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Increasing gabapentinoid use has raised concerns of misuse and abuse in the United States (US). Little is known about the characteristics of gabapentinoid use in general clinical practice over time. This cross-sectional study used data from the National Ambulatory Medical Care Survey. We examined the trends of patient and prescriber characteristics and the diagnoses associated with US ambulatory care visits involving gabapentinoids for adult visits from 2003 to 2016. Using multivariable logistic regression, we estimated the adjusted proportion of gabapentinoid-involved visits among all visits and tested for trend significance. Among the weighted estimate of 260.1 million gabapentinoid-involved visits (aged 18-64 years: 61.8%; female: 61.9%; white: 85.5%), the adjusted annual proportion of gabapentinoid-involved visits nearly quadrupled from 2003 to 2016 (9.1 to 34.9 per 1000 visits; P trend < 0.0001), driven mainly by gabapentin. Nearly half had concurrent use with opioids (32.9%) or benzodiazepines (15.3%). Primary care physicians (45.8%), neurologists (8.2%), surgeons (6.2%), and psychiatrists (4.8%) prescribed two-thirds of the gabapentinoids. Most (96.6%) of the gabapentinoid visits did not have an approved indication for gabapentinoids among the first three diagnoses. Among US ambulatory care visits from 2003 to 2016, gabapentinoid use increased substantially, commonly prescribed by primary care physicians.

In emission tomography, anatomical side information, in the form of organ and lesion boundaries, derived from intra-patient coregistered CT or MR scans can be incorporated into the reconstruction. Our interest is in exploring the efficacy of such side information for lesion detectability. To assess detectability we used the SNR of a channelized Hotelling observer and a signal-known exactly/background-known exactly detection task. In simulation studies, we incorporated anatomical side information into a SPECT MAP (maximum a posteriori) reconstruction by smoothing within but not across organ or lesion boundaries. A non-anatomical prior was applied by uniform smoothing across the entire image. We investigated whether the use of anatomical priors with organ boundaries alone or with perfect lesion boundaries alone would change lesion detectability relative to the case of a prior with no anatomical information. Furthermore, we investigated whether any such detectability changes for the organ-boundary case would be a function of the distance of the lesion to the organ boundary. We also investigated whether any detectability changes for the lesion-boundary case would be a function of the degree of proximity, i.e. a difference in the radius of the true functional lesion and the radius of the anatomical lesion boundary. Our results showed almost no detectability difference with versus without organ boundaries at any lesion-to-organ boundary distance. Our results also showed no difference in lesion detectability with and without lesion boundaries, and no variation of lesion detectability with degree of proximity.

Background and aims Little is known about opioid and gabapentinoid (OPI‐GABA) use duration and dose patterns’ associations with adverse outcome risks. We examined associations between OPI‐GABA dose and duration trajectories and subsequent drug overdose. Design Retrospective cohort study. Setting US Medicare. Participants Using a 5% sample (2011–16), we identified 71 005 fee‐for‐service Medicare beneficiaries with fibromyalgia, low back pain, neuropathy and/or osteoarthritis initiating OPIs and/or GABAs [mean age ± standard deviation (SD) = 65.5 ± 14.5 years, female = 68.1%, white = 76.8%]. Measurements Group‐based multi‐trajectory models identified distinct OPI‐GABA use patterns during the year of OPI and/or GABA initiation, based on weekly average standardized daily dose (i.e. OPIs = morphine milligram equivalent, GABAs = minimum effective daily dose). We estimated models with three to 12 trajectories and selected the best model based on Bayesian information criterion (BIC) and Nagin's criteria. We estimated risk of time to first drug overdose diagnosis within 12 months following the index year, adjusting for socio‐demographic and health factors using inverse probability of treatment weighted multivariable Cox proportional hazards models. Findings We identified 10 distinct trajectories (BIC = –1 176 954; OPI‐only = 3, GABA‐only = 3, OPI‐GABA = 4). Compared with OPI‐only early discontinuers (40.6% of the cohort), 1‐year drug overdose risk varied by trajectory group: consistent low‐dose OPI‐only users [16.6%; hazard ratio (HR) = 1.47, 95% confidence interval (CI) = 1.19–1.82], consistent high‐dose OPI‐only users (1.8%; HR = 4.57, 95% CI = 2.99–6.98), GABA‐only early discontinuers (12.5%; HR = 1.39, 95% CI = 1.09–1.77), consistent low‐dose GABA‐only users (11.0%; HR = 1.44, 95% CI = 1.12–1.85), consistent high‐dose GABA‐only users (3.1%; HR = 1.43, 95% CI = 0.94–2.17), early discontinuation of OPIs and consistent low‐dose GABA users (6.9%; HR = 1.24, 95% CI = 0.90–1.69), consistent low‐dose OPI‐GABA users (3.4%; HR = 2.49, 95% CI = 1.76–3.52), consistent low‐dose OPI and high‐dose GABA users (3.2%; HR = 2.46, 95% CI = 1.71–3.53) and consistent high‐dose OPI and moderate‐dose GABA users (0.9%; HR = 7.22, 95% CI = 4.46–11.69). Conclusions Risk of drug overdose varied substantially among US Medicare beneficiaries on different use trajectories of opioids and gabapentinoids. High‐dose opioid‐only users and all consistent opioid and gabapentinoid users (regardless of doses) had more than double the risk of subsequent drug overdose compared with opioid‐only early discontinuers.

