0092 A Daytime Nap Restores Hippocampal Function and Improves Declarative Learning

Introduction

Daytime naps have been shown to improve learning outcomes. One theory underlying enhanced encoding following a nap is via the synaptic downscaling of neurons potentiated during wake - a process facilitated by slow oscillations. In this study, we sought to investigate neural mechanisms underlying enhanced encoding following a nap compared to a waking period using a combination of PSG and fMRI methods.

Methods

40 healthy undergraduates (M=23.3y, SD=2.96y; 10 males) who slept normally the previous night encoded word pair lists across 2 runs in an MRI scanner at 1PM and 4.30PM. In between encoding sessions, participants either stayed awake and watched a documentary (Wake group; N=20), or napped for 90-min while undergoing polysomnography (Nap group; N=20). Approximately 40min after each encoding session, memory of these word lists were assessed in a cued-recall fashion. Performance in each session was measured by percentage of correct responses.

Results

There were no baseline differences in encoding performance. However, a Session x Group interaction effect (p<0.001) was observed whereby performance significantly improved only in the Nap group in the second encoding session (Nap:20±19% vs. Wake:-1±13%). Concurrent to this, fMRI analyses revealed a Session x Run x Group interaction effect in the hippocampus (p=0.002) whereby hippocampal activation during encoding of the word lists increased only in the Nap group. In addition, although there was no association between degree of performance improvement in the nap group with duration of sleep or the various sleep stages (N1,N2,N3,REM), spindle count (12-15Hz) in the Nap group correlated significantly with both performance improvement (rs=0.46) and increase in hippocampal activation (rs=0.46).

Conclusion

These results confirm the benefit of a nap on encoding processes. Hippocampal activation also increased following the nap, which could indicate renewed hippocampal capacity to store new information. While we hypothesized that slow wave sleep would aid in this transfer, we instead found a relationship between spindle count and both degree of performance improvement and increase in hippocampal activation. The interplay between NREM sleep oscillations, hippocampal downscaling and encoding performance could be more complex than originally thought.

Support

National Medical Research Council, Singapore (NMRC/STaR/015/2013) and the Far East Organization.

0519 Mindfulness Based Therapy for Insomnia Improves Objective Markers of Sleep in the Elderly: Preliminary Data from the Mindfulness Sleep Therapy (MIST) Study

Introduction

Mindfulness-based treatment for insomnia (MBTI) is a viable intervention for improving poor sleep. We report preliminary data from an ongoing pre-registered, randomized controlled trial which investigates the effect of MBTI on elderly adults.

Methods

Participants above 50 years old with PSQI ≥ 5 were recruited and randomised into either MBTI or an active control group (Sleep hygiene education and exercise program, SHEEP) in sequential cohorts with about 20 participants per cohort (10 per group). Before and after the intervention, 1 night of portable polysomnography (PSG) and 1 week of actigraphy (ACT) and sleep diary (DIARY) data were collected. We report the ACT and DIARY results of the first 3 cohorts (n = 46, male = 23, mean age = 62.3, std = 6.3) and PSG data of the first 2 cohorts (n = 29, male = 12, mean age = 62.5, std = 5.7). Time in bed (TIB), total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency (SE) were analysed with mixed-model repeated-measures ANOVA.

Results

We observed increases in TIBDIARY (F1,44 = 5.151, p < .05) and SEDIARY (F1,44 = 22.633, p < .0001), and significant reductions in SOLDIARY (F1,44 = 7.031, p < .05) and WASODIARY (F1,39 = 7.411, p < .05). In the actigraphy data, we found a significant interaction in SOLACT (F1,39 = 4.273, p < .05) with an increase in SHEEP SOLACT (t18= 2.36, p < .05). Significant reductions were also observed in WASOACT (F1,44 = 16.459, p < .0001) Finally, we observed a reduction in SOLPSG (F1,26 = 5.037, p <. 05). All other tests were non-significant.

Conclusion

Preliminary results suggest that both interventions lead to improvements in sleep with more pronounced effects in subjective sleep reports. Objective sleep data suggest that improvements in sleep is a result of improved sleep quality and not simply extending sleep opportunity. These preliminary data shows that MBTI may be a promising intervention for elderly individuals with sleep difficulties.

