Self-supervised learning of accelerometer data provides new insights for sleep and its association with mortality

Sleep is essential to life. Accurate measurement and classification of sleep/wake and sleep stages is important in clinical studies for sleep disorder diagnoses and in the interpretation of data from consumer devices for monitoring physical and mental well-being. Existing non-polysomnography sleep classification techniques mainly rely on heuristic methods developed in relatively small cohorts. Thus, we aimed to establish the accuracy of wrist-worn accelerometers for sleep stage classification and subsequently describe the association between sleep duration and efficiency (proportion of total time asleep when in bed) with mortality outcomes. We developed a self-supervised deep neural network for sleep stage classification using concurrent laboratory-based polysomnography and accelerometry. After exclusion, 1448 participant nights of data were used for training. The difference between polysomnography and the model classifications on the external validation was 34.7 min (95% limits of agreement (LoA): -37.8-107.2 min) for total sleep duration, 2.6 min for REM duration (95% LoA: -68.4-73.4 min) and 32.1 min (95% LoA: -54.4-118.5 min) for NREM duration. The sleep classifier was deployed in the UK Biobank with 100,000 participants to study the association of sleep duration and sleep efficiency with all-cause mortality. Among 66,214 UK Biobank participants, 1642 mortality events were observed. Short sleepers (<6 h) had a higher risk of mortality compared to participants with normal sleep duration of 6-7.9 h, regardless of whether they had low sleep efficiency (Hazard ratios (HRs): 1.58; 95% confidence intervals (CIs): 1.19-2.11) or high sleep efficiency (HRs: 1.45; 95% CIs: 1.16-1.81). Deep-learning-based sleep classification using accelerometers has a fair to moderate agreement with polysomnography. Our findings suggest that having short overnight sleep confers mortality risk irrespective of sleep continuity.

Self-reported walking pace and 10-year cause-specific mortality: A UK biobank investigation

OBJECTIVE

To investigate associations of self-reported walking pace (SRWP) with relative and absolute risks of cause-specific mortality.

PATIENTS AND METHODS

In 391,652 UK Biobank participants recruited in 2006-2010, we estimated sex- and cause-specific (cardiovascular disease [CVD], cancer, other causes) mortality hazard ratios (HRs) and 10-year mortality risks across categories of SRWP (slow, average, brisk), accounting for confounders and competing risk. Censoring occurred in September 30, 2021 (England, Wales) and October 31, 2021 (Scotland).

RESULTS

Over a median follow-up of 12.6 years, 22,413 deaths occurred. In women, the HRs comparing brisk to slow SRWP were 0.74 (95% CI: 0.67, 0.82), 0.40 (0.33, 0.49), and 0.29 (0.26, 0.32) for cancer, CVD, and other causes of death, respectively, and 0.71 (0.64, 0.78), 0.38 (0.33, 0.44), and 0.29 (0.26, 0.32) in men. Compared to CVD, HRs were greater for other causes (women: 39.6% [6.2, 72.9]; men: 31.6% [9.8, 53.5]) and smaller for cancer (-45.8% [-58.3, -33.2] and - 45.9% [-54.8, -36.9], respectively). For all causes in both sexes, the 10-year mortality risk was higher in slow walkers, but varied across sex, age, and cause, resulting in different risk reductions comparing brisk to slow: the largest were for other causes of death at age 75 years [women: -6.8% (-7.7, -5.8); men: -9.5% (-10.6, -8.4)].

CONCLUSION

Compared to slow walkers, brisk SRWP was associated with reduced cancer (smallest reduction), CVD, and other (largest) causes of death and may therefore be a useful clinical predictive marker. As absolute risk reductions varied across age, cause, and SRWP, certain groups may particularly benefit from interventions to increase SRWP.

Impaired lower limb muscle mass, quality and function in end stage liver disease: A cross-sectional study

NEW FINDINGS

What is the central question of this study? To what extent does musculoskeletal impairment occur (i.e., muscle mass, quality and function) in patients with end stage liver disease (ESLD) by comparison to a healthy age/sex-matched control group? What is the main finding and its importance? Muscle mass, quality and function are impaired in patients with ESLD (compared to age/sex matched controls). Importantly, greater impairments were seen in lower limb compared to arm and trunk muscle groups. These findings may suggest that there should be greater consideration of muscle health in functionally relevant lower limb muscle groups.

