Impact of hospital guideline for weight-based antimicrobial dosing in morbidly obese adults and comprehensive literature review

Evaluation and implementation of optimized antimicrobial dosing strategies in obese and underweight patients

PURPOSE

We aimed to develop and implement dosing recommendations for antimicrobials in obese and underweight patients within an academic hospital, and assess their impact on antibiotic prescribing.

METHODS

A multi-step approach project was performed. First, obese and underweight patient prevalence and antimicrobial prescription frequency was determined in a point prevalence study. Second and third, a literature review and e-survey provided dosing evidence. Fourth, a consensus meeting was organized to formulate dosing recommendations. Fifth, these were implemented in our clinical validation service as six clinical rules continuously screening patients' records for potentially inappropriate prescriptions (PIPs). Uptake was evaluated by documenting the number of advices and acceptance rate. Last, an interrupted time series analysis (ITS) compared pre- and post-implementation periods to measure the impact of the intervention on residual PIPs/day. A residual PIP was defined as a PIP which persisted up to 48 h.

RESULTS

First, 41% of 15.896 hospitalized patients received antimicrobials over 20 days; of which 12% were obese and 9% underweight. Antibiotics were predominantly prescribed according to standard dosing regimens, adjusted to renal function. Next, six dosing recommendations, derived from literature, survey, and consensus, were implemented. In the fifth step, during an 18-week period, 219 advices were given, with 86% acceptance rate. Last, in the ITS analysis, at preintervention, a median of 75% residual PIPs/day existed, reduced to 0% postintervention. Use of clinical rules resulted in a significant immediate 84% relative reduction in residual PIPs (95% CI 0.55-0.94).

CONCLUSION

After conducting a literature review, e-survey, and seeking consensus from a panel of experts, dosing recommendations for antimicrobial treatment in both obese and underweight patients were developed. These recommendations have been successfully implemented into clinical practice, addressing the specific needs of these patient populations.

Updated antimicrobial dosing recommendations for obese patients

The prevalence of obesity has increased considerably in the last few decades. Pathophysiological changes in obese patients lead to pharmacokinetic (PK) and pharmacodynamic (PD) alterations that can condition the correct exposure to antimicrobials if standard dosages are used. Inadequate dosing in obese patients can lead to toxicity or therapeutic failure. In recent years, additional antimicrobial PK/PD data, extended infusion strategies, and studies in critically ill patients have made it possible to obtain data to provide a better dosage in obese patients. Despite this, it is usually difficult to find information on drug dosing in this population, which is sometimes contradictory. This is a comprehensive review of the dosing of different types of antimicrobials (antibiotics, antifungals, antivirals, and antituberculosis drugs) in obese patients, where the literature on PK and possible dosing strategies in obese adults was critically assessed.

[An online tool to personalize the drug-doses for obese adults]

BACKGROUND

Between 1975 and 2014, the number of people suffering from obesity tripled, reaching 17% of the adult population in France and more than 35% in the United States. Obesity is defined by a Body Mass Index (BMI)>30kg/m2 and characterized by a significant accumulation of adipose tissue responsible for the increase in weight. This accumulation leads to physiological changes capable of modifying the pharmacokinetics of drugs, which can lead to the administration of inappropriate doses. For this reason, some significant dosage adjustments are necessary for obese patients. However, data on these adaptations are not easily accessible and sometimes complex to implement in practice.

AIM

To perform a new online tool allowing to calculate and propose an adjusted dose of a drug that should be administered to an obese patient.

METHOD

(i) carrying out an extensive bibliographic research according to the PRISMA methodology; and (ii) the development of a new website site proposing an adjusted dose for obese patients.

RESULTS

Firstly, 49 reviews concerning the dose adaptation have been evaluated and, secondly, 319 articles have been selected. Among them, 204 articles have been included in the database to justify the adjusted dose of 84 drugs and administration methods including antibiotics, antifungals, anticoagulants or even cancer drugs. This database is available online through a calculator on the website named Adapt'Obese. Thus, with the sex, height and weight of an obese patient, Adapt'Obese proposes a personalized and adjusted dose of the drug to administer.

PERSPECTIVES

Other drugs will be added soon, and functional improvements are planned, with the aim of adapting the dosages in obese patients, as for patients with renal insufficiency.

Are self-reported anthropometric data reliable enough to meet antibiotic prophylaxis guidelines in orthopedic surgery?

BACKGROUND

Surgical site infection is a serious complication in orthopedic surgery. The use of antibiotic prophylaxis (AP) combined with other prevention strategies has been shown to reduce this risk to 1% for hip arthroplasty and 2% for knee arthroplasty. The French Society of Anesthesia and Intensive Care Medicine (SFAR) recommends doubling the dose when the patient's weight is greater than or equal to 100 kg, and the body mass index (BMI) is greater than or equal to 35 kg/m2. Similarly, patients with a BMIgreater than40 kg/m2 orlesser than18 kg/m2 are ineligible for surgery in our hospital. Self-reported anthropometric measurements are commonly used in clinical practice to calculate BMI, but their validity has not been assessed in the orthopedic literature. Therefore, we conducted a study comparing self-reported with systematically measured values and observed the impact these differences may have on perioperative AP regimens and contra-indications to surgery.

HYPOTHESIS

The hypothesis of our study was that self-reported anthropometric values differed from those measured during preoperative orthopedic consultations.

MATERIALS AND METHODS

This single-center retrospective study with prospective data collection was conducted between October and November 2018. The patient-reported anthropometric data were first collected and then directly measured by an orthopedic nurse. Weight was measured with a precision of 500 g and height was measured with a precision of 1 cm.

RESULTS

A total of 370 patients (259 women and 111 men) with a median age of 67 years (17-90) were enrolled. The data analysis found significant differences between the self-reported and measured height [166 cm (147-191) vs. 164 cm (141-191) (p<0.0001)], weight [72.9 kg (38-149) vs. 73.1 kg (36-140) (p<0.0005)] and BMI [26.3 (16.2-46.4) vs. 27 (16-48.2) (p<0.0001)]. Of these patients, 119 (32%) reported an accurate height, 137 (37%) an accurate weight, and 54 (15%) an accurate BMI. None of the patients had two accurate measurements. The maximum underestimation was 18 kg for weight, 9 cm for height, and 6.15 kg/m2 for BMI. The maximum overestimation was 28 kg for weight, 10 cm for height, and 7.2 kg/m2 for BMI. The verification of the anthropometric measurements identified another 17 patients who had contra-indications to surgery (12 with a BMI>40 kg/m2 and 5 with a BMI<18 kg/m2) and who would not have been detected based on the self-reported values.

CONCLUSIONS

Although patients underestimated their weight and overestimated their height in our study, these had no impact on the perioperative AP regimens. However, this misreporting failed to detect potential contraindications to surgery.

LEVEL OF EVIDENCE

IV; retrospective study with prospective data collection and no control group.