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In SPECT the collimator is a crucial element of the imaging chain and controls the noiseresolution tradeoff of the collected data. Optimizing collimator design has been a long studied topic, with many different criteria used to evaluate the design. One class of criteria is taskedbased, in which the collimator is designed to optimize detection of a signal (lesion). Here we consider a new, more realistic, task, the joint detection and localization of a signal. Furthermore, we use an ideal observer -one that attains a theoretically maximum task performance -to optimize collimator design. The ideal observer operates on the sinogram data. We consider a family of parallel-hole low-energy collimators of varying resolution and efficiency and optimize over this set. We observe that for a 2-D object characterized by noise due to background variability and a sinogram with photon noise, the optimal collimator tends to be of lower resolution and higher efficiency than equivalent commercial collimators. Furthermore, this optimal design is insensitive to the tolerance radius within which the signal must be localized. So for this scenario, the addition of a localization task does not change the optimal collimator. Optimal collimator resolution gets worse as signal size grows, and improves as the level of background variability noise increases. These latter two trends are also observed when the detection task is signal-known-exactly and background variable.

Objective Few studies have compared the risk of recurrent falls across different types of analgesic use, and were limited to adjust for potential confounders (e.g., pain/depression severity). We aimed to assess analgesic use and the subsequent risk of recurrent falls, among participants with or at risk of knee osteoarthritis (OA). Methods A longitudinal analysis included 4,231 participants aged 45–79 years at baseline with 4-year follow-up from the Osteoarthritis Initiative (OAI) cohort study. We grouped participants into six mutually exclusive subgroups based on annually assessed analgesic use in the following hierarchical order of analgesic/central nervous system potency: use of (1)opioids, (2)antidepressants, (3)other prescription pain medications, (4)over-the-counter pain medications, (5)nutraceuticals, and (6)no analgesics. We used multivariable modified Poisson regression models with a robust error variance to estimate the effect of analgesic use on the risk of recurrent falls(≥2) in the following year, adjusted for demographics and health status/behavior factors. Results Opioid use increased from 2.7% at baseline to 3.6% at the 36-month visit (>80% using other analgesics/nutraceuticals), while other prescription pain medication use decreased from 16.7% to 11.9% over this time period. Approximately 15% of participants reported recurrent falls. Compared to those not using analgesics, participants used opioids and/or antidepressants had a 22–25% increased risk of recurrent falls (opioids: RRadjusted=1.22, 95%CI=1.04–1.45; antidepressants: RRadjusted=1.25, 95%CI=1.10–1.41). Conclusion Participants with or at risk of knee OA who were on opioids and antidepressants with/without other analgesics/nutraceuticals may have an increased risk of recurrent falls after adjusting for potential confounders. Use of opioids and antidepressants warrants caution.

For the familiar 2-class detection problem (signal present/absent), ideal observers have been applied to optimization of pinhole and collimator parameters in planar emission imaging. Given photon noise and background and signal variability, such experiments show how to optimize an aperture to maximize detectability of the signal. Here, we consider a fundamentally different, more realistic task in which the observer is required to both detect and localize a signal. The signal is embedded in a variable background and is known except for location. We inquire whether the addition of a localization requirement changes conclusions on aperture optimization. We have previously formulated an ideal observer for this joint detection/localization task, and here apply it to the classic problem of determining an optimal pinhole diameter in a planar emission imaging system. We conclude that as search tolerance on localization decreases, the optimal pinhole diameter shrinks from that required by detection alone, and in addition, task performance becomes more sensitive to fluctuations about the optimal pinhole diameter. As in the case for detection only, the optimal pinhole diameter shrinks as the amount of background variability grows, and in addition, conspicuity limits can be observed. Unlike the case for detection only, our task leads to a finite aperture size in the absence of background variability. For both tasks, the inclusion of background variability yields a finite aperture size.