ABSTRACT

Sarcopenia is associated with reduced quality of life and increased mortality in patients with end stage liver disease (ESLD). Historically, sarcopenia identification in ESLD utilised L3 skeletal muscle index (SMI). There are few data on muscle quality and function within lower limb muscle groups with high functional relevance. The aim of this prospective case-control study was to evaluate the quadriceps muscle in patients with ESLD. Muscle mass and quality were evaluated using MRI (quadriceps anatomical cross sectional area (ACSA), quadriceps volume index, L3 SMI, quadriceps intermuscular adipose tissue (IMAT)), mid-arm muscle circumference (MAMC) and ultrasonography (vastus lateralis (VL) thickness and quadriceps ACSA). Muscle strength/function was assessed by handgrip strength, peak quadriceps isokinetic torque and chair rise time. Thirty-nine patients with ESLD (55 years, 61% male, 48% alcoholic related liver disease (ArLD), 71% Child-Pugh B/C) and 18 age/sex-matched healthy control participants (HC) were studied. Quadriceps mass was significantly reduced in ESLD versus HC (-17%), but L3 SMI and MAMC were unchanged. Quadriceps IMAT percentage was increased in ESLD (+103%). Handgrip strength (-15%), peak isokinetic torque (-29%), and chair rise time (+56%) were impaired in ESLD. Ultrasound measures of VL thickness (r = 0.56, r = 0.57, r = 0.42) and quadriceps ACSA (r = 0.98, r = 0.86, r = 0.67) correlated to MRI quadriceps ACSA, quadriceps volume and L3 SMI, respectively. Quadriceps muscle mass, quality, and function were impaired in patients with ESLD, whereas conventional assessments of muscle (L3 SMI and MAMC) highlighted no differences between ESLD and HC. Full evaluation of lower limb muscle health is essential in ESLD in order to accurately assess sarcopenia and target future interventions.

Self-supervised learning of accelerometer data provides new insights for sleep and its association with mortality

Background

Sleep is essential to life. Accurate measurement and classification of sleep/wake and sleep stages is important in clinical studies for sleep disorder diagnoses and in the interpretation of data from consumer devices for monitoring physical and mental well-being. Existing non-polysomnography sleep classification techniques mainly rely on heuristic methods developed in relatively small cohorts. Thus, we aimed to establish the accuracy of wrist-worn accelerometers for sleep stage classification and subsequently describe the association between sleep duration and efficiency (proportion of total time asleep when in bed) with mortality outcomes.

Methods

We developed and validated a self-supervised deep neural network for sleep stage classification using concurrent laboratory-based polysomnography and accelerometry data from three countries (Australia, the UK, and the USA). The model was validated within-cohort using subject-wise five-fold cross-validation for sleep-wake classification and in a three-class setting for sleep stage classification wake, rapid-eye-movement sleep (REM), non-rapid-eye-movement sleep (NREM) and by external validation. We assessed the face validity of our model for population inference by applying the model to the UK Biobank with 100,000 participants, each of whom wore a wristband for up to seven days. The derived sleep parameters were used in a Cox regression model to study the association of sleep duration and sleep efficiency with all-cause mortality.

Findings

After exclusion, 1,448 participant nights of data were used to train the sleep classifier. The difference between polysomnography and the model classifications on the external validation was 34.7 minutes (95% limits of agreement (LoA): -37.8 to 107.2 minutes) for total sleep duration, 2.6 minutes for REM duration (95% LoA: -68.4 to 73.4 minutes) and 32.1 minutes (95% LoA: -54.4 to 118.5 minutes) for NREM duration. The derived sleep architecture estimate in the UK Biobank sample showed good face validity. Among 66,214 UK Biobank participants, 1,642 mortality events were observed. Short sleepers (<6 hours) had a higher risk of mortality compared to participants with normal sleep duration (6 to 7.9 hours), regardless of whether they had low sleep efficiency (Hazard ratios (HRs): 1.69; 95% confidence intervals (CIs): 1.28 to 2.24 ) or high sleep efficiency (HRs: 1.42; 95% CIs: 1.14 to 1.77).

