Diagnostic accuracy of community optometrists for age-related macular degeneration using colour fundus photographs: A pilot evaluation

PURPOSE

The accurate diagnosis of age-related macular degeneration (AMD) represents an important step in delaying and preventing vision loss and achieving optimal patient care. Therefore, this pilot study aimed to estimate the diagnostic accuracy of community optometrists for identifying AMD using colour fundus photographs (CFPs) to support sample size calculations for subsequent definitive studies.

METHODS

Five practising community optometrists were invited to classify a total of 1023 CFPs for the (1) presence of AMD, and, if applicable, (2) stage of AMD (early/intermediate/late geographic atrophy/late neovascular AMD). Diagnosis by referral centre clinicians formed the reference standard. Diagnostic accuracy was assessed by the area under the receiver operating characteristic curve (aROC). Sensitivity, specificity, positive and negative predictive values were also calculated.

RESULTS

Of the 1023 CFPs included in the study, 226 images were of AMD and 797 images were of other ocular conditions or no abnormal findings. Participating community optometrists had a mean (SD) age of 30.2 (8.9) years, 60.0% (3/5) were female and the mean number of years practising in primary eye care was 5.4 (5.4) years. Community optometrists demonstrated excellent performance for diagnosing AMD, with an aROC of 0.86 (95% CI 0.83 to 0.89), sensitivity of 84.5% (95% CI 79.1 to 89.0) and specificity of 88.0% (95% CI 85.5 to 90.1). The aROC (95% CI) for diagnosing early, intermediate, late geographic atrophy and late neovascular AMD was 0.82 (0.73 to 0.91), 0.76 (0.72 to 0.81), 0.69 (0.49 to 0.90) and 0.55 (0.34 to 0.75), respectively.

CONCLUSIONS

These results justify the need for an appropriately powered definitive study to assess community clinicians' diagnostic accuracy for AMD.

Drusen-aware model for age-related macular degeneration recognition

INTRODUCTION

The purpose of this study was to build an automated age-related macular degeneration (AMD) colour fundus photography (CFP) recognition method that incorporates confounders (other ocular diseases) and normal age-related changes by using drusen masks for spatial feature supervision.

METHODS

A range of clinical sources were used to acquire 7588 CFPs. Contrast limited adaptive histogram equalisation was used for pre-processing. ResNet50 was used as the backbone network, and a spatial attention block was added to integrate prior knowledge of drusen features into the backbone. The evaluation metrics used were sensitivity, specificity and F1 score, which is the harmonic mean of precision and recall (sensitivity) and area under the receiver-operating characteristic (AUC). Fivefold cross-validation was performed, and the results compared with four other methods.

RESULTS

Excellent discrimination results were obtained with the algorithm. On the public dataset (n = 6565), the proposed method achieved a mean (SD) sensitivity of 0.54 (0.09), specificity of 0.99 (0.00), F1 score of 0.62 (0.06) and AUC of 0.92 (0.02). On the private dataset (n = 1023), the proposed method achieved a sensitivity of 0.92 (0.02), specificity of 0.98 (0.01), F1 score of 0.92 (0.01) and AUC of 0.98 (0.01).

CONCLUSION

The proposed drusen-aware model outperformed baseline and other vessel feature-based methods in F1 and AUC on the AMD/normal CFP classification task and achieved comparable results on datasets that included other diseases that often confound classification. The method also improved results when a five-category grading protocol was used, thereby reflecting discriminative ability of the algorithm within a real-life clinical setting.

Optometrists' attitudes toward using OCT angiography lag behind other retinal imaging types

PURPOSE

While optometrists' attitudes toward established retinal imaging types are generally positive, they are unknown for optical coherence tomography angiography (OCTA). We performed a cross-sectional survey to estimate attitudes toward OCTA and identify clinician and/or practice characteristics that influence them.

