Low-Level HIV RNA in Cerebrospinal Fluid and Neurocognitive Performance: A Longitudinal Cohort Study.

BACKGROUND: Cognitive complications persist in persons with HIV during suppressive antiretroviral therapy (ART). Low levels of HIV during ART could contribute to these complications. In this study, we measured cerebrospinal fluid (CSF) HIV using a single-copy assay (SCA) to investigate a possible relationship between low-level HIV and cognition. DESIGN/METHODS: SCA data were analyzed from 3 consecutively paired CSF-plasma specimens collected over a mean of 456 days from 96 participants on suppressive ART. Using mixed models, the presence of CSF HIV by SCA as a risk factor for worse neurocognitive performance was examined. RESULTS: At baseline on the SCA, 45.8% of participants had detectable plasma HIV RNA (median 8 copies/mL and interquartile range = 3-17 among detectable values) and 17.7% had detectable CSF HIV RNA (median CSF concentration= 3 copies/mL and interquartile range= 2-13 among detectable values). The frequency of CSF HIV RNA detection declined over time in CSF (P = 0.018) with a trend toward decline in plasma (P = 0.064). Detectable CSF HIV RNA during the study was associated with worse performance in the domains of recall (P = 0.014) and motor (P = 0.040) and a trend with worse overall global performance (P = 0.078). Integrase inhibitor use, although very infrequent in this cohort, was associated with better performance in 2 domains. CONCLUSIONS: Low-level CSF HIV RNA declines with time but is associated with worse cognitive performance in 2 domains. Additional research is needed to better understand the relationship between HIV RNA persistence during long-term ART and central nervous system complications in persons with HIV.

Cerebrospinal fluid CXCL10 is associated with the presence of low level CSF HIV during suppressive antiretroviral therapy.

Surrogate markers of HIV central nervous system (CNS) persistence are needed because direct HIV measurements from the CNS require specialized protocols and are not always detectable or quantifiable. We analyzed paired plasma and CSF samples from people with HIV (PWH) on suppressive therapy (ART) with a validated HIV single copy RNA assay. Two potential markers of CNS persistence were measured (CXCL10 and sCD30). We then examined associations with CSF HIV RNA positivity in univariable and multivariable analyses. Among 66 individuals, 18.2% had detectable CSF HIV. Individuals who had detectable HIV in CSF had higher CSF CXCL10 concentrations (median 514 pg/ml versus median 317 pg/ml, p = 0.019), but did not have significantly different CSF sCD30 concentrations (median 7.5 ng/ml versus median 7.6 ng/ml, p = 0.78). In the multiple logistic analysis, both higher CSF CXCL10 (p = 0.038) and plasma HIV detectability (p = 0.035) were significantly associated with detectable CSF HIV. Both sCD30 and CXCL10 correlated positively with NfL and NSE, two neuronal markers. This study demonstrates that CSF CXCL10 concentrations reflect low level HIV CNS persistence despite virologic suppression on ART. Given that it is readily detectable and quantifiable, this chemokine may be a promising biomarker to evaluate HIV eradication therapies that target the CNS.

Neurocognitive impairment is worse in HIV/HCV-coinfected individuals with liver dysfunction.

Infections with HIV and hepatitis C virus (HCV) can individually and jointly contribute to neurocognitive impairment (NCI). Rates of NCI in HIV/HCV-coinfected persons range from 40 to 63% but its correlates have not been described. In this study, we examined HIV/HCV-coinfected adults on antiretroviral therapy (ART) with undetectable HIV RNA in blood (n = 412) who were assessed using a comprehensive neuropsychological test battery. Demographics, host and viral biomarkers, and markers of liver dysfunction were compared between impaired (n = 198) and unimpaired (n = 214) participants using logistic regression. The cohort was predominantly middle-aged men, half of whom (48%) had NCI. The odds of NCI increased by almost two-fold when serum albumin was < 4 g/dL, 1.7-fold when alanine aminotransferase (ALT) levels were > 50 IU/L, and 2.2-fold with every unit increase in log10 AST to Platelet Ratio Index (APRI). These readily available clinical biomarkers of NCI measure hepatic injury and/or dysfunction, suggesting a mechanism for the effects of HCV infection on NCI. They may identify patients at increased risk of NCI who could be prioritized for early initiation of HCV treatment to protect or improve cognition.

Cerebrospinal fluid viral escape in aviremic HIV-infected patients receiving antiretroviral therapy: prevalence, risk factors and neurocognitive effects.