Interpretation

Deep-learning-based sleep classification using accelerometers has a fair to moderate agreement with polysomnography. Our findings suggest that having short overnight sleep confers mortality risk irrespective of sleep continuity.

Structured group education programme and accompanying mHealth intervention to promote physical activity in women with a history of gestational diabetes: a randomized controlled trial

AIMS

Assess effectiveness of a hybrid intervention targeting physical activity in women with prior gestational diabetes.

METHODS

Randomised controlled trial with parallel arms. 293 women (35.1±5.1 years; 40% ethnic minority) recruited from two hospitals and randomised to routine care or hybrid lifestyle intervention comprising two group sessions and access to a mobile-web-app. Primary outcome was change in objectively measured physical activity at 12 months. Secondary outcomes included self-efficacy for exercise, quality of life and anxiety and depression. Linear regression compared outcome measures between groups.

RESULTS

83% of intervention participants attended at least one group session, of who 66% registered to use the app. There was a non-significant increase in physical activity at 12 months (between group difference of 0.95mg (95% CI: -0.46 to 2.37)), equivalent to approximately 500 steps per day. Intervention participants reported higher self-efficacy for exercise (0.54, 95%CI: 0.05 to 1.102; p=0.029), lower anxiety (-0.91, 95%CI: -1.74 to -0.09; p=0.031), and higher quality of life (0.05, 95%CI: 0.004 to 0.09; p=0.032), compared to controls.

CONCLUSIONS

The intervention improved confidence in exercise and quality of life. Further research is needed to improve participant engagement with physical activity interventions in multi-ethnic populations with a history of gestational diabetes.

The impact of selected methodological factors on data collection outcomes in observational studies of device-measured physical behaviour in adults: A systematic review

BACKGROUND

Accelerometer measures of physical behaviours (physical activity, sedentary behaviour and sleep) in observational studies offer detailed insight into associations with health and disease. Maximising recruitment and accelerometer wear, and minimising data loss remain key challenges. How varying methods used to collect accelerometer data influence data collection outcomes is poorly understood. We examined the influence of accelerometer placement and other methodological factors on participant recruitment, adherence and data loss in observational studies of adult physical behaviours.

METHODS

The review was in accordance with the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA). Observational studies of adults including accelerometer measurement of physical behaviours were identified using database (MEDLINE (Ovid), Embase, PsychINFO, Health Management Information Consortium, Web of Science, SPORTDiscus and Cumulative Index to Nursing & Allied Health Literature) and supplementary searches to May 2022. Information regarding study design, accelerometer data collection methods and outcomes were extracted for each accelerometer measurement (study wave). Random effects meta-analyses and narrative syntheses were used to examine associations of methodological factors with participant recruitment, adherence and data loss.

RESULTS

123 accelerometer data collection waves were identified from 95 studies (92.5% from high-income countries). In-person distribution of accelerometers was associated with a greater proportion of invited participants consenting to wear an accelerometer (+ 30% [95% CI 18%, 42%] compared to postal distribution), and adhering to minimum wear criteria (+ 15% [4%, 25%]). The proportion of participants meeting minimum wear criteria was higher when accelerometers were worn at the wrist (+ 14% [ 5%, 23%]) compared to waist. Daily wear-time tended to be higher in studies using wrist-worn accelerometers compared to other wear locations. Reporting of information regarding data collection was inconsistent.

CONCLUSION

Methodological decisions including accelerometer wear-location and method of distribution may influence important data collection outcomes including recruitment and accelerometer wear-time. Consistent and comprehensive reporting of accelerometer data collection methods and outcomes is needed to support development of future studies and international consortia. Review supported by the British Heart Foundation (SP/F/20/150002) and registered (Prospero CRD42020213465).

Associations between Hospitalization and Device-Assessed Physical Activity in a Representative Sample of Older Adults

BACKGROUND

Evidence investigating associations between hospitalization and physical activity is scarce and limited to specific populations of older adults.

