Hybrid multimodal fusion for graph learning in disease prediction.

Graph neural networks (GNNs) have gained significant attention in disease prediction where the latent embeddings of patients are modeled as nodes and the similarities among patients are represented through edges. The graph structure, which determines how information is aggregated and propagated, plays a crucial role in graph learning. Recent approaches typically create graphs based on patients' latent embeddings, which may not accurately reflect their real-world closeness. Our analysis reveals that raw data, such as demographic attributes and laboratory results, offers a wealth of information for assessing patient similarities and can serve as a compensatory measure for graphs constructed exclusively from latent embeddings. In this study, we first construct adaptive graphs from both latent representations and raw data respectively, and then merge these graphs via weighted summation. Given that the graphs may contain extraneous and noisy connections, we apply degree-sensitive edge pruning and kNN sparsification techniques to selectively sparsify and prune these edges. We conducted intensive experiments on two diagnostic prediction datasets, and the results demonstrate that our proposed method surpasses current state-of-the-art techniques.

The potential influence of estrogen-containing oral contraception on clozapine metabolism in a patient with known pharmacogenomic status.

Clozapine is primarily metabolized via cytochrome P450(CYP)1A2 and to a lesser extent CYP3A4, CYP2C19, and CYP2D6. Metabolic inhibitors of clozapine, such as fluvoxamine and ciprofloxacin, are important to recognize to avoid adverse drug events. Estrogen-containing oral contraceptives (eOCPs) are weaker CYP1A2 and CYP2C19 inhibitors but are associated with a 2-fold increase of clozapine concentrations. The potential for phenoconversion due to a CYP genetic polymorphism can add additional complexities when considering drug interactions. A case report is presented of a suspected interaction between newly initiated clozapine and a prescribed eOCP for which the patient's pharmacogenomic status was known. A 17-year-old, nonsmoking, White female with a history of schizophrenia was initiated on clozapine 12.5 mg at bedtime with a plan to increase by 25 mg every 4 days in the outpatient setting. The patient was a known rapid CYP1A2 metabolizer without identified sources of CYP1A2 induction and a CYP2C19 rapid metabolizer. Based on pharmacogenomic testing, there was no suspicion for significant gene-drug interactions. Yet, as the patient was prescribed an eOCP, a clozapine concentration was obtained after reaching 150 mg at bedtime. This steady-state clozapine concentration was found to be 560 ng/mL, correlating with worsening sedation and constipation. Given ongoing side effects, clozapine was lowered to 100 mg at bedtime; however, ongoing intolerance ultimately led to clozapine discontinuation. This case highlights the potential interaction between clozapine and eOCP in a CYP1A2 and CYP2C19 rapid metabolizer, leading to clozapine intolerance and discontinuation. The concomitant use of clozapine and eOCPs should be undertaken judiciously.

Evaluation of major adverse events of clozapine based on accordance to an international titration guideline.

Introduction: Clozapine is the only antipsychotic approved for treatment-resistant schizophrenia, but without appropriate monitoring, it can be associated with potentially fatal outcomes. An International Adult Clozapine Titration Guideline categorizes patients into normal or slow metabolizers. Categorization provides clozapine titration schedules and recommends regular c-reactive protein (CRP) and clozapine concentration monitoring to reduce the risk of adverse drug reactions (ADRs). The impact of the guideline on clozapine ADRs has not been evaluated. Methods: A retrospective chart review assessed clozapine titrations, laboratory monitoring, ADRs, and discontinuations for clozapine-naive adult inpatients at a single center from January 1, 2013, to June 1, 2022. Each patient's cumulative weekly clozapine dosage was compared with their guideline recommended dosage to create a percent accordance. Linear logistic regression evaluated the relationship between titration speed and the presence of an ADR, while descriptive statistics analyzed laboratory monitoring. Results: Forty-three patients were included, with the majority being White males with schizophrenia. An inverse relationship existed between the last inpatient week clozapine dose percent accordance and the probability of an ADR. Nonobese patients were less likely than obese patients to experience an ADR (odds ratio = 0.17; 95% CI, 0.03-0.99). CRP and clozapine concentration monitoring was suboptimal. Discussion: Based on our small retrospective review of primarily White males, more aggressive clozapine titrations did not increase ADRs. Future studies with more diverse samples are needed and should focus on specific ADRs, which may have increased occurrence with rapid titrations. Obese patients were at higher risk of ADRs, correlating with the guideline-recommended slower titrations for these patients.

