Fear of falling in community-dwelling older adults: What their gait acceleration pattern reveals

BACKGROUND

Fear of Falling (FOF) is common among community-dwelling older adults and is associated with increased fall-risk, reduced activity, and gait modifications.

OBJECTIVE

In this cross-sectional study, we examined the relationships between FOF and gait quality.

METHODS

Older adults (N=232; age 77±6; 65 % females) reported FOF by a single yes/no question. Gait quality was quantified as (1) harmonic ratio (smoothness) and other time-frequency spatiotemporal variables from triaxial accelerometry (Vertical-V, Mediolateral-ML, Anterior-Posterior -AP) during six-minute walk; (2) gait speed, step-time CoV (variability), and walk-ratio (step-length/cadence) on a 4-m instrumented walkway. Mann Whitney U-tests and Random forest classifier compared gait between those with and without FOF. Selected gait variables were used to build Support Vector Machine (SVM) classifier and performance was evaluated using AUC-ROC.

RESULTS

Individuals with FOF had slower gait speed (103.66 ± 17.09 vs. 110.07 ± 14.83 cm/s), greater step time CoV (4.17 ± 1.66 vs. 3.72 ± 1.24 %), smaller walk-ratio (0.53 ± 0.08 vs. 0.56 ± 0.07 cm/steps/minute), smaller standard deviation V (0.15 ± 0.06 vs. 0.18 ± 0.09 m/s2), and smaller harmonic-ratio V (2.14 ± 0.73 vs. 2.38 ± 0.58), all p<.01. Linear SVM yielded an AUC-ROC of 67 % on test dataset, coefficient values being gait speed (-0.19), standard deviation V (-0.23), walk-ratio (-0.36), and smoothness V (-0.38) describing associations with presence of FOF.

CONCLUSION

Older adults with FOF have reduced gait speed, acceleration adaptability, walk-ratio, and smoothness. Disrupted gait patterns during fear of falling could provide insights into psychosocial distress in older adults. Longitudinal studies are warranted.

Association of Gait Quality With Daily-Life Mobility: An Actigraphy and Global Positioning System Based Analysis in Older Adults

OBJECTIVE

Walking is a key component of daily-life mobility. We examined associations between laboratory-measured gait quality and daily-life mobility through Actigraphy and Global Positioning System (GPS). We also assessed the relationship between two modalities of daily-life mobility i.e., Actigraphy and GPS.

METHODS

In community-dwelling older adults (N = 121, age = 77±5 years, 70% female, 90% white), we obtained gait quality from a 4-m instrumented walkway (gait speed, walk-ratio, variability) and accelerometry during 6-Minute Walk (adaptability, similarity, smoothness, power, and regularity). Physical activity measures of step-count and intensity were captured from an Actigraph. Time out-of-home, vehicular time, activity-space, and circularity were quantified using GPS. Partial Spearman correlations between laboratory gait quality and daily-life mobility were calculated. Linear regression was used to model step-count as a function of gait quality. ANCOVA and Tukey analysis compared GPS measures across activity groups [high, medium, low] based on step-count. Age, BMI, and sex were used as covariates.

RESULTS

Greater gait speed, adaptability, smoothness, power, and lower regularity were associated with higher step-counts (0.20<|ρp| < 0.26, p < .05). Age(β = -0.37), BMI(β = -0.30), speed(β = 0.14), adaptability(β = 0.20), and power(β = 0.18), explained 41.2% variance in step-count. Gait characteristics were not related to GPS measures. Participants with high (>4800 steps) compared to low activity (steps<3100) spent more time out-of-home (23 vs 15%), more vehicular travel (66 vs 38 minutes), and larger activity-space (5.18 vs 1.88 km2), all p < .05.

CONCLUSIONS

Gait quality beyond speed contributes to physical activity. Physical activity and GPS-derived measures capture distinct aspects of daily-life mobility. Wearable-derived measures should be considered in gait and mobility-related interventions.

Weekly minutes of moderate to vigorous physical activity is associated with movement quality in overweight and obese older adults, independent of age

BACKGROUND

Physical activity can improve function and decrease healthcare spending among overweight and obese older adults. Although unstructured physical activity has been related to cardiometabolic improvements, the relationship between unstructured activity and movement quality is unclear.

AIMS

This study aimed to evaluate the association of amount of unstructured free-living moderate-vigorous physical activity (MVPA) with measures of movement quality in overweight and obese older adults.

METHODS

The association of MVPA with movement quality was assessed in 165 overweight and obese older adults (Age: 77.0(8.0) years; Body mass index (BMI): 29.2(5.3) kg/m2). Participants performed overground walking, the Figure of 8 Walk test, and the Five-Times Sit to Stand. Weekly physical activity was measured using a waist-worn Actigraph activity monitor.

RESULTS

Movement quality during straight path [gait speed (ρ = 0.30, p < 0.01), stride length (ρ = 0.33, p < 0.01), double-limb support time (ρ = -0.26, p < 0.01), and gait symmetry (ρ = 0.17, p = 0.02)] and curved path [F8W time (ρ = -0.22, p < 0.01) and steps (ρ = -0.22, p < 0.01)] walking were associated with weekly minutes of MVPA after controlling for age. Five-Times Sit to Stand performance was not significantly associated with weekly minutes of MVPA (ρ = -0.10, p = 0.13).

