Using Real-World Data to Externally Evaluate Population Pharmacokinetic Models of Dexmedetomidine in Children and Infants.

Dexmedetomidine is a sedative used in both adults and off-label in children with considerable reported pharmacokinetic (PK) interindividual variability affecting drug exposure across populations. Several published models describe the population PKs of dexmedetomidine in neonates, infants, children, and adolescents, though very few have been externally evaluated. A prospective PK dataset of dexmedetomidine plasma concentrations in children and young adults aged 0.01-19.9 years was collected as part of a multicenter opportunistic PK study. A PubMed search of studies reporting dexmedetomidine PK identified five population PK models developed with data from demographically similar children that were selected for external validation. A total of 168 plasma concentrations from 102 children were compared with both population (PRED) and individualized (IPRED) predicted values from each of the five published models by quantitative and visual analyses using NONMEM (v7.3) and R (v4.1.3). Mean percent prediction errors from observed values ranged from -1% to 120% for PRED, and -24% to 60% for IPRED. The model by James et al, which was developed using similar "real-world" data, nearly met the generalizability criteria from IPRED predictions. Other models developed using clinical trial data may have been limited by inclusion/exclusion criteria and a less racially diverse population than this study's opportunistic dataset. The James model may represent a useful, but limited tool for model-informed dosing of hospitalized children.

Matching for HLA-DR excluding diabetogenic HLA-DR3 and HLA-DR4 predicts insulin independence after pancreatic islet transplantation.

Introduction: In pancreatic islet transplantation, the exact contribution of human leukocyte antigen (HLA) matching to graft survival remains unclear. Islets may be exposed to allogenic rejection but also the recurrence of type 1 diabetes (T1D). We evaluated the HLA-DR matching, including the impact of diabetogenic HLA-DR3 or HLA-DR4 matches. Methods: We retrospectively examined the HLA profile in 965 transplant recipients and 2327 islet donors. The study population was obtained from patients enrolled in the Collaborative Islet Transplant Registry. We then identified 87 recipients who received a single-islet infusion. Islet-kidney recipients, 2nd islet infusion, and patients with missing data were excluded from the analysis (n=878). Results: HLA-DR3 and HLA-DR4 were present in 29.7% and 32.6% of T1D recipients and 11.6% and 15.8% of the donors, respectively. We identified 52 T1D islet recipients mismatched for HLA-DR (group A), 11 with 1 or 2 HLA-DR-matches but excluding HLA-DR3 and HLA- DR4 (group B), and 24 matched for HLA-DR3 or HLA-DR4 (group C). Insulin-independence was maintained in a significantly higher percentage of group B recipients from year one through five post-transplantation (p<0.01). At five-year post-transplantation, 78% of group B was insulin-independent compared to 24% (group A) and 35% (group C). Insulin-independence correlated with significantly better glycemic control (HbA1c <7%), fasting blood glucose, and reduced severe hypoglycemic events. Matching HLA-A-B-DR (≥3) independently of HLA- DR3 or HLA-DR4 matching did not improve graft survival. Conclusion: This study suggests that matching HLA-DR but excluding the diabetogenic HLA-DR3 and/or 4 is a significant predictor for long-term islet survival.

Predictive Value of C-Peptide Measures for Clinical Outcomes of ß-Cell Replacement Therapy in Type 1 Diabetes: Report From the Collaborative Islet Transplant Registry (CITR).