METHODS

A paper-based survey was mailed to 252 randomly selected optometrists in Australia. Five-point Likert-scale items from a previous survey assessing attitudes toward new technology were included to probe respondent characteristics and attitudes toward retinal imaging. Performance expectancy attitudes toward OCTA were elicited by the statement 'I believe OCTA is useful in daily practice'. Mean scores out of five (mean [SD]) were rounded and mapped to appropriate descriptive statements.

RESULTS

The response rate was 47% (118/252). The mean (SD) age of respondents was 44.0 (13.8) years and 50.8% (60/118) were female. Optometrists had 19.9 (14.0) years of clinical experience and 66.9% (79/118) worked at independent practices. In total, 8.5% (10/118) of respondents used OCTA to provide clinical care. Optometrists agreed that optical coherence tomography (OCT), colour fundus imaging, ultra-wide field imaging and fundus autofluorescence (mean scores 3.6-4.7 out of 5) were useful in daily practice but felt neutral about whether OCTA was useful (3.4 [0.8]). Optometrists believed that OCTA was less enjoyable to use (p < 0.0001), less endorsed by peers (p < 0.0001) and felt less confident that they had the knowledge to interpret OCTA (p < 0.0001) compared to other retinal imaging types.

CONCLUSIONS

Optometrists are undecided on whether OCTA is useful in daily practice and had lower expectations that using OCTA would confer job performance benefits compared to other retinal imaging types. Further work is needed to advocate the benefits of using OCTA across the profession.

A steamed broccoli sprout diet preparation that reduces colitis via the gut microbiota

Sulforaphane is a bioactive metabolite with anti-inflammatory activity and is derived from the glucosinolate glucoraphanin, which is highly abundant in broccoli sprouts. However, due to its inherent instability its use as a therapeutic against inflammatory diseases has been limited. There are few studies to investigate a whole food approach to increase sulforaphane levels with therapeutic effect and reduce inflammation. In the current study, using a mouse model of inflammatory bowel disease, we investigated the ability of steamed broccoli sprouts to ameliorate colitis and the role of the gut microbiota in mediating any effects. We observed that despite inactivation of the plant myrosinase enzyme responsible for the generation of sulforaphane via steaming, measurable levels of sulforaphane were detectable in the colon tissue and feces of mice after ingestion of steamed broccoli sprouts. In addition, this preparation of broccoli sprouts was also capable of reducing chemically-induced colitis. This protective effect was dependent on the presence of an intact microbiota, highlighting an important role for the gut microbiota in the metabolism of cruciferous vegetables to generate bioactive metabolites and promote their anti-inflammatory effects.

Diagnostic accuracy of OCTA and OCT for myopic choroidal neovascularisation: a systematic review and meta-analysis

BACKGROUND/OBJECTIVES

The purpose of this project was to systematically review and meta-analyse studies assessing the diagnostic accuracy of optical coherence tomography angiography (OCTA) and optical coherence tomography (OCT) for myopic choroidal neovascularisation (mCNV). Fluorescein angiography (FA) was accepted as the reference standard.

METHODS

PUBMED and EMBASE were searched from inception to March 2021 for studies evaluating the test accuracy of OCTA and/or OCT for diagnosing mCNV. The Preferred Reporting Items for Systematic Reviews and Meta-analyses of Diagnostic Test Accuracy Studies guideline was followed, and the Grading of Recommendations, Assessment, Development and Evaluation approach was used to frame clinical recommendations. Pooled estimates of test accuracy were obtained using a bivariate model.

RESULTS

Of 410 studies assessed for eligibility, 3 studies were identified that compared OCTA to FA and 3 studies were identified that compared spectral domain (SD) OCT to FA. All studies had at least one major methodological flaw leading to an overall high risk of bias. On meta-analysis, the pooled sensitivity of OCTA was 0.89 (95% CI 0.78-0.94) and pooled specificity was 0.93 (95% CI 0.79-0.98). The pooled sensitivity of SD-OCT was 0.99 (95% CI 0.91-1.00). Due to uncertainty in individual studies, the pooled specificity of SD-OCT could not be estimated.

