Doctors are striking for a pay-rise, but better conditions are needed to make them feel valued. Key insights from New Zealand.

Degradation of junior doctors pay has led to strikes in the UK. Improved pay is important, however to feel valued at work, doctors must have good conditions as well. The author describes how their experience working in New Zealand (NZ) highlighted several insights into how better working conditions make doctors feel more valued. Three factors are discussed which improve doctors daily experience. Firstly, the use of 'relief doctors', who cover inevitable absences caused by sickness or holiday, allow maintenance of proper staffing levels. Secondly, NZ doctors get 6 weeks of paid study leave to prepare for exams, whereas in UK this does not exist. Lastly, in NZ meals are provided whilst at work, this is not the case in the UK. NZ demonstrates appreciation for its doctors through real and tangible improvements to their working environment. In the UK, pay needs to be improved, but so do working conditions.

Variable Selection When Estimating Effects in External Target Populations.

External validity is an important part of epidemiologic research. To validly estimate effects in specific external target populations using a chosen effect measure (i.e., "transport"), some methods require that one account for all effect measure modifiers [EMMs]. However, little is known about how including other variables that are not EMMs (i.e., non-EMMs) in adjustment sets impacts estimates. Using simulations, we evaluated how inclusion of non-EMMs affected estimation of the transported risk difference (RD) by assessing impacts of covariates that A) differ (or not) between the trial and the target, B) are associated with the outcome (or not), and C) modify the RD (or not). We assessed variation and bias when covariates with each possible combination of these factors were used to transport RDs using outcome modeling or inverse odds weighting. Including variables that differed in distribution between the populations but were non-EMMs reduced precision, regardless of whether they were associated with the outcome. However, non-EMMs associated with selection did not amplify bias resulting from omitting necessary EMMs. Including all variables associated with the outcome may result in unnecessarily imprecise estimates when estimating treatment effects in external target populations.

Clarifying the causal contrast: An empirical example applying the prevalent new user study design.

PURPOSE: The prevalent new user design extends the active comparator new user design to include patients switching to a treatment of interest from a comparator. We examined the impact of adding "switchers" to incident new users on the estimated hazard ratio (HR) of hospitalized heart failure. METHODS: Using MarketScan claims data (2000-2014), we estimated HRs of hospitalized heart failure between patients initiating GLP-1 receptor agonists (GLP-1 RA) and sulfonylureas (SU). We considered three estimands: (1) the effect of incident new use; (2) the effect of switching; and (3) the effect of incident new use or switching, combining the two population. We used time-conditional propensity scores (TCPS) and time-stratified standardized morbidity ratio (SMR) weighting to adjust for confounding. RESULTS: We identified 76 179 GLP-1 RA new users, of which 12% were direct switchers (within 30 days) from SU. Among incident new users, GLP-1 RA was protective against heart failure (adjHRSMR = 0.74 [0.69, 0.80]). Among switchers, GLP-1 RA was not protective (adjHRSMR = 0.99 [0.83, 1.18]). Results in the combined population were largely driven by the incident new users, with GLP-1 RA having a protective effect (adjHRSMR = 0.77 [0.72, 0.83]). Results using TCPS were consistent with those estimated using SMR weighting. CONCLUSIONS: When analyses were conducted only among incident new users, GLP-1 RA had a protective effect. However, among switchers from SU to GLP-1 RA, the effect estimates substantially shifted toward the null. Combining patients with varying treatment histories can result in poor confounding control and camouflage important heterogeneity.

Interplay between gain and loss in arrays of nonlinear plasmonic nanoparticles: toward parametric downconversion and amplification.

With the help of a theoretical model and finite-difference time-domain (FDTD) simulations based on the hydrodynamic-Maxwell model, we examine the effect of difference-frequency generation (DFG) in an array of L-shaped metal nanoparticles (MNPs) characterized by intrinsic plasmonic nonlinearity. The outcomes of the calculations reveal the spectral interplay between gain and loss in the vicinity of the fundamental frequency of the localized surface plasmon resonances. Subsequently, we identify different array thicknesses and pumping regimes facilitating parametric amplification and spontaneous parametric downconversion. Our results suggest that the parametric amplification regime becomes feasible on a scale of hundreds of nanometers and spontaneous parametric downconversion on the scale of tens of nanometers, opening up new exciting opportunities for developing building blocks of photonic metasurfaces.