OBJECTIVE

The current study aimed to describe the impact of past hospitalization on current physical activity levels of a large representative sample of European older adults with accelerometry data.

METHODS

A representative sample of 856 European older adults aged 50 years and over was included in this study. Hospital admission and utilization (i.e., accumulated times and length of stay in hospital) in the last 12 months were self-reported retrospectively. Physical activity volume (mg) and distribution of intensity (intensity gradient) were assessed with thigh-worn accelerometers.

RESULTS

Multivariate linear regressions indicated that hospital admission (15% of the sample) was associated with reduced physical activity volume (-4.29 mg; 95% confidence interval (95% CI), -9.07 to 0.47) of participants. Each additional hospital admission was associated with lower volume (-2.29 mg; 95% CI, -4.65 to 0.06) and poorer distribution of intensity (-0.07; 95% CI, -0.11 to -0.04). Total length of stay was not associated with physical activity.

CONCLUSIONS

This study suggests that hospital admission and the number of times admitted, but not accumulated length of stay, may curb physical activity levels of older adults. Public health strategies to promote successful aging should target post-hospitalization physical activity.

Ethnic differences in the relationship between step cadence and physical function in older adults

This study investigated associations between step cadence and physical function in healthy South Asian (SA) and White European (WE) older adults, aged ≥60. Participants completed the 60-s Sit-to-Stand (STS-60) test of physical function. Free-living stepping was measured using the activPAL3™. Seventy-one WEs (age = 72 ± 5, 53% male) and 33 SAs (age = 71 ± 5, 55% male) were included. WEs scored higher than SAs in the STS-60 (23 vs 20 repetitions, p = 0.045). Compared to WEs, SAs had significantly lower total and brisk (≥100 steps/min) steps (total: 8971 vs 7780 steps/day, p = 0.041; brisk: 5515 vs 3723 steps/day, p = 0.001). In WEs, 1000 brisk steps and each decile higher proportion of steps spent brisk stepping were associated with STS-60 (β = 0.72 95% CI 0.05, 1.38 and β = 1.01 95% CI 0.19, 1.82, respectively), with associations persisting across mean peak 1 min (β = 1.42 95% CI 0.12, 2.71), 30 min (β = 1.71 95% CI 0.22, 3.20), and 60 min (β = 2.16 95% CI 0.62, 3.71) stepping periods. Associations were not observed in SAs. Ethnic differences in associations between ambulation and physical function may exist in older adults which warrant further investigationi.

Admission Blood Glucose Level and Its Association With Cardiovascular and Renal Complications in Patients Hospitalized With COVID-19

OBJECTIVE

To investigate the association between admission blood glucose levels and risk of in-hospital cardiovascular and renal complications.

RESEARCH DESIGN AND METHODS

In this multicenter prospective study of 36,269 adults hospitalized with COVID-19 between 6 February 2020 and 16 March 2021 (N = 143,266), logistic regression models were used to explore associations between admission glucose level (mmol/L and mg/dL) and odds of in-hospital complications, including heart failure, arrhythmia, cardiac ischemia, cardiac arrest, coagulation complications, stroke, and renal injury. Nonlinearity was investigated using restricted cubic splines. Interaction models explored whether associations between glucose levels and complications were modified by clinically relevant factors.

RESULTS

Cardiovascular and renal complications occurred in 10,421 (28.7%) patients; median admission glucose level was 6.7 mmol/L (interquartile range 5.8-8.7) (120.6 mg/dL [104.4-156.6]). While accounting for confounders, for all complications except cardiac ischemia and stroke, there was a nonlinear association between glucose and cardiovascular and renal complications. For example, odds of heart failure, arrhythmia, coagulation complications, and renal injury decreased to a nadir at 6.4 mmol/L (115 mg/dL), 4.9 mmol/L (88.2 mg/dL), 4.7 mmol/L (84.6 mg/dL), and 5.8 mmol/L (104.4 mg/dL), respectively, and increased thereafter until 26.0 mmol/L (468 mg/dL), 50.0 mmol/L (900 mg/dL), 8.5 mmol/L (153 mg/dL), and 32.4 mmol/L (583.2 mg/dL). Compared with 5 mmol/L (90 mg/dL), odds ratios at these glucose levels were 1.28 (95% CI 0.96, 1.69) for heart failure, 2.23 (1.03, 4.81) for arrhythmia, 1.59 (1.36, 1.86) for coagulation complications, and 2.42 (2.01, 2.92) for renal injury. For most complications, a modifying effect of age was observed, with higher odds of complications at higher glucose levels for patients age <69 years. Preexisting diabetes status had a similar modifying effect on odds of complications, but evidence was strongest for renal injury, cardiac ischemia, and any cardiovascular/renal complication.