Improving the Diagnosis of Rib Fractures in the Emergency Department: A Quality Improvement Project in a District General Hospital in the United Kingdom.

Background Falls in older people are a common presentation in emergency departments (ED) in the United Kingdom. They can lead to multiple injuries, including chest wall injuries (CWIs). Untreated CWI carries significant morbidity and mortality. However, its diagnosis remains challenging during the initial ED encounter. This led to a quality improvement project (QIP) to improve the diagnosis of CWI in patients presenting to William Harvey Hospital, a district general, trauma-unit ED in Willesborough, England. Methods The QIP was run from February 2020 to April 2021 for 14 months. A series of plan-do-study-act (PDSA) cycles were completed to increase the proportion of CWIs diagnosed during the initial ED encounter to 90%. The primary interventions involved designing a new thoracic trauma proforma and the introduction of the modified pain, inspiratory effort, and cough (PIC) score to evaluate and triage patients with CWI. Other interventions included the delivery of an education programme on CWI. The secondary aims were to increase modified PIC score use and to reduce the time between ED presentation and computerised tomography (CT) scanning. Results A total of 147 patients were included in three PDSA cycles. The diagnosis of CWI during the initial ED encounter increased from 61% at baseline to 91%. The median time from ED attendance to the first CT reduced from 477 minutes to 169 minutes. Lastly, following the introduction of the thoracic trauma proforma, the modified PIC score was used in 26% of cases of CWI by the end of the QIP period. Conclusion Our QIP led to improvement in the early diagnosis of CWIs in ED, with significant improvements in door to CT time and the creation of a thoracic injury pathway in the trust leading to multi-specialty improvement of care of such patients.

The occurrence of mental health symptoms in isotretinoin-treated adolescents.

BACKGROUND: Isotretinoin treatment for acne can reduce adverse psychiatric outcomes in adults, but there has been little investigation of the incidence of psychiatric outcomes in treated adolescents. METHODS: This retrospective cohort study using the Rochester Epidemiology Project identified 606 patients aged 12-18 prescribed isotretinoin over a 10-year period between January 1, 2008 and December 31, 2017. Medical records were reviewed to identify psychiatric diagnoses before and during isotretinoin therapy, as well as psychiatric symptoms not captured by formal diagnoses and changes to isotretinoin dosing because of psychiatric diagnoses or symptoms. RESULTS: One hundred seventy-seven (29.2%) had a psychiatric diagnosis prior to isotretinoin initiation, but 98 (16.2%) had a new psychiatric diagnosis or psychiatric symptom while taking isotretinoin. Patients with a psychiatric history were no more likely than those without to receive a new psychiatric diagnosis during treatment (4.5% vs. 3.7%; p = .650), but did experience more psychiatric symptoms, primarily low mood and mood swings (23.7% vs. 7.7%; p < .001). Only 25.5% of the 98 with a new psychiatric diagnosis or psychiatric symptom had a subsequent dose change. A dose change was more likely if patients received a new psychiatric diagnosis (41.7% vs. 20.3%; p = .037) or patients did not have a psychosocial explanation for psychiatric symptoms (34.4% vs. 10.8%; p = .009). CONCLUSIONS: A substantial proportion of adolescent patients prescribed isotretinoin had a prior psychiatric diagnosis. This predicts more psychiatric symptoms during isotretinoin treatment. Adolescents with a psychiatric history who have worsening symptoms and those with new-onset psychiatric symptoms would benefit from close monitoring while taking isotretinoin.

Pharmacogenomic overlap between antidepressant treatment response in major depression & antidepressant associated treatment emergent mania in bipolar disorder.