Projected future climatic forcing on the global distribution of vegetation types.

Most emissions scenarios suggest temperature and precipitation regimes will change dramatically across the globe over the next 500 years. These changes will have large impacts on the biosphere, with species forced to migrate to follow their preferred environmental conditions, therefore moving and fragmenting ecosystems. However, most projections of the impacts of climate change only reach 2100, limiting our understanding of the temporal scope of climate impacts, and potentially impeding suitable adaptive action. To address this data gap, we model future climate change every 20 years from 2000 to 2500 CE, under different CO2 emissions scenarios, using a general circulation model. We then apply a biome model to these modelled climate futures, to investigate shifts in climatic forcing on vegetation worldwide, the feasibility of the migration required to enact these modelled vegetation changes, and potential overlap with human land use based on modern-day anthromes. Under a business-as-usual scenario, up to 40% of terrestrial area is expected to be suited to a different biome by 2500. Cold-adapted biomes, particularly boreal forest and dry tundra, are predicted to experience the greatest losses of suitable area. Without mitigation, these changes could have severe consequences both for global biodiversity and the provision of ecosystem services. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Fentanyl as a marker of illicit drug use in morphine-positive urine specimens from workplace drug testing.

Total morphine is an important urinary marker of heroin use but can also be present from prescriptions or poppy seed ingestion. In specimens with morphine concentrations consistent with poppy seed ingestion (<4,000 ng/mL), 6-acetylmorphine has served as an important marker of illicit drug use. However, as illicit fentanyl has become increasingly prevalent as a contaminant in the drug supply, fentanyl might be an alternative marker of illicit opioid use instead of or in combination with 6-acetylmorphine. The aim of this study was to quantify opiates, 6-acetylmorphine, fentanyl and fentanyl analogs in 504 morphine-positive (immunoassay 2,000 ng/mL cutoff) urine specimens from workplace drug testing. Almost half (43%) of morphine-positive specimens had morphine concentrations below 4,000 ng/mL, illustrating the need for markers to differentiate illicit drug use. In these specimens, fentanyl (22% co-positivity) was more prevalent than 6-acetylmorphine (12%). Co-positivity of 6-acetylmorphine and semi-synthetic opioids increased with morphine concentration, while fentanyl prevalence did not. In 110 fentanyl-positive specimens, the median norfentanyl concentration (1,520 ng/mL) was 9.6× higher than the median fentanyl concentration (159 ng/mL), illustrating the possibility of using norfentanyl as a urinary marker of fentanyl use. The only fentanyl analog identified was para-fluorofentanyl (n = 50), with results from most specimens consistent with para-fluorofentanyl contamination in illicit fentanyl. The results confirm the use of fentanyl by employees subject to workplace drug testing and highlight the potential of fentanyl and/or norfentanyl as important markers of illicit drug use.

Standardizing to Specific Target Populations in Distributed Networks and Multi-Site Pharmacoepidemiologic Studies.

Distributed networks and other multi-site studies assess drug safety and effectiveness in diverse populations by pooling information. Targeting groups of clinical or policy interest (including specific sites or site combinations) and applying weights based on effect measure modifiers (EMMs) prior to pooling estimates within multi-site studies may increase interpretability and improve precision. We simulated a four-site study, standardized each site using inverse odds weights (IOW) to resemble the three smallest sites or the smallest site, estimated IOW-weighted RDs, and combined estimates with inverse variance weights (IVW). We also created an artificial distributed network in the Clinical Practice Research Datalink (CPRD) Aurum consisting of one site for each geographic region. We compared metformin and sulfonylurea initiators with respect to mortality, targeting the smallest region. In the simulation, IOW reduced differences between estimates and increased precision when targeting the three smallest sites or the smallest site. In the CPRD study, the IOW + IVW estimate was also more precise (smallest region RD and 95% CI: 5.41%, 1.03%-9.79%), IOW+IVW RD and 95% CI: 3.25%, 3.07%-3.43%). When performing pharmacoepidemiologic research in distributed networks or multi-site studies in the presence of EMMs, designating target populations has the potential to improve estimate precision and interpretability.