Therapeutic Drug Monitoring of Antimicrobials in Critically Ill Obese Patients

Obesity is a significant global public health concern that is associated with an elevated risk of comorbidities as well as severe postoperative and nosocomial infections. The treatment of infections in critically ill obese patients can be challenging because obesity affects the pharmacokinetics and pharmacodynamics of antibiotics, leading to an increased risk of antibiotic therapy failure and toxicity due to inappropriate dosages. Precision dosing of antibiotics using therapeutic drug monitoring may help to improve the management of this patient population. This narrative review outlines the pharmacokinetic and pharmacodynamic changes that result from obesity and provides a comprehensive critical review of the current available data on dosage adjustment of antibiotics in critically ill obese patients.

The Effects of Obesity on Health Care Delivery

The rates of obesity continue to rise among adults and children in the United States; hence, it is natural that obesity is reshaping health care delivery. This is seen in numerous ways, including physiologic, physical, social, and economic impacts. This article reviews a broad range of topics, from the effects of increased adiposity on drug pharmacokinetics and pharmacodynamics to the changes health care environments are making to accommodate patients with obesity. The significant social impacts of weight bias are reviewed, as are the economic consequences of the obesity epidemic. Finally, a patient case that demonstrates the effects of obesity on health care delivery is examined.

Characterization of plasma daptomycin in patients with serum highly glycated albumin and obesity

PURPOSE

Plasma daptomycin has not been fully characterized in diabetic and obese patients. This study aimed to evaluate the associations of plasma daptomycin with glycation of serum albumin and obesity.

METHODS

Infectious patients (n = 70) receiving intravenous daptomycin were enrolled. The plasma concentration of total and free daptomycin were determined using liquid chromatograph-tandem mass spectrometer. The associations of the plasma concentrations of daptomycin with clinical factors including serum albumin fractionations and physical status (obese including overweight, body mass index ≥ 25.0) were investigated. Daptomycin doses were adjusted using total body-weight.

RESULTS

The serum albumin level was positively and negatively correlated with the plasma concentration of total daptomycin and its free fraction proportion, respectively. The serum non-glycated albumin was negatively correlated with the free fraction proportion. The dose-normalized plasma concentration of total daptomycin was higher in the obese patients than in non-obese patients when the body-weight was corrected with total and adjusted values. For the dose adjustment with lean body-weight, no difference was observed in the dose-normalized plasma concentration of total daptomycin between the physical statuses. For each body-weight correction method, physical status did not affect the dose-normalized plasma concentration of free daptomycin.

CONCLUSION

The glycation of serum albumin and obesity did not associate with dose-normalized plasma free daptomycin. In obese patients, daptomycin dosage adjustment with total body-weight and adjusted body-weight may lead to an apparent excessive exposure resulting in overdosage compared to lean body-weight.

Fluid Stewardship of Maintenance Intravenous Fluids

Despite the frequent use of maintenance intravenous fluids (mIVF) in critically ill patients, limited guidance is available. Notably, fluid overload secondary to mIVF mismanagement is associated with significant adverse patient outcomes. The Four Rights (right drug, right dose, right duration, right patient) construct of fluid stewardship has been proposed for the safe evaluation and use of fluids. The purpose of this evidence-based review is to offer practical insights for the clinician regarding mIVF selection, dosing, and duration in line with the Four Rights of Fluid Stewardship.

Vancomycin dosing in an obese patient with acute renal failure: A case report and review of literature

BACKGROUND

Vancomycin is the most commonly used drug for methicillin-resistant Staphylococcus aureus. The empirical clinical doses of vancomycin based on non-obese patients may not be optimal for obese ones.

CASE SUMMARY

This study reports a case of vancomycin dosing adjustment in an obese patient (body mass index 78.4 kg/m²) with necrotizing fasciitis of the scrotum and left lower extremity accompanied with acute renal failure. Dosing adjustment was performed based on literature review and factors that influence pharmacokinetic parameters are analyzed. The results of the blood drug concentration monitoring confirmed the successful application of our dosing adjustment strategy in this obese patient. Total body weight is an important consideration for vancomycin administration in obese patients, which affects the volume of distribution and clearance of vancomycin. The alterations of pharmacokinetic parameters dictate that vancomycin should be dose-adjusted when applied to obese patients. At the same time, the pathophysiological status of patients, such as renal function, which also affects the dose adjustment of the patient, should be considered.

CONCLUSION

Monitoring vancomycin blood levels in obese patients is critical to help adjust the dosing regimen to ensure that vancomycin concentrations are within the effective therapeutic range and to reduce the incidence of renal injury.

Surgical Antibiotic Prophylaxis in an Era of Antibiotic Resistance: Common Resistant Bacteria and Wider Considerations for Practice

The increasing incidence of antimicrobial resistance (AMR) presents a global crisis to healthcare, with longstanding antimicrobial agents becoming less effective at treating and preventing infection. In the surgical setting, antibiotic prophylaxis has long been established as routine standard of care to prevent surgical site infection (SSI), which remains one of the most common hospital-acquired infections. The growing incidence of AMR increases the risk of SSI complicated with resistant bacteria, resulting in poorer surgical outcomes (prolonged hospitalisation, extended durations of antibiotic therapy, higher rates of surgical revision and mortality). Despite these increasing challenges, more data are required on approaches at the institutional and patient level to optimise surgical antibiotic prophylaxis in the era of antibiotic resistance (AR). This review provides an overview of the common resistant bacteria encountered in the surgical setting and covers wider considerations for practice to optimise surgical antibiotic prophylaxis in the perioperative setting.

Population Pharmacokinetics of Polymyxin B in Obese Patients for Resistant Gram-Negative Infections

Polymyxin B is an effective but potentially nephrotoxic antibiotic that is commonly used to treat resistant Gram-negative infections. As a weight-based dosing drug, obese patients may be at a high risk of nephrotoxicity. However, the pharmacokinetics and dosing recommendations for this population are currently lacking. This study aimed to describe the polymyxin B population pharmacokinetics and to evaluate pharmacokinetic/pharmacodynamics (PK/PD) target attainment for obese patients. This study included 26 patients (body mass index, BMI >30) who received polymyxin B for ≥3 days. The total body weight (TBW) ranged from 75 to 125 kg, and the BMI ranged from 30.04 to 40.35. A two-compartment model adequately described the data using Phoenix NLME software. Monte Carlo simulation was used to assess polymyxin B exposure and the probability of target attainment (PTA). As a result, body weight had no significant effect on polymyxin B pharmacokinetics. According to model-based simulation, adjusted body weight (ABW)-based regimens had a high probability of achieving optimal exposure with minimal toxicity risk by comparing TBW and ideal body weight (IBW)-based regimens. The fixed dose of 125 mg or 150 mg q12h had a high toxicity risk. PTA results showed that TBW, IBW, and ABW-based regimens had similar PTA values. Therefore, for obese patients, ABW-based regimens but with a daily dose <250 mg have a high likelihood of achieving an AUC_ss,24h of 50-100 mg h/L and attaining PK/PD targets with the MIC ≤0.5 mg/L.