BACKGROUND: During antiretroviral therapy, HIV RNA can be detected in cerebrospinal fluid (CSF) when it is undetectable in plasma, a condition termed 'CSF viral escape'. The aim of the current study was to determine the prevalence and risk factors for CSF viral escape in two large cohorts in the USA. METHODS: A total of 1264 HIV-infected volunteers enrolled in two US cohorts at their most recent visit between 2003 and 2011 were included in this cross-sectional analysis if their HIV RNA level in plasma was less than 50 copies/ml while receiving stable antiretroviral therapy (ART) (>6 months) and if they had HIV RNA measured in CSF at their most recent visit between 2003 and 2011. Potential risk factors were identified using univariable and multivariable regression. RESULTS: CSF viral escape was detected in 55 adults (4.4%; 95% CI: 3.4-5.6), who had a median CSF HIV RNA of 155 copies/ml [interquartile range (IQR: 80-283)]. Patients with or without CSF viral escape had similar rates of neurocognitive impairment (38.2 vs. 37.7%; P = 0.91). CSF viral escape was independently associated with the use of ritonavir-boosted protease inhibitors [odds ratio (OR): 2.0; 95% CI: 1.1-3.8] or unboosted atazanavir (OR: 5.1; 95% CI: 1.3-16.1), CSF pleocytosis (OR: 7.6; 95% CI: 4.2-13.7) and abnormal CSF total protein (OR: 2.1; 95% CI: 1.1-3.7). CONCLUSIONS: In this large study of aviremic patients receiving ART, CSF viral escape was uncommon and was linked to evidence of central nervous system inflammation and the use of protease inhibitors, but not with worse neurocognitive performance.

Accuracy of predictive ability measures for survival models.

One aspect of an analysis of survival data based on the proportional hazards model that has been receiving increasing attention is that of the predictive ability or explained variation of the model. A number of contending measures have been suggested, including one measure, R2 (ß), which has been proposed given its several desirable properties, including its capacity to accommodate time-dependent covariates, a major feature of the model and one that gives rise to great generality. A thorough study of the properties of available measures, including the aforementioned measure, has been carried out recently. In that work, the authors used bootstrap techniques, particularly complex in the setting of censored data, in order to obtain estimates of precision. The motivation of this work is to provide analytical expressions of precision, in particular confidence interval estimates for R2 (ß). We use Taylor series approximations with and without local linearizing transforms. We also consider a very simple expression based on the Fisher's transformation. This latter approach has two great advantages. It is very easy and quick to calculate, and secondly, it can be obtained for any of the methods given in the recent review. A large simulation study is carried out to investigate the properties of the different methods. Finally, three well-known datasets in breast cancer, lymphoma and lung cancer research are given as illustrations. Copyright © 2017 John Wiley & Sons, Ltd.

Latent Toxoplasma Infection and Higher Toxoplasma gondii Immunoglobulin G Levels Are Associated With Worse Neurocognitive Functioning in HIV-Infected Adults.

BACKGROUND: Human immunodeficiency virus (HIV)-associated neurocognitive disorders persist despite suppressive antiretroviral therapy (ART). Because latent Toxoplasma infection (LTI) may adversely impact brain function, we investigated its impact on neurocognitive impairment (NCI) in people living with HIV disease. METHODS: Two hundred sixty-three HIV-infected adults underwent comprehensive neurocognitive assessments and had anti-Toxoplasma gondii immunoglobulin G (anti-Toxo IgG) measured by qualitative and quantitative enzyme-linked immunosorbent assays. RESULTS: Participants were mostly middle-aged white men who were taking ART (70%). LTI was detected in 30 (11.4%) participants and was associated with a significantly greater prevalence of global NCI (LTI positive [LTI+] = 57% and LTI negative [LTI-] = 34%) (odds ratio, 1.67; 95% confidence interval, 1.17-2.40; P = .017). Deficits were more prevalent in the LTI+ vs the LTI- group in 6 of 7 cognitive domains with statistical significance reached for delayed recall (P < .01). The probability of NCI increased with higher CD4+ T-cell counts among LTI+ individuals but with lower CD4+ T-cell counts in LTI- persons. A strong correlation (r = .93) between anti-Toxo IgG levels and global deficit score was found in a subgroup of 9 patients. Biomarkers indicative of central nervous system inflammation did not differ between LTI+ and LTI- participants. CONCLUSIONS: In this cross-sectional analysis, LTI was associated with NCI, especially in those with higher CD4+ T-cell counts. Longitudinal studies to investigate the role of neuroinflammation and neuronal injury in LTI patients with NCI and trials of anti-Toxoplasma therapy should be pursued.