Pharmacokinetics and pharmacodynamics of five distinct commercially available hemp-derived topical cannabidiol products.

Products containing cannabidiol (CBD) have proliferated after the 2018 Farm Bill legalized hemp (cannabis with ≤0.3% delta-9-tetrahydrocannabinol (Δ9-THC)). CBD-containing topical products have surged in popularity, but controlled clinical studies on them are limited. This study characterized the effects of five commercially available hemp-derived high CBD/low Δ9-THC topical products. Healthy adults (N = 46) received one of six study drugs: a CBD-containing cream (N = 8), lotion (N = 8), patch (N = 7), balm (N = 8), gel (N = 6) or placebo (N = 9; matched to an active formulation). The protocol included three phases conducted over 17 days: (i) an acute drug application laboratory session, (ii) a 9-day outpatient phase with twice daily product application (visits occurred on Days 2, 3, 7 and 10) (iii) a 1-week washout phase. In each phase, whole blood, oral fluid and urine specimens were collected and analyzed via liquid chromatography with tandem mass spectrometry (LC-MS-MS) for CBD, Δ9-THC and primary metabolites of each and pharmacodynamic outcomes (subjective, cognitive/psychomotor and physiological effects) were assessed. Transdermal absorption of CBD was observed for three active products. On average, CBD/metabolite concentrations peaked after 7-10 days of product use and were highest for the lotion, which contained the most CBD and a permeation enhancer (vitamin E). Δ9-THC/metabolites were below the limit of detection in blood for all products, and no urine samples tested "positive" for cannabis using current US federal workplace drug testing criteria (immunoassay cut-off of 50 ng/mL and confirmatory LC-MS-MS cut-off of 15 ng/mL). Unexpectedly, nine participants (seven lotions, one patch and one gel) exhibited Δ9-THC oral fluid concentrations ≥2 ng/mL (current US federal workplace threshold for a "positive" test). Products did not produce discernable pharmacodynamic effects and were well-tolerated. This study provides important initial data on the acute/chronic effects of hemp-derived topical CBD products, but more research is needed given the diversity of products in this market.

Sustainability benefits of transitioning from current diets to plant-based alternatives or whole-food diets in Sweden.

Plant-based alternatives (PBAs) are increasingly becoming part of diets. Here, we investigate the environmental, nutritional, and economic implications of replacing animal-source foods (ASFs) with PBAs or whole foods (WFs) in the Swedish diet. Utilising two functional units (mass and energy), we model vegan, vegetarian, and flexitarian scenarios, each based on PBAs or WFs. Our results demonstrate that PBA-rich diets substantially reduce greenhouse gas emissions (30-52%), land use (20-45%), and freshwater use (14-27%), with the vegan diet showing the highest reduction potential. We observe comparable environmental benefits when ASFs are replaced with WFs, underscoring the need to reduce ASF consumption. PBA scenarios meet most Nordic Nutrition Recommendations, except for vitamin B12, vitamin D and selenium, while enhancing iron, magnesium, folate, and fibre supply and decreasing saturated fat. Daily food expenditure slightly increases in the PBA scenarios (3-5%) and decreases in the WF scenarios (4-17%), with PBA diets being 10-20% more expensive than WF diets. Here we show, that replacing ASFs with PBAs can reduce the environmental impact of current Swedish diets while meeting most nutritional recommendations, but slightly increases food expenditure. We recommend prioritising ASF reduction and diversifying WFs and healthier PBAs to accommodate diverse consumer preferences during dietary transitions.