CONCLUSIONS

OCTA can reliably diagnose mCNV in clinically suspected patients, however, SD-OCT may not reliably establish a positive diagnosis of mCNV. Future large, prospective studies with improvements in conduct and reporting are needed to strengthen these clinical recommendations.

Attitudes of optometrists towards artificial intelligence for the diagnosis of retinal disease: A cross-sectional mail-out survey

PURPOSE

Artificial intelligence (AI)-based systems have demonstrated great potential in improving the diagnostic accuracy of retinal disease but are yet to achieve widespread acceptance in routine clinical practice. Clinician attitudes are known to influence implementation. Therefore, this study aimed to identify optometrists' attitudes towards the use of AI to assist in diagnosing retinal disease.

METHODS

A paper-based survey was designed to assess general attitudes towards AI in diagnosing retinal disease and motivators/barriers for future use. Two clinical scenarios for using AI were evaluated: (1) at the point of care to obtain a diagnostic recommendation, versus (2) after the consultation to provide a second opinion. Relationships between participant characteristics and attitudes towards AI were explored. The survey was mailed to 252 randomly selected practising optometrists across Australia, with repeat mail-outs to non-respondents.

RESULTS

The response rate was 53% (133/252). Respondents' mean (SD) age was 42.7 (13.3) years, and 44.4% (59/133) identified as female, whilst 1.5% (2/133) identified as gender diverse. The mean number of years practising in primary eye care was 18.8 (13.2) years with 64.7% (86/133) working in an independently owned practice. On average, responding optometrists reported positive attitudes (mean score 4.0 out of 5, SD 0.8) towards using AI as a tool to aid the diagnosis of retinal disease, and would be more likely to use AI if it is proven to increase patient access to healthcare (mean score 4.4 out of 5, SD 0.6). Furthermore, optometrists expressed a statistically significant preference for using AI after the consultation to provide a second opinion rather than during the consultation, at the point-of-care (+0.12, p = 0.01).

CONCLUSIONS

Optometrists have positive attitudes towards the future use of AI as an aid to diagnose retinal disease. Understanding clinician attitudes and preferences for using AI may help maximise its clinical potential and ensure its successful translation into practice.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

A Specific Broccoli Sprout Preparation Reduces Chemically-Induced Colitis Via Gut Microbiota

Objectives

Sulforaphane is a bioactive metabolite with anti-inflammatory activity that is derived from glucosinolates, which are highly abundant in cruciferous vegetables including broccoli sprouts. There have been limited studies to investigate a whole foods approach to increase sulforaphane levels with therapeutic effect and reduce inflammation. In the current study, using a mouse model of inflammatory bowel disease, we aimed to investigate the ability of steamed broccoli sprouts to ameliorate colitis and the role of the microbiota in mediating any effects.

Methods

C57BL/6J male mice were fed base diet or 5% steamed broccoli sprout diet for 2 weeks prior to induction of colitis with 2–3% DSS (5–7 days) and kept on their respective diets until sacrifice. Body weight and disease activity index scores were recorded daily, and histological assessment was performed on H&E sections of colon. Urine, feces, blood, and GI tract tissues and intestinal content were collected for LC-MS/MS quantification of sulforaphane and glucoraphanin. The 16S rRNA sequencing was performed to analyze gut microbiome. Germ-free mice were fed base diet or 5% steamed broccoli sprout diet for 2 weeks followed by treatment with 5 days of DSS to determine the role of gut microbiota in mediating the anti-inflammatory effects of the steamed broccoli sprout diet.

Results

We observed that despite inactivation of the plant myrosinase enzyme responsible for the generation of sulforaphane via steaming, measurable levels of sulforaphane were detectable in the colon tissue and feces of mice after ingestion of steamed broccoli sprouts. In addition, this preparation of broccoli sprouts was also capable of reducing chemically-induced colitis. This protective effect was dependent on the presence of an intact gut microbiota, highlighting an important role for the microbiota in the metabolism of cruciferous vegetables to generate bioactive metabolites and promote their anti-inflammatory effects.