Support

This study was supported by an award from the 7th grant call of the Singapore Millennium Foundation Research Grant Programme

Distribution and seasonal fluctuations of Ae. aegypti and Ae. albopictus larval and pupae in residential areas in an urban landscape

Dengue, a vector-borne disease spread by Aedes mosquitoes, is a global threat. In the absence of an efficacious dengue vaccine, vector control is the key intervention tool in Singapore. A good understanding of vector habitats is essential to formulate operational strategies. We examined the distribution, long-term trend and seasonality of Aedes data collected during regulatory inspections in residences and public areas from 2008 to 2017. We also studied the seasonality of climate factors to understand their influence on the detection of Aedes-positive containers. The most frequently reported Aedes-positive containers were domestic containers, drains, discarded receptacles, ornamental containers, flower pot plates/trays, plants, gully traps, canvas/plastic sheet, bins, ground puddle, inspection chambers and roof tops/gutters. We found more Ae. aegypti and Ae. albopictus-positive containers per inspection in residences and public areas, respectively. The seasonality of Ae. aegypti-positive containers in residences and public areas coincided with that of mean temperature. However, the seasonality of Ae. albopictus-positive containers lagged by one month compared to that of mean temperature. Our study demonstrates the seasonal fluctuations of Aedes-positive containers in an urban environment. Understanding the distribution and seasonality of Aedes breeding helps to facilitate resource planning and community awareness to moderate dengue transmission.

The effects of climate variability and seasonal influence on diarrhoeal disease in the tropical city-state of Singapore - A time-series analysis

BACKGROUND

Diarrhoeal disease is common and imposes substantial health and economic burdens across the globe, especially in the African and Southeast Asian regions. Besides causing high mortality and morbidity, diarrhoeal disease has also been associated with growth and cognitive shortfalls in children in low-resource settings. Extreme weather events brought about by climate change may increase diarrhoeal disease and impact vulnerable populations in countries regardless of levels of development. We examined the seasonal and climatic influences of acute diarrhoeal disease reports in Singapore, a city-state located in Southeast Asia.

METHODS

We used a time-series analysis, adjusting for time-varying potential confounders in a negative binomial regression model and fitting fractional polynomials to investigate the relationship between climatic factors (temperature, relative humidity and rainfall) and reported diarrhoeal disease.

RESULTS

We included 1,798,198 reports of diarrhoeal disease from 2005 to 2018. We observed annual trimodal peaks in the number of reports. Every 10% increase in relative humidity in the present week was positively associated with an increase in reports one week later [Incidence Rate Ratio (IRR): 1.030, 95% CI 1.004-1.057] and negatively associated with a decrease in reports six weeks later (IRR: 0.979, 95% CI 0.961-0.997). We observed effect modification of relative humidity on the risk of diarrhoeal disease in the first calendar quarter (January to March). There was weak evidence of a delayed effect of ambient air temperature on reports of diarrhoeal disease one week later (IRR: 1.013, 95% CI 0.998-1.027). No threshold effects of climatic factors were observed. Each week of school holidays was associated with a 14.4% reduction in diarrhoeal disease reports (IRR: 0.856, 95% CI: 0.840 to 0.871). Public holidays were associated with a reduction in reports in the same week and an increase a week later.

CONCLUSIONS

Diarrhoeal disease is highly seasonal and is associated with climate variability. Food safety and primary healthcare resource mitigation could be timed in anticipation of seasonal and climate driven increases in disease reports.

A 24-month cost and outcome analysis comparing traditional fronto-orbital advancment and remodeling with endoscopic strip craniectomy and molding helmet in the management of unicoronal craniosynostosis: A retrospective bi-institutional review

Introduction

Endoscopic strip craniectomy with helmeting (ESCH) has been shown to be a safe and efficacious alternative to fronto-orbital remodeling (FOR) for selected children with craniosynostosis. In addition to clinical factors, there may be economic benefits from the use of ESCH instead of FOR.

