for illustration below. An arc or edge is any line segment (with or without arrowheads) connecting two variables. If there is an arrow from a variable X to another variable Y in a graph, X is called a parent of Y and Y is called a child of X. If a variable has an arrow into it (i.e. it has a parent in the graph) it is called endogenous; otherwise it is exogenous. A path between two variables X and Y is a sequence of arcs connecting X and Y. A back-door path from X to Y is a path whose
Biostatistics, 2000
Chorionic villus sampling (CVS) is a valued method of prenatal diagnosis that is often preferred ... more Chorionic villus sampling (CVS) is a valued method of prenatal diagnosis that is often preferred over amniocentesis because it can be performed earlier, but which has also raised concern over a possible association with increased risk of terminal transverse limb deficiency (TTLD). We present and apply a meta-analytic method for estimating a combined dose-response effect from a series of case-control and cohort studies in which the exposure variable is interval-censored. Assuming coarsening at random for the interval-censoring, and calling upon the familiar result of Cornfield to pool case-control and cohort information on the association between a rare binary outcome and a multilevel exposure variable, we form a likelihood-based model to assess the effect of gestational age at the time of CVS on the presence or absence of a rare birth defect. Effect estimates are computed with a variant of the EM algorithm termed the method of weights, which enables the use of standard weighted regression software. Our findings suggest that CVS exposure at early gestational age leads to an increased risk of TTLD.
Biometrics, 2003
Outline 1. Introduction and review of popular methods 2. Influence functions 3. Robins, Rotnitzky... more Outline 1. Introduction and review of popular methods 2. Influence functions 3. Robins, Rotnitzky, and Zhao (1994) 4. Estimation when full data are available 5. Estimation when posttest response is missing at random (MAR) 6. Full data influence functions, revisited 7. Simulation evidence 8. Application-ACTG 175 9. Discussion
Biometrics, 2001
We describe a method for assessing dose-response effects from a series of case-control and cohort... more We describe a method for assessing dose-response effects from a series of case-control and cohort studies in which the exposure information is interval censored. The interval censoring of the exposure variable is dealt with through the use of retrospective models in which the exposure is treated as a multinomial response and disease status as a binary covariate. Polychotomous logistic regression models are adopted in which the dose-response relationship between exposure and disease may be modeled in a discrete or continuous fashion. Partial conditioning is possible to eliminate some of the nuisance parameters. The methods are applied to the motivating study of the relationship between chorionic villus sampling and the occurrence of terminal transverse limb reduction.
Biometrics, 2003
In a recent article on the efficacy of antihypertensive therapy, Berlowitz et al. (1998, New Engl... more In a recent article on the efficacy of antihypertensive therapy, Berlowitz et al. (1998, New England Journal of Medicine 339, 1957-1963) introduced an ad hoc method of adjusting for serial confounding assessed via an intensity score, which records cumulative differences over time between therapy actually received and therapy predicted by prior medical history. Outcomes are subsequently regressed on the intensity score and baseline covariates to determine whether intense treatment or exposure predicts a favorable response. We use a structural nested mean model to derive conditions sufficient for interpreting the Berlowitz results causally. We also consider a modified approach that scales the intensity at each time by the inverse expected treatment given prior medical history. This leads to a simple, two-step implementation of G-estimation if we assume a nonstandard but useful structural nested mean model in which subjects less likely to receive treatment are more likely to benefit from it. These modeling assumptions apply, for example, to health services research contexts in which differential access to care is a primary concern. They are also plausible in our analysis of the causal effect of potent antiretroviral therapy on change in CD4 cell count, because men in the sample who are less likely to initiate treatment when baseline CD4 counts are high are more likely to experience large positive changes. We further extend the methods to accomodate repeated outcomes and time-varying effects of time-varying exposures.
Cornell University - arXiv, May 15, 2021
Stratifying factors, like age and gender, can modify the effect of treatments and exposures on ri... more Stratifying factors, like age and gender, can modify the effect of treatments and exposures on risk of a studied outcome. Several effect measures, including the relative risk, hazard ratio, odds ratio, and risk difference, can be used to measure this modification. It is known that choice of effect measure may determine the presence and direction of effect-measure modification. We show that considering the opposite outcome-for example, recovery instead of death-may similarly influence effect-measure modification. In fact, if the relative risk for the studied outcome and the relative risk for the opposite outcome agree about the direction of effect-measure modification, then so will the two cumulative hazard ratios, the risk difference, and the odds ratio. When risks are randomly sampled from the uniform (0,1) distribution, the probability of this happening is 5/6. Disagreement is probable enough that researchers considering one relative risk should also consider the other and further discussion if they disagree. (If possible, researchers should also report estimated risks.) We provide examples through case studies on HCV, COVID-19, and bankruptcy following melanoma treatment.