Visualizing External Validity: Graphical Displays to Inform the Extension of Treatment Effects from Trials to Clinical Practice.

BACKGROUND: In the presence of effect measure modification, estimates of treatment effects from randomized controlled trials may not be valid in clinical practice settings. The development and application of quantitative approaches for extending treatment effects from trials to clinical practice settings is an active area of research. METHODS: In this article, we provide researchers with a practical roadmap and four visualizations to assist in variable selection for models to extend treatment effects observed in trials to clinical practice settings and to assess model specification and performance. We apply this roadmap and visualizations to an example extending the effects of adjuvant chemotherapy (5-fluorouracil vs. plus oxaliplatin) for colon cancer from a trial population to a population of individuals treated in community oncology practices in the United States. RESULTS: The first visualization screens for potential effect measure modifiers to include in models extending trial treatment effects to clinical practice populations. The second visualization displays a measure of covariate overlap between the clinical practice populations and the trial population. The third and fourth visualizations highlight considerations for model specification and influential observations. The conceptual roadmap describes how the output from the visualizations helps interrogate the assumptions required to extend treatment effects from trials to target populations. CONCLUSIONS: The roadmap and visualizations can inform practical decisions required for quantitatively extending treatment effects from trials to clinical practice settings.

UK flockdown: A survey of smallscale poultry keepers and their understanding of governmental guidance on highly pathogenic avian influenza (HPAI).

The scale of the current outbreak of highly pathogenic avian influenza (HPAI) due to the A/H5N1 virus in the United Kingdom is unprecedented. In addition to its economic impact on the commercial poultry sector, the disease has devastated wild bird colonies and represents a potential public health concern on account of its zoonotic potential. Although the implementation of biosecurity measures is paramount to reducing the spread of HPAI in domestic and commercial settings, little is known about the attitudes and perspectives of backyard poultry keepers, who often keep their flocks in close proximity to the public. A large nationwide survey of backyard poultry keepers was undertaken in December 2021-March 2022, contemporaneous with the enforcement of an Avian Influenza Prevention Zone (AIPZ) and additional housing measures in England, Scotland and Wales. The survey explored keepers' understanding of the clinical manifestations of HPAI, compliance with housing and biosecurity measures, attitudes towards obligatory culling on confirmation of HPAI in their flocks, and the potential use of vaccination to control HPAI. Summary statistical analysis of the closed question responses was supplemented with qualitative data analysis and corpus linguistic approaches to draw out key themes and salient patterns in responses to open text questions. Survey responses were received from 1559 small-scale poultry keepers across the United Kingdom. Awareness of the HPAI outbreak was very high (99.0%). The majority of respondents learned of it via social media (53%), with Defra (49.7%), British Hen Welfare Trust (33.8%) and the APHA (22.0%) identified as the principal sources of information. Analysis revealed that backyard keepers lacked knowledge of the clinical signs of avian influenza and legal requirements relating to compliance with biosecurity measures. Some respondents dismissed the seriousness of HPAI and were unwilling to comply with the measures in force. The issue of obligatory culling proved highly emotive, and some expressed a lack of trust in authorities. Most respondents (93.1%) indicated a willingness to pay for vaccination if the option was available. Communications on biosecurity measures that are relevant to large-scale industrial setups are inappropriate for backyard contexts. Understanding the barriers that backyard keepers face is essential if official agencies are to communicate biosecurity information effectively to such groups. Lack of trust in authorities is likely to make elimination of the virus in the UK difficult. We make recommendations for tailoring HPAI-related information for backyard contexts, to aid future HPAI control measures in the UK.

Veterinarians' knowledge and experience of avian influenza and perspectives on control measures in the UK.