Methods

A retrospective review of 23 patients with nonsyndromic unicoronal craniosynostosis (UCS) treated with FOR was carried out at Great Ormond Street Hospital (GOSH) for Children in London, UK. Secondary data were used for the ESCH cohort from a paper published by Jimenez and Barone (2013). Data were collected on surgical time, transfusion rates, length of hospital stay, adverse event rates, reintervention rates, and overall costs. Costs were categorized and then assigned to the appropriate data sets.

Results

The mean age of patients undergoing FOR (vs. ESCH) was 17.4 mo (vs. 3.1 mo) with a mean surgical time of 234 min (vs. 55 min), mean transfusion volume of 221.6 mL (vs. 80.0 mL), mean transfusion rate of 14/23 (vs. 2/115), and a total immediate overnight stay of 3.13 days (vs. 97% next-day discharge). The FOR group had a higher adverse event rate (5/23 vs. 4/115, p=<0.005) and a higher number requiring extraocular muscle surgery (4/23 vs. 7/109, p=0.16). There was a substantial difference in overall costs between the two groups. Total variance cost for the FOR group was £7436.5 vs. £4951.35, representing a cost difference of £2485.15 over the 24-month study period.

Conclusion

ESCH, in comparison to FOR, appears as a more economical method in the management of USC patients, as well as having clinical benefits including reduced adverse event rate and improved ophthalmic outcomes.

P847 Echocardiographic imaging in primary cardiac tumour-leiomyosarcoma

Funding Acknowledgements

N.A

Primary cardiac tumours are rare entities with an incidence rate of 0.0017% to 0.019% of which 25% are malignant. Leiomyosarcomas, a form of primary cardiac sarcoma, accounts for 8-9% of all the cardiac sarcomas (1). Primary cardiac sarcomas typically present late with either quite advanced local cardiac symptoms or non-specific symptoms arising from metastasis (2). We herein report a rare presentation of leiomyosarcoma in a sixty-seven year old female Caucasian female, originally suspected following transthoracic echocardiogram.

A large mass filling the Left Atrium(L.A) with a degree obstruction to the Mitral Valve (M.V) was firstly noted on transthoracic echocardiogram. This mass had a broad base, appeared to be originating from the pulmonary veins and was not encapsulated. A small circumferential pericardial effusion was noted. Overall biventricular function was preserved and there was no evidence of pulmonary hypertension. A contrast-enhanced computed tomography scan of the chest, abdomen and pelvis was performed for staging which in addition to known cardiac mass revealed widespread bony metastases. A core biopsy of one of the lumbar paravertebral metastatic deposit was carried out to establish the diagnosis.

We hope to add to the pool of increasing overall understanding of primary cardiac sarcomas and share our fascinating echocardiogram findings. In addition, we believe this case supports our recommendation for general practitioners in the United Kingdom to have open access to requesting echocardiograms in order to identify such aggressive cardiac malignancies at an earlier stage, with the hope to improve prognosis.

Abstract P847 Figure. Depicting LA mass occupying the whole of

Marked TGF-β-regulated miRNA expression changes in both COPD and control lung fibroblasts

COPD is associated with disturbed tissue repair, possibly due to TGF-β-regulated miRNA changes in fibroblasts. Our aim was to identify TGF-β-regulated miRNAs and their differential regulation and expression in COPD compared to control fibroblasts. Small RNA sequencing was performed on TGF-β-stimulated and unstimulated lung fibroblasts from 15 COPD patients and 15 controls. Linear regression was used to identify TGF-β-regulated and COPD-associated miRNAs. Interaction analysis was performed to compare miRNAs that responded differently to TGF-β in COPD and control. Re-analysis of previously generated Ago2-IP data and Enrichr were used to identify presence and function of potential target genes in the miRNA-targetome of lung fibroblasts. In total, 46 TGF-β-regulated miRNAs were identified in COPD and 86 in control fibroblasts (FDR < 0.05). MiR-27a-5p was the most significantly upregulated miRNA. MiR-148b-3p, miR-589-5p and miR-376b-3p responded differently to TGF-β in COPD compared to control (FDR < 0.25). MiR-660-5p was significantly upregulated in COPD compared to control (FDR < 0.05). Several predicted targets of miR-27a-5p, miR-148b-3p and miR-660-5p were present in the miRNA-targetome, and were mainly involved in the regulation of gene transcription. In conclusion, altered TGF-β-induced miRNA regulation and differential expression of miR-660-5p in COPD fibroblasts, may represent one of the mechanisms underlying aberrant tissue repair and remodelling in COPD.

