Background: Early and appropriate antibiotic dosing is associated with improved clinical outcomes in critically ill patients, yet target attainment remains a challenge. Traditional antibiotic... Show moreBackground: Early and appropriate antibiotic dosing is associated with improved clinical outcomes in critically ill patients, yet target attainment remains a challenge. Traditional antibiotic dosing is not suitable in critically ill patients, since these patients undergo physiological alterations that strongly affect antibiotic exposure. For beta-lactam antibiotics, the unbound plasma concentrations above at least one to four times the minimal inhibitory concentration (MIC) for 100% of the dosing interval (100%integral T > 1-4xMIC) have been proposed as pharmacodynamic targets (PDTs) to maximize bacteriological and clinical responses. The objectives of this study are to describe the PDT attainment in critically ill patients and to identify risk factors for target non-attainment.Methods: This prospective observational study was performed in two ICUs in the Netherlands. We enrolled adult patients treated with the following beta-lactam antibiotics: amoxicillin (with or without clavulanic acid), cefotaxime, ceftazidime, ceftriaxone, cefuroxime, and meropenem. Based on five samples within a dosing interval at day 2 of therapy, the time unbound concentrations above the epidemiological cut-off (integral T > MICECOFF and integral T > 4xMIC(ECOFF)) were determined. Secondary endpoints were estimated multivariate binomial and binary logistic regression models, for examining the association of PDT attainment with patient characteristics and clinical outcomes.Results: A total of 147 patients were included, of whom 63.3% achieved PDT of 100% integral T > MICECOFF and 36.7% achieved 100% integral T > 4xMIC(ECOFF). Regression analysis identified male gender, estimated glomerular filtration rate (eGFR) >= 90 mL/min/1.73 m(2), and high body mass index (BMI) as risk factors for target non-attainment. Use of continuous renal replacement therapy (CRRT) and high serum urea significantly increased the probability of target attainment. In addition, we found a significant association between the 100% integral T > MICECOFF target attainment and ICU length of stay (LOS), but no significant correlation was found for the 30-day survival.Conclusions Traditional beta-lactam dosing results in low target attainment in the majority of critically ill patients. Male gender, high BMI, and high eGFR were significant risk factors for target non-attainment. These predictors, together with therapeutic drug monitoring, may help ICU clinicians in optimizing beta-lactam dosing in critically ill patients. Show less
Purpose To develop and validate a population pharmacokinetic model of ciprofloxacin intravenously in critically ill patients, and determine target attainment to provide guidance for more effective... Show morePurpose To develop and validate a population pharmacokinetic model of ciprofloxacin intravenously in critically ill patients, and determine target attainment to provide guidance for more effective regimens. Methods Non-linear mixed-effects modelling was used for the model development and covariate analysis. Target attainment of an integral AUC(0-24)/MIC >= 100 for different MICs was calculated for standard dosing regimens. Monte Carlo simulations were performed to define the probability of target attainment (PTA) of several dosing regimens. Results A total of 204 blood samples were collected from 42 ICU patients treated with ciprofloxacin 400-1200 mg/day, with median values for age of 66 years, APACHE II score of 22, BMI of 26 kg/m(2), and eGFR of 58.5 mL/min/1.73 m(2). The median integral AUC(0-24) and integral C-max were 29.9 mg center dot h/L and 3.1 mg/L, respectively. Ciprofloxacin pharmacokinetics were best described by a two-compartment model. We did not find any significant covariate to add to the structural model. The proportion of patients achieving the target integral AUC(0-24)/MIC >= 100 were 61.9% and 16.7% with MICs of 0.25 and 0.5 mg/L, respectively. Results of the PTA simulations suggest that a dose of >= 1200 mg/day is needed to achieve sufficient integral AUC(0-24)/MIC ratios. Conclusions The model described the pharmacokinetics of ciprofloxacin in ICU patients adequately. No significant covariates were found and high inter-individual variability of ciprofloxacin pharmacokinetics in ICU patients was observed. The poor target attainment supports the use of higher doses such as 1200 mg/day in critically ill patients, while the variability of inter-individual pharmacokinetics parameters emphasizes the need for therapeutic drug monitoring to ensure optimal exposure. Show less
Heida, A.; Dijkstra, A.; Kobold, A.M.; Rossen, J.W.; Kindermann, A.; Kokke, F.; ... ; Rheenen, P.F. van 2018
Objective: Although it has been found that identity constructs related to smoking are associated with changes in smoking behaviour, the direction of causal associations is as yet unclear. This... Show moreObjective: Although it has been found that identity constructs related to smoking are associated with changes in smoking behaviour, the direction of causal associations is as yet unclear. This study aims to clarify the nature and direction of these associations.Methods: In this longitudinal study we examined the reciprocal relations between identity constructs (i.e., smoker self-identity, quitter self-identity and smoker group-identity), intention to quit and smoking and quitting behaviour among a sample of 1036 smokers and ex-smokers, using cross-lagged structural equation modelling. Moreover, we tested whether these relations differed by socio-economic status (SES).Results: Identity and smoking behaviour were reciprocally related in that in intention to quit and smoking behaviour consistently predicted identity change, and identity predicted (changes in) intentions to quit and smoking behaviour. Behaviour appears more important for identity change than identity for behaviour change. Furthermore, quitter self-identity appears more important than smoker self- and group-identity. Relationships did not differ significantly between SES-groups. The findings were replicated using a cross-validation sample.Conclusion: Results imply that changing smoking behaviour may be a vehicle to change smoking-related identity. Moreover, strengthening identification with quitting is more crucial for quit success than decreasing smoker identities. The finding that behaviour may be more important for identity than vice versa, if replicated, may call for additions to identity theories. Show less
Meijer, E.; Putte, B. van den; Gebhardt, W.A.; Laar, C. van; Bakk, Z.; Dijkstra, A.; ... ; Willemsen, M.C. 2018
Although it has been found that identity constructs related to smoking are associated with changes in smoking behaviour, the direction of causal associations is as yet unclear. This study aims to... Show moreAlthough it has been found that identity constructs related to smoking are associated with changes in smoking behaviour, the direction of causal associations is as yet unclear. This study aims to clarify the nature and direction of these associations. In this longitudinal study we examined the reciprocal relations between identity constructs (i.e., smoker self-identity, quitter self-identity and smoker group-identity), intention to quit and smoking and quitting behaviour among a sample of 1036 smokers and ex-smokers, using cross-lagged structural equation modelling. Moreover, we tested whether these relations differed by socio-economic status (SES). Identity and smoking behaviour were reciprocally related in that in intention to quit and smoking behaviour consistently predicted identity change, and identity predicted (changes in) intentions to quit and smoking behaviour. Behaviour appears more important for identity change than identity for behaviour change. Furthermore, quitter self-identity appears more important than smoker self- and group-identity. Relationships did not differ significantly between SES-groups. The findings were replicated using a cross-validation sample. Results imply that changing smoking behaviour may be a vehicle to change smoking-related identity. Moreover, strengthening identification with quitting is more crucial for quit success than decreasing smoker identities. The finding that behaviour may be more important for identity than vice versa, if replicated, may call for additions to identity theories. OBJECTIVE METHODS RESULTS CONCLUSION Show less
Meijer, E.; Laar, C. van; Gebhardt, W.A.; Fokkema, M.; Putte, B. van den; Dijkstra, A.; ... ; Willemsen, M.C. 2017