OBJECTIVE: To determine C-peptide measures and levels associated with positive glycemic control outcomes following islet transplant (ITx) in type 1 diabetes. RESEARCH DESIGN AND METHODS: We evaluated Collaborative Islet Transplant Registry (CITR) islet-alone recipients with pretransplant C-peptide <0.1 nmol/L and mean follow-up of 4.6 ± 1.1 years (n = 677). Receiver operating characteristic area under the curve (ROC-AUC) was used to evaluate the predictive value of fasting and stimulated glucose and C-peptide measures for seven primary outcomes: 1) absence of severe hypoglycemic events (ASHEs); 2) HbA1c <7.0%; 3) HbA1c <7.0% and ASHEs; 4) HbA1c ≤6.5%; 5) HbA1c ≤6.5% and ASHEs; 6) insulin independence; and 7) ASHEs, HbA1c ≤6.5%, and insulin independence (the optimal outcome). Measures with the highest ROC-AUC were selected for determination of optimal cut points. RESULTS: Fasting C-peptide was highly predictive for ASHE (ROC-AUC 0.906; optimal cut point 0.070 nmol/L) and the optimal outcome (ROC-AUC 0.845; optimal cut point 0.33 nmol/L). Mixed-meal tolerance test (MMTT)-stimulated C-peptide-to-glucose ratio (CPGR) outperformed both fasting and stimulated C-peptide for all outcomes except ASHE. The optimal cut point for the optimal outcome was 0.12 nmol/mmol for MMTT-stimulated CPGR and 0.97 nmol/L for MMTT-stimulated C-peptide. CONCLUSIONS: Fasting C-peptide reliably predicts ITx primary outcomes. MMTT-stimulated CPGR provides marginally better prediction for composite ITx outcomes, including insulin independence. In the absence of an MMTT, a fasting C-peptide ≥0.33 nmol/L is a reassuring measure of optimal islet graft function. C-peptide targets represent excellent and easily determinable means to predict glycemic control outcomes after ITx and should be considered as potential goals of ß-cell replacement.

Factors associated with favourable 5 year outcomes in islet transplant alone recipients with type 1 diabetes complicated by severe hypoglycaemia in the Collaborative Islet Transplant Registry.

AIMS/HYPOTHESIS: Islet transplantation has been studied in small cohorts of recipients with type 1 diabetes complicated by severe hypoglycaemic events (SHEs). We determined factors associated with favourable outcomes in a large cohort of recipients reported to the Collaborative Islet Transplant Registry (CITR). METHODS: In 398 non-uraemic islet transplant alone (ITA) recipients with type 1 diabetes and SHEs, transplanted between 1999 and 2015 and with at least 1 year follow-up, we analysed specified favourable outcomes against each of all available characteristics of pancreas donors, islet grafts, recipients and immunosuppressive regimens, as well as immunosuppression and procedure-related serious adverse events (SAEs). RESULTS: Four factors were associated with the highest rates of favourable outcomes: recipient age ≥35 years; total infused islets ≥325,000 islet equivalents; induction immunosuppression with T cell depletion and/or TNF-α inhibition; and maintenance with both mechanistic target of rapamycin (mTOR) and calcineurin inhibitors. At 5 years after the last islet infusion, of the recipients meeting these four common favourable factors (4CFF; N=126), 95% were free of SHEs, 76% had HbA1c <53 mmol/mol (7.0%), 73% had HbA1c <53 mmol/mol (7.0%) and absence of SHEs, and 53% were insulin independent, significantly higher rates than in the remaining recipients (<4CFF; N=272). The incidence of procedural and immunosuppression-related SAEs per recipient that resulted in sequelae, disability or death was low in both the 4CFF (0.056 per person) and <4CFF (0.074 per person) groups. CONCLUSIONS/INTERPRETATION: In recipients with type 1 diabetes complicated by SHEs, islet transplantation meeting 4CFF protected 95% from SHEs at 5 years after the last islet infusion and exerted a large and significant benefit on glycaemic control, with an acceptable safety profile for this subgroup of type 1 diabetes.

Exposure-safety relationship for acyclovir in the treatment of neonatal herpes simplex virus disease.