Weight-based cefuroxime dosing provides comparable orthopedic target tissue concentrations between weight groups - a microdialysis porcine study

Antibiotic prophylaxis is a key element in prevention of surgical site infections. For the majority of orthopedic procedures, antibiotic administration follows fixed dosing regimens irrespective of weight. However, this may result in insufficient antibiotic target tissue concentrations and higher risk of surgical site infections in obese individuals. The aim of this study was to investigate the effect of weight-based cefuroxime dosing on plasma and target tissue concentrations. Eighteen female pigs were allocated into three groups differentiated by weight: 53-57 kg, 73-77 kg, and 93-97 kg. Microdialysis catheters were placed for continuous sampling in bone, muscle, and subcutaneous tissue during an 8h sampling interval. Blood samples were collected as reference. Cefuroxime was administered intravenously as a bolus according to weight (20 mg/kg). The primary endpoint was the time above the cefuroxime minimal inhibitory concentration for Staphylococcus aureus (T > MIC (4 μg/mL)). Comparable target tissue T > MICs (4 μg/mL) were found between weight groups. Mean T > MIC ranged between 116-137 min for plasma, 118-154 min for bone, 109-146 min for the skeletal muscle, and 117-165 min for subcutaneous tissue across the groups. Weight-based cefuroxime (20 mg/kg) dosing approach provides comparable perioperative plasma and target tissue T > MIC (4 μg/mL) in animals between 50-100 kg body weight, and thus a comparable prophylaxis of surgical site infections.

Impact of a hospital-wide computerised approach to optimise the quality of antimicrobial prescriptions in patients with severe obesity: a quasi-experimental study

Background

Rates of adherence to available recommendations for dose adjustments in patients with severe obesity are generally low. Hence, antimicrobials are often underdosed in these patients. Antimicrobial stewardship programmes can improve the use of antimicrobials in hospitalised patients. The aim of the study was to analyse the impact of an antimicrobial stewardship programme based on a computerised clinical decision support system for optimal dosing and antimicrobial use in inpatients with severe obesity.

Methods

This quasi-experimental retrospective study using interrupted time series was conducted in an academic centre in Canada from August 2008 to June 2018. The Antimicrobial Prescription Surveillance System was implemented in August 2010 (intervention 1) and specific rules targeting patients with class III obesity (body mass index ≥ 40 kg/m²) were added in June 2014 (intervention 2). Data were collected from all hospitalised adults receiving antimicrobials which required dose adjustment for severe obesity and were stratified by body mass index. Segmented regression analysis of interrupted time series was used to evaluate the impact of the Antimicrobial Prescription Surveillance System on the proportion of inappropriate days of therapy according to posology and on antimicrobial consumption.

Results

Overall, 65 205 antimicrobial prescriptions (68% non-obese, 25% class I-II obesity, and 7% class III obesity) were analysed. In patients with class III obesity, the intervention was associated with a decrease in the proportion of inappropriate days of therapy (trend after the first intervention, −0.8% per 2-month period [95% CI −1.1 to −0.5], p < 0.001; intercept, 11.3% [95% CI 8.2 to 14.5], p < 0.001), which led to a reduction of 35% over an eight-year period (from pre-intervention level of 19.1%). Intervention 1 resulted in a downward trend in antimicrobial consumption, followed by an increasing trend after intervention 2. In these patients, the most frequent interventions made by pharmacists targeted posology (46%).

Conclusions

Antimicrobial Prescription Surveillance System had a positive impact on dosing optimisation and antimicrobial consumption in patients with class III obesity. Improving antimicrobial prescriptions in these patients is important because suboptimal dosing could be associated with unfavourable outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06682-8.

Pharmacological management of antifungal agents in pulmonary aspergillosis: an updated review

INTRODUCTION

Aspergillus may cause different types of lung infections: invasive, chronic pulmonary or allergic bronchopulmonary aspergillosis. Pharmacological management with antifungals poses as a challenge. Patients diagnosed with pulmonary aspergillosis are complex, as well as the problems associated with antifungal agents.

AREAS COVERED

This article reviews the pharmacology of antifungal agents in development and currently used to treat pulmonary aspergillosis, including the mechanisms of action, pharmacokinetics, pharmacodynamics, dosing, therapeutic drug monitoring and safety. Recommendations to manage situations that arise in daily clinical practice are provided. A literature search of PubMed was conducted on November 15^th, 2020 and updated on March 30^th, 2021.

EXPERT OPINION

Recent and relevant developments in the treatment of pulmonary aspergillosis have taken place. Novel antifungals with new mechanisms of action that extend antifungal spectrum and improve pharmacokinetic-related aspects, drug-drug interactions and safety are under current study. For those antifungals already marketed, new data related to pharmacokinetics, pharmacodynamics, dose adjustments in special situations, therapeutic drug monitoring and safety are available. To maximize efficacy and reduce the risk of associated toxicities, it is essential to choose the most appropriate antifungal; optimize its dose, interval, route of administration and length of treatment; and prevent side effects.

Population pharmacokinetics and individual analysis of daptomycin in kidney transplant recipients

BACKGROUND

Little is known about the population pharmacokinetics (PPK) of daptomycin in kidney transplant patients. The present study established a pharmacokinetic model for daptomycin in kidney transplant patients in China and examinee the important factors affecting the pharmacokinetic parameters of daptomycin.

METHODS

The study population included 49 kidney transplant patients with 537 daptomycin concentrations. The PPK model of daptomycin was developed using a nonlinear mixed-effects model, a two-compartment structural model, and a mixed residual error model. The stability and predictive ability of the final model were evaluated based on bootstrapping, visual prediction checks and normalized prediction distribution errors.

RESULTS

Glomerular filtration rate (GFR) and total body weight significantly affected clearance, and body weight influenced the central volume of distribution. The average clearance of the population was 0.316 L/h, the central volume of distribution was 6.04 L, the intercompartmental clearance was 2.31 L/h, and the peripheral volume of distribution was 2.46 L. Based on the established model and the target of area under curve (AUC_0-24h)/minimum inhibition concentration (MIC) ≥666, we developed a recommended dose regimen for kidney transplant patients according to their renal function and weight. The daily doses were 4.0±0.31, 4.7±0.36, 5.1±0.40, 5.5±0.43, 5.8±0.45, and 6.1±0.48 mg/kg when the GFRs were 15, 30, 45, 60, 75, and 90 ml/min/1.73 m², respectively.

CONCLUSION

This study provides a reference for individualized daptomycin administration in kidney transplant recipients, and it is a valuable resource for improving the treatment effect and reducing the toxic effects of daptomycin.

