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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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