BACKGROUND: Neonatal herpes simplex virus (HSV) disease has been treated with high-dose (20 mg/kg/dose) acyclovir since 1991. AIMS: Determine the safety of acyclovir in infants with neonatal HSV treated with high-dose acyclovir; examine the association between acyclovir dose and exposure with adverse events (AEs). STUDY DESIGN: We obtained demographic information and acyclovir dosing via medical records. Acyclovir exposure was calculated using an established pharmacokinetic model. SUBJECTS: Infants <120 days of age with neonatal HSV discharged from four academic children's hospitals. OUTCOME MEASURES: We identified clinical and laboratory adverse events (AEs). RESULTS AND CONCLUSIONS: We identified 49 infants with neonatal HSV treated with acyclovir; 42 infants had complete 21-day dosing information. Median mean daily dose was 59 mg/kg/day. Clinical AEs were common among all gestational and postnatal age groups. Rash was the most common clinical AE (37 %). Mild laboratory AEs occurred in 2-37 % of infants. The median maximum doses (mg/kg/day) were higher among infants with hypokalemia, elevated blood urea nitrogen, and thrombocytosis. For all other laboratory AEs, the median maximum doses for infants without events were higher or equal to the median maximum dose of infants with the AE. The odds of experiencing any clinical or laboratory AE did not differ by predicted acyclovir exposure for either area under the curve (AUC) or maximum concentration (Cmax) (odds ratio [OR] = 1.00 [0.98, 1.03] and OR = 1.01 [0.93, 1.12], respectively). Although AEs were common with high-dose acyclovir exposure, severe AEs were rare. Acyclovir exposure was not associated with AEs.

HIV clinic-based extended-release naltrexone versus treatment as usual for people with HIV and opioid use disorder: a non-blinded, randomized non-inferiority trial.

BACKGROUND AND AIM: Opioid agonist medications for treatment of opioid use disorder (OUD) can improve human immunodeficiency virus (HIV) outcomes and reduce opioid use. We tested whether outpatient antagonist treatment with naltrexone could achieve similar results. DESIGN: Open-label, non-inferiority randomized trial. SETTING: Six US HIV primary care clinics. PARTICIPANTS: A total of 114 participants with untreated HIV and OUD (62% male; 56% black, 12% Hispanic; positive for fentanyl (62%), other opioids (47%) and cocaine (60%) at baseline). Enrollment halted early due to slow recruitment. INTERVENTION: HIV clinic-based extended-release naltrexone (XR-NTX; n = 55) versus treatment as usual (TAU) with buprenorphine or methadone (TAU; n = 59). MEASUREMENTS: Treatment group differences were compared for the primary outcome of viral suppression (HIV RNA ≤ 200 copies/ml) at 24 weeks and secondary outcomes included past 30-day use of opioids at 24 weeks. FINDINGS: Fewer XR-NTX participants initiated medication compared with TAU participants (47 versus 73%). The primary outcome of viral suppression was comparable for XR-NTX (52.7%) and TAU (49.2%) [risk ratio (RR) = 1.064; 95% confidence interval (CI) = 0.748, 1.514] at 24 weeks. Non-inferiority could not be demonstrated, as the lower confidence limit of the RR did not exceed the pre-specified margin of 0.75 in intention-to-treat (ITT) analysis. The main secondary outcome of past 30-day opioid use was comparable for XR-NTX versus TAU (11.7 versus 14.8 days; mean difference = -3.1; 95% CI = -8.7, 1.1) in ITT analysis. Among those initiating medication, XR-NTX resulted in fewer days of opioid use compared with TAU in the past 30 days (6.0 versus 13.6, mean difference = -7.6; 95% CI = -13.8, -0.2). CONCLUSIONS: A randomized controlled trial found supportive, but not conclusive, evidence that human immunodeficiency virus clinic-based extended-release naltrexone is not inferior to treatment as usual for facilitating human immunodeficiency virus viral suppression. Participants who initiated extended-release naltrexone used fewer opioids than those who received treatment as usual.

Pharmacokinetics of Ceftazidime in Children and Adolescents with Obesity.