Antimicrobial Dosing in Specific Populations and Novel Clinical Methodologies: Obesity

Obesity and its related comorbidities can negatively influence the outcomes of certain infectious diseases. Specific dosing recommendations are often lacking in the product label for patients with obesity that leads to unclear guidance in practice. Higher rates of therapeutic failure have been reported with some fixed dose antibiotics and pragmatic approaches to dose modification are limited for orally administered agents. For i.v. antimicrobials dosed on weight, alternate body size descriptors (ABSDs) have been used to reduce the risk of overdosing. These ABSDs are mathematical transformations of height and weight that represent fat-free weight and follow the same principles as body surface area (BSA)-based dosing of cancer chemotherapy. However, ABSDs are rarely studied in pivotal phase III studies and so can risk the underdosing of antimicrobials in patients with obesity when incorrectly applied in the real-world setting. Specific case examples are presented to highlight these risks. Although general principles may be considered by clinicians, a universal approach to dose modification in obesity is unlikely. Studies that can better distinguish human body phenotypes may help reduce our reliance on height and weight to define dosing. Simple and complex technologies exist to quantify individual body composition that could improve upon our current approach. Early evidence suggests that body composition parameters repurposed from medical imaging data may improve upon height and weight as covariates of drug clearance and distribution. Clinical trials that can integrate human body phenotyping may help us identify new approaches to optimal dose selection of antimicrobials in patients with obesity.

Drug dosing in the critically ill obese patient: a focus on medications for hemodynamic support and prophylaxis

Medications used for supportive care or prophylaxis constitute a significant portion of drug utilization in the intensive care unit. Evidence-based guidelines are available for many aspects of supportive care but drug doses listed are typically for patients with normal body habitus and not morbid obesity. Failure to account for the pharmacokinetic changes that occur with obesity can lead to an incorrect dose and treatment failure or toxicity. This paper is intended to help clinicians design initial dosing regimens in critically ill obese patients for medications commonly used for hemodynamic support or prophylaxis. A detailed literature search of medications used for supportive care or prophylaxis listed in practice guidelines was conducted with an emphasis on obesity, pharmacokinetics and dosing. Relevant manuscripts were reviewed and strategies for dosing are provided. For medications used for hemodynamic support, a similar strategy can be used as in non-obese patients. Similarly, medications for stress ulcer prophylaxis do not need to be adjusted. Anticoagulants for venous thromboembolism prophylaxis, on the other hand, require an individualized approach where higher doses are necessary.

Surgical Infection Society Research Priorities: A Narrative Review of Fourteen Years of Progress

Background: In 2006, the Surgical Infection Society (SIS) utilized a modified Delphi approach to define 15 specific priority research questions that remained unanswered in the field of surgical infections. The aim of the current study was to evaluate the scientific progress achieved during the ensuing period in answering each of the 15 research questions and to determine if additional research in these fields is warranted. Methods: For each of the questions, a literature search using the National Center for Biotechnology Information (NCBI) was performed by the Scientific Studies Committee of the SIS to identify studies that attempted to address each of the defined questions. This literature was analyzed and summarized. The data on each question were evaluated by a surgical infections expert to determine if the question was answered definitively or remains unanswered. Results: All 15 priority research questions were studied in the last 14 years; six questions (40%) were definitively answered and 9 questions (60%) remain unanswered in whole or in part, mainly because of the low quality of the studies available on this topic. Several of the 9 unanswered questions were deemed to remain research priorities in 2020 and warrant further investigation. These included, for example, the role of empiric antimicrobial agents in nosocomial infections, the use of inotropes/vasopressors versus volume loading to raise the mean arterial pressure, and the role of increased antimicrobial dosing and frequency in the obese patient. Conclusions: Several surgical infection-related research questions prioritized in 2006 remain unanswered. Further high-quality research is required to provide a definitive answer to many of these priority knowledge gaps. An updated research agenda by the SIS is warranted at this time to define research priorities for the future.

Efficacy and Safety of Eravacycline in Obese Patients: A Post Hoc Analysis of Pooled Data From the IGNITE1 and IGNITE4 Clinical Trials

Background

The increasing prevalence of obesity worldwide merits an examination of the efficacy and safety profiles of agents dosed by weight.

Methods

Data for patients (n = 1037) were obtained from the pooled IGNITE1 and IGNITE4 randomized double-blind trials in which patients with complicated intra-abdominal infections received eravacycline 1 mg/kg (actual body weight [ABW]) every 12 hours or comparator (ertapenem 1 g every 24 hours or meropenem 1 g every 8 hours) intravenously. This post hoc analysis evaluated clinical cure rates, adverse events, and drug discontinuation rates stratified by body mass index (BMI) categories of BMI >40 kg/m² (Obese, Class III), BMI 35–39.9 kg/m² (Obese, Class II), BMI 30–34.9 kg/m² (Obese, Class I), BMI 25–29.9 kg/m² (Overweight), BMI 18.5–24.9 kg/m² (Healthy weight), and BMI <18.5 kg/m² (Underweight).

Results

Clinical cure rates were high across BMI categories and ranged from 82% to 94% in the eravacycline group and 88.5%–100% in the comparator group. Similar cure rates were observed among eravacycline-treated healthy weight (126/134; 94%), overweight (127/146; 87%), and obese (BMI ≥30 kg/m²; 110/129; 85.3%) patients. In the comparator group, a similar proportion of patients demonstrated clinical response (healthy weight [132/145; 91%], overweight [130/144; 90.3%], and obese [115/129; 89.1%]). Of the treatment-emergent adverse events that occurred in eravacycline-treated obese patients, a larger proportion were gastrointestinal-related (ie, nausea and vomiting); however, discontinuation rates were low and similar between eravacycline and carbapenems.

Conclusions

This post hoc analysis demonstrates the therapeutic utility and acceptable safety profile of eravacycline dosed by ABW in obese patients (BMI ≥30 kg/m²).

A Prospective Clinical Study Characterizing the Influence of Morbid Obesity on the Pharmacokinetics of Gentamicin: Towards Individualized Dosing in Obese Patients

Background and Objective

Gentamicin is an aminoglycoside antibiotic predominantly used in bloodstream infections. Although the prevalence of obesity is increasing dramatically, there is no consensus on how to adjust the dose in obese individuals. In this prospective clinical study, we study the pharmacokinetics of gentamicin in morbidly obese and non-obese individuals to develop a dosing algorithm that results in adequate drug exposure across body weights.

Methods

Morbidly obese subjects undergoing bariatric surgery and non-obese healthy volunteers received one intravenous dose of gentamicin (obese: 5 mg/kg based on lean body weight, non-obese: 5 mg/kg based on total body weight [TBW]) with subsequent 24-h sampling. All individuals had a normal renal function. Statistical analysis, modelling and Monte Carlo simulations were performed using R version 3.4.4 and NONMEM^® version 7.3.

Results

A two-compartment model best described the data. TBW was the best predictor for both clearance [CL = 0.089 × (TBW/70)^0.73] and central volume of distribution [V_c = 11.9 × (TBW/70)^1.25] (both p < 0.001). Simulations showed how gentamicin exposure changes across the weight range with currently used dosing algorithms and illustrated that using a nomogram based on a ‘dose weight’ [70 × (TBW/70)^0.73] will lead to similar exposure across the entire population.