A preliminary evaluation of the relationship of cannabinoid blood concentrations with the analgesic response to vaporized cannabis.

A randomized, placebo-controlled crossover trial utilizing vaporized cannabis containing placebo and 6.7% and 2.9% delta-9-tetrahydrocannabinol (THC) was performed in 42 subjects with central neuropathic pain related to spinal cord injury and disease. Subjects received two administrations of the study medication in a 4-hour interval. Blood samples for pharmacokinetic evaluation were collected, and pain assessment tests were performed immediately after the second administration and 3 hours later. Pharmacokinetic data, although limited, were consistent with literature reports, namely dose-dependent increase in systemic exposure followed by rapid disappearance of THC. Dose-dependent improvement in pain score was evident across all pain scale elements. Using mixed model regression, an evaluation of the relationship between plasma concentrations of selected cannabinoids and percent change in items from the Neuropathic Pain Scale was conducted. Changes in the concentration of THC and its nonpsychotropic metabolite, 11-nor-9-carboxy-THC, were related to percent change from baseline of several descriptors (eg, itching, burning, and deep pain). However, given the large number of multiple comparisons, false-discovery-rate-adjusted P-values were not significant. Plans for future work are outlined to explore the relationship of plasma concentrations with the analgesic response to different cannabinoids. Such an appraisal of descriptors might contribute to the identification of distinct pathophysiologic mechanisms and, ultimately, the development of mechanism-based treatment approaches for neuropathic pain, a condition that remains difficult to treat.

An Exploratory Human Laboratory Experiment Evaluating Vaporized Cannabis in the Treatment of Neuropathic Pain From Spinal Cord Injury and Disease.

UNLABELLED: Using 8-hour human laboratory experiments, we evaluated the analgesic efficacy of vaporized cannabis in patients with neuropathic pain related to injury or disease of the spinal cord, most of whom were experiencing pain despite traditional treatment. After obtaining baseline data, 42 participants underwent a standardized procedure for inhaling 4 puffs of vaporized cannabis containing either placebo, 2.9%, or 6.7% delta 9-THC on 3 separate occasions. A second dosing occurred 3 hours later; participants chose to inhale 4 to 8 puffs. This flexible dosing was used to attempt to reduce the placebo effect. Using an 11-point numerical pain intensity rating scale as the primary outcome, a mixed effects linear regression model showed a significant analgesic response for vaporized cannabis. When subjective and psychoactive side effects (eg, good drug effect, feeling high, etc) were added as covariates to the model, the reduction in pain intensity remained significant above and beyond any effect of these measures (all P < .0004). Psychoactive and subjective effects were dose-dependent. Measurement of neuropsychological performance proved challenging because of various disabilities in the population studied. Because the 2 active doses did not significantly differ from each other in terms of analgesic potency, the lower dose appears to offer the best risk-benefit ratio in patients with neuropathic pain associated with injury or disease of the spinal cord. PERSPECTIVE: A crossover, randomized, placebo-controlled human laboratory experiment involving administration of vaporized cannabis was performed in patients with neuropathic pain related to spinal cord injury and disease. This study supports consideration of future research that would include longer duration studies over weeks to months to evaluate the efficacy of medicinal cannabis in patients with central neuropathic pain.

Maintenance of Blinding in Clinical Trials and the Implications for Studying Analgesia Using Cannabinoids.

The design of analgesic clinical trials invariably involves a comparison between placebo and active study medication. An assumption is made that treatment effects can be approximated by subtracting the response to placebo from that attained with the use of active study medication. However, the psychoactivity of cannabinoids may unmask their presence and lead to an expectation and/or conditioning of pain relief. For example, study participants biased toward the belief that cannabis is beneficial for their condition might be more inclined to report positive effects if they were to accurately identify the active treatment because of its psychoactivity. This may lead to incorrect assumptions regarding the efficacy of a cannabinoid. Methodologies designed to counteract unmasking need to be implemented in the design phase of a study. During the clinical trial, it is also important to query participants as to which treatment they believe they have received. Blinding can be considered to be preserved when the accuracy of treatment guesses is not considerably different than random guessing, which is estimated to be correct 50% of the time. After a study has been completed, the use of statistical methodologies such as regression and mediation analysis are worthy of consideration to see whether psychoactive effects biased the results.

The effects of antiretroviral treatment initiation on cognition in HIV-infected individuals with advanced disease in Pune, India.