PURPOSE: The aim of this study was to evaluate ceftazidime pharmacokinetics (PK) in a cohort that includes a predominate number of children and adolescents with obesity and assess the efficacy of competing dosing strategies. METHODS: A population PK model was developed using opportunistically collected plasma samples. For each dosing strategy, model-based probability of target attainment (PTA) estimates were computed for study participants using empirical Bayes estimates. In addition, the effects of body size and renal function on PTA were evaluated using stochastic model simulations with virtually generated subjects. RESULTS: Twenty-nine participants, 24 of whom were obese, contributed data towards the analysis. The median (range) age, body weight, and body mass index of participants were 12.2 years (2.3-20.6), 59.2 kg (8.4-121), and 25.2 kg/m2 (13.8-42.9), respectively. Administration of 50 mg/kg intravenously (IV) every 8 hours (q8h; max 6 g/day) or 40 mg/kg IV q6h (max 6 g/day) resulted in PTA values of ≥ 90% (minimum inhibitory concentration 8 mg/L) for the subset of obese participants with estimated glomerular filtration rates (GFR) ≥ ~ 80 mL/min/1.73 m2. However, for both regimens, stochastic model simulations denoted lower PTA values (< 90%) with increasing body weight for virtual subjects with GFR ≥ 120 mL/min/1.73 m2. Alternatively, permitting for a maximum daily dose of 8 g/day using a 40 mg/kg IV q6h regimen provided PTA values that were near or above target (90%) for virtual subjects between 10 to 120 kg with GFR ≥ 80 mL/min/1.73 m2. CONCLUSION: Our analysis suggests administration of 40 mg/kg IV q6h (max 8 g/day) maximizes PTA in children and adolescents with obesity and GFR ≥ 80 mL/min/1.73 m2. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT01431326.

Personality and responses to Covid-19 health and safety prevention.

In this study, we examine the respective effects of prosocial personality and grandiose narcissism on individual social responsibility, and attitudinal and behavioral responses to Covid-19 health and safety preventive measures. We further analyze the extent to which individuals feel targeted by bullies for wearing a mask in order to shed light on the psychological consequences of the current pandemic. We employed a cross-sectional technique using a snowball sampling method to recruit participants from the United States and Canada. We obtained a total of 968 completed surveys. Results of SEM reveal that prosocial personality enhances individual social responsibility and positive responses to health and safety preventive measures, whereas grandiose narcissism augments negative responses. Results highlight that socially responsible individuals report being bullied for wearing a mask. Findings are discussed in light of the characteristics of the respondents, and cultural aspects.

Population pharmacokinetics of olanzapine in children.

AIMS: The aim of this study was to evaluate the population pharmacokinetics (PopPK) of olanzapine in children and devise a model-informed paediatric dosing scheme. METHODS: The PopPK of olanzapine was characterized using opportunistically collected plasma samples from children receiving olanzapine per standard of care for any indication. A nonlinear mixed effect modelling approach was employed for model development using the software NONMEM (v7.4). Simulations from the developed PopPK model were used to devise a paediatric dosing scheme that targeted comparable plasma exposures to adolescents and adults. RESULTS: Forty-five participants contributed 83 plasma samples towards the analysis. The median (range) postnatal age and body weight of participants were 3.8 years (0.2-19.2) and 14.1 kg (4.2-111.7), respectively. The analysis was restricted to pharmacokinetic (PK) samples collected following enteral administration (oral and feeding tube). A one-compartment model with linear elimination provided an appropriate fit to the data. The final model included the covariates body weight and postmenstrual age (PMA) on apparent olanzapine clearance (CL/F). Typical CL/F and apparent volume of distribution (scaled to 70 kg) were 16.8 L/h (21% RSE) and 663 L (13% RSE), respectively. Developed dosing schemes used weight-normalized doses for children ≤6 months postnatal age or <15 kg and fixed doses for children ≥15 kg. CONCLUSION: We developed a paediatric PopPK model for enterally-administered olanzapine. To our knowledge, this analysis is the first study to characterize the PK of olanzapine in participants ranging from infants to adolescents. Body weight and PMA were identified as influential covariates for characterizing developmental changes in olanzapine apparent clearance.

Using a health information technology survey to explore the availability of addiction treatment data in the electronic health records: A National Drug Abuse Treatment Clinical Trials Network study.