CONCLUSIONS

Increased odds of cardiovascular or renal complications were observed for admission glucose levels indicative of both hypo- and hyperglycemia. Admission glucose could be used as a marker for risk stratification of high-risk patients. Further research should evaluate interventions to optimize admission glucose on improving COVID-19 outcomes.

Promoting physical activity with self-management support for those with multimorbidity: a randomised controlled trial

BACKGROUND

Targeted self-management programmes may improve health and increase physical activity (PA) in people with multimorbidity.

AIM

To investigate the impact of a structured, theoretically driven, self-management group education programme on habitual PA levels in people with multimorbidity.

DESIGN AND SETTING

Individually randomised controlled trial with 12-month follow-up, involving nine primary care practices in Leicestershire, UK.

METHOD

In total, 353 adults with multimorbidity (age 67.8 years [±9 years], 161 male sex) were randomised to intervention (n = 180) or control (n = 173) groups. Intervention participants were invited to attend four group-based self-management sessions, centred primarily on increasing PA, and received motivational text-message support. The primary outcome measure was change in overall volume (time and intensity) of daily PA at 12 months, as measured by the GENEActiv wrist-worn accelerometer device.

RESULTS

At baseline, the total sample achieved 22 min of moderate-vigorous intensity PA per day (mean/participant). At 12 months, in the complete-case analysis, a reduction in daily mean PA volume was seen in the intervention group relative to control (-0.80 milligravity [m g]; 95% confidence interval [CI] = -1.57 to -0.03; P = 0.04). Reductions were also seen in the intervention group in time spent in moderate-vigorous PA (-3.86 min per day; 95% CI= -6.70 to -1.03; P = 0.008) and time spent at an intensity equivalent to a slow walk (-4.66 min per day; 95% CI = -8.82 to -0.51; P = 0.028). However, the per-protocol analysis (excluding participants who did not attend at least one education session) found no between-group differences in overall daily PA at 12 months (-0.65 mg; 95% CI = -1.46 to 0.15; P = 0.11).

CONCLUSION

The self-management programme elicited a slight reduction in PA levels in people with multimorbidity. Future research should identify and target subgroups of those with multimorbidity in greatest need of PA promotion in order to maximise potential capacity for benefit, and also focus on refining the intervention in order to increase efficacy in increasing PA.

Obesity, chronic disease, age, and in-hospital mortality in patients with covid-19: analysis of ISARIC clinical characterisation protocol UK cohort

Background

Although age, obesity and pre-existing chronic diseases are established risk factors for COVID-19 outcomes, their interactions have not been well researched.

Methods

We used data from the Clinical Characterisation Protocol UK (CCP-UK) for Severe Emerging Infection developed by the International Severe Acute Respiratory and emerging Infections Consortium (ISARIC). Patients admitted to hospital with COVID-19 from 6th February to 12th October 2020 were included where there was a coded outcome following hospital admission. Obesity was determined by an assessment from a clinician and chronic disease by medical records. Chronic diseases included: chronic cardiac disease, hypertension, chronic kidney disease, chronic pulmonary disease, diabetes and cancer. Mutually exclusive categories of obesity, with or without chronic disease, were created. Associations with in-hospital mortality were examined across sex and age categories.