Does the gene matter? Genotype-phenotype and genotype-outcome associations in congenital melanocytic naevi

Background

Genotype–phenotype studies can identify subgroups of patients with specific clinical features or differing outcomes, which can help shape management.

Objectives

To characterize the frequency of different causative genotypes in congenital melanocytic naevi (CMN), and to investigate genotype–phenotype and genotype–outcome associations.

Methods

We conducted a large cohort study in which we undertook MC1R genotyping from blood, and high‐sensitivity genotyping of NRAS and BRAF hotspots in 156 naevus biopsies from 134 patients with CMN [male 40%; multiple CMN 76%; projected adult size (PAS) > 20 cm, 59%].

Results

Mosaic NRAS mutations were detected in 68%, mutually exclusive with BRAF mutations in 7%, with double wild‐type in 25%. Two separate naevi were sequenced in five of seven patients with BRAF mutations, confirming clonality. Five of seven patients with BRAF mutations had a dramatic multinodular phenotype, with characteristic histology distinct from classical proliferative nodules. NRAS mutation was the commonest in all sizes of CMN, but was particularly common in naevi with PAS > 60 cm, implying more tolerance to that mutation early in embryogenesis. Facial features were less common in double wild‐type patients. Importantly, the incidence of congenital neurological disease, and apparently of melanoma, was not altered by genotype; no cases of melanoma were seen in BRAF‐mutant multiple CMN, however, this genotype is rare.

Conclusions

CMN of all sizes are most commonly caused by mutations in NRAS. BRAF is confirmed as a much rarer cause of multiple CMN, and appears to be commonly associated with a multinodular phenotype. Genotype in this cohort was not associated with differences in incidence of neurological disease in childhood. However, genotyping should be undertaken in suspected melanoma, for guidance of treatment.

What's already known about this topic?

Multiple congenital melanocytic naevi (CMN) have been shown to be caused by NRAS mosaic mutations in 70–80% of cases, by BRAF mosaicism in one case report and by inference in some previous cases.

There has been debate about genotypic association with different sizes of CMN, and no data on genotype–outcome.

What does this study add?

NRAS mosaicism was found in 68%, BRAF in 7% and double wild‐type in 25% of cases of CMN.

NRAS was the commonest mutation in all sizes of CMN, but was nearly universal in projected adult size > 60 cm.

BRAF is often associated with a distinct multinodular clinical/histological phenotype.

Adverse outcomes did not differ between genotypes on current numbers.

https://doi.org/10.1111/bjd.18747 available online

Using Human Movement Data to Identify Potential Areas of Zika Transmission: Case Study of the Largest Zika Cluster in Singapore

Singapore experienced its first Zika virus (ZIKV) cluster in August 2016. To understand the implication of human movement on disease spread, a retrospective study was conducted using aggregated and anonymized mobile phone data to examine movement from the cluster to identify areas of possible transmission. An origin–destination model was developed based on the movement of three groups of individuals: (i) construction workers, (ii) residents and (iii) visitors out of the cluster locality to other parts of the island. The odds ratio of ZIKV cases in a hexagon visited by an individual from the cluster, independent of the group of individuals, is 3.20 (95% CI: 2.65–3.87, p-value < 0.05), reflecting a higher count of ZIKV cases when there is a movement into a hexagon from the cluster locality. A comparison of independent ROC curves tested the statistical significance of the difference between the areas under the curves of the three groups of individuals. Visitors (difference in AUC = 0.119) and residents (difference in AUC = 0.124) have a significantly larger difference in area under the curve compared to the construction workers (p-value < 0.05). This study supports the proof of concept of using mobile phone data to approximate population movement, thus identifying areas at risk of disease transmission.

WPI-13 Lack of association of cranial lacunae with intracranial hypertension in children with crouzon syndrome and apert syndrome: a 3D morphometric quantitative analysis

Objectives

Cranial lacunae on CT is equivalent to the plain X-ray ‘copper beating’ seen in craniosynostosis. Copper beating has not been shown to correlate to intracranial hypertension (IH). However it is a purely quantitative assessment – can qualitative measurement of CT cranial lacunae more accurately predict IH in children with craniosynostosis?

