Inconclusiveness of psychometric testing of medication adherence questionnaires.

PURPOSE: To propose a paradigm change for the validation procedures of medication adherence questionnaires. METHODS: A total of 121 validation procedures of unique questionnaires for medication adherence were analyzed. RESULTS: "Construct validity" and "internal consistency" were most often assessed, and test results varied largely. A more in-depth analysis indicated that the assessment of medication non-adherence included distinct but related constructs, such as the extent to which doses are missed, and the attempt to identify different facets of medication-taking behavior. Consequently, each construct requires a different measurement approach with different psychometric tests for establishing its validity and reliability. CONCLUSION: Results show that assessing the validity and reliability of adherence questionnaires with standard procedures including statistical tests is inconclusive. Refinement of the constructs of non-adherence is needed in pharmacy and medical practice. We suggest a distinction between the (i) extent of missed doses over the past 2 weeks, (ii) modifiable reasons for non-adherence behavior, and (iii) unmodifiable factors of non-adherence. Validation procedures and corresponding statistical methods should be selected according to the specific single constructs.

Medication adherence to inflammatory bowel disease medications in Aotearoa New Zealand and correlation with health outcomes: A nationwide database analysis.

AIMS: Inflammatory bowel disease (IBD) management entails long-term medication therapy. Worse disease outcomes and reduced quality of life might arise from poor medication adherence (MA). This study is the first to investigate patients with IBD's adherence across Aotearoa New Zealand and its relationship with disease outcomes. METHODS: Dispensing claims data (Pharmaceutical Collection) were used to calculate (3- and 5-year) adherence, using daily polypharmacy possession ratio. Using hospitalization data (National Minimum Dataset), the relationship between adherence and the numbers of hospitalizations and corticosteroid dispensings was investigated. RESULTS: In total, 4654 patients (53% female; 55% Crohn's disease [CD], 45% ulcerative colitis [UC]; median age-at-first-dispensing, 43 years) and 3148 patients (54% female; 55% CD, 44% UC; median age-at-first-dispensing, 44 years) were in the 3- and 5-year cohorts, respectively. The 3- and 5-year cohorts had mean 4.6 and 4.2 IBD-related hospitalizations and 6.9 and 9.2 corticosteroid dispensings, respectively. Average adherence estimates were 77.4% (95% confidence interval: 76.9-78.0%) and 74.9% (95% confidence interval: 74.1-75.6%; 3 and 5 years), while 54% and 51% of patients, respectively, had good adherence (MA ≥ 80%). There was no correlation between adherence and the numbers of hospitalizations (Pearson's R = -.0007; P = .65 and R = -.04; P = .02 [3 and 5 years]) and corticosteroid dispensings (R = .08; P = <.0001 and R = .08; P = <.0001, respectively). CONCLUSION: MA of Aotearoa New Zealand patients with IBD is moderately high but just over half of patients meet the adherent threshold. There was no correlation between adherence and hospitalizations or corticosteroid dispensings; hence, research into longitudinal adherence patterns and associated factors is needed.

Relationship between electronically monitored adherence to direct oral anticoagulants and ischemic or hemorrhagic events after an initial ischemic stroke-A case control study.