Conclusions

In this study in morbidly obese and non-obese individuals ranging from 53 to 221 kg we identified body weight as an important determinant for both gentamicin CL and V_c. Using a body weight-based dosing algorithm, optimized exposure across the entire population can be achieved, thereby potentially improving efficacy and safety of gentamicin in the obese and morbidly obese population.

Trial Registration

Registered in the Dutch Trial Registry (NTR6058).

Electronic supplementary material

The online version of this article (10.1007/s40262-019-00762-4) contains supplementary material, which is available to authorized users.

Direct Oral Anticoagulants in Obesity: An Updated Literature Review

OBJECTIVE

To review literature on the use of direct-acting oral anticoagulants (DOACs) in patients with high body weight (BW) and/or high body mass index (BMI) and to make recommendations regarding use in this patient population.

DATA SOURCES

A search using PubMed was conducted (inception to April 13, 2020) using the term DOAC AND the terms obesity OR body weight. A separate search was also conducted with individual DOACs (dabigatran, apixaban, rivaroxaban, edoxaban) and the aforementioned terms.

STUDY SELECTION AND DATA EXTRACTION

Studies included examined the effect of BW and/or BMI on DOAC pharmacokinetics, efficacy, or safety. Included studies had DOAC indications of prevention of stroke in nonvalvular atrial fibrillation, or treatment or long-term prevention of venous thromboembolism.

DATA SYNTHESIS

The efficacy and safety of DOACs in patients with high BW/BMI has not yet been elucidated by randomized trials; however, 2016 international guidelines suggest avoiding their use in patients with a BW >120 kg or BMI >40 kg/m². Since 2016, several studies have been published examining use of DOACs in this patient population.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review thoroughly discusses the literature on DOACs in patients with a BW >120 kg or BMI >40 kg/m² pre-2016 and post-2016 guidelines.

CONCLUSIONS

Evidence indicates that each DOAC may have differences in outcomes when used in patients with a high BW/BMI. Currently, low-quality data are available that support avoiding dabigatran and considering apixaban or rivaroxaban; lack of sufficient data preclude a recommendation for edoxaban use in this patient population.

Rising prevalence of BMI ≥40 kg/m2 : A high-demand epidemic needing better documentation

Whilst previously rare, some surveys indicate substantial increases in the population with body mass index (BMI) ≥40 kg/m2 since the 1980s. Clinicians report emerging care challenges for this population, often with high resource demands. Accurate prevalence data, gathered using reliable methods, are needed to inform health care practice, planning, and research. We searched digitally for English language sources with measured prevalence data on adult BMI ≥40 collected since 2010. The search strategy included sources identified from recent work by NCD-RisC (2017), grey sources, a literature search to find current sources, and digital snowball searching. Eighteen countries, across five continents, reported BMI ≥40 prevalence data in surveys since 2010: 12% of eligible national surveys examined. Prevalence of BMI ≥40 ranged from 1.3% (Spain) to 7.7% (USA) for all adults, 0.7% (Serbia) to 5.6% (USA) for men, and 1.8% (Poland) to 9.7% (USA) for women. Limited trend data covering recent decades support significant growth of BMI ≥40 population. Methodological limitations include small samples and data collection methods likely to exclude people with very high BMIs. BMI ≥40 data are not routinely reported in international surveys. Lack of data impairs surveillance of population trends, understanding of causation, and societal provision for individuals living with higher weights.

Assessment of Body Composition in Health and Disease Using Bioelectrical Impedance Analysis (BIA) and Dual Energy X-Ray Absorptiometry (DXA): A Critical Overview

The measurement of body composition (BC) represents a valuable tool to assess nutritional status in health and disease. The most used methods to evaluate BC in the clinical practice are based on bicompartment models and measure, directly or indirectly, fat mass (FM) and fat-free mass (FFM). Bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DXA) (nowadays considered as the reference technique in clinical practice) are extensively used in epidemiological (mainly BIA) and clinical (mainly DXA) settings to evaluate BC. DXA is primarily used for the measurements of bone mineral content (BMC) and density to assess bone health and diagnose osteoporosis in defined anatomical regions (femur and spine). However, total body DXA scans are used to derive a three-compartment BC model, including BMC, FM, and FFM. Both these methods feature some limitations: the accuracy of BIA measurements is reduced when specific predictive equations and standardized measurement protocols are not utilized whereas the limitations of DXA are the safety of repeated measurements (no more than two body scans per year are currently advised), cost, and technical expertise. This review aims to provide useful insights mostly into the use of BC methods in prevention and clinical practice (ambulatory or bedridden patients). We believe that it will stimulate a discussion on the topic and reinvigorate the crucial role of BC evaluation in diagnostic and clinical investigation protocols.

Plasma and tissue pharmacokinetics of fosfomycin in morbidly obese and non-obese surgical patients: a controlled clinical trial

Objectives

To assess the pharmacokinetics and tissue penetration of fosfomycin in obese and non-obese surgical patients.

Methods

Fifteen obese patients undergoing bariatric surgery and 15 non-obese patients undergoing major intra-abdominal surgery received an intravenous single short infusion of 8 g of fosfomycin. Fosfomycin concentrations were determined by LC-MS/MS in plasma and microdialysate from subcutaneous tissue up to 8 h after dosing. The pharmacokinetic analysis was performed in plasma and interstitial fluid (ISF) by non-compartmental methods.

Results

Thirteen obese patients (BMI 38–50 kg/m2) and 14 non-obese patients (BMI 0–29 kg/m2) were evaluable. The pharmacokinetics of fosfomycin in obese versus non-obese patients were characterized by lower peak plasma concentrations (468 ± 139 versus 594 ± 149 mg/L, P = 0.040) and higher V (24.4 ± 6.4 versus 19.0 ± 3.1 L, P = 0.010). The differences in AUC∞ were not significant (1275 ± 477 versus 1515 ± 352 mg·h/L, P = 0.16). The peak concentrations in subcutaneous tissue were reached rapidly and declined in parallel with the plasma concentrations. The drug exposure in tissue was nearly halved in obese compared with non-obese patients (AUC∞ 1052 ± 394 versus 1929 ± 725 mg·h/L, P = 0.0010). The tissue/plasma ratio (AUCISF/AUCplasma) was 0.86 ± 0.32 versus 1.27 ± 0.34 (P = 0.0047).

Conclusions

Whereas the pharmacokinetics of fosfomycin in plasma of surgical patients were only marginally different between obese and non-obese patients, the drug exposure in subcutaneous tissue was significantly lower in the obese patients.

Evaluation of treatment options for methicillin-resistant Staphylococcus aureus infections in the obese patient

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major cause of infection in both the hospital and community setting. Obesity is a risk factor for infection, and the prevalence of this disease has reached epidemic proportions worldwide. Treatment of infections in this special population is a challenge given the lack of data on the optimal antibiotic choice and dosing strategies, particularly for treatment of MRSA infections. Obesity is associated with various physiological changes that may lead to altered pharmacokinetic parameters. These changes include altered drug biodistribution, elimination, and absorption. This review provides clinicians with a summary of the literature pertaining to the pharmacokinetic and pharmacodynamic considerations when selecting antibiotic therapy for the treatment of MRSA infections in obese patients.