Results

The analysis included 27,624 women with 6407 (23.2%) in-hospital deaths and 35,065 men with 10,001 (28.5%) in-hospital deaths. The prevalence of chronic disease in women and men was 66.3 and 68.5%, respectively, while that of obesity was 12.9 and 11.1%, respectively. Association of obesity and chronic disease status varied by age (p < 0.001). Under 50 years of age, obesity and chronic disease were associated with in-hospital mortality within 28 days of admission in a dose-response manner, such that patients with both obesity and chronic disease had the highest risk with a hazard ratio (HR) of in-hospital mortality of 2.99 (95% CI: 2.12, 4.21) in men and 2.16 (1.42, 3.26) in women compared to patients without obesity or chronic disease. Between the ages of 50–69 years, obesity and chronic disease remained associated with in-hospital COVID-19 mortality, but survival in those with obesity was similar to those with and without prevalent chronic disease. Beyond the age of 70 years in men and 80 years in women there was no meaningful difference between those with and without obesity and/or chronic disease.

Conclusion

Obesity and chronic disease are important risk factors for in-hospital mortality in younger age groups, with the combination of chronic disease and obesity being particularly important in those under 50 years of age. These findings have implications for targeted public health interventions, vaccination strategies and in-hospital clinical decision making.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06466-0.

Ethnic minorities and COVID-19: examining whether excess risk is mediated through deprivation

BACKGROUND

People from South Asian and black minority ethnic groups are disproportionately affected by the COVID-19 pandemic. It is unknown whether deprivation mediates this excess ethnic risk.

METHODS

We used UK Biobank with linked COVID-19 outcomes occurring between 16th March 2020 and 24th August 2020. A four-way decomposition mediation analysis was used to model the extent to which the excess risk of testing positive, severe disease and mortality for COVID-19 in South Asian and black individuals, relative to white individuals, would be eliminated if levels of high material deprivation were reduced within the population.

RESULTS

We included 15 044 (53.0% women) South Asian and black and 392 786 (55.2% women) white individuals. There were 151 (1.0%) positive tests, 91 (0.6%) severe cases and 31 (0.2%) deaths due to COVID-19 in South Asian and black individuals compared with 1471 (0.4%), 895 (0.2%) and 313 (0.1%), respectively, in white individuals. Compared with white individuals, the relative risk of testing positive for COVID-19, developing severe disease and COVID-19 mortality in South Asian and black individuals were 2.73 (95% CI: 2.26, 3.19), 2.96 (2.31, 3.61) and 4.04 (2.54, 5.55), respectively. A hypothetical intervention moving the 25% most deprived in the population out of deprivation was modelled to eliminate between 40 and 50% of the excess risk of all COVID-19 outcomes in South Asian and black populations, whereas moving the 50% most deprived out of deprivation would eliminate over 80% of the excess risk of COVID-19 outcomes.

CONCLUSIONS

The excess risk of COVID-19 outcomes in South Asian and black communities could be substantially reduced with population level policies targeting material deprivation.

Obesity, Ethnicity, and Risk of Critical Care, Mechanical Ventilation, and Mortality in Patients Admitted to Hospital with COVID-19: Analysis of the ISARIC CCP-UK Cohort

OBJECTIVE

The aim of this study was to investigate the association of obesity with in-hospital coronavirus disease 2019 (COVID-19) outcomes in different ethnic groups.

METHODS

Patients admitted to hospital with COVID-19 in the United Kingdom through the Clinical Characterisation Protocol UK (CCP-UK) developed by the International Severe Acute Respiratory and emerging Infections Consortium (ISARIC) were included from February 6 to October 12, 2020. Ethnicity was classified as White, South Asian, Black, and other minority ethnic groups. Outcomes were admission to critical care, mechanical ventilation, and in-hospital mortality, adjusted for age, sex, and chronic diseases.

RESULTS

Of the participants included, 54,254 (age = 76 years; 45.0% women) were White, 3,728 (57 years; 41.1% women) were South Asian, 2,523 (58 years; 44.9% women) were Black, and 5,427 (61 years; 40.8% women) were other ethnicities. Obesity was associated with all outcomes in all ethnic groups, with associations strongest for black ethnicities. When stratified by ethnicity and obesity status, the odds ratios for admission to critical care, mechanical ventilation, and mortality in black ethnicities with obesity were 3.91 (3.13-4.88), 5.03 (3.94-6.63), and 1.93 (1.49-2.51), respectively, compared with White ethnicities without obesity.