BACKGROUND: Patients with atrial fibrillation (AF) have a high risk for recurrent clinical events after an ischemic stroke. Direct oral anticoagulants (DOAC) are prescribed for secondary prevention. Adherence to DOAC is crucial mainly because of their short elimination half-life. Non-adherence to DOAC can negatively impact patients' outcomes. The relationship between (non-)adherence and recurrent clinical events is unknown in AF patients after initial stroke. We investigated adherence to DOAC in stroke survivors with AF who were included in the MAAESTRO study at the University Hospital Basel, Switzerland, between 2008 and 2022. METHODS: This study is a secondary analysis of data from MAAESTRO with a matched nested case-control design and 1:2 ratio. DOAC intake was measured with a small electronic device (Time4MedTM). We defined two arbitrary intervals of 17 days and 95 days as the longest time spans with electronic monitoring data per patient to maximize the number of participants with adequate amount of observation time available for analysis. Taking and timing adherence were calculated retrospectively i.e., prior to the recurrent event for cases. Trendline analysis of adherence over 95 days was calculated. Linear regression analysis was performed after adjusting for the co-variables age and daily pill burden. Sensitivity analysis was performed with controls for intervals in the reverse direction (prospectively). RESULTS: We analyzed 11 cases and 22 matched controls (mean age: 75.9 ± 9.2 years vs. 73.1 ± 8.4 years; n.s.) with similar stroke characteristics (NIHSS, mRS, MoCA) and 36.4% women in each group. Mean adherence values were high and similar between cases and controls (95 days taking: 87.0 ± 18.9% (cases) vs. 90.8 ± 9.8% (controls), n.s.; similar values for timing adherence). Six hemorrhagic and five ischemic events had occurred. Compared to controls, a significantly higher 95 days taking adherence was observed for hemorrhagic events (96.0 ± 5.0% (cases) vs. 88.1 ± 11.5% (controls); p<0.01) and a significantly lower 95 days taking adherence was observed for ischemic events (75.7 ± 24.8% (cases) vs. 94.2 ± 6.2% (controls), p = 0.024). Values for timing adherence were similar. A non-significant downward linear trend of adherence was observed over 95 days independently of the clinical events. The sensitivity analysis showed that the direction of the interval had negligible impact on the 95 days adherence. CONCLUSION: Because recurrent ischemic events after an AF-related stroke were associated with low adherence to DOAC <76%, adherence enhancing interventions seem crucial in anticoagulated AF-patients. However, AF-patients with high adherence might benefit from a regular re-assessment of the bleeding risk as hemorrhagic complications were associated with adherence to DOAC >96%. TRIAL REGISTRATION: ClinicalTrials.gov NCT03344146.

Initiation of oral hepatitis C virus treatment: Which barriers are pertinent for ambulatory individuals with a history of illicit substance use? A qualitative interview study.

Background and Aims: The World Health Organization has set a goal to eradicate hepatitis C virus (HCV) by the year 2030. Nonadherence to HCV treatment has substantial economic implications due to high treatment costs, among others. Barriers to start HCV treatment may be critical. The aim of this study was to assess pertinent barriers to HCV treatment in ambulatory patients with a history of illicit substance use and to compare them to the literature. Methods: Barriers to HCV treatment mentioned by the key risk group (i.e., people who inject drugs) were retrieved from literature through a pragmatic literature search. From 34 published articles, we identified 80 modifiable barriers that were bundled in 23 items within the four topics "Personal difficulties and barriers to treatment," "Personal motivation to be treated," "Knowledge about the disease," and "Received information about the medicine." In-depth semistructured interviews were performed face-to-face with ambulatory patients from the University Psychiatric Clinics in Basel, Switzerland. Transcripts were coded inductively. Results: Interviews were performed with seven individuals (mean age: 48.3 years; range: 38-63 years; one woman) treated with oral direct-acting antivirals between 2014 and 2022. Thirteen barriers to start HCV treatment were mentioned that corresponded to the five categories: information, attitudes, swallowing difficulties, social environment, and unfavorable lifestyle. The barrier "swallowing difficulties" emerged exclusively from the statements provided by the interviewees. Conclusion: Barriers to the initiation of HCV treatment indicated by our interviewees clearly differed from the literature. Notably, the challenge of swallowing medicines may be particularly relevant for physicians prescribing and pharmacists dispensing HCV medication.

Knowledge and attitudes of German and Swiss community pharmacists towards biologicals and biosimilars - a prospective survey before and after the COVID-19 pandemic.