BACKGROUND: Healthcare data from electronic health records (EHRs) and related health information technology (IT) tools are critical data sources for pragmatic clinical trials and observational studies aimed at producing real-world evidence. To unlock the full potential of such data to advance science, the data must be complete and in structured formats to facilitate research use. METHODS: A Health IT survey was conducted within the National Drug Abuse Treatment Clinical Trials Network (CTN) to explore information related to data completeness and presence of unstructured data (e.g., clinical notes, free text) for conducting the EHR-based research for substance use disorders (SUDs). The analysis was based on 36 participants from 36 facilities located in 14 states and affiliated with the CTN. RESULTS: The mean age of the participants (n = 34) was 48.0 years (SD = 9.8). Of the participants enrolled, 50.0% were female and 82.4% were white. Participants' facilities were from four census-defined regions (South 35.3%, Northeast 29.4%, West 20.6%, Midwest 11.8%, Missing 2.9%) and represented diverse settings. The EHR was used by all surveyed facilities including 17 different kinds of EHR platforms or vendors, and 17.6% (n = 6) of surveyed facilities also used a separate EHR for behavioral health care (e.g., SUD care). Paper records were also used by 76.5% of surveyed facilities for clinical care (e.g., for health risk appraisal questionnaires, substance use screening or assessment, check-in screening, substance use specific intervention/treatment or referral, or labs/testing). The prevalence of using a patient portal, practice management system, and mHealth for patient care was 76.5%, 50.0%, and 29.4%, respectively. CONCLUSION: While results are descriptive in nature, they reveal the heterogeneity in the existing EHRs and frequent use of paper records to document patient care tasks, especially for SUD care. The use of a separate EHR for behavioral healthcare also suggests the challenge of obtaining complete EHR data to support research for SUDs. Much EHR development, integration, and standardization needs to be done especially in regard to SUD treatment to facilitate research across disparate healthcare systems.

Dosing of Continuous Fentanyl Infusions in Obese Children: A Population Pharmacokinetic Analysis.

Differences in fentanyl pharmacokinetics (PK) between obese and nonobese adults have previously been reported; however, the impact of childhood obesity on fentanyl PK is relatively unknown. We developed a population pharmacokinetic (PopPK) model using opportunistically collected samples from a cohort of predominately obese children receiving fentanyl per the standard of care. Using a probability-based approach, we evaluated the ability of different continuous infusion strategies to provide steady-state concentrations (Css ) within an analgesic concentration range (1-3 ng/mL). Fifty-three samples from 32 children were used for PopPK model development. Median (range) age and body weight of study participants were 13 years (2-19 years) and 52 kg (16-164 kg), respectively. The majority of children (94%) were obese. A 2-compartment model allometrically scaled by total body weight provided an appropriate fit to the data. Estimated typical clearance was 32.5 L/h (scaled to 70 kg). A fixed dose rate infusion of 1 µg/kg/h was associated with probabilities between 49% and 58% for achieving Css within target; however, the risk of achieving Css > 3 ng/mL increased with increasing body weight (15% at 16 kg vs 43% at 164 kg). A proposed model-based infusion strategy maintained consistent probabilities across the examined weight range for achieving Css within (58%) and above (20%) target. Use of an allometric relationship between weight and clearance was appropriate for describing the PK of intravenous fentanyl in our cohort of predominately obese children. Our proposed model-derived continuous infusion strategy maximized the probability of achieving target Css in children of varying weights.

Population Pharmacokinetics of Doxycycline in Children.

Doxycycline is a tetracycline-class antimicrobial labeled by the United States (U.S.) Food and Drug Administration for children >8 years of age for many common childhood infections. Doxycycline is not labeled for children ≤8 years of age, due to the association between tetracycline class antibiotics and tooth staining, although doxycycline may be used off-label in severe conditions. Accordingly, there is a paucity of pharmacokinetic (PK) data to guide dosing in children 8 years and younger. We leveraged opportunistically-collected plasma samples after intravenous (IV) and oral doxycycline doses received per standard of care to characterize the PK of doxycycline in children of different ages, and evaluated the effect of obesity and fasting status on PK parameters.We developed a population PK model of doxycycline using data collected from 47 patients 0-18 years of age, including 14 participants ≤8 years. We developed a 1 compartment PK model and found doxycycline clearance to be 3.32 L/h/70 kg and volume to be 96.8 L/70kg for all patients; comparable to values reported in adults. We estimated a bioavailability of 89.6%, also consistent with adult data. Allometrically scaled clearance and volume of distribution did not differ between children 2 to ≤8 years of age and children >8 to ≤18 years of age, suggesting that younger children may be given the same per kg dosing. Obese and fasting status were not selected for inclusion in the final model. Additional doxycycline PK samples collected in future studies may be used to improve model performance and maximize its clinical value.