There is increasing interest in individualizing treatment selection for more than 25 regulatory approved treatments for major depressive disorder (MDD). Despite an inconclusive efficacy evidence base, antidepressants (ADs) are prescribed for the depressive phase of bipolar disorder (BD) with oftentimes, an inadequate treatment response and or clinical concern for mood destabilization. This study explored the relationship between antidepressant response in MDD and antidepressant-associated treatment emergent mania (TEM) in BD. We conducted a genome-wide association study (GWAS) and polygenic score analysis of TEM and tested its association in a subset of BD-type I patients treated with SSRIs or SNRIs. Our results did not identify any genome-wide significant variants although, we found that a higher polygenic score (PGS) for antidepressant response in MDD was associated with higher odds of TEM in BD. Future studies with larger transdiagnostic depressed cohorts treated with antidepressants are encouraged to identify a neurobiological mechanism associated with a spectrum of depression improvement from response to emergent mania.

Striving for health equity: Stigmatizing language in inpatient pharmacy notes - A pilot study.

BACKGROUND: As pharmacy evolves, pharmacists have an increasing role in documentation. Publications examining the actions of other health professionals show that negative perception in written notes translates to patients receiving lower quality of care, resulting in worse health outcomes, suggesting that the use of stigmatizing language towards patients has concerning consequences. OBJECTIVES: To identify the prevalence of stigmatizing language in inpatient pharmacy progress. notes based on patient specific characteristics and diagnoses. METHODS: This retrospective pilot study reviewed inpatient pharmacy progress notes of a Midwestern (United States) tertiary academic institution from May to June 2023. Stigmatizing words and phrases associated with specified disease states were separated into the categories of general language, substance use disorders, and mental health. Notes of patients on internal medicine, family medicine, kidney/pancreas transplant, liver transplant, and gastroenterology services were included. RESULTS: Stigmatizing language was found in 22% (n = 43) of notes. The words "abuse" and "dependence" had the highest prevalence. Patients diagnosed with substance use disorders experienced stigmatizing language at a high rate, exaggerated further if their note lacked a documented diagnosis. CONCLUSIONS: This study demonstrated that stigmatizing language is present in pharmacy documentation. Providing context and resources of the proper documentation to reflect equitable healthcare is crucial for patient care.

Can PFAS threaten the health of fish consumers? A comprehensive analysis linking fish consumption behaviour and health risk.

Despite being phased out for decades, per- and polyfluoroalkyl substances (PFAS) are still widely detected in the environment and accumulated in many aquaculture organisms for human consumption. Thus, there is growing concern about whether fish consumption can cause PFAS-associated health impacts on humans since fish is a vital protein source for global populations. Here, we assess the potential driving factors of fish consumption by analysing the aquaculture, demographic and socio-economic data across 31 provinces/municipalities in China, followed by estimating the health risk of PFAS via fish consumption. We found that per capita fish consumption was primarily driven by fish production and total area for freshwater aquaculture, while urbanization rate and median age of consumers were also important. The health risk of PFAS was low (hazard quotient <1) in most provinces, while urban consumers were more prone to PFAS than rural consumers across all provinces. Since PFAS have been phased out worldwide, their health risk to humans through fish consumption would be lower than previously thought. To reduce PFAS intake for the high-risk populations, we recommend that fish should be well cooked before consumption, preferably using water-based cooking methods, and that alternative protein sources should be consumed more as the substitute for fish.

Hydrogel-polyurethane fiber composites with enhanced microarchitectural control for heart valve replacement.

Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. However, developing a single-phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde-fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D-printed hydrogel coating setup was developed to make valve composites for device-level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2 ) met ISO 5840-2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post-spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel-polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model-directed fabrication toward optimizing durability as a function of fiber microarchitecture.

Ethnopsychopharmacology: Clinical and scientific writing pearls.