Conclusions

Altogether, these results suggest that the incorporation of a steamed broccoli sprouts diet is a viable dietary intervention to complement current medical therapies for patients with inflammatory bowel disease.

Funding Sources

This work was supported by USDA-NIFA-AFRI Foundational Program [Grant No. 2018–67,017-27,520].

Clinical decision support in primary care for better diagnosis and management of retinal disease

Misdiagnosis of retinal disease is a common problem in primary care that can lead to irreversible vision loss and false-positive referrals, resulting in inappropriate use of health services. Clinical decision support systems describe tools that leverage information technology to provide timely recommendations that assist clinicians in the decisions they make about the care of a patient. They, therefore, have the potential to reduce the rate of misdiagnosis by promoting evidence-based medicine and more effective and efficient healthcare. This narrative review aims to support primary care practitioners in better understanding the current and emerging capacity of clinical decision support systems in eye care. Different types of clinical decision support systems are discussed, using current examples and evidence from the available literature to demonstrate how they may improve diagnostic effectiveness and aid the management of retinal disease. Comments are made on the future directions of clinical decision support in primary eye care and the potential applications of artificial intelligence.

The nature effect in motion: visual exposure to environmental scenes impacts cognitive load and human gait kinematics

Prolonged exposure to urban environments requires higher cognitive processing resources than exposure to nature environments, even if only visual cues are available. Here, we explored the moment-to-moment impact of environment type on visual cognitive processing load, measuring gait kinematics and reaction times. In Experiment 1, participants (n = 20) walked toward nature and urban images projected in front of them, one image per walk, and rated each image for visual discomfort. Gait speed and step length decreased for exposure to urban as compared with nature scenes in line with gait changes observed during verbal cognitive load tasks. We teased apart factors that might contribute to cognitive load: image statistics and visual discomfort. Gait changes correlated with subjective ratings of visual discomfort and their interaction with the environment but not with low-level image statistics. In Experiment 2, participants (n = 45) performed a classic shape discrimination task with the same environmental scenes serving as task-irrelevant distractors. Shape discrimination was slower when urban scenes were presented, suggesting that it is harder to disengage attention from urban than from nature scenes. This provides converging evidence that increased cognitive demands posed by exposure to urban scenes can be measured with gait kinematics and reaction times even for short exposure times.

SAT0445 TRABECULAR BONE SCORE IMPROVES FRACTURE RISK STRATIFICATION IN PATIENTS WITH REDUCED BONE MINERAL DENSITY

Background:

Trabecular bone score (TBS) is a textural index of bone microarchitecture and has been found to be related to 3D bone structure. A number of cohort studies have demonstrated the value of TBS as an independent fracture risk in clinical trials. Yet, very little is known about the performance and clinical value of TBS in real life practice.

Objectives:

To investigate the sensitivity and specificity of TBS in identifying prevalent fractures when compared with bone mineral density (BMD) measured by DXA. To evaluate the added value of TBS in fracture risk prediction above that obtained from DXA.

Methods:

Consecutive patients aged ≥ 18 with BMI 15-37 attnding a DXA plus TBS assessment were considered eligible. Sensitivity, specificity, and area under the curve (AUC) for prevalent major osteoporotic fracture (MOF) and clinical vertebral fractures (VF) were assessed for the following parameters: BMD lowest T-score ≤-2.5 (neck of femur, total hip, or spine), TBS T-score ≤-2.5, and either TBS or BMD T-score ≤-2.5. BMD categories (normal, osteopenia, and osteoporosis) were stratified by TBS T-score: normal (T-score ≥-1), moderate (-1≥T-score≥-2.5), and degraded TBS (T-score ≤-2.5) resulting in 9 risk groups. Odds ratios were calculated for all risk categories and fracture prevalence was compared between the best and worst TBS strata at each BMD level using chi-square test.