CONCLUSIONS

Obesity was associated with an elevated risk of in-hospital COVID-19 outcomes in all ethnic groups, with associations strongest in Black ethnicities.

Framework to aid analysis and interpretation of ongoing COVID-19 research

The global coronavirus pandemic has precipitated a rapid unprecedented research response, including investigations into risk factors for COVID-19 infection, severity, or death. However, results from this research have produced heterogeneous findings, including articles published in Wellcome Open Research. Here, we use ethnicity, obesity, and smoking as illustrative examples to demonstrate how a research question can produce very different answers depending on how it is framed. For example, these factors can be both strongly associated or have a null association with death due to COVID-19, even when using the same dataset and statistical modelling. Highlighting the reasons underpinning this apparent paradox provides an important framework for reporting and interpreting ongoing COVID-19 research.

Metabolic Effects of Breaking Prolonged Sitting With Standing or Light Walking in Older South Asians and White Europeans: A Randomized Acute Study

Background

Prolonged sitting is common in older adults and is associated with insulin resistance and poor cardiometabolic health. We investigate whether breaking prolonged sitting with regular short bouts of standing or light walking improves postprandial metabolism in older white European and South Asian adults and whether effects are modified by ethnic group.

Methods

Thirty South Asian (15 women) and 30 white European (14 women) older adults (aged 65–79 years) undertook three experimental conditions in random order. (a) Prolonged sitting: continuous sitting during an observation period if 7.5 hours consuming two standardized mixed meals. (b) Standing breaks: sitting interrupted with 5 minutes of standing every 30 minutes (accumulating 60 minutes of standing over the observation period). (c) Walking breaks: sitting interrupted with 5 minutes of self-paced light walking every 30 minutes (accumulating 60 minutes of walking). Blood samples (glucose, insulin, triglycerides) and blood pressure were sampled regularly throughout each condition.

Results

Compared with prolonged sitting, walking breaks lowered postprandial insulin by 16.3 mU/L, (95% CI: 19.7, 22.0) with greater reductions (p = .029) seen in South Asians (22.4 mU/L; 12.4, 32.4) than white Europeans (10.3 mU/L; 5.9, 14.7). Glucose (0.3 mmol/L; 0.1, 0.5) and blood pressure (4 mm Hg; 2, 6), but not triglycerides, were lower with walking breaks, with no ethnic differences. Standing breaks did not improve any outcome.

Conclusions

Breaking prolonged sitting with short bouts of light walking, but not standing, resulted in clinically meaningful improvements in markers of metabolic health in older adults, with South Asians gaining a greater reduction in postprandial insulin.

Trial Registration

NCT02453204

Using accelerometry to classify physical activity intensity in older adults: What is the optimal wear-site?

Abstract This study aimed to determine the optimal accelerometer wear-site specific cut-points for discrimination of the sedentary time, light physical activity and moderate-to-vigorous physical activity (MVPA) in older adults. Twenty-three adults (14 females) aged 55-77 years wore a GENEActiv accelerometer on their non-dominant wrist, dominant wrist, waist and dominant ankle whilst undertaking eight, five-minute bouts of activity: lay supine, seated reading, slow walking, medium walking, fast walking, folding laundry, sweeping and stationary cycling. VO₂ was assessed concurrently using indirect calorimetry. Receiver-operating-characteristic (ROC) analyses were used to derive wear-site specific cut-points for classifying intensity. Indirect calorimetry indicated that being lay supine and seated reading were classified as sedentary (<1.5 METs), laundry as light (1.51-2.99 METs) and sweeping, slow, medium and fast walking and cycling all classified as moderate intensity (>3 METs). Areas under ROC curves indicated that the classification of sedentary activity was good for the non-dominant wrist and excellent for all other wear sites. Classification of MVPA was excellent for the waist and ankle, good for the waist and poor for the dominant and non-dominant wrists. Overall, the ankle location performed better than in other locations. Ankle-worn accelerometry appears to provide the most suitable wear-site to discriminate between sedentary time and MVPA in older adults.