BACKGROUND: Knowledge, attitudes and substitution laws of biosimilars are not consistent across countries. Biosimilar acceptance among patients and healthcare professionals may be suffering from gaps in knowledge and understanding about biosimilars and their regulatory approval process. Pharmacists' roles and responsibilities changed considerably during the COVID-19 pandemic. Thus, they might have gained new skills and self-confidence in counseling and substitution of biosimilars. AIMS: To examine and compare the knowledge, perceptions and information needs of German and Swiss pharmacists regarding original biologicals and biosimilars in 2020 and 2022. METHODS: We conducted an online survey among Swiss and German community pharmacies in February 2020 (before) and August 2022 (after the COVID-19 pandemic). Descriptive statistics were calculated and the Chi-Square test was used for comparisons among categorical variables. RESULTS: A total of 764 pharmacists took part in the survey (390 in 2020 and 374 in 2022) with comparable demographics. The frequency of dispensing biologicals remained similar between German and Swiss pharmacists in 2020 and 2022, but the Swiss dispensation of biosimilars increased significantly in 2022 compared to 2020. Concerning the understanding of the term biosimilars, knowledge remained moderate in both countries in both years. Participants were equally familiar with the term and most felt sufficiently informed. In both countries, substitution with a biosimilar showed the least confidence of all attitudes. A third of the participants indicated correct substitution rules in their country. In both years, around 85% of the participants were highly interested in additional training on this topic. DISCUSSION/CONCLUSION: The results indicate that similarities and differences between Germany and Switzerland regarding knowledge and attitudes towards biologicals and biosimilars remained unchanged before and after the COVID-19 pandemic. An influence of the pandemic is unlikely. There is still a clear lack of knowledge among community pharmacists on biosimilars, especially regarding the substitution rules. Due to a rising market with many benefits but also big challenges to overcome, the topic of biosimilars should receive more attention in the future. This requires additional training for pharmacists.

Severe systemic adverse reactions to ophthalmic timolol in a CYP2D6 homozygous *4 allele carrier: a case report.

A woman with ocular hypertension suffered from severe bradycardia, hypotension and syncope attacks in temporal relation with ophthalmic timolol application. Topically applied timolol is nasally absorbed and has been shown to reach potentially relevant systemic concentrations. Timolol is mainly metabolized by CYP2D6, which exhibits interindividual metabolic capacity due to genetic variations. A reactive pharmacogenetic panel test identified the patient as a CYP2D6 homozygous *4 allele carrier, which has been associated with a poor metabolizer phenotype and lacking enzyme activity. Thus, the adverse drug reactions possibly resulted from increased systemic timolol exposure. This case report highlights that pharmacogenetic panel testing can contribute to safe and effective pharmacotherapy, even for topically applied drugs.

Genotyping of Patients with Adverse Drug Reaction or Therapy Failure: Database Analysis of a Pharmacogenetics Case Series Study.

Purpose: Pharmacogenetics (PGx) is an emerging aspect of personalized medicine with the potential to increase efficacy and safety of pharmacotherapy. However, PGx testing is still not routinely integrated into clinical practice. We conducted an observational case series study where PGx information from a commercially available panel test covering 30 genes was integrated into medication reviews. The aim of the study was to identify the drugs that are most frequently object of drug-gene-interactions (DGI) in the study population. Patients and Methods: In out-patient and in-patient settings, we recruited 142 patients experiencing adverse drug reaction (ADR) and/or therapy failure (TF). Collected anonymized data from the individual patient was harmonized and transferred to a structured database. Results: The majority of the patients had a main diagnosis of a mental or behavioral disorder (ICD-10: F, 61%), of musculoskeletal system and connective tissue diseases (ICD-10: M, 21%), and of the circulatory system (ICD-10: I, 11%). The number of prescribed medicines reached a median of 7 per person, resulting in a majority of patients with polypharmacy (≥5 prescribed medicines, 65%). In total, 559 suspected DGI were identified in 142 patients. After genetic testing, an association with at least one genetic variation was confirmed for 324 suspected DGI (58%) caused by 64 different drugs and 21 different genes in 141 patients. After 6 months, PGx-based medication adjustments were recorded for 62% of the study population, whereby differences were identified in subgroups. Conclusion: The data analysis from this study provides valuable insights for the main focus of further research in the context of PGx. The results indicate that most of the selected patients in our sample represent suitable target groups for PGx panel testing in clinical practice, notably those taking drugs for mental or behavioral disorder, circulatory diseases, immunological diseases, pain-related diseases, and patients experiencing polypharmacy.