Results:

540 patients (87% females, 68.1 ± 11.6 years) were included. 238 (44%) had MOF including 81 (15%) clinical VF. For MOF, BMD had higher sensitivity (49.6% vs 30.7%), lower specificity (68.2% vs 82.1%), and similar AUC (0.59 vs 0.56) versus TBS. For VF, the sensitivity, specificity and AUC for BMD were 60%, 64%, and 0.62 respectively versus 42%, 79.7%, and 0.61 for TBS. Combining TBS and BMD (either T-score ≤ -2.5) increased the sensitivity to 63% for MOF and 75.3% for VF without affecting AUC (0.6 and 0.64 respectively). Patients with osteoporosis and degraded TBS had the highest OR of 2.65 for MOF and 3.8 for VF. The fracture risk increased at the same level of BMD when TBS was degraded. Numerically, the risk of MOF increased steadily from strata 1 to 9 and was statistically significant for osteoporosis with degraded TBS and osteoporosis with moderate TBS. When both TBS and BMD were normal, the risk of fracture was significantly reduced. In the osteopenia and osteoporosis BMD categories, patients with degraded TBS had significantly higher prevalence of fracture compared to those with normal TBS in the same BMD category.

Conclusion:

Fracture risk stratification can be improved when TBS is added to BMD. The sensitivity of predicting fracture may also improve when TBS and BMD are combined. Patients with both normal TBS and BMD have the lowest fracture risk, whereas those with degraded TBS and osteoporosis have the highest risk of fracture and should be targeted for early or more aggressive treatment.

References:

[1]Hans D et al. J Bone Miner Res. 2011;26(11).

[2]McCloskey EV et al. Calcif Tissue Int. 2015;96(6).

Table 1.

Prevalence and risk of MOF and VF according to BMD stratified by TBS T-score

Patients within categoryNumber of MOFOR for MOFNumber of VFOR for VFNormal BMD & TBS497 (14.3%)0.19(0.08-0.43)*00.83(0.80-.87)*Normal BMD moderate TBS195 (26.3%)0.44(0.16-1.24)2 (10.5%)0.66(0.15-2.9)Normal BMD degraded TBS72 (28.6%)0.50(0.1-2.6)1 (14.3%)0.94(0.11-7.9)Osteopenia normal TBS9633 (34.4%)0.61(0.39-0.97)7 (7.3%)0.39(0.18-0.88)*Osteopenia moderate TBS9843 (43.9%)0.99(0.64-1.54)11 (11.2%)0.67(0.34-1.32)Osteopenia degraded TBS5730 (52.6%)1.47(.085-2.55)11 (19.3%)1.41(0.7-2.86)Osteoporosis normal TBS3918 (46.2%)1.1(0.57-2.1)6 (15.4%)1(0.42-2.6)Osteoporosis moderate TBS11259 (52.7%)1.55(1.02-2.35)*21 (18.8%)1.42(0.82-2.45)Osteoporosis degraded TBS6341 (65.1%)2.65(1.53-4.59)*22 (34.9%)3.8(2.12-6.83)*Total54023881

Acknowledgments:

Bone density team, Robert Jones and Agnes Hunt Orthopaedic Hospital

Disclosure of Interests:

None declared

SAT0479 IMPACT OF TRABECULAR BONE SCORE ON INTERVENTION THRESHOLD FOR BONE SPARING THERAPY IN PATIENTS REFERRED FOR BONE MINERAL DENSITY

Background:

Trabecular bone score (TBS) is an index of skeletal quality that has been validated as an independent risk factor for fracture and incorporated into fracture risk assessment (FRAX). TBS provides information on bone microarchitecture not captured from standard bone mineral density (BMD) measured by dual energy X-ray absorptiometry (DXA). Nonetheless, the clinical implications of using TBS in routine practice are not yet fully understood and warrant further evaluation.