Clinical Workflow and Substance Use Screening, Brief Intervention, and Referral to Treatment Data in the Electronic Health Records: A National Drug Abuse Treatment Clinical Trials Network Study.

INTRODUCTION: The use of electronic health records (EHR) data in research to inform recruitment and outcomes is considered a critical element for pragmatic studies. However, there is a lack of research on the availability of substance use disorder (SUD) treatment data in the EHR to inform research. METHODS: This study recruited providers who used an EHR for patient care and whose facilities were affiliated with the National Institute on Drug Abuse's National Drug Abuse Treatment Clinical Trials Network (NIDA CTN). Data about providers' use of an EHR and other methods to support and document clinical tasks for Substance use screening, Brief Intervention, and Referral to Treatment (SBIRT) were collected. RESULTS: Participants (n = 26) were from facilities across the country (South 46.2%, West 23.1%, Midwest 19.2 percent, Northeast 11.5 percent), representing 26 different health systems/facilities at various settings: primary care (30.8 percent), ambulatory other/specialty (26.9 percent), mixed setting (11.5 percent), hospital outpatient (11.5 percent), emergency department (7.7 percent), inpatient (3.8 percent), and other (7.7 percent). Validated tools were rarely used for substance use screen and SUD assessment. Structured and unstructured EHR fields were commonly used to document SBIRT. The following tasks had high proportions of using unstructured EHR fields: substance use screen, treatment exploration, brief intervention, referral, and follow-up. CONCLUSION: This study is the first of its kind to investigate the documentation of SBIRT in the EHR outside of unique settings (e.g., Veterans Health Administration). While results are descriptive, they emphasize the importance of developing EHR features to collect structured data for SBIRT to improve health care quality evaluation and SUD research.

Population Pharmacokinetics of Milrinone in Infants, Children, and Adolescents.

Milrinone is a type 3 phosphodiesterase inhibitor used to improve cardiac output in critically ill infants and children. Milrinone is primarily excreted unchanged in the urine, raising concerns for toxic accumulation in the setting of renal dysfunction of critical illness. We developed a population pharmacokinetic model of milrinone using nonlinear mixed-effects modeling in NONMEM to perform dose-exposure simulations in children with variable renal function. We included children aged <21 years who received intravenous milrinone per clinical care. Plasma milrinone concentrations were measured using a validated liquid chromatography-tandem mass spectrometry assay (range 1-5000 ng/mL). We performed dose-exposure simulations targeting steady-state therapeutic concentrations of 100-300 ng/mL previously established in adults and children with cardiac dysfunction. We simulated concentrations over 48 hours in typical subjects with decreasing creatinine clearance (CrCl), estimated using the updated bedside Schwartz equation. Seventy-four patients contributed 111 plasma samples (concentration range, 4-634 ng/mL). The median (range) postmenstrual age (PMA) was 3.7 years (0-18), and median weight (WT) was 13.1 kg (2.6-157.7). The median serum creatinine and CrCl were 0.5 mg/dL (0.1-3.1) and 117.2 mL/min/1.73 m2 (13.1-261.3), respectively. A 1-compartment model characterized the pharmacokinetic data well. The final model parameterization was: Clearance (L/h) = 15.9*(WT [kg] / 70)0.75 * (PMA1.12 / (67.71.12 +PMA1.12 )*(CrCl / 117)0.522 ; and Volume of Distribution (L) = 32.2*(WT [kg] / 70). A loading dose of 50 µg/kg followed by a continuous infusion of 0.5 µg/kg/min resulted in therapeutic concentrations, except when CrCl was severely impaired at ≤30 mL/min/1.73 m2 . In this setting, a 25 µg/kg loading dose and 0.25 µg/kg/min continuous infusion resulted in therapeutic exposures.

Dosing and Safety of Off-label Use of Caffeine Citrate in Premature Infants.