CONCLUSIONS

Older adults with high BMIs who are less active also demonstrate poorer movement quality, independent of age. Physical activity engagement and task-specific training should be targeted in interventions to promote healthy aging, decrease falls, and delay disability development. Future work should consider the interconnected nature of movement quality with physical activity engagement and investigate if targeting one influences the other.

Uneven surface and cognitive dual-task independently affect gait quality in older adults

BACKGROUND

Real-world mobility involves walking in challenging conditions. Assessing gait during simultaneous physical and cognitive challenges provides insights on cognitive health.

RESEARCH QUESTION

How does uneven surface, cognitive task, and their combination affect gait quality and does this gait performance relate to cognitive functioning?

METHODS

Community-dwelling older adults (N = 104, age=75 ± 6 years, 60 % females) performed dual-task walking paradigms (even and uneven surface; with and without alphabeting cognitive task (ABC)) to mimic real-world demands. Gait quality measures [speed(m/s), rhythmicity(steps/minute), stride time variability (%), adaptability (m/s2), similarity, smoothness, power (Hz) and regularity] were calculated from an accelerometer worn on the lower back. Linear-mixed modelling and Tukey analysis were used to analyze independent effects of surface and cognitive task and their interaction on gait quality. Partial Spearman correlations compared gait quality with global cognition and executive function.

RESULTS

No interaction effects between surface and cognitive task were found. Uneven surface reduced gait speed(m/s) (β = -0.07). Adjusted for speed, uneven surface reduced gait smoothness (β = -0.27) and increased regularity (β = 0.09), Tukey p < .05, for even vs uneven and even-ABC vs uneven-ABC. Cognitive task reduced gait speed(m/s) (β = -0.12). Adjusted for speed, cognitive task increased variability (β = 7.60), reduced rhythmicity (β = -6.68) and increased regularity (β = 0.05), Tukey p < .05, for even vs even-ABC and uneven vs uneven-ABC. With demographics as covariates, gait speed was not associated with cognition. Gait quality [lower variability during even-ABC (ρp =-.31) and uneven-ABC (ρp =-.28); greater rhythmicity (ρp between.22 and.29) and greater signal-adaptability AP (ρp between.22 and.26) during all walking tasks] was associated with better global cognition. Gait adaptability during even (ρp =-0.21, p = 0.03) and uneven(ρp =-0.19, p = 0.04) walking was associated with executive function.

SIGNIFICANCE

Surface and cognitive walking tasks independently affected gait quality. Our study with high-functioning older adults suggests that task-related changes in gait quality are related to subtle changes in cognitive functioning.

Weekly minutes of moderate to vigorous physical activity is associated with movement quality in overweight and obese older adults

Background

Physical activity can improve function and decrease healthcare spending among overweight and obese older adults. Although unstructured physical activity has been related to cardiometabolic improvements, the relationship between unstructured activity and movement quality is unclear.

Aims

This study aimed to evaluate the association of amount of unstructured free-living moderate-vigorous physical activity (MVPA) with measures of movement quality in overweight and obese older adults.

Methods

The association of MVPA with movement quality was assessed in 165 overweight and obese older adults (Age: 77.0(8.0) years; Body mass index (BMI): 29.2(5.3) kg/m2). Participants performed overground walking, the Figure of 8 Walk test, and the Five-Times Sit to Stand. Weekly physical activity was measured using a waist-worn Actigraph activity monitor.

Results

Movement quality during straight path (gait speed (ρ = 0.30, p < 0.01), stride length (ρ = 0.33, p < 0.01), double-limb support time (ρ=-0.26, p < 0.01), and gait symmetry (ρ = 0.17, p = 0.02)) and curved path (F8W time (ρ=-0.22, p < 0.01) and steps (ρ=-0.22, p < 0.01)) walking were associated with weekly minutes of MVPA after controlling for age. Five-Times Sit to Stand performance was not significantly associated with weekly minutes of MVPA (ρ=-0.10, p = 0.13).

Conclusions

Older adults with high BMIs who are less active also demonstrate poorer movement quality which should be targeted in interventions to promote healthy aging, decrease falls, and delay disability development. Future work should explore if these associations are observed in middle-aged adults so targeted interventions can be implemented even earlier in the disability development continuum.

NEIGHBORHOOD WALKABILITY INFLUENCES ASSOCIATIONS BETWEEN PHYSICAL ACTIVITY AND GAIT MEASURES IN OLDER ADULTS

Neighborhood walkability can influence physical activity and of older adults. Residential neighborhoods of participants (N=186, 77±6 years, 70% females) were audited for walkability using Google Street View. Factor analysis categorized neighborhood walkability as high, medium, and low. Gait quality was derived from a 4-m instrumented walkway (pace, variability, walk-ratio) and accelerometry signals at the lower back during a 6-minute walk test (adaptability, similarity, and smoothness). Activity was step-count from seven-day actigraphy. We studied associations between gait variables and step-count across high, medium, and low walkability neighborhoods using linear regression (age and sex as covariates). Pace(m/s) [High(β=0.46, p<.05), Medium(β=0.43, p<.05), Low(β=0.25, p>.05)], adaptability(m/s2) [High(β=0.47, p<.05), Medium(β=0.24, p<.05), Low(β=0.37, p<.05)], and similarity [High(β=0.39, p<.05), Medium(β=0.28, p<.05), and Low(β=0.18, p>.05)] were associated with step-count, stronger associations for high walkability neighborhoods (p for interactions <0.01). No associations with variability, walk-ratio, and smoothness were found. Associations between gait and activity differed by neighborhood walkability.