The concept of ethnopsychopharmacology aims to predict or explain the pharmacologic response to psychiatric medications based on the influence of biologic and nonbiologic factors. Interactions involving these factors are complex and influence patient outcomes in health care. Pharmacists and other clinicians working in patient care environments, research, or medical education should engage in lifelong learning to enhance ethnopsychopharmacologic knowledge gaps, which ultimately may improve and individualize care across diverse populations. Through two cases, this paper provides pearls on how biogeographical ancestry and cytochrome P450 status may influence pharmacotherapy selection, dosing, or response. A third scenario highlights a publication, like many other published works, with deficiencies in how data on ancestry, race, and ethnicity are collected or reported. Current recommendations on the use of inclusive language in scientific writing are reviewed, with attention to specific examples.

Impact of sex on antidepressant discontinuation in groups of similar cytochrome P450 phenotypes.

Introduction: Although there are studies assessing reasons for antidepressant discontinuation, little is known about the impact of sex differences or cytochrome P450 phenotypes. Our objective is to assess discontinuation rates between males and females and whether CYP450 phenotype influences discontinuation. Methods: This is a retrospective review of patients previously enrolled in the Right Drug, Right Dose, Right Time: Using Genomic Data to Individualize Treatment database with major depressive disorder. Patients were evaluated for antidepressants trialed between January 1, 2009, and September 30, 2019. Survival analyses with competing risks were used to analyze discontinuation reasons. A Kaplan-Meier estimation method was used to assess the time to discontinuation and discontinuation rates. Analyses were also completed to assess discontinuation between men and women by phenotypic groups. All tests were two-sided, and p-values ≤ .05 were considered statistically significant. Results: There were 620 antidepressant discontinuation events discovered from 1015 antidepressant trials included. Overall, the median time to discontinuation for males was 2.6 years and 1.9 years for females (hazard ratio [HR] 0.97 [95% confidence interval (CI): 0.80, 1.19], p = .77). The risk of discontinuation was not different between males and females in any of the phenotype groups, which was consistent in the multivariable analyses. Concomitant use of medications that inhibited or induced antidepressant metabolism increased the overall risk of discontinuation (HR 1.45, 95% CI [1.06, 1.99], p = .020) in a time-dependent analysis. Discussion: We did not detect a significant difference in risk of antidepressant discontinuation rates between males and females even when accounting for cytochrome P450 phenotype. Future studies should account for whether medications that inhibit or induce antidepressant metabolism may be a crucial factor in antidepressant discontinuation.

A systematic review of clozapine-associated inflammation and related monitoring.

Clozapine is an effective antipsychotic medication used for treatment-resistant schizophrenia. However, it is underutilized due to rigorous hematologic monitoring requirements and many adverse drug reactions. Publications have highlighted the occurrence of inflammatory reactions, some life-threatening, particularly during the early stages of clozapine treatment. Although guidelines have suggested monitoring for inflammatory processes during clozapine initiation, screening in clinical practice is not universal. This systematic review aimed to investigate the relationship between clozapine and inflammation and assess the importance of monitoring for inflammatory reactions. A comprehensive literature search yielded 6915 unique publication records after removal of duplicates. After a rigorous screening process, 75 publications were included in the review, which focused on three main aspects: (i) the impact of clozapine on inflammatory markers, (ii) monitoring cardiac and other organ function during clozapine-associated inflammatory processes, and (iii) monitoring non-specific signs and symptoms of inflammation. Elevated levels of C-reactive protein (CRP) and several proinflammatory cytokines have been observed in association with clozapine treatment. However, the practicality of measuring specific markers in clinical practice remains uncertain. Current evidence supports monitoring CRP levels during the first 4-8 weeks of treatment, especially to facilitate myocarditis screening. Further research is needed to establish clinically relevant CRP thresholds for intervention. The implementation of monitoring protocols during the early phase of clozapine treatment may mitigate adverse reactions and allow for continued use of clozapine. Future studies should also explore the association between clozapine-associated inflammation and pneumonia, as well as investigate the impact of inflammation on clozapine metabolism to predict the need for dose adjustment. These endeavors may facilitate the development and implementation of evidence-based guidelines for the monitoring of clozapine-associated inflammation.

Antidepressant-Associated Treatment Emergent Mania: A Meta-Analysis to Guide Risk Modeling Pharmacogenomic Targets of Potential Clinical Value.