OBJECTIVE: To characterize the dosing and safety of off-label caffeine citrate in a contemporary cohort of extremely premature infants. STUDY DESIGN: We used electronic health records (2010-2013) from 4 neonatal intensive care units to identify infants of ≤28 weeks of gestational age exposed to caffeine citrate. Safety outcomes included death, bronchopulmonary dysplasia, necrotizing enterocolitis, spontaneous intestinal perforation, intraventricular hemorrhage, patent ductus arteriosus ligation, seizures, and arrhythmias. We used multivariable logistic regression to evaluate the association of caffeine citrate exposure with clinical events. RESULTS: Of 410 infants with a median (IQR) gestational age of 26 (24-27) weeks, 95% received caffeine citrate for >0 days. Infants received a median (IQR) daily dose of 8 (5-10) mg/kg/day. Incidences of clinical events on day of caffeine citrate exposure were death 2%, patent ductus arteriosus ligation 12%, and medical and surgical necrotizing enterocolitis 5% and 4%, respectively. Bronchopulmonary dysplasia occurred in 37% of infants and was not associated with caffeine dose. Increased caffeine citrate dose was associated with lower odds of patent ductus arteriosus ligation and necrotizing enterocolitis. CONCLUSIONS: Caffeine citrate was used in extremely premature infants at younger gestation, at higher doses, and for longer durations than recommended on the drug label. Increased caffeine citrate exposure, dose, or therapy duration was not associated with increased risk of necrotizing enterocolitis.

An empirical approach to determine a threshold for assessing overdispersion in Poisson and negative binomial models for count data.

Overdispersion is a problem encountered in the analysis of count data that can lead to invalid inference if unaddressed. Decision about whether data are overdispersed is often reached by checking whether the ratio of the Pearson chi-square statistic to its degrees of freedom is greater than one; however, there is currently no fixed threshold for declaring the need for statistical intervention. We consider simulated cross-sectional and longitudinal datasets containing varying magnitudes of overdispersion caused by outliers or zero inflation, as well as real datasets, to determine an appropriate threshold value of this statistic which indicates when overdispersion should be addressed.

Effect of psychotherapy for depression via home telehealth on glycemic control in adults with type 2 diabetes: Subgroup analysis of a randomized clinical trial.

Objective We evaluated the impact of telemedicine-delivered behaviour activation treatment (BAT) on glycemic control in a subgroup of older adults with diabetes who participated in a randomized controlled trial for depression. Research design and methods We randomized older adults with major depression to same-room or telemedicine BAT. Each group received eight weekly sessions. For the subgroup analysis, we identified individuals with type 2 diabetes and obtained hemoglobin A1c at baseline and 12 months' follow-up. We used mixed-effects models (MEM) for repeated measures analysis to compare the longitudinal mean A1c. We estimated model-derived mean A1c values and considered an adjusted model to account for baseline health status. Results We included 90 individuals with type 2 diabetes of the original 241 in the subgroup analysis (43 in telemedicine and 47 in same room). Treatment groups were not significantly different at baseline for demographics, depression, anxiety or A1c levels (telemedicine 6.9 vs. same room 7.3, p = 0.19). Baseline mean A1c for the telemedicine group remained at 6.9 (55 mmol/mol) at 12 months, whereas baseline mean A1c for the same-room group increased to 7.7 (61 mmol/mol). Longitudinal trajectories of model-derived mean A1c indicated a significant main effect of treatment group on mean A1c value at study end (difference = -0.82, 95% CI -1.41, -0.24). Adjusted analyses gave comparable results. Conclusions Telemedicine-delivered BAT was superior to same room in achieving lower mean A1c values in participants with type 2 diabetes, suggesting BAT-delivered via telemedicine is a viable treatment option for adults with diabetes.

Approaches for dealing with various sources of overdispersion in modeling count data: Scale adjustment versus modeling.