Alcoholism: Clinical and Experimental Research, 2019
Background: Alcohol consumption is associated with poor health outcomes in women living with HIV ... more Background: Alcohol consumption is associated with poor health outcomes in women living with HIV (WLWH), but whether medication can help to reduce drinking in non-treatment-seeking women or whether reduction in drinking improves HIV outcomes is unclear. We conducted a randomized clinical trial (RCT) of daily oral naltrexone (50 mg) versus placebo in WLWH who met criteria for current unhealthy alcohol use. Methods: WLWH with current unhealthy alcohol use (>7 drinks/wk or >3 drinks/occasion) were randomly assigned to daily oral naltrexone 50 mg (n = 96) or placebo (n = 98) for 4 months. Drinking outcomes, including the proportion of women who reduced (<unhealthy use criteria) or quit drinking, were assessed at baseline, 2 months, 4 months (end of treatment), and 7 months. In a secondary analysis, HIV viral suppression and changes in CD4 counts were compared in women who did or did not reduce/quit drinking, regardless of intervention assignment. Results: The participants' mean age was 48 years, 86% were African American, and 94% were receiving HIV antiretroviral therapy. Among all participants, 89% and 85% completed the 4-month and 7-month follow-ups, respectively. Participants in both groups substantially reduced drinking over time. At 1 and 3 months, naltrexone was associated with a greater reduction in drinking (p < 0.05), but the proportion who reduced/quit drinking at 4 months (52% vs. 45%, p = 0.36) or 7 months (64% in both groups) was not different. HIV viral suppression at follow-up was significantly better in participants who reduced/quit drinking versus those continuing unhealthy alcohol use at 4 months (72% vs. 53%, p = 0.02) and 7 months (74% vs. 54%, p = 0.02). Conclusions: Participating in an RCT to reduce drinking was associated with significant drinking reduction regardless of medication assignment, suggesting that nonmedication aspects of research study participation (e.g., repeated assessments and support from research staff) could be important interventions to help reduce drinking outside of research studies. Drinking reduction was associated with improved HIV viral suppression, providing evidence to support recommendations to avoid unhealthy alcohol use among WLWH.
Communications in Statistics - Simulation and Computation, 2016
In investigating the correlation between an alcohol biomarker and self-report, we developed a met... more In investigating the correlation between an alcohol biomarker and self-report, we developed a method to estimate the canonical correlation between two high-dimensional random vectors with a small sample size. In reviewing the relevant literature, we found that our method is somewhat similar to an existing method, but that the existing method has been criticized as lacking theoretical grounding in comparison with an alternative approach. We provide theoretical and empirical grounding for our method, and we customize it for our application to produce a novel method, which selects linear combinations that are step functions with a sparse number of steps.
Addiction Science & Clinical Practice, 2017
Background: Alcohol consumption has been associated with poor antiretroviral therapy (ART) adhere... more Background: Alcohol consumption has been associated with poor antiretroviral therapy (ART) adherence but less is known about its relationship to HIV viral suppression, or whether certain drinking patterns have a stronger association than others. The objectives of this study were to determine the association of different patterns of alcohol consumption to HIV viral suppression and ART adherence, and to determine whether any associations of alcohol with HIV viral suppression were mediated by poor ART adherence. Methods: This observational study used baseline data from 619 HIV+ participants, recruited across 8 clinical and community settings across Florida as part of the Florida Cohort from 2014 to 2016. Alcohol consumption was measured by self-report, and grouped into four categories: heavy drinking (>7/week for women or >14 drinks/week for men); binge, but not heavy drinking (≥4 or >5 drinks/occasion for women and men, respectively), low level drinking (neither heavy nor binge), and abstinence. Serum HIV RNA measurements were obtained from statewide HIV surveillance data, and durable viral suppression was defined as achieving HIV viral suppression (<200 copies/ml) at every assessment in the past 12 months. Results: The majority of the 619 participants were male (63%) and aged 45 or greater (65%). The proportion of participants with heavy, binge, low-level drinking and abstinence was 9, 25, 37 and 30%, respectively. Optimal ART adherence (≥95%) was reported by 68%, and 60% achieved durable viral suppression. In multivariable analysis controlling for demographic factors, drug use, and homelessness, heavy drinking (compared to abstinence) was associated with increased odds of failing to achieve durable viral suppression (OR 2.16, 95% CI 1.08-4.32) whereas binge drinking alone was not significantly associated with this outcome (OR 1.04, 95% CI 0.64-1.70). Both heavy drinking and binge drinking were significantly associated with suboptimal ART adherence. Mediation analyses suggested that only a small proportion of the relationship between heavy drinking and suboptimal viral suppression was due to poor ART adherence. Conclusions: Exceeding weekly recommended levels of alcohol consumption (heavy drinking) was significantly associated with poor HIV viral suppression and ART non-adherence, while binge drinking was associated with suboptimal ART adherence in this sample. Clinicians should attempt to address heavy drinking in their patients with HIV.
Uploads
Papers by Babette Brumback