Evaluation of a vancomycin dosing nomogram in obese patients weighing at least 100 kilograms

Background

There remains variability in both practice and evidence related to optimal initial empiric dosing strategies for vancomycin.

Objective

Our primary objective was to describe the percentage of obese patients receiving vancomycin doses consistent with nomogram recommendations achieving targeted initial steady-state serum vancomycin concentrations. Secondary objectives were to describe the primary endpoint in subgroups based on patient weight and estimated creatinine clearance, to describe the rate of supratherapeutic vancomycin accumulation following an initial therapeutic trough concentration, and to describe the rate of vancomycin-related adverse events.

Methods

This single-center, IRB-approved, retrospective cohort included adult patients ≥ 100 kilograms total body weight with a body mass index (BMI) >30 kilograms/m2 who received a stable nomogram-based vancomycin regimen and had at least one steady-state vancomycin trough concentration. Data collected included vancomycin regimens and concentrations, vancomycin indication, serum creatinine, and vancomycin-related adverse events. Patients were divided into two cohorts by goal trough concentration: 10-15 mcg/mL and 15-20 mcg/mL.

Results

Of 325 patients screened, 85 were included. Goal steady-state concentrations were reached in 42/85 (49.4%) of total patients.

Conclusions

Achievement of initial steady-state vancomycin serum concentrations in the present study (approximately 50%) was consistent with the use of published vancomycin dosing nomograms.

Trends in NP and RN enrollment, graduation, and practice

The employment outlook for NPs is expected to continue its growth trend in the coming years. This article summarizes graduation and employment trends for nursing students and provides a synopsis of data from the Bureau of Labor Statistics about the growing demand for NPs and nurses. A brief overview of the history of recent workforce trends is also provided.

The AAHKS Clinical Research Award: Intraosseous Regional Prophylaxis Provides Higher Tissue Concentrations in High BMI Patients in Total Knee Arthroplasty: A Randomized Trial

BACKGROUND

Obesity is an established risk factor for periprosthetic joint infections after total knee arthroplasty (TKA). In obese patients, a larger dose of prophylactic vancomycin based on actual body weight is required to reach therapeutic concentrations. It is unclear how tissue concentrations are affected when intraosseous regional administration (IORA) is used in this population. This study compared tissue concentrations of low-dose vancomycin via IORA vs actual body weight-adjusted systemic intravenous (IV) dose in primary TKA.

METHODS

Twenty-two patients with a body mass index (BMI) >35 undergoing TKA were randomized into 2 groups. The IV group received 15 mg/kg (maximum of 2 g) of systemic IV vancomycin and the IORA group received 500 mg vancomycin into the tibia. Subcutaneous fat and bone samples were taken at regular intervals. Tissue antibiotic concentrations were measured using liquid chromatography coupled with tandem mass spectrometry. A blood sample was taken 1 to 2 hours after tourniquet deflation to measure systemic concentration.

RESULTS

The mean BMI was 41.1 in the IORA group and 40.1 in the IV systemic group. The overall mean tissue concentration in subcutaneous fat was 39.3 μg/g in the IORA group and 4.4 μg/g in the IV systemic group (P < .01). Mean tissue concentrations in bones were 34.4 μg/g in the IORA group and 6.1 μg/g in the IV systemic group (P < .01).

CONCLUSION

Low-dose IORA was effective in the high-BMI population group, providing tissue concentrations of vancomycin 5-9 times higher than systemic administration. IORA optimizes timing of vancomycin administration and provides high tissue antibiotic concentrations during TKA in this high-risk patient group.

Enoxaparin Dosing at Extremes of Weight: Literature Review and Dosing Recommendations

OBJECTIVE

To review the literature on both thromboprophylaxis and treatment of venous thromboembolism (VTE) with enoxaparin in low- and high-body-weight patients and to make dosing and monitoring recommendations in these patient populations.

DATA SOURCES

A search using PubMed was conducted (1995 to January 2018) using the following key words: enoxaparin, body weight, AND thromboprophylaxis, or AND treatment. Additional references were identified from a review of citations.

STUDY SELECTION AND DATA EXTRACTION

Studies included examined the effect of body weight and/or body mass index (BMI) on VTE, bleeding, enoxaparin dosing, and/or anti-Xa concentrations for thromboprophylaxis and treatment-dose enoxaparin. Studies in pediatric and pregnant patients were excluded.

DATA SYNTHESIS

Optimal enoxaparin dosing strategies for VTE prophylaxis and treatment for patients at extremes of weight have not yet been elucidated by clinical trials; however, data suggest that standard dosing regimens may not be appropriate in these patients. Relevance to Patient Care and Clinical Practice: This review provides a thorough discussion on both thromboprophylaxis and treatment of VTE with enoxaparin in low- and high-body-weight patients. It includes dosing recommendations to guide clinicians caring for these patient populations.

CONCLUSIONS

Patients at extremes of weight require special consideration to determine appropriate enoxaparin doses. Specifically, low-body-weight patients may benefit from 30 mg subcutaneously daily for VTE prophylaxis, and standard weight-based dosing for VTE treatment. Conversely, in patients with BMIs ≥40 kg/m², 40 mg subcutaneously twice daily is recommended, with consideration for higher doses in patients with BMIs ≥50 kg/m².

Safety of high-dose daptomycin in patients with severe renal impairment

Background

Treatment options are limited for infections due to multidrug-resistant Gram-positive pathogens. Daptomycin is a lipopeptide antibiotic with concentration-dependent killing characteristic and dose-dependent post-antibiotic effect. To achieve optimized pharma-codynamic effect, some experts advocated using a high dose of daptomycin (≥9 mg/kg) for severe infections. However, the safety of high-dose therapy in patients with renal impairment remains unknown. This study was aimed to evaluate the safety of daptomycin in patients with severe renal impairment.

Methods

This was a retrospective study performed by reviewing electronic medical records. Patients with severe renal impairment who were treated with daptomycin in a tertiary teaching hospital between January 1, 2013, and June 30, 2016, were included for evaluation. The incidence rates of creatine kinase (CK) elevation between high-dose (≥9 mg/kg) and standard-dose (<9 mg/kg) groups were compared.

Results

Overall, 164 patients met the inclusion criteria, and 114 (69.5%) of them were on renal replacement therapy. Vancomycin-resistant enterococci were the most common pathogens (61.3%) of the patients with documented pathogens. The treatment success rate was 51.6% in the 91 patients with bacteremia. The average dose of daptomycin was 8.0±2.3 mg/kg, and 37 (22.6%) patients received ≥9 mg/kg. CK levels were followed in 108 (65.9%) patients. Significantly higher incidence of CK elevation was found in the high-dose group compared with that in the standard-dose group (10.8% vs 1.6%, P<0.05). Moreover, patients with elevated CK received a higher dose of daptomycin than those without (9.3±1.2 vs 7.9±2.3 mg/kg, P<0.05). There was no significant difference in the rate of CK elevation between patients treated with different dosing frequency or with the concurrent use of statins, fibrate, or colchicine.