BACKGROUND: The purpose of this study was to review the association between the SLC6A4 5-HTTLPR polymorphism and antidepressant (AD)-associated treatment emergent mania (TEM) in bipolar disorder alongside starting a discussion on the merits of developing risk stratification models to guide when not to provide AD treatment for bipolar depression. METHODS: Studies that examined the association between clinical and genetic risk factors, specifically monoaminergic transporter genetic variation, and TEM were identified. A meta-analysis was performed using the odds ratio to estimate the effect size under the Der-Simonian and Laird model. RESULTS: Seven studies, referencing the SLC6A4 5-HTTLPR polymorphism and TEM (total N = 1578; TEM+ =594, TEM- = 984), of 142 identified articles were included. The time duration between the start of the AD to emergence of TEM ranged from 4 to 12 weeks. There was a nominally significant association between the s allele of the 5-HTTLPR polymorphism and TEM (odds ratio, 1.434; 95% confidence interval, 1.001-2.055; P = 0.0493; I2 = 52%). No studies have investigated norepinephrine or dopamine transporters. CONCLUSION: Although the serotonin transporter genetic variation is commercially available in pharmacogenomic decision support tools, greater efforts, more broadly, should focus on complete genome-wide approaches to determine genetic variants that may contribute to TEM. Moreover, these data are exemplary to the merits of developing risk stratification models, which include both clinical and biological risk factors, to guide when not to use ADs in bipolar disorder. Future studies will need to validate new risk models that best inform the development of personalized medicine best practices treating bipolar depression.

Can antimony contamination in soil undermine the ecological contributions of earthworms?

As antimony (Sb) has been increasingly used in manufacturing industries (e.g., alloy, polymer and electronics industries), Sb contamination in the soil environment becomes widely reported and has drawn growing attention due to the toxicity of Sb to living organisms. Whether soil-dwelling organisms can tolerate Sb toxicity and maintain their ecological functions remains poorly understood. Using a cosmopolitan, ecologically important earthworm species (Eisenia fetida) as an ideal model organism, we examine the effects of Sb on the physiological, molecular and behavioural responses of earthworms to different levels of Sb contamination in soil (0, 10, 50, 100, 250 and 500 mg/kg). We found that earthworms could tolerate heavy Sb contamination (100 mg/kg) by boosting their antioxidant defence (POD and GST) and immune systems (ACP) so that their body weight and survival rate were sustained (c.f. control). However, these systems were compromised under extreme Sb contamination (500 mg/kg), leading to mortality. As such, earthworms exhibited avoidance behaviour to escape from the Sb-contaminated soil, implying the loss of their ecological contributions to the environment (e.g., increase in soil aeration and maintenance of soil structure). By measuring various types of biomarkers along a concentration gradient, this study provides a mechanistic understanding of how earthworms resist or succumb to Sb toxicity. Since extreme Sb contamination in soil (>100 mg/kg) is rarely found in nature, we are optimistic that the health and performance of earthworms are not influenced by Sb in most circumstances, but regular monitoring of Sb in soil is recommended to ensure the integrity and functioning of soil environment. Further studies are recommended to evaluate the long-term impact of Sb in the soil ecosystem through bioaccumulation and trophic transfer among soil-dwelling organisms.

Use of Gabapentin for Alcohol Withdrawal Syndrome in the Hospital Setting: A Randomized Open-Label Controlled Trial.