There has been a reduction in the most severe cases of HIV-associated neurocognitive disorders (HAND) with advances in antiretroviral treatment (ART). But the prevalence of milder forms of HAND still remains high. Data from systematically conducted studies on the effects of ART on cognition are scanty in India, where HIV-1 clade C is prevalent. The purpose of the present study was to assess the effect of antiretroviral therapy in HIV-seropositive (HIV+) individuals (n = 92) with CD4 cell counts <200 cells/mm(3). The overall and domain-specific levels of cognitive functioning were determined using a locally recruited normative sample, and a change in neurocognitive functioning at the 1-year follow-up visit was analyzed. Results revealed cognitive impairment in 44.6 % of the HIV+ group at baseline. At the 1-year follow-up, the group showed significant improvement in the Learning domain (p < 0.05). HIV+ individuals showing improvement in the global cognitive scores had a significantly lower baseline CD4 cell count compared to others. Overall, the degree of improvement associated with the magnitude of rise in CD4 suggests the possibility that early, mild subclinical deficits may also benefit from treatment.

Cerebrospinal fluid metabolomics implicate bioenergetic adaptation as a neural mechanism regulating shifts in cognitive states of HIV-infected patients.

OBJECTIVES: To identify prognostic surrogate markers for change in cognitive states of HIV-infected patients. DESIGN: Longitudinal cerebrospinal fluid (CSF) samples were collected from 98 HIV-infected patients identified by temporal change in cognitive states classified as normal, stably impaired, improving and worsening. METHODS: The metabolic composition of CSF was analysed using H nuclear magnetic resonance (H NMR) spectroscopy that focused on energy metabolites. Metabolic biomarkers for cognitive states were identified using multivariate partial least squares regression modelling of the acquired spectra, combined with nonparametric analyses of metabolites with clinical features. RESULTS: Multivariate modelling and cross-validated recursive partitioning identified several energy metabolites that, when combined with clinical variables, classified patients based on change in neurocognitive states. Prognostic identification for worsening was achieved with four features that included no change in a detectable plasma viral load, elevated citrate and acetate; decreased creatine, to produce a model with a predictive accuracy of 92%, sensitivity of 88% and 96% specificity. Prognosis for improvement contained seven features that included first visit age less than 47 years, new or continued use of antiretrovirals, elevated glutamine and glucose; decreased myo-inositol, ß-glucose and creatinine to generate a model with a predictive accuracy of 92%, sensitivity of 100% and specificity of 84%. CONCLUSION: These CSF metabolic results suggest that worsening cognitive status in HIV-infected patients is associated with increased aerobic glycolysis, and improvements in cognitive status are associated with a shift to anaerobic glycolysis. Dietary, lifestyle and pharmacologic interventions that promote anaerobic glycolysis could protect the brain in setting of HIV infection with combined antiretroviral therapy.

Neurocognitive change in the era of HIV combination antiretroviral therapy: the longitudinal CHARTER study.

BACKGROUND: Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) can show variable clinical trajectories. Previous longitudinal studies of HAND typically have been brief, did not use adequate normative standards, or were conducted in the context of a clinical trial, thereby limiting our understanding of incident neurocognitive (NC) decline and recovery. METHODS: We investigated the incidence and predictors of NC change over 16-72 (mean, 35) months in 436 HIV-infected participants in the CNS HIV Anti-Retroviral Therapy Effects Research cohort. Comprehensive laboratory, neuromedical, and NC assessments were obtained every 6 months. Published, regression-based norms for NC change were used to generate overall change status (decline vs stable vs improved) at each study visit. Survival analysis was used to examine the predictors of time to NC change. RESULTS: Ninety-nine participants (22.7%) declined, 265 (60.8%) remained stable, and 72 (16.5%) improved. In multivariable analyses, predictors of NC improvements or declines included time-dependent treatment status and indicators of disease severity (current hematocrit, albumin, total protein, aspartate aminotransferase), and baseline demographics and estimated premorbid intelligence quotient, non-HIV-related comorbidities, current depressive symptoms, and lifetime psychiatric diagnoses (overall model P < .0001). CONCLUSIONS: NC change is common in HIV infection and appears to be driven by a complex set of risk factors involving HIV disease, its treatment, and comorbid conditions.

Individualized texting for adherence building (iTAB): improving antiretroviral dose timing among HIV-infected persons with co-occurring bipolar disorder.