Pharmacogenetic testing and counselling in the community pharmacy: mixed-methods study of a new pharmacist-led service.

BACKGROUND: Pharmacogenetic (PGx) testing and counselling (short: PGx service) in the community pharmacy is not routinely practiced. We propose a comprehensive pharmacist-led service where PGx information is integrated into medication reviews. AIM: To evaluate the pharmacist-led service comprising PGx testing and counselling (PGx service) from the perspective of patients. METHOD: For this mixed-methods study, we conducted two follow-up interviews F1 and F2 with patients recruited for the PGx service in a community pharmacy after 1st of January 2020. The semi-structured interviews were held by phone call and covered understanding of PGx, the implementation of recommendations, handling of PGx documents (list of concerned substances and PGx recommendation), gain in medication knowledge, and willingness to pay for the PGx service. RESULTS: We interviewed 25 patients in F1 and 42 patients in F2. Patients were generally able to understand and use results of the PGx service. At least one PGx recommendation was implemented for 69% of the patients. Handling of PGx documents ranged from patients having forgotten about the PGx results to patients consulting the list for every medication-related decision; the latter often expecting negative effects. Finally, 62% of the patients were willing to pay for the PGx service. CONCLUSION: For future PGx testing and counselling, HCPs should consider the patients' health literacy in a standardized way and use adequate communication skills to enhance the patient's understanding in PGx and to attenuate potential negative expectations.

Pharmacogenetic Analysis Enables Optimization of Pain Therapy: A Case Report of Ineffective Oxycodone Therapy.

Patients suffering from chronic pain may respond differently to analgesic medications. For some, pain relief is insufficient, while others experience side effects. Although pharmacogenetic testing is rarely performed in the context of analgesics, response to opiates, non-opioid analgesics, and antidepressants for the treatment of neuropathic pain can be affected by genetic variants. We describe a female patient who suffered from a complex chronic pain syndrome due to a disc hernia. Due to insufficient response to oxycodone, fentanyl, and morphine in addition to non-steroidal anti-inflammatory drug (NSAID)-induced side effects reported in the past, we performed panel-based pharmacogenotyping and compiled a medication recommendation. The ineffectiveness of opiates could be explained by a combined effect of the decreased activity in cytochrome P450 2D6 (CYP2D6), an increased activity in CYP3A, and an impaired drug response at the µ-opioid receptor. Decreased activity for CYP2C9 led to a slowed metabolism of ibuprofen and thus increased the risk for gastrointestinal side effects. Based on these findings we recommended hydromorphone and paracetamol, of which the metabolism was not affected by genetic variants. Our case report illustrates that an in-depth medication review including pharmacogenetic analysis can be helpful for patients with complex pain syndrome. Our approach highlights how genetic information could be applied to analyze a patient's history of medication ineffectiveness or poor tolerability and help to find better treatment options.

Adherence patterns in antiseizure medications influencing risk of sudden unexplained death in epilepsy: A data linkage study using dispensed prescriptions.