BACKGROUND: The scale of the outbreak of highly pathogenic avian influenza (HPAI) in 2021-23 due to the influenza A/H5N1 virus is unprecedented. METHODS: An online survey was designed to explore veterinarians' experiences of and confidence in treating avian species, experiences of dealing with suspected HPAI and perspectives on control measures in the UK. The survey ran between December 2021 and March 2022. RESULTS: Survey responses were received from 26 veterinarians. Although veterinarians are well placed to communicate HPAI-related information and guidance, a lack of confidence around treating birds and dealing with suspected cases of HPAI represent key barriers for non-specialist practices, and this limits opportunities to educate clients. LIMITATIONS: This study presents the views of a small group of self-selected respondents and may over-represent veterinarians with existing interests in avian species and/or avian influenza and who engage with online fora. CONCLUSIONS: Improved training and resources designed to increase confidence with avian species, along with guidance on diagnosing and reporting notifiable diseases, are needed for first opinion practices. Governing bodies should clarify regulations on treating birds in veterinary practices when HPAI outbreak numbers are high.

Control of Neuronal Survival and Development Using Conductive Diamond.

This study demonstrates the control of neuronal survival and development using nitrogen-doped ultrananocrystalline diamond (N-UNCD). We highlight the role of N-UNCD in regulating neuronal activity via near-infrared illumination, demonstrating the generation of stable photocurrents that enhance neuronal survival and neurite outgrowth and foster a more active, synchronized neuronal network. Whole transcriptome RNA sequencing reveals that diamond substrates improve cellular-substrate interaction by upregulating extracellular matrix and gap junction-related genes. Our findings underscore the potential of conductive diamond as a robust and biocompatible platform for noninvasive and effective neural tissue engineering.

Prognostic models for clinical outcomes in patients with venous leg ulcers: A systematic review.

OBJECTIVE: The purpose of this review was to identify prognostic models for clinical application in patients with venous leg ulcers (VLUs). METHODS: Literature searches were conducted in Embase, Medline, Cochrane, and CINAHL databases from inception to December 22, 2021. Eligible studies reported prognostic models aimed at developing, validating, and adjusting multivariable prognostic models that include multiple prognostic factors combined, and that predicted clinical outcomes. Methodological quality was assessed using the CHARMS checklist and PROBAST short form questionnaire. RESULTS: Thirteen studies were identified, of which three were validation studies of previously published models, four reported derivation and validation of models, and the remainder reported derivation models only. There was substantial heterogeneity in the model characteristics, including 11 studies focused on wound healing outcomes reporting 91 different predictors. Three studies shared similar predicted outcomes, follow-up timepoint and used a Cox proportional hazards model. However, these models reported different predictor selection methods and different predictors and it was therefore not feasible to summarize performance, such as discriminative ability. CONCLUSIONS: There are no standout risk prediction models in the literature with promising clinical application for patients with VLUs. Future research should focus on developing and validating high-performing models in wider VLU populations.

A high-resolution transcriptomic and spatial atlas of cell types in the whole mouse brain.

The mammalian brain consists of millions to billions of cells that are organized into many cell types with specific spatial distribution patterns and structural and functional properties1-3. Here we report a comprehensive and high-resolution transcriptomic and spatial cell-type atlas for the whole adult mouse brain. The cell-type atlas was created by combining a single-cell RNA-sequencing (scRNA-seq) dataset of around 7 million cells profiled (approximately 4.0 million cells passing quality control), and a spatial transcriptomic dataset of approximately 4.3 million cells using multiplexed error-robust fluorescence in situ hybridization (MERFISH). The atlas is hierarchically organized into 4 nested levels of classification: 34 classes, 338 subclasses, 1,201 supertypes and 5,322 clusters. We present an online platform, Allen Brain Cell Atlas, to visualize the mouse whole-brain cell-type atlas along with the single-cell RNA-sequencing and MERFISH datasets. We systematically analysed the neuronal and non-neuronal cell types across the brain and identified a high degree of correspondence between transcriptomic identity and spatial specificity for each cell type. The results reveal unique features of cell-type organization in different brain regions-in particular, a dichotomy between the dorsal and ventral parts of the brain. The dorsal part contains relatively fewer yet highly divergent neuronal types, whereas the ventral part contains more numerous neuronal types that are more closely related to each other. Our study also uncovered extraordinary diversity and heterogeneity in neurotransmitter and neuropeptide expression and co-expression patterns in different cell types. Finally, we found that transcription factors are major determinants of cell-type classification and identified a combinatorial transcription factor code that defines cell types across all parts of the brain. The whole mouse brain transcriptomic and spatial cell-type atlas establishes a benchmark reference atlas and a foundational resource for integrative investigations of cellular and circuit function, development and evolution of the mammalian brain.