Objectives:

To determine whether lumbar TBS can have an impact on clinician’s treatment threshold derived from DXA and clinical risk factors: does the addition of TBS to DXA measurements make the clinician more or less likely to recommend bone sparing therapy?

Methods:

A cross-sectional study at a tertiary metabolic bone centre in the West Midlands region of England. Three expert metabolic bone physicians, two rheumatologists and one elderly care, assessed consecutive patients referred for a DXA scan ± clinic review and provided treatment recommendations with and without TBS. Patients ≥ 18 years old with BMI of 15-37 who were not on bone sparing therapy were considered eligible. TBS was defined according to T-score as normal (T-score ≥ -1), moderate (-1 > T-score ≥ -2.5) or degraded (T-score ≤ -2.5). TBS groups were stratified by BMD T-scores (normal, osteopenia, or osteoporosis) using minimum T-score of total hip, femoral neck, and spine to identify categories in which TBS may be of more clinical use. The main outcome measure was the proportion of change in clinician’s treatment threshold between BMD alone and BMD plus TBS. The difference was assessed for significance using Chi-square test. Additionally, the change in UK National Osteoporosis Guideline Group (NOGG) threshold was also assessed using TBS-adjusted FRAX scores. Correlations between BMD-TBS strata and the change in intervention threshold (yes/no) were carried out using Spearman test.

Results:

540 patients were analysed. The inclusion of TBS resulted in 8.2% change in clinician’s treatment threshold (p <0.001) shifting the outcome 6.5 % for and 1.7 % against treatment. More than half of the cases in which the clinical decision was changed were for patients with osteopenia and degraded TBS (significant correlation; P <0.001). NOGG intervention threshold was changed in 7.4% of the cases (P<0.001); 6.1% for and 1.3% against treatment. 37.5% of NOGG changed outcome was related to osteopenia with degraded TBS (p<0.001). Kappa agreement between the clinician and NOGG was fair at 0.42 (p<0.001).

Conclusion:

These results demonstrate that using TBS in routine clinical practice is most likely to impact treatment decision in patients with osteopenia who have compromised bone microarchitecture. Incorporating TBS in routine DXA scans may lead to a net increase in bone protective therapy of approximately 5%. It is unknown whether adopting such an approach universally can reduce future fracture risk, and prospective studies are needed to address this question.

References:

[1]Hans D et al. J Bone Miner Res. 2011;26(11):2762-9.

[2]McCloskey EV et al. Calcif Tissue Int. 2015;96(6):500-9.

Table 1.

Demographic and baseline characteristics (n = 540)

Female470 (87%)Age (years)68.1 ± 11.6Body mass index (BMI)26.2 ± 4.6Femoral neck T-score-1.80 ± 1.04Total hip T-score-1.32 ± 1.07Lumbar spine T-score-1.37 ± 1.42Lumbar spine TBS1.32 ± 0.13Major osteoporotic fractures238 (44%)Spinal fractures81 (15%)FRAX major osteoporotic fracture14.43 ± 9.03FRAX hip fracture4.60 ± 6.20TBS-adjusted FRAX major osteoporotic fracture13.82 ± 8.80TBS-adjusted FRAX hip fracture4.45 ± 5.73Figure 1.

Distribution of changed clinical treatment threshold in normal, moderate, and degraded TBS according to BMD T-score

Acknowledgments:

Bone density unit &Rheumatology team, Robert Jones and Agnes Hunt Orthopaedic Hospital

Disclosure of Interests:

None declared

Gut Microbiota Modulate CD8 T Cell Responses to Influence Colitis-Associated Tumorigenesis