Facilitators and barriers to real-life mobility in community-dwelling older adults: a narrative review of accelerometry- and global positioning system-based studies

Real-life mobility, also called "enacted" mobility, characterizes an individual's activity and participation in the community. Real-life mobility may be facilitated or hindered by a variety of factors, such as physical abilities, cognitive function, psychosocial aspects, and external environment characteristics. Advances in technology have allowed for objective quantification of real-life mobility using wearable sensors, specifically, accelerometry and global positioning systems (GPSs). In this review article, first, we summarize the common mobility measures extracted from accelerometry and GPS. Second, we summarize studies assessing the associations of facilitators and barriers influencing mobility of community-dwelling older adults with mobility measures from sensor technology. We found the most used accelerometry measures focus on the duration and intensity of activity in daily life. Gait quality measures, e.g., cadence, variability, and symmetry, are not usually included. GPS has been used to investigate mobility behavior, such as spatial and temporal measures of path traveled, location nodes traversed, and mode of transportation. Factors of note that facilitate/hinder community mobility were cognition and psychosocial influences. Fewer studies have included the influence of external environments, such as sidewalk quality, and socio-economic status in defining enacted mobility. Increasing our understanding of the facilitators and barriers to enacted mobility can inform wearable technology-enabled interventions targeted at delaying mobility-related disability and improving participation of older adults in the community.

A large, curated, open-source stroke neuroimaging dataset to improve lesion segmentation algorithms

Accurate lesion segmentation is critical in stroke rehabilitation research for the quantification of lesion burden and accurate image processing. Current automated lesion segmentation methods for T1-weighted (T1w) MRIs, commonly used in stroke research, lack accuracy and reliability. Manual segmentation remains the gold standard, but it is time-consuming, subjective, and requires neuroanatomical expertise. We previously released an open-source dataset of stroke T1w MRIs and manually-segmented lesion masks (ATLAS v1.2, N = 304) to encourage the development of better algorithms. However, many methods developed with ATLAS v1.2 report low accuracy, are not publicly accessible or are improperly validated, limiting their utility to the field. Here we present ATLAS v2.0 (N = 1271), a larger dataset of T1w MRIs and manually segmented lesion masks that includes training (n = 655), test (hidden masks, n = 300), and generalizability (hidden MRIs and masks, n = 316) datasets. Algorithm development using this larger sample should lead to more robust solutions; the hidden datasets allow for unbiased performance evaluation via segmentation challenges. We anticipate that ATLAS v2.0 will lead to improved algorithms, facilitating large-scale stroke research.

The ENIGMA Stroke Recovery Working Group: Big data neuroimaging to study brain-behavior relationships after stroke

The goal of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Stroke Recovery working group is to understand brain and behavior relationships using well-powered meta- and mega-analytic approaches. ENIGMA Stroke Recovery has data from over 2,100 stroke patients collected across 39 research studies and 10 countries around the world, comprising the largest multisite retrospective stroke data collaboration to date. This article outlines the efforts taken by the ENIGMA Stroke Recovery working group to develop neuroinformatics protocols and methods to manage multisite stroke brain magnetic resonance imaging, behavioral and demographics data. Specifically, the processes for scalable data intake and preprocessing, multisite data harmonization, and large-scale stroke lesion analysis are described, and challenges unique to this type of big data collaboration in stroke research are discussed. Finally, future directions and limitations, as well as recommendations for improved data harmonization through prospective data collection and data management, are provided.

Association Between Dual-Task Gait and Cognitive Function in Older Adults

Community mobility involves walking with physical and cognitive challenges. In older adults (N=116; results here from initial analyses: N=29, Age=75±5 years, 51% females), we assessed gait speed and smoothness (harmonic-ratio) while walking on even and uneven surfaces, with or without an alternate alphabeting dual-task (ABC). ANOVA assessed surface and dual-task effects; Pearson correlations compared gait with global cognition and executive function composite z-scores. The four conditions (even, uneven, even-ABC and uneven-ABC) affected speed(m/s) (0.97±0.14 vs 0.90±0.15 vs 0.83±0.17 vs 0.79±0.16). Smoothness (2.19±0.48 vs 1.89±0.38 vs 1.92±0.53 vs 1.7±0.43) was affected by only surface (controlled for speed). Greater speed was associated with better global cognition(ρ=0.47 to 0.49, p<0.05) for all conditions and with better executive function for even-ABC(ρ=0.39, p=0.04) and uneven-ABC(ρ=0.40, p=0.03). Executive function was associated with smoothness during even(ρp=-0.42, p=0.03) and uneven(ρp=-0.39, p=0.04) walking. Type of walking challenge differentially affects gait quality and associations with cognitive function.