Social workers and acquired brain injury: A systematic review of the current evidence-base.

Social work plays an important role in the assessment and treatment of people with acquired brain injury. Acquired brain injury is a complex and highly prevalent condition which can impact on cognitive, emotional and social domains. As acquired brain injury is a hidden disability it can be misdiagnosed or classified as another condition entirely. We sought to systematically explore the evidence base to examine how social workers have been prepared to work with their clients with brain injury. Employing six electronic databases (Social Policy & Practice, Web of Science, Scopus, PubMed, PsycINFO, CINAHL Plus) we reviewed 1071 papers. After applying eligibility criteria 17 papers were included in this review. We utilised standardised data extraction and quality appraisal tools to assess all included papers. Following appraisal, 9 papers were judged as possessing high methodological quality whilst 8 were judged as medium. Employing narrative synthesis, we identified four themes which captured the key findings of these papers. Themes were named as (i) advocacy and social work (ii) training and multidisciplinary team working (iii) inclusion of social networks and (iv) societal barriers. In order to meet their statutory responsibilities to practice safely, social workers must receive training in how to identify ABI and develop understanding of its consequences and subsequent need for provision. Social workers are also in a unique position to advocate for their clients and should make every effort to ensure their needs are met.

Evaluating Educational Outcomes Using Patient Outcomes of New Surgeons Performing Partial Colectomy Compared to Cholecystectomy.

PURPOSE: Despite ongoing efforts to improve surgical education, surgical residents face gaps in their training. However, it is unknown if differences in the training of surgeons are reflected in the patient outcomes of those surgeons once they enter practice. This study aimed to compare the patient outcomes among new surgeons performing partial colectomy-a common procedure for which training is limited-and cholecystectomy-a common procedure for which training is robust. METHOD: The authors retrospectively analyzed all adult Medicare claims data for patients undergoing inpatient partial colectomy and inpatient cholecystectomy between 2007 and 2018. Generalized additive mixed models were used to investigate the associations between surgeon years in practice and risk-adjusted rates of 30-day serious complications and death for patients undergoing partial colectomy and cholecystectomy. RESULTS: A total of 14,449 surgeons at 4,011 hospitals performed 340,114 partial colectomy and 355,923 cholecystectomy inpatient operations during the study period. Patients undergoing a partial colectomy by a surgeon in their 1st vs 15th year of practice had higher rates of serious complications (5.22% [95% CI, 4.85%-5.60%] vs 4.37% [95% CI, 4.22%-4.52%]; P < .01) and death (3.05% [95% CI, 2.92%-3.17%] vs 2.83% [95% CI, 2.75%-2.91%]; P < .01). Patients undergoing a cholecystectomy by a surgeon in their 1st vs 15th year of practice had similar rates of 30-day serious complications (4.11% vs 3.89%; P = .11) and death (1.71% vs 1.70%; P = .93). CONCLUSIONS: Patients undergoing partial colectomy faced a higher risk of serious complications and death when the operation was performed by a new surgeon compared to an experienced surgeon. Conversely, patient outcomes following cholecystectomy were similar for new and experienced surgeons. More attention to partial colectomy during residency training may benefit patients.

Fear extinction is regulated by the activity of long noncoding RNAs at the synapse.