There is increasing evidence that gut microbiome perturbations, also known as dysbiosis, can influence colorectal cancer development. To understand the mechanisms by which the gut microbiome modulates cancer susceptibility, we examine two wild-type mouse colonies with distinct gut microbial communities that develop significantly different tumor numbers using a mouse model of inflammation-associated tumorigenesis. We demonstrate that adaptive immune cells contribute to the different tumor susceptibilities associated with the two microbial communities. Mice that develop more tumors have increased colon lamina propria CD8+ IFNγ+ T cells before tumorigenesis but reduced CD8+ IFNγ+ T cells in tumors and adjacent tissues compared with mice that develop fewer tumors. Notably, intratumoral T cells in mice that develop more tumors exhibit increased exhaustion. Thus, these studies suggest that microbial dysbiosis can contribute to colon tumor susceptibility by hyperstimulating CD8 T cells to promote chronic inflammation and early T cell exhaustion, which can reduce anti-tumor immunity.

The gut microbiome can contribute to colon tumor susceptibility via an effect on CD8+ T cell responses

There is increasing evidence that colorectal cancer patients have altered gut microbiomes compared to healthy controls, but the mechanisms by which the microbiota contribute to colon carcinogenesis remain to be fully elucidated. Using the azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model of inflammation-associated colon tumorigenesis, our lab discovered two colonies of specific pathogen free (SPF) C57BL/6J wild type (WT) mice housed in the same mouse room that develop differential tumor burdens. Mice from the “WT1” colony developed five tumors on average while mice from the “WT2” colony developed 15 tumors on average. The increased tumor susceptibility in WT2 mice can be directly attributed to the gut microbiome as germ-free (GF) mice colonized with WT2 bacteria developed more tumors compared to that of GF mice colonized with WT1 bacteria. Additionally, 16S rRNA gene sequencing of fecal bacteria from WT1 and WT2 mice revealed distinct microbiomes with certain bacteria consistently associated with high or low tumor numbers. Furthermore, naïve and acutely-inflamed (day 10 of AOM/DSS) WT2 mice have increased colon lamina propria CD8+ IFNγ+ T cells compared to WT1 mice as measured by flow cytometry. However, in tumor-bearing WT2 mice, there was decreased tumor-infiltrating CD8+ T cells with reduced IFNγ production, possibly due to T cell exhaustion. GF Rag1−/− mice as well as SPF CD8−/− mice inoculated with WT2 gut microbiota developed fewer tumors than SPF WT2 mice, suggesting that the WT2 gut microbiome increases tumor susceptibility, in part, through an effect on CD8+ T cells. Altogether, our data reveal a potential novel role of microbiota in altering colon CD8+ T cell function that ultimately impacts colon cancer risk.

Abstract P1-12-07: Prospective 36-month follow-up to determine changes in body mass index and weight among Chinese breast cancer survivors

Background:Anticancer treatment for breast cancer has been associated with weight gain but such observation has mainly been reported in western patients. More recent data in Asian patients have inconsistent findings. Factors including socio-demographic, clinical and lifestyle may be associated with post-diagnosis weight gain. In this prospective cohort study of women with breast cancer, the objectives were to determine the body mass index (BMI) and weight changes over 36 months after initial diagnosis and the factors associated with such changes.

Methods: Chinese women with newly diagnosed early-stage breast cancer were recruited. Individual woman had her weight measured at breast cancer diagnosis (W0), at study entry (W1) and at 36-month follow-up (W2). Body height was measured at W0. We evaluated change in weight and body mass index (BMI) before and after breast cancer diagnosis.Socio-demographic, clinical and lifestyle factors were assessed to identify potential associated factors with weight changes.

Results: A total of 1133 women with breast cancer had detailed weight measurements at the 3 time-points of assessment. The mean age at diagnosis was 52 years. Fifty-four percent were premenopausal at W1. The proportion of patients with stage 0-I, II and III diseases were 35%, 46% and 19%, respectively.