Prefrontal Activation is Associated With Gait Quality During an Attentional Task in Older Adults

Prefrontal cortical activation varies by walking task and is a marker of attentional demand. We compared prefrontal activation by functional near-infrared spectroscopy (fNIRS) to accelerometry-derived gait quality. We hypothesized greater activation with lower gait quality (greater step-time coefficient-of-variation, decreased cadence, smoothness, regularity, and signal variability). Participants (n=114; age 74.4±6.0 years, 59.6% female) were independently ambulating individuals &gt;64 years. Attentional (reciting every-other alphabet letter) and physical (uneven surface) challenges mimicked community mobility and provided four 15m walking conditions: even, uneven, ABC-even, and ABC-uneven. fNIRS data were referenced to quiet standing and averaged within left and right hemispheres. Gait metrics from a tri-axial accelerometer at the lower-back included cadence (steps/min), step-time coefficient-of-variation, signal variability (standard deviation), smoothness (harmonic ratio), and regularity (entropy). Associations between fNIRS and gait were quantified using Pearson correlations (α=0.05). Results were consistent across hemispheres, gait axes, and robust to adjustment for age and gait speed; we report unadjusted coefficients for left hemisphere and anterior-posterior gait direction. Greater prefrontal activation was associated with slower cadence (r=-0.220, p=0.019), lower signal variability (r=-0.228, p=0.015), and reduced smoothness (r=-0.194, p=0.039) during ABC-even. No relation was observed for step-time coefficient-of-variation or regularity. Results were similar for the ABC-uneven condition, except there was no association with gait smoothness but was with step-time coefficient-of-variation (r=0.25, p=0.007). Prefrontal activation was not correlated to gait quality in non-ABC conditions. Our findings support our hypothesis only during the ABC challenge, suggesting that older adults may rely on prefrontal activation to complete attentional but not physical challenges during gait.

Smaller spared subcortical nuclei are associated with worse post-stroke sensorimotor outcomes in 28 cohorts worldwide

Up to two-thirds of stroke survivors experience persistent sensorimotor impairments. Recovery relies on the integrity of spared brain areas to compensate for damaged tissue. Deep grey matter structures play a critical role in the control and regulation of sensorimotor circuits. The goal of this work is to identify associations between volumes of spared subcortical nuclei and sensorimotor behaviour at different timepoints after stroke. We pooled high-resolution T1-weighted MRI brain scans and behavioural data in 828 individuals with unilateral stroke from 28 cohorts worldwide. Cross-sectional analyses using linear mixed-effects models related post-stroke sensorimotor behaviour to non-lesioned subcortical volumes (Bonferroni-corrected, P < 0.004). We tested subacute (≤90 days) and chronic (≥180 days) stroke subgroups separately, with exploratory analyses in early stroke (≤21 days) and across all time. Sub-analyses in chronic stroke were also performed based on class of sensorimotor deficits (impairment, activity limitations) and side of lesioned hemisphere. Worse sensorimotor behaviour was associated with a smaller ipsilesional thalamic volume in both early (n = 179; d = 0.68) and subacute (n = 274, d = 0.46) stroke. In chronic stroke (n = 404), worse sensorimotor behaviour was associated with smaller ipsilesional putamen (d = 0.52) and nucleus accumbens (d = 0.39) volumes, and a larger ipsilesional lateral ventricle (d = -0.42). Worse chronic sensorimotor impairment specifically (measured by the Fugl-Meyer Assessment; n = 256) was associated with smaller ipsilesional putamen (d = 0.72) and larger lateral ventricle (d = -0.41) volumes, while several measures of activity limitations (n = 116) showed no significant relationships. In the full cohort across all time (n = 828), sensorimotor behaviour was associated with the volumes of the ipsilesional nucleus accumbens (d = 0.23), putamen (d = 0.33), thalamus (d = 0.33) and lateral ventricle (d = -0.23). We demonstrate significant relationships between post-stroke sensorimotor behaviour and reduced volumes of deep grey matter structures that were spared by stroke, which differ by time and class of sensorimotor measure. These findings provide additional insight into how different cortico-thalamo-striatal circuits support post-stroke sensorimotor outcomes.

Mobility of Older Adults: Gait Quality Measures are associated with Life-Space Assessment Scores

BACKGROUND

The relation of gait quality to real-life mobility among older adults is poorly understood. This study examined the association between gait quality, consisting of step variability, smoothness, regularity, symmetry and gait speed with the Life-Space Assessment (LSA).

METHODS

In community-dwelling older adults (N=232, age 77.5±6.6, 65% females), gait quality was derived from: a) an instrumented walkway: gait speed, variability and walk-ratio; and b) accelerometer: signal variability, smoothness, regularity, symmetry, and time-frequency spatiotemporal variables during 6-minute walk. In addition to collecting LSA scores, cognitive functioning, walking-confidence, and falls were recorded. Spearman correlations (speed as covariate) and Random Forest Regression were used to assess associations between gait quality and LSA, and Gaussian-mixture modeling (GMM) was used to cluster participants.

RESULTS

Spearman correlations of ρp=0.11 (signal amplitude variability ML), ρp=0.15, ρp=-0.13 (symmetry AP-V, ML-AP), ρp=0.16 (power V) and ρ=0.26 (speed), all p<0.05 and marginally related, ρp=-0.12 (regularity V), ρp=0.11 (smoothness AP) and ρp=-0.11 (step-time variability), p<0.1 were obtained. The cross-validated Random Forest model indicated good fit LSA prediction error of 17.77; gait and cognition were greater contributors than age and gender. GMM indicated two clusters. Group-1(N=189) had better gait quality than Group-2(N=43): greater smoothness AP (2.94±0.75 vs 2.30±0.71); greater similarity AP-V (0.58±0.13 vs 0.40±0.19); lower regularity V (0.83±0.08 vs 0.87±0.10); greater power V (1.86±0.18 vs 0.97±1.84); greater speed (1.09±0.16 vs 1.00±0.16 m/s); lower step time CoV (3.70±1.09 vs 5.09±2.37) and better LSA (76±18 vs 67±18), padjusted<0.004.