Conclusions

In patients with severe renal impairment, high-dose (≥9 mg/kg) daptomycin therapy may result in a significantly higher incidence of CK elevation. More frequent CK monitoring is warranted to avoid potential harm in this population.

The ABCDs of Managing Morbidly Obese Patients in Intensive Care Units

More than one-third of the US adult population and 17% of the youth are now obese, and obesity is associated with more than $147 billion a year in health care costs. Critical care nurses should understand the physiological differences and practice guidelines for patients with a body mass index greater than 30. The ABCD approach encompasses key clinical concepts in the management of critically ill obese and morbidly obese patients, including management of airways and breathing, minimizing nurses' back and other injuries, increasing awareness of bias, circulation problems, risks of decubitus ulcers and other skin breakdown, differences in drug calculations and metabolism, limitations in diagnostic equipment and imaging, diet and nutritional recommendations, and concerns with durable medical equipment.

Application of Antibiotic Pharmacodynamics and Dosing Principles in Patients With Sepsis

Sepsis is associated with marked mortality, which may be reduced by prompt initiation of adequate, appropriate doses of antibiotic. Critically ill patients often have physiological changes that reduce blood and tissue concentrations of antibiotic and high rates of multidrug-resistant pathogens, which may affect patients' outcomes. All critical care professionals, including critical care nurses, should understand antibiotic pharmacokinetics and pharmacodynamics to ensure sound antibiotic dosing and administration strategies for optimal microbial killing and patients' outcomes. Effective pathogen eradication occurs when the dose of antibiotic reaches or maintains optimal concentrations relative to the minimum inhibitory concentration for the pathogen. Time-dependent antibiotics, such as β-lactams, can be given as extended or continuous infusions. Concentration-dependent antibiotics such as aminoglycosides are optimized by using high, once-daily dosing strategies with serum concentration monitoring. Vancomycin and fluoroquinolones are dependent on both time and concentration above the minimum inhibitory concentration.

Managing acute bacterial skin and skin structure infections: Focus on new lipoglycopeptides

Acute bacterial skin and skin structure infections (ABSSSI) are some of the most commonly encountered infections worldwide. Hospitalizations as a result of ABSSSI are associated with high mortality. This article discusses the role of oritavancin and dalbavancin, two new lipoglycopeptides, in the context of the other I.V. available standard therapy options.

Management of Viral Central Nervous System Infections: A Primer for Clinicians

Viruses are a common cause of central nervous system (CNS) infections with many host, agent, and environmental factors influencing the expression of viral diseases. Viruses can be responsible for CNS disease through a variety of mechanisms including direct infection and replication within the CNS resulting in encephalitis, infection limited to the meninges, or immune-related processes such as acute disseminated encephalomyelitis. Common pathogens including herpes simplex virus, varicella zoster, and enterovirus are responsible for the greatest number of cases in immunocompetent hosts. Other herpes viruses (eg, cytomegalovirus, John Cunningham virus) are more common in immunocompromised hosts. Arboviruses such as Japanese encephalitis virus and Zika virus are important pathogens globally, but the prevalence varies significantly by geographic region and often season. Early diagnosis from radiographic evidence and molecular (eg, rapid) diagnostics is important for targeted therapy. Antivirals may be used effectively against some pathogens, although several viruses have no effective treatment. This article provides a review of epidemiology, diagnostics, and management of common viral pathogens in CNS disease.

Overweight Kidney Transplant Recipients Are at Risk of Being Overdosed Following Standard Bodyweight-Based Tacrolimus Starting Dose

BACKGROUND

Bodyweight-based dosing of tacrolimus (Tac) is considered standard care, even though the available evidence is thin. An increasing proportion of transplant recipients is overweight, prompting the question if the starting dose should always be based on bodyweight.

METHODS

For this analysis, data were used from a randomized-controlled trial in which patients received either a standard Tac starting dose or a dose that was based on CYP3A5 genotype. The hypothesis was that overweight patients would have Tac overexposure following standard bodyweight-based dosing.

RESULTS

Data were available for 203 kidney transplant recipients, with a median body mass index (BMI) of 25.6 (range, 17.2-42.2). More than 50% of the overweight or obese patients had a Tac predose concentration above the target range. The CYP3A5 nonexpressers tended to be above target when they weighed more than 67.5 kg or had a BMI of 24.5 or higher. Dosing guidelines were proposed with a decrease up to 40% in Tac starting doses for different BMI groups. The dosing guideline for patients with an unknown genotype was validated using the fixed-dose versus concentration controlled data set.

CONCLUSIONS

This study demonstrates that dosing Tac solely on bodyweight results in overexposure in more than half of overweight or obese patients.

Application of guidelines for aminoglycosides use in French hospitals in 2013-2014

In 2011, the French Agency for Safety of Health Products issued guidelines underlining the principles of proper aminoglycosides' use. The aim of the survey was to evaluate adherence to these guidelines two years after their issue. Characteristics of patients receiving aminoglycosides were recorded by voluntary facilities during a 3-month survey in 2013-2014. The modalities of aminoglycosides treatment were analysed by comparison with the French guidelines. A total of 3,323 patients were included by 176 facilities. Patients were mainly hospitalized in medical wards (33.0%), and treated for urinary-tract infections (24.7%). Compliance regarding the clinical indication and the daily aminoglycosides dose was observed in 65.2% and 62.9% of the cases, respectively. A 30-min once-daily IV administration was recorded in 62.5% of the cases. Aminoglycosides treatment duration was appropriate (≤5 days) for 93.6% of the patients. When considering the four criteria together, 23.2% of the patients had a treatment regimen aligned with the guidelines. Requests for measurements of peak and trough AG serum concentrations matched the guidelines in 24.9% and 67.4% of the cases, respectively. Two years after guidelines issue, aminoglycosides use remains unsatisfactory in French health-care facilities. Efforts should be made for guidelines promotion, especially regarding the issue of underdosing.

Liposomal Amphotericin B (AmBisome(®)): A Review of the Pharmacokinetics, Pharmacodynamics, Clinical Experience and Future Directions

Liposomal amphotericin B (AmBisome(®); LAmB) is a unique lipid formulation of amphotericin B. LAmB is a standard of care for a wide range of medically important opportunistic fungal pathogens. LAmB has a significantly improved toxicity profile compared with conventional amphotericin B deoxycholate (DAmB). Despite nearly 20 years of clinical use, the pharmacokinetics and pharmacodynamics of this agent, which differ considerably from DAmB, remain relatively poorly understood and underutilized in the clinical setting. The molecular pharmacology, preclinical and clinical pharmacokinetics, and clinical experience with LAmB for the most commonly encountered fungal pathogens are reviewed. In vitro, experimental animal models and human clinical trial data are summarized, and novel routes of administration and dosing schedules are discussed. LAmB is a formulation that results in reduced toxicity as compared with DAmB while retaining the antifungal effect of the active agent. Its long terminal half-life and retention in tissues suggest that single or intermittent dosing regimens are feasible, and these should be actively investigated in both preclinical models and in clinical trials. Significant gaps remain in knowledge of pharmacokinetics and pharmacodynamics in special populations such as neonates and children, pregnant women and obese patients.