HIV+ persons with co-occurring bipolar disorder (HIV+/BD+) have elevated rates of medication nonadherence. We conducted a 30-day randomized controlled trial of a two-way, text messaging system, iTAB (n = 25), compared to an active comparison (CTRL) (n = 25) to improve antiretroviral (ARV) and psychotropic (PSY) adherence and dose timing. Both groups received medication adherence psychoeducation and daily texts assessing mood. The iTAB group additionally received personalized medication reminder texts. Participants responded to over 90 % of the mood and adherence text messages. Mean adherence, as assessed via electronic monitoring caps, was high and comparable between groups for both ARV (iTAB 86.2 % vs. CTRL 84.8 %; p = 0.95, Cliff's d = 0.01) and PSY (iTAB 78.9 % vs. CTRL 77.3 %; p = 0.43, Cliff's d = -0.13) medications. However, iTAB participants took ARVs significantly closer to their intended dosing time than CTRL participants (iTAB: 27.8 vs. CTRL: 77.0 min from target time; p = 0.02, Cliff's d = 0.37). There was no group difference on PSY dose timing. Text messaging interventions may represent a low-burden approach to improving timeliness of medication-taking behaviors among difficult-to-treat populations. The benefits of improved dose timing for long-term medication adherence require additional investigation.

Asymptomatic HIV-associated neurocognitive impairment increases risk for symptomatic decline.

OBJECTIVE: While HIV-associated neurocognitive disorders (HAND) remain prevalent despite combination antiretroviral therapy (CART), the clinical relevance of asymptomatic neurocognitive impairment (ANI), the most common HAND diagnosis, remains unclear. We investigated whether HIV-infected persons with ANI were more likely than those who were neurocognitively normal (NCN) to experience a decline in everyday functioning (symptomatic decline). METHODS: A total of 347 human participants from the CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) cohort were NCN (n = 226) or had ANI (n = 121) at baseline. Neurocognitive assessments occurred approximately every 6 months, with median (interquartile range) follow-up of 45.2 (28.7-63.7) months. Symptomatic decline was based on self-report (SR) or objective, performance-based (PB) problems in everyday functioning. Proportional hazards modeling was used to generate risk ratios for progression to symptomatic HAND after adjusting for baseline and time-dependent covariates, including CD4+ T-lymphocyte count (CD4), virologic suppression, CART, and mood. RESULTS: The ANI group had a shorter time to symptomatic HAND than the NCN after adjusting for baseline predictors: adjusted risk ratios for symptomatic HAND were 2.0 (confidence interval [CI] 1.1-3.6; p = 0.02) for SR, 5.8 (CI 3.2-10.7; p < 0.0001) for PB, and 3.2 (CI 2.0-5.0; p < 0.0001) for either SR or PB. Current CD4 and depression were significant time-dependent covariates, but antiretroviral regimen, virologic suppression, and substance abuse or dependence were not. CONCLUSIONS: This longitudinal study demonstrates that ANI conveys a 2-fold to 6-fold increase in risk for earlier development of symptomatic HAND, supporting the prognostic value of the ANI diagnosis in clinical settings. Identifying those at highest risk for symptomatic decline may offer an opportunity to modify treatment to delay progression.

"Frontal systems" behaviors in comorbid human immunodeficiency virus infection and methamphetamine dependency.

Human immunodeficiency virus (HIV) infection and methamphetamine (MA) dependence are associated with neural injury preferentially involving frontostriatal circuits. Little is known, however, about how these commonly comorbid conditions impact behavioral presentations typically associated with frontal systems dysfunction. Our sample comprised 47 HIV-uninfected/MA-nondependent; 25 HIV-uninfected/MA-dependent; 36 HIV-infected/MA-nondependent; and 28 HIV-infected/MA-dependent subjects. Participants completed self-report measures of "frontal systems" behaviors, including impulsivity/disinhibition, sensation-seeking, and apathy. They also underwent comprehensive neurocognitive and neuropsychiatric assessments that allowed for detailed characterization of neurocognitive deficits and comorbid/premorbid conditions, including lifetime Mood and Substance Use Disorders, Attention-Deficit/Hyperactivity Disorder, and Antisocial Personality Disorder. Multivariable regression models adjusting for potential confounds (i.e., demographics and comorbid/premorbid conditions) showed that MA dependence was independently associated with increased impulsivity/disinhibition, sensation-seeking and apathy, and HIV infection with greater apathy. However, we did not see synergistic/additive effects of HIV and MA on frontal systems behaviors. Global neurocognitive impairment was relatively independent of the frontal systems behaviors, which is consistent with the view that these constructs may have relatively separable biopsychosocial underpinnings. Future research should explore whether both neurocognitive impairment and frontal systems behaviors may independently contribute to everyday functioning outcomes relevant to HIV and MA.