Overdispersion is a common problem in count data. It can occur due to extra population-heterogeneity, omission of key predictors, and outliers. Unless properly handled, this can lead to invalid inference. Our goal is to assess the differential performance of methods for dealing with overdispersion from several sources. We considered six different approaches: unadjusted Poisson regression (Poisson), deviance-scale-adjusted Poisson regression (DS-Poisson), Pearson-scale-adjusted Poisson regression (PS-Poisson), negative-binomial regression (NB), and two generalized linear mixed models (GLMM) with random intercept, log-link and Poisson (Poisson-GLMM) and negative-binomial (NB-GLMM) distributions. To rank order the preference of the models, we used Akaike's information criteria/Bayesian information criteria values, standard error, and 95% confidence-interval coverage of the parameter values. To compare these methods, we used simulated count data with overdispersion of different magnitude from three different sources. Mean of the count response was associated with three predictors. Data from two real-case studies are also analyzed. The simulation results showed that NB and NB-GLMM were preferred for dealing with overdispersion resulting from any of the sources we considered. Poisson and DS-Poisson often produced smaller standard-error estimates than expected, while PS-Poisson conversely produced larger standard-error estimates. Thus, it is good practice to compare several model options to determine the best method of modeling count data.

Overall Graft Loss Versus Death-Censored Graft Loss: Unmasking the Magnitude of Racial Disparities in Outcomes Among US Kidney Transplant Recipients.

BACKGROUND: Black kidney transplant recipients experience disproportionately high rates of graft loss. This disparity has persisted for 40 years, and improvements may be impeded based on the current public reporting of overall graft loss by US regulatory organizations for transplantation. METHODS: Longitudinal cohort study of kidney transplant recipients using a data set created by linking Veterans Affairs and US Renal Data System information, including 4918 veterans transplanted between January 2001 and December 2007, with follow-up through December 2010. Multivariable analysis was conducted using 2-stage joint modeling of random and fixed effects of longitudinal data (linear mixed model) with time to event outcomes (Cox regression). RESULTS: Three thousand three hundred six non-Hispanic whites (67%) were compared with 1612 non-Hispanic black (33%) recipients with 6.0 ± 2.2 years of follow-up. In the unadjusted analysis, black recipients were significantly more likely to have overall graft loss (hazard ratio [HR], 1.19; 95% confidence interval [95% CI], 1.07-1.33), death-censored graft loss (HR, 1.67; 95% CI, 1.45-1.92), and lower mortality (HR, 0.83; 95% CI, 0.72-0.96). In fully adjusted models, only death-censored graft loss remained significant (HR, 1.38; 95% CI, 1.12-1.71; overall graft loss [HR, 1.08; 95% CI, 0.91-1.28]; mortality [HR, 0.84; 95% CI, 0.67-1.06]). A composite definition of graft loss reduced the magnitude of disparities in blacks by 22%. CONCLUSIONS: Non-Hispanic black kidney transplant recipients experience a substantial disparity in graft loss, but not mortality. This study of US data provides evidence to suggest that researchers should focus on using death-censored graft loss as the primary outcome of interest to facilitate a better understanding of racial disparities in kidney transplantation.

Trajectory of cost overtime after psychotherapy for depression in older Veterans via telemedicine.

BACKGROUND: Little evidence exists regarding the costs of telemedicine, especially considering changes over time. This analysis aimed to analyze trajectory of healthcare cost before, during, and after a behavioral activation intervention delivered via telepsychology and same-room delivery to elderly Veterans with depression. METHODS: 241 participants were randomly assigned into one of two study groups: behavioral activation for depression via telemedicine or via same-room treatment. Patients received 8 weeks of weekly 60-min individual sessions of behavioral activation for depression. Primary outcomes were collected at 12-months. Inpatient, outpatient, pharmacy, and total costs were collected from VA Health Economics Resource Center (HERC) datasets for FY 1998-2014 and compared between the two treatment groups. Generalized mixed models were used to investigate the trajectories over time. RESULTS: Overall cost, as well as, outpatient and pharmacy cost show increasing trend over time. Unadjusted and adjusted trajectories over time for any cost were not different between the two treatment groups. There was a significant overall increasing trend over time for outpatient (p<0.001) and total cost (p<0.001) but not for inpatient (p=0.543) or pharmacy cost (p=0.084). LIMITATIONS: Generalizability to younger, healthier populations may be limited due to inclusion criteria for study participants. CONCLUSION: Healthcare costs before, during, and after intervention did not differ between the telemedicine and in-person delivery methods. Outpatient costs accounted for most of the increasing trend of cost over time. These results support policies to use both telehealth and in-person treatment modalities to effectively and efficiently provide high quality care.