Long noncoding RNAs (lncRNAs) represent a multidimensional class of regulatory molecules that are involved in many aspects of brain function. Emerging evidence indicates that lncRNAs are localized to the synapse; however, a direct role for their activity in this subcellular compartment in memory formation has yet to be demonstrated. Using lncRNA capture-seq, we identified a specific set of lncRNAs that accumulate in the synaptic compartment within the infralimbic prefrontal cortex of adult male C57/Bl6 mice. Among these was a splice variant related to the stress-associated lncRNA, Gas5. RNA immunoprecipitation followed by mass spectrometry and single-molecule imaging revealed that this Gas5 isoform, in association with the RNA binding proteins G3BP2 and CAPRIN1, regulates the activity-dependent trafficking and clustering of RNA granules. In addition, we found that cell-type-specific, activity-dependent, and synapse-specific knockdown of the Gas5 variant led to impaired fear extinction memory. These findings identify a new mechanism of fear extinction that involves the dynamic interaction between local lncRNA activity and RNA condensates in the synaptic compartment.

Transcriptomic diversity of cell types across the adult human brain.

The human brain directs complex behaviors, ranging from fine motor skills to abstract intelligence, but the diversity of cell types that support these skills has not been fully described. In this work, we used single-nucleus RNA sequencing to systematically survey cells across the entire adult human brain. We sampled more than three million nuclei from approximately 100 dissections across the forebrain, midbrain, and hindbrain in three postmortem donors. Our analysis identified 461 clusters and 3313 subclusters organized largely according to developmental origins and revealing high diversity in midbrain and hindbrain neurons. Astrocytes and oligodendrocyte-lineage cells also exhibited regional diversity at multiple scales. The transcriptomic census of the entire human brain presented in this work provides a resource for understanding the molecular diversity of the human brain in health and disease.

Prevalence of ∆8-tetrahydrocannabinol carboxylic acid in workplace drug testing.

∆8-Tetrahydrocannabinol (∆8-THC) recently became widely available as an alternative to cannabis. ∆8-THC is likely impairing and poses a threat to workplace and traffic safety. In the present study, the prevalence of ∆8-THC in workplace drug testing was investigated by analyzing 1,504 urine specimens with a positive immunoassay cannabinoid initial test using a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method quantifying 15 cannabinoid analytes after hydrolysis. ∆8-tetrahydrocannabinol-9-carboxylic acid (∆8-THC-COOH) was detected in 378 urine specimens (15 ng/mL cutoff), compared to 1,144 specimens containing ∆9-THC-COOH. The data could be divided into three general groups. There were 964 (76%) ∆9-THC-COOH-dominant (<10% ∆8-THC-COOH) and 139 (11%) ∆8-THC-COOH-dominant (>90% ∆8-THC-COOH) specimens, with the remaining 164 (13%) specimens showing a mixture of both analytes (>90% ∆8-THC-COOH). Similar concentrations of ∆9-THC-COOH (median 187 ng/mL) and ∆8-THC-COOH (150 ng/mL) as the dominant species support the use of similar cutoffs and decision rules for both analytes. Apart from the carboxylic acid metabolites, 11-hydroxy-∆9-tetrahydrocannabinol (11-OH-∆9-THC, n = 1,282), ∆9-tetrahydrocannabivarin-9-carboxylic acid (∆9-THCV-COOH, n = 1,058), ∆9-THC (n = 746) and 7-hydroxy-cannabidiol (7-OH-CBD, n = 506) were the most prevalent analytes. Two specimens (0.13%) contained ≥140 ng/mL ∆9-THC without ∆9-THC-COOH, which could be due to genetic variability in the drug-metabolizing enzyme CYP2C9 or an adulterant targeting ∆9-THC-COOH. The cannabinoid immunoassay was repeated, and five specimens (0.33%) generated negative initial tests despite ∆9-THC-COOH concentrations of 54-1,000 ng/mL, potentially indicative of adulteration. The use of ∆8-THC is widespread in the US population, and all forensic laboratories should consider adding ∆8-THC and/or ∆8-THC-COOH to their scope of testing. Similar urinary concentrations were observed for both analytes, indicating that the decision rules used for ∆9-THC-COOH are also appropriate for ∆8-THC-COOH.