OBJECTIVE: Medication adherence is considered an important risk factor for sudden unexpected death in epilepsy (SUDEP), although measurement accuracy is difficult. Using prescription dispensations, this study aims to estimate antiseizure medication (ASM) adherence and identify adherence patterns that influence epilepsy mortality. METHODS: This is a retrospective cohort study of tertiary epilepsy outpatients seen at St Vincent's Hospital Melbourne, Victoria, Australia, from January 1, 2012 until December 31, 2017. Privacy-preserving data linkage with the Australian national prescription, death, and coroner's databases was performed. We fitted a four-cluster longitudinal group-based trajectory model for ASM adherence from recurring 90-day windows of prescription dispensations during a 3-year "landmark period" from January 1, 2012 to December 31, 2014, using the AdhereR package. We estimated the risk of SUDEP and all-cause death for each adherence pattern during an "observation period" from January 1, 2015 to December 31, 2017. The Cox proportional hazards and logistic regression models were adjusted for age, sex, socioeconomic status, epilepsy duration, comorbidity, drug resistance, and inadequate seizure control. RESULTS: One thousand one hundred eighty-seven participants were observed for a median of 3.2 years (interquartile range = 2.4-4.0 years). We observed 66 deaths with 10 SUDEP cases during the observation period. We identified four patterns of ASM adherence: good, 51%; declining, 24%; poor, 16%; and very poor, 9%. Declining adherence was associated with an increased risk for SUDEP, with hazard ratio (HR) = 8.43 (95% confidence interval [CI] = 1.10-64.45) at 1 year and HR = 9.17 (95% CI = 1.16-72.21) at 3 years. Compared to no ASM therapeutic change, the addition of a second to fourth ASM offered increased protection against SUDEP in patients with continuing drug-resistant epilepsy. SIGNIFICANCE: ASM nonadherence was observed in half of outpatients with epilepsy. A declining pattern of adherence, observed in a quarter of patients, was associated with more than eight times increased risk of SUDEP. Any ongoing medication interventions must include strategies to maintain and improve ASM adherence if we are to reduce the risk of SUDEP.

Renal insufficiency and magnesium deficiency correlate with a decreased formation of biologically active cholecalciferol: a retrospective observational study.

BACKGROUND: Vitamin D is synthesized in the skin or supplied. Cholecalciferol is hydroxylated in the liver to 25(OH) vitamin D [25D]. 25D is further hydroxylated in the kidney to 1,25(OH) vitamin D [1,25D]. Catabolism occurs by further hydroxylation. Magnesium is a cofactor of all involved hydroxylases. AIM: To investigate the association between renal function and serum magnesium levels, and the biologically active hormone 1,25D. METHOD: Anonymised serum values of 25D, 1,25D, magnesium and creatinine measured in an outpatient cohort over 2 years were analysed. RESULTS: Renal function and magnesium level did not influence 25D values (r = - 0.144 and 0.030, respectively). Mean serum 1,25D values decreased from 106.5 ± 44.3 pmol/l in individuals with normal renal function to 51.7 ± 18.9 pmol/l in those with severe renal insufficiency (p < 0.01). A weak positive correlation was observed between 1,25D and eGFR (r = 0.317), and between 1,25D and serum magnesium (r = 0.217). CONCLUSION: Impaired renal function and low magnesium serum levels are slightly associated with low 1,25D concentrations. Measuring 25D, but not 1,25D, may overestimate the patient's vitamin D status. In patients with renal insufficiency adequate magnesium supply should be ensured.

Methodological considerations on estimating medication adherence from self-report, electronic monitoring and electronic healthcare databases using the TEOS framework.