Design

Retrospective cohort study.

Subjects

18 consecutive children with Crouzon and 17 with Apert syndrome were identified.

Methods

Patients were divided into IH and non-IH groups defined on an intention to treat basis. 3D software was used to analyse% of calvarial lacunae.

Results

Mean age at CT scan was 380 days (range 6–1778). Of the 35 children, 21 required surgery for raised ICP (17 posterior vault expansion 2 ventriculo-peritoneal shunts (VPS), 1 spring-assisted cranioplasty and 1 fronto-orbital advancement) at mean age of 512 days (range 38–1710). Of the 21 children with raised ICP, 15 had lacunae with mean lacuna/calvarium percentage of 3% (0%–28%). Of the 14 non-raised ICP children, 8 had lacunae with mean lacuna/calvarium percentage of 2% (0%–8%). T-test demonstrated no significant difference between the 2 groups. For both groups, parietal bones were most likely to show lacunae (IH 14/21, non-IH 9/14), followed by occipital (IH 8/21, non-IH 3/14), followed by frontal (IH 6/21, non-IH 2/14).

Conclusions

Results suggest that cranial lacunae, measured using quantitative 3D methods, do not predict IH, in agreement with evidence from qualitative plain skull radiograph studies.

A novel entomological index, Aedes aegypti Breeding Percentage, reveals the geographical spread of the dengue vector in Singapore and serves as a spatial risk indicator for dengue

Background

Aedes aegypti is an efficient primary vector of dengue, and has a heterogeneous distribution in Singapore. Aedes albopictus, a poor vector of dengue, is native and ubiquitous on the island. Though dengue risk follows the dispersal of Ae. aegypti, the spatial distribution of the vector is often poorly characterized. Here, based on the ubiquitous presence of Ae. albopictus, we developed a novel entomological index, Ae. aegypti Breeding Percentage (BP), to demonstrate the expansion of Ae. aegypti into new territories that redefined the dengue burden map in Singapore. We also determined the thresholds of BP that render the specific area higher risk of dengue transmission.

Methods

We performed analysis of dengue fever incidence and Aedes mosquito breeding in Singapore by utilizing island-wide dengue cases and vector surveillance data from 2003 to 2013. The percentage of Ae. aegypti breeding among the total Aedes breeding habitats (BP), and the reported number of dengue fever cases in each year were calculated for each residential grid.

Results

The BP of grids, for every year over the 11-year study period, had a consistent positive correlation with the annual case counts. Our findings suggest that the geographical expansion of Ae. aegypti to previously “non-dengue” areas have contributed substantially to the recent dengue fever incidence in Singapore. Our analysis further indicated that non-endemic areas in Singapore are likely to be at risk of dengue fever outbreaks beyond an Ae. aegypti BP of 20%.

Conclusions

Our analyses indicate areas with increasing Ae. aegypti BP are likely to become more vulnerable to dengue outbreaks. We propose the usage of Ae. aegypti BP as a factor for spatial risk stratification of dengue fever in endemic countries. The Ae. aegypti BP could be recommended as an indicator for decision making in vector control efforts, and also be used to monitor the geographical expansion of Ae. aegypti.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3281-y) contains supplementary material, which is available to authorized users.

Factors influencing patient decision-making between simple mastectomy and surgical alternatives

Background

Despite similar survival rates, breast‐conserving therapy (BCT) remains a distant second choice after simple mastectomy for patients with early‐stage breast cancer in Singapore. Uptake of reconstruction after mastectomy is also low (18 per cent). The aim of this study was to explore the factors influencing a patient's choice for mastectomy when eligible for BCT, and why patients decline reconstruction after mastectomy.

Methods

Patients from the National Cancer Centre Singapore, who were eligible for BCT but chose mastectomy without reconstruction, between December 2014 and December 2015 were included. An interviewer‐administered questionnaire focusing on patients' reasons for choosing mastectomy over BCT and not opting for immediate breast reconstruction after mastectomy was used. Tumour characteristics were retrieved from medical records. Spearman's rank correlation coefficient, Mann–Whitney U and Kruskal–Wallis tests were used to analyse the correlation between the patient's self‐rated influential factors and variables. Statistical significance was taken as P < 0·050.