CONCLUSIONS

Gait quality measures taken in the clinic are associated with real-life mobility in the community.

Fear of Falling and Walking Quality: What Your Walking Reveals

Fear of Falling (FOF) is common among community-dwelling older adults and is associated with increased fall-risk. In this cross-sectional study we examined the relationships between FOF and factors associated with fall-risk such as gait quality, cognition, and walking-confidence. Using baseline data from older adult participants in a randomized exercise trial (N=232; age 77±6; 65% females; 40% reported FOF), we quantified the following outcome measure for (1) gait quality: harmonic ratio (smoothness) and time-frequency spatiotemporal variables from triaxial accelerometry during 6 minute walk; gait speed, step-time CoV (variability) and walk-ratio (step-length/cadence) on an instrumented walkway; (2) cognition: Trails A and B (3) walking-confidence: Gait efficacy Scale. Mann Whitney U-tests indicated individuals without FOF had better gait quality (p<0.05): greater smoothness (2.38±.58 vs 1.14±.73), speed (1.10±.15 vs 1.04±.17 m/s) and walk-ratio (.56±.07 vs .53±.08 cm/steps/min), lower step-time CoV (3.72±1.24 vs 4.17±1.66), and greater walking-confidence (89±11 vs 79±13). A random forest classifier predicted FOF with 64% (gait only) and 70% (additional variables: cognition, walking-confidence) accuracy; Gini-index based ranking indicated gait quality (smoothness vertical (V) direction, walking speed) were consistently important variables. Linear Support Vector Machine learning yielded accuracies of 60% (only gait) and 68% (with additional measures): smoothness V, mediolateral frequency bandwidth, gait speed among top 4 ranked variables in both models, and walking-confidence in the additional measures model; smoothness-V the highest weighted coefficient (-0.52). Based on these findings, interventions targeted for gait quality and walking-confidence may be important to overcome FOF and reduce fall risks.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

P04.19 Analysis of tumor immune microenvironment and immune checkpoint modulators across infantile and pediatric pilocytic astrocytomas to elucidate the role of immunotherapy in these tumors

BACKGROUND

Pilocytic astrocytomas are the most common central nervous system tumors in pediatric age-group. Although grade I, some of the cases show recurrence and progression, and few might not be amenable to surgery due to location or size, and hence have a less favorable prognosis. Drugs blocking immune check-point interactions such as those including programmed cell death ligand-1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are now in clinical use for certain tumors. We performed this study to understand the potential candidature of pilocytic astrocytomas in infants and children for immunotherapy by analyzing the expression of immune checkpoint proteins and immune infiltrate, and correlating with clinical details, wherever possible.

MATERIALS AND METHODS

Cases with adequate tissue (2010–2017) diagnosed in pediatric age-group (<18 years) were retreived from the archives of Department of Pathology, AIIMS, New Delhi. Immunohistochemistry for PD-L1 (SP263, Ventana), CTLA-4, CD3, CD8, CD4 and CD68 was performed. Quantification of cytotoxic lymphocytes was done using digital imaging in the core of the tumor.

RESULTS

A total of 50 pilocytic astrocytomas were included, 14 of them were <3 years (infants), while 36 were of pediatric age-group (3–18 years). Overall, male preponderance was noted. Cerebellum was the most common location, followed by 4th venrticle, optic pathway, hypothalamus, cerebrum and thalamus. Almost all CD3 lymphocytes were cytotoxic T-lymphocyes (CD8 positive, CTLs). Helper T-lymphocyte infiltration was not seen. Median CTL density/mm3 was 13/mm3(Range:1–85/mm3). CTLA-4 was positive in 4 cases, positivity ranged from 1–4 cells/lpf. PD-L1 was found to be positive in 7 cases, and the positivity ranged from 1+ to 2+ in 1 to 5% of tumor cells. A median TAM (tumor associated macrophages) density of 44/hpf (range: 1–98/hpf) was noted. There was no correlation of CTL density with PD-L1 or CTLA-4 expression, and neither with TAM density. On correlation with clinical parameters, a higher density of CTLs and TAMs was noted in infants, and a higher proportion of cases revealed PD-L1 positivity, though not statistically significant. There was no correlation of TILs or TAMs with the tumor location.

CONCLUSION

Immune check point blockade using PD-(L)1 or CTLA4 inhibitors may not be a potential therapeutic option for unresectable or recurrent pilocytic astrocytomas, as low positivity rate as well as extremely low percentage of tumor/ immune cells found to be positive. However, alternate forms of immunotherapy might be helpful as most of the cases showed immune infiltrates and a high density of tumor-associated macrophages (TAMs). Large scale studies with larger numbers and longer follow-up periods including in-vitro and clinical studies are warranted for decoding the tumor immunogram.

P14.117 Cost efficient test algorithm for molecular subgrouping of medulloblastomas for day-to-day practice in resource limited countries

INTRODUCTION

Molecular classification of medulloblastomas(MB) is prognostically and therapeutically relevant and helps in better risk-stratification. Translation of this subgrouping to routine practice still remains a challenge. The most pathologist-accessible techniques for molecular subgrouping include immunohistochemistry(IHC), fluorescent in-situ hybridization(FISH) and Nanostring assay. Objectives:(1)Molecular subgrouping of MBs by IHC and FISH, and Nanostring Assay (2)To compare their efficacy against sequencing and DNA methylation, and cost for applicability in resource-constrained centers

METHODS

Ninety-five cases of MB with adequate tissue were included. Molecular subgrouping was performed by IHC for β-catenin, GAB1, YAP1, and p53; FISH for MYC amplification, and sequencing for CTNNB1, and by Nanostring Assay on the same set of MBs. Further, a subset of cases were subjected to 850k DNA methylation array.

