Development of a nomogram for the estimation of long-term adherence to clozapine therapy using neutrophil fluorescence.

AIMS: Previously, we have reported an association between clozapine use and elevated FL3 neutrophil fluorescence, a flow-cytometric parameter for cell viability. Here, we developed and evaluated a pharmacokinetic-pharmacodynamic model relating FL3-fluorescence to clozapine exposure and derived a nomogram for estimation of long-term adherence. METHODS: Data from 27 patients initiating clozapine were analysed using nonlinear mixed effects modelling. A previously described pharmacokinetic model for clozapine was coupled to a FL3 fluorescence model. For this, an effect compartment with clozapine concentrations as input and a first order decay rate as output was linked with an Emax model to FL3-fluorescence. FL3-fluorescence was simulated for clozapine doses of 50, 150 and 400 mg daily (n = 10 000) to establish the nomogram. Finally, true simulated adherence (% of daily doses taken over 100 days) was compared to nomogram-estimated adherence to evaluate the performance of the nomogram. RESULTS: The half-life of FL3-fluorescence was estimated at 228 h (coefficient of variation 35%). Median absolute prediction errors of the nomogram in case of fully random adherence for 50, 150 and 400 mg ranged from -0.193% to -0.525%. The nomogram performed slightly worse in case of nonrandom adherence (median prediction error up to 5.19%), but was still clinically acceptable. Compliance patterns containing longer drug holidays revealed that the nomogram adequately estimates compliance over approximately the last 3 weeks prior to FL3-measurement. CONCLUSION: Our nomogram could provide information regarding long-term adherence based on prescribed clozapine dose and FL3-fluorescence. Future studies should further explore the clinical value of this biomarker and nomogram.

Impact of infant pneumococcal conjugate vaccination on community acquired pneumonia hospitalization in all ages in the Netherlands.

BACKGROUND: The long-term impact of pneumococcal conjugate vaccines on pneumonia hospitalizations in all age-groups varies between countries. In the Netherlands, the 7-valent pneumococcal conjugate vaccine (PCV7) was implemented for newborns in 2006 and replaced by PCV10 in 2011. We assessed the impact of PCVs on community-acquired pneumonia (CAP) hospitalization rates in all age-groups. METHODS: A time series analysis using Poisson regression was performed on 155,994 CAP hospitalizations. Hospitalization rates were calculated using the total number of hospitalizations as denominator. The time trend in the pre-PCV period (1999-2006) was extrapolated to predict the hospitalization rate in the post-PCV period (2006-2014) if PCV had not been implemented. Rate ratios over time were calculated by comparing observed and predicted time trends. RESULTS: In children <5 years of age, the observed hospitalization rates during the post-PCV period were significantly lower than predicted if PCV had not been implemented (0-6 months: 0.62, 95% CI: 0.41-0.96; 6 months - 1 year: 0.67, 95% CI: 0.50-0.90; 2-4 years: 0.78, 95% CI: 0.61-0.97). In all other age-groups, rate ratios declined over time but did not reach statistical significance. CONCLUSIONS: After introduction of PCV, CAP hospitalizations declined in young children but no clear impact of PCV on CAP hospitalizations was seen in other age-groups.