Results

Ninety‐one patients were included (90·1 per cent response rate). The main reasons for choosing mastectomy over BCT were: fear of cancer recurrence (considered very important in 74 per cent), the perception that health outweighs breast retention (49 per cent) and the possibility of second surgery for margins (40 per cent). Key factors for rejecting immediate reconstruction after mastectomy were: patient‐perceived ‘old age’ (very important in 53 per cent), concern about two sites of surgery (42 per cent) and financial cost (29 per cent). Given a second chance, 19·8 per cent of patients would undergo BCT instead of mastectomy.

Conclusion

This study has identified the considerations that women in Singapore have when deciding on breast cancer surgery. Some perceptions need to be addressed for women to make a fully informed decision, especially as one‐fifth regret their initial choice.

Highly Selective Transmission Success of Dengue Virus Type 1 Lineages in a Dynamic Virus Population: An Evolutionary and Fitness Perspective

Arbovirus transmission is modulated by host, vector, virus, and environmental factors. Even though viral fitness plays a salient role in host and vector adaptation, the transmission success of individual strains in a heterogeneous population may be stochastic. Our large-scale molecular epidemiological analyses of a dengue virus type 1 population revealed that only a subset of strains (16.7%; n = 6) were able to sustain transmission, despite the population being widely dispersed, dynamic, and heterogeneous. The overall dominance was variable even among the “established” lineages, albeit sharing comparable evolutionary characteristics and replication profiles. These findings indicated that virological parameters alone were unlikely to have a profound effect on the survival of viral lineages, suggesting an important role for non-viral factors in the transmission success of lineages. Our observations, therefore, emphasize the strategic importance of a holistic understanding of vector, human host, and viral factors in the control of vector-borne diseases.

•

The sustained transmission of dengue virus 1 lineages is highly selective

•

The overall dominance is variable even among the “established” lineages

•

The lineage dominance is not merely determined by virus evolution and fitness

•

The non-viral factors play an important role in the survival of virus lineages

Mapping dengue risk in Singapore using Random Forest

BACKGROUND

Singapore experiences endemic dengue, with 2013 being the largest outbreak year known to date, culminating in 22,170 cases. Given the limited resources available, and that vector control is the key approach for prevention in Singapore, it is important that public health professionals know where resources should be invested in. This study aims to stratify the spatial risk of dengue transmission in Singapore for effective deployment of resources.

METHODOLOGY/PRINCIPAL FINDINGS

Random Forest was used to predict the risk rank of dengue transmission in 1km2 grids, with dengue, population, entomological and environmental data. The predicted risk ranks are categorized and mapped to four color-coded risk groups for easy operation application. The risk maps were evaluated with dengue case and cluster data. Risk maps produced by Random Forest have high accuracy. More than 80% of the observed risk ranks fell within the 80% prediction interval. The observed and predicted risk ranks were highly correlated ([Formula: see text]≥0.86, P <0.01). Furthermore, the predicted risk levels were in excellent agreement with case density, a weighted Kappa coefficient of more than 0.80 (P <0.01). Close to 90% of the dengue clusters occur in high risk areas, and the odds of cluster forming in high risk areas were higher than in low risk areas.

CONCLUSIONS

This study demonstrates the potential of Random Forest and its strong predictive capability in stratifying the spatial risk of dengue transmission in Singapore. Dengue risk map produced using Random Forest has high accuracy, and is a good surveillance tool to guide vector control operations.

Mapping dengue risk in Singapore using Random Forest

BACKGROUND

Singapore experiences endemic dengue, with 2013 being the largest outbreak year known to date, culminating in 22,170 cases. Given the limited resources available, and that vector control is the key approach for prevention in Singapore, it is important that public health professionals know where resources should be invested in. This study aims to stratify the spatial risk of dengue transmission in Singapore for effective deployment of resources.