RESULTS

IHC+FISH classified MBs into 15.8% WNT, 16.8% SHH, and 67.4% non-WNT/non-SHH subgroups; with MYC amplification identified in 20.3% cases of non-WNT/non-SHH. A single showed diffuse strong p53 positivity among the SHH subgroup. Nanostring successfully classified 91.5% MBs into 25.3% WNT, 17.2% SHH, 23% Group3 and 34.5% Group4. However, Nanostring assay failure was seen in eight cases, all of which were >8-years-old formalin-fixed paraffin-embedded tissue blocks. Concordant subgroup assignment was noted in 88.5% cases, while subgroup switching was seen in 11.5% cases. Both methods showed prognostic correlation. Among the 5 discrepant cases, which switched to WNT subgroup by Nanostring, only 2 were found to have CTNNB1 mutation. Methylation profiling performed on discordant cases revealed 1 out of 4 extra WNT identified by Nanostring to be WNT, others aligned with IHC subgroups; extra SHH by Nanostring turned out to be SHH by methylation.

CONCLUSIONS

Both IHC supplemented by FISH and Nanostring are robust methods for molecular subgrouping, albeit with few disadvantages. IHC cannot differentiate between Groups 3 and 4, while Nanostring cannot classify older-archived tumors, and is not available at most centres. WNT subgroup with the best prognosis is best detected by IHC or IHC followed by sequencing for confirmation. Nanostring Assay is better suitable to separate Group 3, the worst prognostic group from Group 4. Thus, both the methods complement each other and can be used in concert for high confidence allotment of molecular subgroups in clinical practice. The cost of IHC plus Nanostring will almost be the same as IHC plus FISH. We recommend a cost-efficient algorithmic approach using histopathological subtype and IHC as the first step followed by Nanostring or FISH, wherever suitable.

Variations in Cerebral Haemodynamics during Irrigation Phase in Neuroendoscopic Procedures

Not many centres measure intracranial pressure during an endoscopic procedure. However, if the irrigation fluid during endoscopy is not simultaneously drained, then some rise in intracranial pressure can be anticipated. This study was carried out to measure and monitor changes in intracranial pressure during the irrigation phase in a neuroendoscopic procedure using a Codman catheter placed in the parenchyma. Intracranial pressure was monitored in 13 patients undergoing surgical neuroendoscopic procedures under a standardised anaesthetic technique. Heart rate, mean arterial pressure, intracranial pressure and cerebral perfusion pressure were recorded at baseline and during the irrigation phase of the procedure. The heart rate during irrigation was comparable to baseline values, but the mean arterial pressure at the time of irrigation increased an average of 7 mmHg (P =0.02). At the same time there was an average 34 mmHg increase in intracranial pressure (P <0.001), producing an average 26 mmHg decrease in the cerebral perfusion pressure (P <0.001) during irrigation. There was an average of four episodes of raised intracranial pressure (> 25 mmHg) during the irrigation phase per patient. We suggest that the intracranial pressure be routinely monitored during neuroendoscopic procedures. Only then can the potential adverse effect of irrigation on intracranial pressure and cerebral perfusion pressure be assessed.

Coagulase-negative staphylococci causing blood stream infection at an Indian tertiary care hospital: Prevalence, antimicrobial resistance and molecular characterisation

INTRODUCTION

Recent years have seen a rise of coagulase-negative staphylococci (CoNS) from common contaminants to agents of nosocomial blood stream infections (BSI's). Molecular typing and establishing a correlation with antibiotic resistance is essential particularly in countries like India where genotyping studies for drug-resistant CoNS are sparse.

METHODS

A prospective study was done over 18 months, wherein 42,693 blood samples were received, and 59 patients with BSI due to CoNS were evaluated. The isolates recovered were identified by a biochemical test panel and matrix-assisted laser desorption ionization - time of flight mass spectrometry followed by antimicrobial susceptibility testing by Kirby-Baur disc diffusion method and E-test strips. Staphylococcal chromosomal cassette mec (SCCmec) element was characterised by multiplex polymerase chain reaction for all methicillin-resistant (MR) isolates.

RESULTS

The majority of CoNS isolated were constituted by Staphylococcus haemolyticus (47.5%) followed by Staphylococcus epidermidis (33.9%), Staphylococcus hominis (11.86%), Staphylococcus cohnii (5.08%) and Staphylococcus warneri (1.69%). Among all isolates 57.6% were MR with statistically significant higher resistance versus methicillin sensitive-CoNS. This difference was significant for erythromycin (76% vs. 44%, P = 0.011), rifampicin (50% vs. 12%,P= 0.002) and amikacin (26.5% vs. 4%, P = 0.023), ciprofloxacin (64.7% vs. 20%, P = 0.001) and cotrimoxazole (55.9% vs. 20%, P = 0.006). SCCmec type I was predominant (61.8%, P = 0.028) and exhibited multidrug resistance (76.2%). Coexistence of SCCmec type I and III was seen in 8.82% MR isolates.