AIMS: Measuring adherence to medication is complex due to the diversity of contexts in which medications are prescribed, dispensed and used. The Timelines-Events-Objectives-Sources (TEOS) framework outlined a process to operationalize adherence. We aimed to develop practical recommendations for quantification of medication adherence using self-report (SR), electronic monitoring (EM) and electronic healthcare databases (EHD) consistent with the TEOS framework for adherence operationalization. METHODS: An adherence methodology working group of the International Society for Medication Adherence (ESPACOMP) analysed implications of the process of medication adherence for all data sources and discussed considerations specific to SR, EM and EHD regarding the information available on the prescribing, dispensing, recommended and actual use timelines, the four events relevant for distinguishing the adherence phases, the study objectives commonly addressed with each type of data, and the potential sources of measurement error and quality criteria applicable. RESULTS: Four key implications for medication adherence measurement are common to all data sources: adherence is a comparison between two series of events (recommended and actual use); it refers to one or more specific medication(s); it applies to regular repeated events coinciding with known recommended dosing; and it requires separate measurement of the three adherence phases for a complete picture of patients' adherence. We propose recommendations deriving from these statements, and aspects to be considered in study design when measuring adherence with SR, EM and EHD using the TEOS framework. CONCLUSION: The quality of medication adherence estimates is the result of several design choices that may optimize the data available.

Case report: Non-response to fluoxetine in a homozygous 5-HTTLPR S-allele carrier of the serotonin transporter gene.

We report the case of a 50-year-old male with major depressive disorder (MDD) to illustrate the challenge of finding effective antidepressant pharmacotherapy and the role that the patient's genetic makeup may play. Recent treatment attempts before clinic admission included venlafaxine and fluoxetine. Venlafaxine was discontinued due to lack of response, and subsequently switched to fluoxetine based on pharmacogenotyping of the P-glycoprotein transporter (P-gp, encoded by ABCB1) by the outpatient psychiatrist. Despite steady state serum levels within the therapeutic range, the patient did not benefit from fluoxetine either, necessitating admission to our clinic. Here a clinical pharmacist-led medication review including additional pharmacogenetic (PGx) analysis resulted in the change of the antidepressant therapy to bupropion. Under the new regimen, established in the in-patient-setting, the patient remitted. However, based on the assessed pharmacokinetics-related gene variants, including CYPs and ABCB1, non-response to fluoxetine could not be conclusively explained. Therefore, we retrospectively selected the serotonin transporter (SERT1, encoded by SLC6A4) for further genetic analysis of pharmacodynamic variability. The patient presented to be a homozygous carrier of the short allele variant in the 5-HTTLPR (S/S) located within the SLC6A4 promoter region, which has been associated with a reduced expression of the SERT1. This case points out the potential relevance of panel PGx testing considering polymorphisms in genes of pharmacokinetic as well as pharmacodynamic relevance.

A Guide to a Pharmacist-Led Pharmacogenetic Testing and Counselling Service in an Interprofessional Healthcare Setting.

Genetic predisposition is one factor influencing interindividual drug response. Pharmacogenetic information can be used to guide the selection and dosing of certain drugs. However, the implementation of pharmacogenetics (PGx) in clinical practice remains challenging. Defining a formal structure, as well as concrete procedures and clearly defined responsibilities, may facilitate and increase the use of PGx in clinical practice. Over 140 patient cases from an observational study in Switzerland formed the basis for the design and refinement of a pharmacist-led pharmacogenetics testing and counselling service (PGx service) in an interprofessional setting. Herein, we defined a six-step approach, including: (1) patient referral; (2) pre-test-counselling; (3) PGx testing; (4) medication review; (5) counselling; (6) follow-up. The six-step approach supports the importance of an interprofessional collaboration and the role of pharmacists in PGx testing and counselling across healthcare settings.

Is Pharmacogenetic Panel Testing Applicable to Low-Dose Methotrexate in Rheumatoid Arthritis? - A Case Report.