METHODOLOGY/PRINCIPAL FINDINGS

Random Forest was used to predict the risk rank of dengue transmission in 1km2 grids, with dengue, population, entomological and environmental data. The predicted risk ranks are categorized and mapped to four color-coded risk groups for easy operation application. The risk maps were evaluated with dengue case and cluster data. Risk maps produced by Random Forest have high accuracy. More than 80% of the observed risk ranks fell within the 80% prediction interval. The observed and predicted risk ranks were highly correlated ([Formula: see text]≥0.86, P <0.01). Furthermore, the predicted risk levels were in excellent agreement with case density, a weighted Kappa coefficient of more than 0.80 (P <0.01). Close to 90% of the dengue clusters occur in high risk areas, and the odds of cluster forming in high risk areas were higher than in low risk areas.

CONCLUSIONS

This study demonstrates the potential of Random Forest and its strong predictive capability in stratifying the spatial risk of dengue transmission in Singapore. Dengue risk map produced using Random Forest has high accuracy, and is a good surveillance tool to guide vector control operations.

Dengue in Singapore from 2004 to 2016: Cyclical Epidemic Patterns Dominated by Serotypes 1 and 2

Singapore has experienced periodic dengue epidemics despite maintaining a low Aedes house index. Each epidemic was associated with a switch in the predominant serotype. We investigated the temporal dynamics of dengue fever and dengue virus (DENV) and analyzed the epidemiological and entomological patterns of dengue in Singapore from 2004 to 2016. The case surveillance is based on a mandatory notification system that requires all medical practitioners to report clinically suspected and laboratory-confirmed cases. Circulating (DENV) serotypes are monitored through a virus surveillance program. Entomological surveillance involves inspections for larval breeding and monitoring of adults using gravitraps. Singapore experienced a similar epidemic pattern during 2004–2007 and 2013–2016. The pattern involved a 2-year DENV-1 epidemic occurring after a switch in the predominant serotype from DENV-2 to DENV-1, followed by a “lull” year. Thereafter, the predominant serotype switched back to DENV-2, tailed by a small-scale epidemic. Across the years, the highest incidence group was in the 25–44 years age group. The incidence rate of those aged ≥ 55 years was about half of that of the 15–24 years age group during DENV-1 predominant years. However, it was almost equal to the younger age group in DENV-2 predominant years. Types of Aedes aegypti breeding habitats remained similar. Dengue incidence was significantly higher in areas with high breeding percentage (BP) than areas with low BP (P < 0.05). In conclusion, the oscillation of DENV-1 and DENV-2, throughout the 13-year period, led to a cyclical epidemic pattern and older adults were more affected by DENV-2 than DENV-1.

A smoking cessation programme for current and recent ex-smokers following diagnosis of a potentially curable cancer

BACKGROUND

Cancer patients who quit smoking have improved survival rates. The time of diagnosis provides a 'teachable moment' when healthcare providers can offer smoking-cessation treatment.

AIMS

To assess the impact on quit rates of a tailored smoking-cessation intervention for patients diagnosed with a potentially curable cancer.

METHODS

A prospective, one-arm cohort study of current smokers and recent quitters (<30 days) who had commenced treatment for a potentially curable cancer was performed. Intervention involved an initial motivational interview, regular follow up and pharmacotherapy when appropriate. Quit rates were measured at 1, 3, 6 and 12 months by self-reported abstinence and biochemical confirmation. The primary end point was prolonged abstinence at 12 months. Changes in quality of life parameters and distress were also assessed.

RESULTS

Seventy-one patients were recruited, with a median age of 56 years. Forty-one patients (58%) had a smoking-related cancer. The prolonged abstinence rate at 12 months was 24% (95% confidence interval 14-36%). Factors associated with successful quitting included being in the preparation or action phase of readiness to change at study entry (P = 0.012) and having complications of treatment requiring hospitalisation (P = 0.024). Between baseline and 12 months, quitters reported improvement in self-control (P < 0.001) and reduced levels of distress (P = 0.03) compared to non-quitters.

CONCLUSION

Patients who continue to smoke after being diagnosed with cancer require intensive support to quit. An individualised behavioural and pharmacological intervention can be successful in helping patients quit smoking, with quality of life improvements seen amongst successful quitters. Population measures to stop people starting smoking remain essential.