CONCLUSION

CoNS exhibit high antimicrobial resistance thereby limiting treatment options. The presence of new variants of SCCmec type in hospital-acquired CoNS may predict the antibiotic resistance pattern. This is the first evaluation of the molecular epidemiology of CoNS causing BSI from India and can serve as a guide in the formulation of hospital infection control and treatment guidelines.

Physiologically based and population PK modeling in optimizing drug development: A predict-learn-confirm analysis

Physiologically based pharmacokinetic (PBPK) modeling and classical population pharmacokinetic (PK) model‐based simulations are increasingly used to answer various drug development questions. In this study, we propose a methodology to optimize the development of drugs, primarily cleared by the kidney, using model‐based approaches to determine the need for a dedicated renal impairment (RI) study. First, the impact of RI on drug exposure is simulated via PBPK modeling and then confirmed using classical population PK modeling of phase 2/3 data. This methodology was successfully evaluated and applied to an investigational agent, orteronel (nonsteroidal, reversible, selective 17,20‐lyase inhibitor). A phase 1 RI study confirmed the accuracy of model‐based predictions. Hence, for drugs eliminated primarily via renal clearance, this modeling approach can enable inclusion of patients with RI in phase 3 trials at appropriate doses, which may be an alternative to a dedicated RI study, or suggest that only a reduced‐size study in severe RI may be sufficient.

Conversion of Lapachol to Rhinacanthin-A and other Cyclized Products

A facile synthesis of rhinacanthin-A is achieved by the side chain cyclization of lapachol with meta-chloroperbenzoic acid along with stenocarpoquinone-A, stenocarpoquinone-B and its isomer.

An anti-CD154 domain antibody prolongs graft survival and induces Foxp3(+) iTreg in the absence and presence of CTLA-4 Ig

The use of monoclonal antibodies targeting the CD154 molecule remains one of the most effective means of promoting graft tolerance in animal models, but thromboembolic complications during early clinical trials have precluded their use in humans. Furthermore, the role of Fc-mediated deletion of CD154-expressing cells in the observed efficacy of these reagents remains controversial. Therefore, determining the requirements for anti-CD154-induced tolerance will instruct the development of safer but equally efficacious treatments. To investigate the mechanisms of action of anti-CD154 therapy, two alternative means of targeting the CD40-CD154 pathway were used: a nonagonistic anti-CD40 antibody and an Fc-silent anti-CD154 domain antibody. We compared these therapies to an Fc-intact anti-CD154 antibody in both a fully allogeneic model and a surrogate minor antigen model in which the fate of alloreactive cells could be tracked. Results indicated that anti-CD40 mAbs as well as Fc-silent anti-CD154 domain antibodies were equivalent to Fc-intact anti-CD154 mAbs in their ability to inhibit alloreactive T cell expansion, attenuate cytokine production of antigen-specific T cells and promote the conversion of Foxp3(+) iTreg. Importantly, iTreg conversion observed with Fc-silent anti-CD154 domain antibodies was preserved in the presence of CTLA4-Ig, suggesting that this therapy is a promising candidate for translation to clinical use.

Role of simvastatin in prevention of vasospasm and improving functional outcome after aneurysmal sub-arachnoid hemorrhage: a prospective, randomized, double-blind, placebo-controlled pilot trial

BACKGROUND

Vasospasm plays a major role in the morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). The preliminary studies suggest that statins protect against cerebral vasospasm.

OBJECTIVE

The aim of the study was to determine the role of simvastatin in preventing clinical vasospasm and improving functional outcome in patients with aSAH.

METHODS

All patients with aSAH admitted within 96 h of ictus were randomized to receive either Simvastatin or placebo - 80 mg/day for 14 days. Thirty eight patients were recruited in the study- 19 received Simvastatin and 19 placebo. All the patients underwent surgical clipping of the aneurysm. The primary outcome of the study was the development of clinical cerebral vasospasm. The secondary outcomes included Glasgow Outcome Score (GOS), Modified Rankin Scale (MRS) and Barthel Index Score (MBI) at follow-up at 1, 3 and 6 months.

RESULTS

16% of the patients in the simvastatin group had high Middle Cerebral Artery velocities (> 160 cm/sec) on transcranial Doppler on one or more than one day during the study duration as compared to 26% of the patients in the placebo group (p = 0.70). Neurological deterioration occurred in 26% and 42% of the patients in simvastatin group versus placebo group, respectively (p = 0.31). There was an improvement in the functional outcome in the simvastatin group at 1, 3 or 6 months in the follow-up; however, this difference was not statistically significant.

CONCLUSIONS

There was benefit of simvastatin in terms of reduction in clinical vasospasm, mortality or improved functional outcome, however, this was not statistically significant.

Use of intravenous immune globulin in the ICU: a retrospective review of prescribing practices and patient outcomes

RATIONALE

Intravenous immune globulin (IVIG) is a pooled human blood product. Much of IVIG use in Canada is prescribed for 'unlabelled' or 'off-label' indications. Due to costs, risk of use and limited supply, knowledge about the use of IVIG is important. We collected data regarding the usage of IVIG and outcomes of patients receiving IVIG in the intensive care units (ICUs) of two community and three academic hospitals.

METHODS

We reviewed the charts of adult patients who received IVIG in the five ICUs over a 5-year period. Data collection included demographics, severity of illness, indication for and dose of IVIG, mortality and adverse effects. On the basis of a classification developed by Canadian Blood Services, the indications for IVIG were then classified as 'appropriate' or 'inappropriate'.