Purpose: Pharmacogenetic (PGx) panel testing could help to determine the heritable component of a rheumatoid arthritis (RA) patient's susceptibility for therapy failure and/or adverse drug reactions (ADRs) from methotrexate (MTX). Considering the literature mentioning the potential applicability of PGx panel testing within MTX regimens, we discuss the case of a patient who was treated with MTX, suffered from ADRs, and obtained a reactive PGx panel testing. Genotyping: We used a commercial PGx panel test involving the ABC-transporters P-glycoprotein (P-gp; gene: ABCB1), and breast cancer resistance protein (BCRP; gene: ABCG2), the solute carriers reduced folate carrier 1 (RFC1; gene: SLC19A1), and organic anion transporting polypeptide 1B1 (OATP1B1; gene: SLCO1B1), and the enzymes inosine triphosphatase (ITPA), and glutathione transferase P1 (GSTP1). In addition, we genotyped the patient for the enzymes 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase (AICAR)/inosine monophosphate (IMP) cyclohydrolase (gene name: ATIC), gamma-glutamyl hydrolase (gene name: GGH) and methylenetetrahydrofolate reductase (gene name: MTHFR). Results: The PGx profile of the patient revealed genetic variants in SLC19A1, ABCB1, and MTHFR, which may explain the ADRs experienced during the treatment with MTX and a potentially lower efficacy of MTX. Based on our interpretation of the PGx profile, we recommended the patient to avoid MTX in the future. Conclusion: The MTX pathway is complex, which makes the interpretation of genetic variants affecting metabolism challenging. A reactive PGx panel test was applicable to explain ADRs experienced during MTX treatment for a patient with RA. However, the clinical utility of PGx-guided MTX treatment in a primary care setting is still limited. In order to base a recommendation for MTX on PGx data, we need genome-wide association studies, large prospective multicenter studies and PGx studies, which analyze different multi-gene haplotypes and gene-drug-drug interactions for MTX.

TEOS: A framework for constructing operational definitions of medication adherence based on Timelines-Events-Objectives-Sources.

AIMS: Managing adherence to medications is a priority for health systems worldwide. Adherence research is accumulating, yet the quality of the evidence is reduced by various methodological limitations. In particular, the heterogeneity and low accuracy of adherence measures have been highlighted in many literature reviews. Recent consensus-based guidelines advise on best practices in defining adherence (ABC) and reporting of empirical studies (EMERGE). While these guidelines highlight the importance of operational definitions in adherence measurement, such definitions are rarely included in study reports. To support researchers in their measurement decisions, we developed a structured approach to formulate operational definitions of adherence. METHODS: A group of adherence and research methodology experts used theoretical, methodological and practical considerations to examine the process of applying adherence definitions to various research settings, questions and data sources. Consensus was reached through iterative review of discussion summaries and framework versions. RESULTS: We introduce TEOS, a four-component framework to guide the operationalization of adherence concepts: (1) describe treatment as four simultaneous interdependent timelines (recommended and actual use, conditional on prescribing and dispensing); (2) locate four key events along these timelines to delimit the three ABC phases (first and last recommended use, first and last actual use); (3) revisit study objectives and design to fine-tune research questions and assess measurement validity and reliability needs, and (4) select data sources (e.g., electronic monitoring, self-report, electronic healthcare databases) that best address measurement needs. CONCLUSION: Using the TEOS framework when designing research and reporting explicitly on these components can improve measurement quality.

National Poison Center Calls Before vs After Availability of High-Dose Acetaminophen (Paracetamol) Tablets in Switzerland.