Dual-mixed HIV-1 coreceptor tropism and HIV-associated neurocognitive deficits.

HIV coreceptor usage of CXCR4 (X4) is associated with decreased CD4+ T-cell counts and accelerated disease progression, but the role of X4 tropism in HIV-associated neurocognitive disorders (HAND) has not previously been described. This longitudinal study evaluated data on 197 visits from 72 recently HIV-infected persons who had undergone up to four sequential neurocognitive assessments over a median of 160 days (IQR, 138­192). Phenotypic tropism testing (Trofile ES, Monogram, Biosciences) was performed on stored blood samples. Multivariable mixed model repeated measures regression was used to determine the association between HAND and dual-mixed (DM) viral tropism, estimated duration of infection (EDI), HIV RNA, CD4 count, and problematic methamphetamine use. Six subjects (8.3 %) had DM at their first neurocognitive assessment and four converted to DM in subsequent sampling (for total of 10 DM) at a median EDI of 10.1 months (IQR, 7.2­12.2). There were 44 (61.1 %) subjects who demonstrated HAND on at least one study visit. HAND was associated with DM tropism (odds ratio, 4.4; 95 % CI, 0.9­20.5) and shorter EDI (odds ratio 1.1 per month earlier; 95 % CI, 1.0­1.2). This study found that recency of HIV-1 infection and the development of DM tropism may be associated with HAND in the relatively early stage of infection. Together, these data suggest that viral interaction with cellular receptors may play an important role in the early manifestation of HAND.

A concise panel of biomarkers identifies neurocognitive functioning changes in HIV-infected individuals.

Neurocognitive (NC) impairment (NCI) occurs commonly in people living with HIV. Despite substantial effort, no biomarkers have been sufficiently validated for diagnosis and prognosis of NCI in the clinic. The goal of this project was to identify diagnostic or prognostic biomarkers for NCI in a comprehensively characterized HIV cohort. Multidisciplinary case review selected 98 HIV-infected individuals and categorized them into four NC groups using normative data: stably normal (SN), stably impaired (SI), worsening (Wo), or improving (Im). All subjects underwent comprehensive NC testing, phlebotomy, and lumbar puncture at two timepoints separated by a median of 6.2 months. Eight biomarkers were measured in CSF and blood by immunoassay. Results were analyzed using mixed model linear regression and staged recursive partitioning. At the first visit, subjects were mostly middle-aged (median 45) white (58 %) men (84 %) who had AIDS (70 %). Of the 73 % who took antiretroviral therapy (ART), 54 % had HIV RNA levels below 50 c/mL in plasma. Mixed model linear regression identified that only MCP-1 in CSF was associated with neurocognitive change group. Recursive partitioning models aimed at diagnosis (i.e., correctly classifying neurocognitive status at the first visit) were complex and required most biomarkers to achieve misclassification limits. In contrast, prognostic models were more efficient. A combination of three biomarkers (sCD14, MCP-1, SDF-1α) correctly classified 82 % of Wo and SN subjects, including 88 % of SN subjects. A combination of two biomarkers (MCP-1, TNF-α) correctly classified 81 % of Im and SI subjects, including 100 % of SI subjects. This analysis of well-characterized individuals identified concise panels of biomarkers associated with NC change. Across all analyses, the two most frequently identified biomarkers were sCD14 and MCP-1, indicators of monocyte/macrophage activation. While the panels differed depending on the outcome and on the degree of misclassification, nearly all stable patients were correctly classified.

Low-dose vaporized cannabis significantly improves neuropathic pain.

UNLABELLED: We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling medium-dose (3.53%), low-dose (1.29%), or placebo cannabis with the primary outcome being visual analog scale pain intensity. Psychoactive side effects and neuropsychological performance were also evaluated. Mixed-effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the 2 active dose groups' results (P > .7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo versus low-dose, 2.9 for placebo versus medium-dose, and 25 for medium- versus low-dose. As these NNTs are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well tolerated, and neuropsychological effects were of limited duration and readily reversible within 1 to 2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain. PERSPECTIVE: The analgesia obtained from a low dose of delta-9-tetrahydrocannabinol (1.29%) in patients, most of whom were experiencing neuropathic pain despite conventional treatments, is a clinically significant outcome. In general, the effect sizes on cognitive testing were consistent with this minimal dose. As a result, one might not anticipate a significant impact on daily functioning.