Obesity Is Not Associated with Antimicrobial Treatment Failure for Intra-Abdominal Infection

BACKGROUND

Obesity and commonly associated comorbidities are known risk factors for the development of infections. However, the intensity and duration of antimicrobial treatment are rarely conditioned on body mass index (BMI). In particular, the influence of obesity on failure of antimicrobial treatment for intra-abdominal infection (IAI) remains unknown. We hypothesized that obesity is associated with recurrent infectious complications in patients treated for IAI.

METHODS

Five hundred eighteen patients randomized to treatment in the Surgical Infection Society Study to Optimize Peritoneal Infection Therapy (STOP-IT) trial were evaluated. Patients were stratified by obese (BMI ≥30) versus non-obese (BMI≥30) status. Descriptive comparisons were performed using Chi-square test, Fisher exact test, or Wilcoxon rank-sum tests as appropriate. Multivariable logistic regression using a priori selected variables was performed to assess the independent association between obesity and treatment failure in patients with IAI.

RESULTS

Overall, 198 (38.3%) of patients were obese (BMI ≥30) versus 319 (61.7%) who were non-obese. Mean antibiotic d and total hospital d were similar between both groups. Unadjusted outcomes of surgical site infection (9.1% vs. 6.9%, p = 0.36), recurrent intra-abdominal infection (16.2% vs. 13.8, p = 0.46), death (1.0% vs. 0.9%, p = 1.0), and a composite of all complications (25.3% vs. 19.8%, p = 0.14) were also similar between both groups. After controlling for appropriate demographics, comorbidities, severity of illness, treatment group, and duration of antimicrobial therapy, obesity was not independently associated with treatment failure (c-statistic: 0.64).

CONCLUSIONS

Obesity is not associated with antimicrobial treatment failure among patients with IAI. These results suggest that obesity may not independently influence the need for longer duration of antimicrobial therapy in treatment of IAI versus non-obese patients.

Identification of Risk Factors for Initial Elevated Vancomyin Trough Concentrations

Background: Recent literature suggests that elevated vancomycin trough concentrations (>20 µg/mL) may be associated with an increased risk of nephrotoxicity and lead to an increase in mortality and hospital length of stay. Objective: The purpose of this study was to identify variables that may be predictive of elevated initial vancomycin trough concentrations. Methods: Retrospective case–control study of all adult patients who had an initial vancomycin trough concentration measured between January 1, 2013, and December 31, 2014. Case patients had an initial trough concentration >20 µg/mL, while control patients had an initial trough concentration of ≤20 µg/mL. Patients were excluded from the study if they were in the intensive care unit, had unstable renal function, or if they had cystic fibrosis, solid organ transplant, or bone marrow transplant. Results: Of the 512 vancomycin trough concentrations reviewed, 54 patients met the case definition, while 140 patients were randomly selected as controls. In a multivariate model, baseline serum creatinine, body mass index, heart failure, and malignancy were all independently predictive of an initial vancomycin concentration >20 µg/mL. Conclusions: Reduced baseline renal function coupled with increasing body mass index is associated with an increased risk of an elevated initial vancomycin trough concentration. This risk is further enhanced by the presence of heart failure and/or malignancy. When these risk factors are present, it may be prudent to consider implementation of individualized dosing to achieve initial target concentrations.

Cellulitis in Obesity

Purpose: Cellulitis in obese patients is associated with increased rates of treatment failure compared to those with normal body mass index (BMI); however, patients have not been extensively studied in the outpatient environment or stratified based on range of obesity and associated risk factors. This study looked at antibiotic dosing and treatment failure in the obese population from the primary care perspective and accounts for BMI range, weight, comorbid diabetes, and tobacco use. Methods: This study was a retrospective chart review of 637 adult primary care patients designed to evaluate rates of treatment failure of outpatient cellulitis among patients of varying BMI. Treatment failure was defined as ( a) hospital admission for intravenous antibiotics, ( b) prolonged antibiotic course, or ( c) requiring a different antibiotic after initial course. Results: Adverse outcomes were not statistically significant between normal BMI and those with BMI ≥40 kg/m2. A subset of patients with a BMI ≥50 kg/m2 was noted to have approximately twice the rate of adverse outcomes as the normal BMI group. While controlling for age, gender, race, diagnosis of diabetes mellitus, and tobacco use, a BMI of ≥50 kg/m2 and a weight ≥120 kg was associated with adverse outcomes with an odds ratio of 2.440 (95% CI, 1.260-4.724; P = .008) and 2.246 (95% CI, 1.154-4.369; P = .017), respectively. Conclusions: Patients with cellulitis weighing >120kg or with a BMI ≥50 kg/m2 were at greatest risk for treatment failure in the outpatient setting, even when controlling for comorbid diabetes and tobacco use. As morbid obesity continues to become more prevalent, it becomes imperative that primary care physicians have better antibiotic dosing guidelines to account for the physiologic effects of obesity to minimize the risk of increased morbidity, health care costs, and antibiotic resistance.

Does obesity affect outcomes of adult burn patients?

BACKGROUND

Obesity negatively affects outcomes after trauma and surgery; results after burns are more limited and controversial. The purpose of this study was to determine the effect of obesity on clinical and economic outcomes after thermal injury.

METHODS

The National Inpatient Sample was queried for adults from 2005-2009 with International Classification of Diseases-9 codes for burn injury. Demographics and clinical outcomes of obese and nonobese cohorts were compared. Univariate and multivariate analysis using logistic regression models were performed. Data are expressed as median (interquartile range) or mean ± standard deviation and compared at P < 0.05.

RESULTS

In 14,602 patients, 3.3% were obese (body mass index ≥30 kg/m(2)). The rate of obesity increased significantly by year (P < 0.001). Univariate analysis revealed significant differences between obese and nonobese patients in incidence of wound infection (7.2% versus 5.0%), urinary tract infection (7.2% versus 4.6%), deep vein thrombosis in total body surface area (TBSA) ≥10% (3.1% versus 1.1%), pulmonary embolism in TBSA ≥10% (2.3% versus 0.6%), length of stay [6 d (8) versus 5 d (9)], and hospital costs ($10,122.12 [$18,074.72] versus $7892.07 [$17,191.96]) (all P < 0.05). Death occurred less frequently in the obese group (1.9% versus 4%, P = 0.021). Significant predictors of grouped adverse events (urinary tract infection, wound infection, deep vein thrombosis, and pulmonary embolism) on multivariate analysis include obesity, TBSA ≥20%, age, and black race (all P ≤ 0.05).

CONCLUSIONS

Obesity is an independent predictor of adverse events after burn injury; however, obesity is associated with decreased mortality. Our findings highlight the potential clinical and economic impact of the obesity epidemic on burn patients nationwide.