Background/objectives: Patients hospitalized with alcohol withdrawal syndrome (AWS) are typically treated with CIWA-directed benzodiazepines to prevent complications, such as seizures and delirium tremens. Gabapentin is an evidence-based alternative to benzodiazepines in the outpatient setting, but there is limited data for hospitalized patients with AWS. This study compared fixed-dose gabapentin to CIWA-directed benzodiazepines for AWS in the hospital setting. Methods: This open-label, randomized controlled trial enrolled 88 adults from February 1, 2017 to August 16, 2020 with a risk of complicated alcohol withdrawal as defined by the Prediction of Alcohol Withdrawal Severity Scale (PAWSS) ≥4. Patients were randomized within 16 h of admission to either fixed-dose gabapentin taper or continued CIWA-directed benzodiazepine administration. The primary outcome was the length of stay (LOS). Secondary outcomes included seizure, delirium tremens, ICU transfer, and patient-reported symptoms (alcohol cravings, anxiety, sleepiness). Results: LOS was shorter, but not statistically different in the gabapentin group compared to the benzodiazepine group. Because benzodiazepines were received in both gabapentin and benzodiazepine groups before randomization, the mean amount of benzodiazepines received in each group was also not statistically different, although the amount received by the gabapentin group was less than half of that received by the benzodiazepine group (4.3 vs. 10.6 mg, p = 0.146 by per protocol analysis). There were no statistical differences in secondary measures. Conclusions: Fixed-dose gabapentin taper showed similar outcomes compared to CIWA-directed benzodiazepines for the treatment of hospitalized patients with mild/moderate AWS, but the interpretation of the results is limited due to under-enrollment and the use of benzodiazepines in both groups pre-enrollment.Clinical trial registration: NCT03012815.

Trends in Stimulant and Sedative/Hypnotic Dispensing: An Exploratory Study.

OBJECTIVE: To investigate patterns and trends of co-prescriptions of stimulants and sedatives within the last 6 years at a tertiary care center. METHOD: Patients 18 years of age and older who were dispensed at least one stimulant prescription from an institutional pharmacy between 1/1/2015 and 7/1/2021 were included. Prescription data for any co-prescribed sedative/hypnotic were collected. RESULTS: Both the number of stimulant dispenses and the number of patients with stimulant dispenses increased significantly with yearly incidence rate ratios of 1.115 (95% CI [1.110, 1.119]) and 1.090 (95% CI [1.084, 1.096]), respectively. The number of patients with a stimulant dispensed who also had a benzodiazepine or "Z-drug" sedative-hypnotic dispensed at any point in the search timeframe increased significantly with incidence rate ratios of 1.077 and 1.092, respectively. The number of stimulant dispenses, number of patients with stimulant dispenses, and number of patients with a stimulant dispensed who also had both a benzodiazepine and Z-drug dispensed at any point in the search timeframe increased significantly more in Non-White than in White patients. CONCLUSIONS: The results confirm previous findings of increases in dispensing of stimulants over the past 6 years and report increased polypharmacy of stimulants and sedative-hypnotics.

Exploring low clozapine C/D ratios, inverted clozapine-norclozapine ratios and undetectable concentrations as measures of non-adherence in clozapine patients: A literature review and a case series of 17 patients from 3 studies.

BACKGROUND: Up to 1/2 of outpatients prescribed clozapine may be partially/fully non-adherent, based on therapeutic drug monitoring (TDM). Three indices for measuring partial/full non-adherence are proposed a: 1) clozapine concentration/dose (C/D) ratio which drops to half or more of what is expected in the patient; 2) clozapine/norclozapine ratio that becomes inverted; and 3) clozapine concentration that becomes non-detectable. METHODS: These 3 proposed indices are based on a literature review and 17 cases of possible non-adherence from 3 samples: 1) an inpatient study in a Chinese hospital, 2) an inpatient randomized clinical trial in a United States hospital, and 3) and a Uruguayan outpatient study. RESULTS: The first index of non-adherence is a clozapine C/D ratio which is less than half the ratio corresponding to the patient's specific ancestry group and sex-smoking subgroup. Knowing the minimum therapeutic dose of the patient based on repeated TDM makes it much easier to establish non-adherence. The second index is inverted clozapine/norclozapine ratios in the absence of alternative explanations. The third index is undetectable concentrations. By using half-lives, the chronology of the 3 indices of non-adherence was modeled in two patients: 1) the clozapine C/D ratio dropped to ≥1/2 of what is expected from the patient (around day 2); 2) the clozapine/norclozapine ratio became inverted (around day 3); and 3) the clozapine concentration became undetectable by the laboratory (around days 9-11). CONCLUSION: Prospective studies should further explore these proposed clozapine indices in average patients, poor metabolizers (3 presented) and ultrarapid metabolizers (2 presented).