Importance: Acetaminophen (paracetamol) is among the most widely used pain medications worldwide; while safe within the therapeutic range, intake exceeding 4000 mg/d can lead to hepatotoxicity. Prior evidence suggests that limiting the availability of large quantities of acetaminophen is associated with decreased acetaminophen-related poisonings and mortality; in Switzerland, 500-mg tablets are available over-the-counter (OTC) and, as of October 2003, 1000-mg tablets are available with prescription. Objective: To evaluate the association of adding 1000-mg acetaminophen tablets to the Swiss market with utilization and poisonings. Design, Setting, and Participants: This cross-sectional study used a quasi-experimental interrupted time series analysis to evaluate 15 790 acetaminophen poison records from January 1, 2000, to December 31, 2018. All calls for acetaminophen-related poisonings identified from the National Swiss Poisons Centre and all sales for oral acetaminophen tablets (prescription and OTC) dispensed between January 2000 and December 2018 were included. Exposure: October 3, 2003 (Q4 2003), was defined as the intervention date, corresponding to the date of market entry for 1000-mg acetaminophen tablets in Switzerland. Main Outcomes and Measures: The primary outcome was the number of quarterly acetaminophen-related poison calls to the National Poison Centre. Additional outcomes included quarterly sales for acetaminophen and change in poisoning circumstances, stratified by preintervention and postintervention periods and by formulation (ie, 500-mg and 1000-mg tablets). Results: Between 2000 and 2018, 15 790 acetaminophen-related poisoning calls were identified, of which 10 628 (67.3%) were regarding women, and the mean (SD) age of patients was 25.2 (18.2) years. The interrupted time series analysis identified a significant increase in the slope for the number of reported poisonings following the intervention point, particularly for accidental circumstances (z score, -3.62; P < .001). In the preintervention period, 120 of 961 poisonings (15.3%) involved a dose greater than 10 000 mg, while for the postintervention period, 1140 of 5696 (30.6%) had a dose larger than 10 000 mg (P < .001). There was a rapid uptake in 1000-mg acetaminophen sales, while sales of the 500-mg tablet decreased slightly. Since 2012, a mean (SD) of 20.7 million (1.4 million) 1000-mg tablets were dispensed quarterly compared with 2.7 million (0.5 million) 500-mg tablets. Conclusions and Relevance: This study found a significant increase in acetaminophen dispensing and acetaminophen-related poisonings in Switzerland following the approval of 1000-mg tablets in 2003. The availability of 1000-mg acetaminophen should be re-evaluated to minimize the potential for accidental poisonings.

Beyond Adherence Thresholds: A Simulation Study of the Optimal Classification of Longitudinal Adherence Trajectories From Medication Refill Histories.

Background: The description of adherence based on medication refill histories relies on the estimation of continuous medication availability (CMA) during an observation period. Thresholds to distinguish adherence from non-adherence typically refer to an aggregated value across the entire observation period, disregarding differences in adherence over time. Sliding windows to divide the observation period into smaller portions, estimating adherence for these increments, and classify individuals with similar trajectories into clusters can retain this temporal information. Optimal methods to estimate adherence trajectories to identify underlying patterns have not yet been established. This simulation study aimed to provide guidance for future studies by analyzing the effect of different longitudinal adherence estimates, sliding window parameters, and sample characteristics on the performance of a longitudinal clustering algorithm. Methods: We generated samples of 250-25,000 individuals with one of six longitudinal refill patterns over a 2-year period. We used two longitudinal CMA estimates (LCMA1 and LCMA2) and their dichotomized variants (with a threshold of 80%) to create adherence trajectories. LCMA1 assumes full adherence until the supply ends while LCMA2 assumes constant adherence between refills. We assessed scenarios with different LCMA estimates and sliding window parameters for 350 independent samples. Individual trajectories were clustered with kml, an implementation of k-means for longitudinal data in R. We compared performance between the four LCMA estimates using the adjusted Rand Index (cARI). Results: Cluster analysis with LCMA2 outperformed other estimates in overall performance, correct identification of groups, and classification accuracy, irrespective of sliding window parameters. Pairwise comparison between LCMA estimates showed a relative cARI-advantage of 0.12-0.22 (p < 0.001) for LCMA2. Sample size did not affect overall performance. Conclusion: The choice of LCMA estimate and sliding window parameters has a major impact on the performance of a clustering algorithm to identify distinct longitudinal adherence trajectories. We recommend (a) to assume constant adherence between refills, (b) to avoid dichotomization based on a threshold, and (c) to explore optimal sliding windows parameters in simulation studies or selecting shorter non-overlapping windows for the identification of different adherence patterns from medication refill data.