The proportions of patients who were overweight and obese at the three assessment time-points were 21.2% and 28.5% at W0, 19.7% and 26.6% at W1, and 21.7% and 30.9% at W2 assessment, respectively. When compared to W0, the proportions of women who gained weight within 2-5kg at W1 and W2 were 2.4% and 20.6% respectively, that with weight gain of &gt;5kg at W1 and W2 were 0.5% and 10.0% respectively; 6.1% and 19.6% of women had weight loss &gt;2kg at W1 and W2 respectively.

Compared to W0, the median value of weight change was -0.5 kg (range: -11.4, 18.3) at W1 and 0.6 kg (range: -19.6, 20.5) at W2. On multivariate analysis, only BMI at diagnosis were significantly associated with weight change betweenassessments at diagnosis and W2; the median (range) for weight changes for women who were underweight, normal, overweight and obese were respectively 0.9 (-4.8, 7.6), 0.6 (-13.2, 20.5), 0.5 (-11.5, 13.0) and 0.5 (-19.6, 12.6) kg, p &lt;0.001.

Conclusions: In this prospective study of Chinese women with a history of breast cancer who were followed-up over a 36-months' period, the proportions of women with overweight and obese statuses were relatively stable; weight gain was uncommon among Hong Kong women with breast cancer during the same period. These findings are in contrast with studies conducted in the West, where weight gains were more commonly reported.

Funding: World Cancer Research Fund International (Grant Number WCRF 2010/249 and WCRF 2014/1197)

Citation Format: Yeo W, Lei YY, Cheng AC, Kwok CC, Cheung KL, Lee R, Lee IC, He YQ, Ho S. Prospective 36-month follow-up to determine changes in body mass index and weight among Chinese breast cancer survivors [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-12-07.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Critical Role of Central Facilitation in the Glottic Closure Reflex

The sphincteric function of the larynx, essential to lower airway protection, is most efficiently achieved through strong reflex adduction by both vocal cords. We hypothesize that central facilitation is an essential component of a bilateral adductor reflex and that its disturbance could result in weakened sphincteric closure. Six adult 50-kg pigs underwent evoked response laryngeal electromyography under 0.5 to 1.0 minimal alveolar concentration (MAC) isoflurane anesthesia. The internal branch of the superior laryngeal nerve was stimulated through bipolar platinum-iridium electrodes, and recording electrodes were positioned in the ipsilateral and contralateral thyroarytenoid muscles. Consistent threshold responses were obtained ipsilaterally from 0.5 to 1.0 MAC anesthesia. However, the contralateral reflex responses approached 0% in successive trials as anesthetic levels approached 1.0 MAC. Alteration of central facilitation by deepening anesthesia abolishes the crossed adductor reflex, predisposing to a weakened glottic closure response. A precise understanding of this effect may improve the prevention of aspiration in patients emerging from prolonged sedation or under heavy psychotropic control.

Bioengineering bacteriophages to enhance the sensitivity of phage amplification-based paper fluidic detection of bacteria

Bacteriophage (phage) amplification is an attractive method for the detection of bacteria due to a narrow phage-host specificity, short amplification times, and the phages' ability to differentiate between viable and non-viable bacterial cells. The next step in phage-based bacteria detection is leveraging bioengineered phages to create low-cost, rapid, and easy-to-use detection platforms such as lateral flow assays. Our work establishes the proof-of-concept for the use of bioengineered T7 phage strains to increase the sensitivity of phage amplification-based lateral flow assays. We have demonstrated a greater than 10-fold increase in sensitivity using a phage-based protein reporter, maltose-binding protein, over the detection of replicated T7 phage viron itself, and a greater then 100-fold increase in sensitivity using a phage-based enzymatic reporter, alkaline phosphatase. This increase in sensitivity enabled us to detect 10(3)CFU/mL of Escherichia coli in broth after 7h, and by adding a filter concentration step, the ability to detect a regulatory relevant E. coli concentration of 100CFU/100mL in inoculated river water after 9h, where the current standard requires days for results. The combination of the paper fluidic format with phage-based detection provides a platform for the development of novel diagnostics that are sensitive, rapid, and easy to use.