RESULTS

One hundred and forty-five patients received IVIG in the ICU. In all, 19% of IVIG prescriptions were for 'appropriate' indications and 7% were 'inappropriate'. The remaining 74% were prescribed for indications with some evidence to support their use. Three indications accounted for 50% of all IVIG prescribed: Guillain-Barre syndrome (GBS), necrotising fasciitis (NF) and toxic epidermal necrolysis (TEN). Both the community and academic centres prescribed IVIG for similar indications. Adverse effects associated with IVIG administration included deep vein thrombosis/pulmonary embolism, fever and renal failure, although direct causation related to IVIG could not be established. The overall mortality rate was 55%.

CONCLUSIONS

IVIG is used relatively infrequently in the critical care setting. The most common indications were GBS, TEN and NF. Mortality was high. There was no difference between community and academic ICUs.

Abstract P1-01-19: Comparison of Ultrasound-Guided Fine Needles Aspiration Cytology and Ultrasound Guided Core Biopsy in Pre-Operative Axillary Staging for Early Breast Cancer

Introduction: Pre-operative axillary staging is now widely accepted as a prerequisite in surgical management of the axilla for patients newly diagnosed with early breast cancer. For those patients having breast tumour excision who are found to have nodal involvement, axillary clearance can be performed at the same time without prior sentinel node biopsy. Ultrasound (US) alone has low sensitivity, but can be used to direct needle biopsy. We assessed and compared the sensitivity and specificity of US-guided core biopsies (USCB) and US-guided fine needle cytology (USFNAC) used in our unit.

Patients and methods: A retrospective and prospective data collection was performed between November 2007 and May 2010 on all newly diagnosed breast cancer patients in our unit since the introduction of routine pre-operative axillary US. Patients whose nodes looked benign or normal on US were offered sentinel node biopsy (SNB). Patients found to have suspicious nodes were offered USFNAC or USCB, according to the individual preference of the radiologists. Patients with positive cytology or histology underwent axillary node clearances (ANC), those with benign cytology or histology were offered SNB. The final histology results were reviewed and correlated to their pre-operative histology or cytology.

Results: Of 559 Axillary ultrasound scans performed in our department between November 2007 and May 2010, 229 patients had pre-operative US scans of the axilla for newly diagnosed, clinically node-negative breast cancer. Of these 46 had USFNAC, 44 had USCB and 139 had normal/benign US. The USFNAC and USCB groups had similar proportions of positive results on postoperative histology, namely 70% and 79% respectively, allowing direct comparisons to be made. Of the 46 USFNAC patients, 17 (37%) had positive cytology (all confirmed by axillary clearance final histology). The 29 USFNAC patients with negative cytology had 15 (52%) with positive histology on sentinel node biopsy. The sensitivity of USFNAC was 53% and the specificity 100%. Of the 44 USCB patients, 26 (59%) were positive (all confirmed by axillary clearance final histology). Of the 18 USCB-negative patients, 7 (39%) were found to be positive on axillary clearance. The sensitivity of USCB was 79% and the specificity 100%. Of the 139 patients with normal US, 42 (30%) were found to be positive on sentinel node biopsies. For US alone, sensitivity was 61% and specificity was 80%.

Conclusion: US staging of the axilla is superior to clinical staging. However, there is still a high incidence of false negative results, making US a crude way of assessing the axilla and confirming the necessity for sentinel node biopsy in US-negative axillae. For patients with axillae that are indeterminate on US, our data supports routine use of ultrasound core biopsy (USCB) over Ultrasound fine needle aspiration cytology (USFNAC) for preoperative staging of the axilla, where technically feasible.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-01-19.

Targeted therapy for high-grade glioma with the TGF-β2 inhibitor trabedersen: results of a randomized and controlled phase IIb study

This randomized, open-label, active-controlled, dose-finding phase IIb study evaluated the efficacy and safety of trabedersen (AP 12009) administered intratumorally by convection-enhanced delivery compared with standard chemotherapy in patients with recurrent/refractory high-grade glioma. One hundred and forty-five patients with central reference histopathology of recurrent/refractory glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA) were randomly assigned to receive trabedersen at doses of 10 or 80 µM or standard chemotherapy (temozolomide or procarbazine/lomustine/vincristine). Primary endpoint was 6-month tumor control rate, and secondary endpoints included response at further timepoints, survival, and safety. Six-month tumor control rates were not significantly different in the entire study population (AA and GBM). Prespecified AA subgroup analysis showed a significant benefit regarding the 14-month tumor control rate for 10 µM trabedersen vs chemotherapy (p= .0032). The 2-year survival rate had a trend for superiority for 10 µM trabedersen vs chemotherapy (p = .10). Median survival for 10 µM trabedersen was 39.1 months compared with 35.2 months for 80 µM trabedersen and 21.7 months for chemotherapy (not significant). In GBM patients, response and survival results were comparable among the 3 arms. Exploratory analysis on GBM patients aged ≤55 years with Karnofsky performance status >80% at baseline indicated a 3-fold survival at 2 and 3 years for 10 µM trabedersen vs chemotherapy. The frequency of patients with related or possibly drug-related adverse events was higher with standard chemotherapy (64%) than with 80 µM trabedersen (43%) and 10 µM trabedersen (27%). Superior efficacy and safety for 10 µM trabedersen over 80 µM trabedersen and chemotherapy and positive risk–benefit assessment suggest it as the optimal dose for further clinical development in high-grade glioma.