Rationale and design of a cross-sectional study to investigate and describe the chronotype of patients with type 2 diabetes and the effect on glycaemic control: the CODEC study

INTRODUCTION

A person's chronotype is their entrained preference for sleep time within the 24 hours clock. It is described by the well-known concept of the 'lark' (early riser) and 'owl' (late sleeper). Evidence suggests that the 'owl' is metabolically disadvantaged due to the standard organisation of our society which favours the 'lark' and places physiological stresses on this chronotype. The aim of this study is to explore cardiometabolic health between the lark and owl in a population with an established metabolic condition - type 2 diabetes.

METHODS

This cross-sectional, multisite study aims to recruit 2247 participants from both secondary and primary care settings. The primary objective is to compare glycaemic control between late and early chronotypes. Secondary objectives include determining if late-chronotype is associated with poorer cardiometabolic health and other lifestyle factors, including well-being, compared with early-chronotype; describing the prevalence of the five different chronotypes in this cohort and examining the trends in glycaemic control, cardiometabolic health, well-being and lifestyle factors across chronotype.

ANALYSIS

The primary outcome (glycated haemoglobin (HbA1c)), linear regression analysis will compare HbA1c between early and late chronotypes, with and without adjustment for confounding variables. Chronotype will be modelled as a categorical variable with all five levels (from extreme-morning to extreme-late type), and as a continuous variable to calculate p for trend across the five categories. A number of models will be created; unadjusted through to adjusted with age, sex, ethnicity, body mass index, duration of diabetes, family history of diabetes, current medication and dietary habits. All secondary outcomes will be analysed using the same method.

ETHICS

Ethical approval from the West Midlands - Black Country Research Ethics Committee (16/WM/0457).

DISSEMINATION

The results will be disseminated through publication in peer-reviewed medical journal, relevant medical/health conferences and a summary report sent to patients.

TRIAL REGISTRATION NUMBER

NCT02973412 (Pre-Results).

Associations between objectively assessed and questionnaire-based sedentary behaviour with body mass index and systolic blood pressure in Kuwaiti adolescents

Objective

Kuwait has one of the highest obesity rates in the world. This study examined the associations between sedentary behaviour (objectively measured and self-reported), adiposity and systolic blood pressure in a sample of adolescents residing in Kuwait. Data was obtained from the Study of Health and Activity among adolescents in Kuwait (2012–2013). The sample included a total of 435 adolescents (201 boys). Outcomes were age- and sex specific body mass index Z-scores and systolic blood pressure. Exposures were total sedentary behaviour measured by accelerometry and time spent in some sedentary behaviours (television viewing, video games, computer use and total screen-time). We used multiple linear regression analyses, adjusted for age, governorate, maternal education and physical activity, to examine associations between sedentary behaviour and adiposity and systolic blood pressure.

Results

Only 2 statistically significant associations were found between sedentary behaviour and the study outcomes: body mass in boys was directly associated with higher sedentary time [β (95% CIs) 0.003 (0.00 to 0.06)]; body mass index was inversely associated with videogames in both sexes [girls: β (95% CIs) − 0.17 (− 0.48 to − 0.04); boys: − 0.24 (− 0.57 to − 0.12)]. In this sample of Kuwaiti adolescents, sedentary behaviour showed limited deleterious associations with adiposity and systolic blood pressure.

Not all sedentary behaviour is equal: Children's adiposity and sedentary behaviour volumes, patterns and types

OBJECTIVE

The importance of different constructs of sedentary behaviours in relation to childhood obesity is uncertain. Thus, this study aimed to investigate relationships between volume, patterns and types of sedentary behaviour and adiposity in children.

METHODS

A case-control study was undertaken involving 234 children aged 10-13years who were either of a healthy-weight (74 boys, 56 girls) or classified as obese (56 boys, 48 girls). Percent body fat (by dual-energy X-ray absorptiometry) and waist-to-height ratio were assessed. Time, type (television, videogame, computer, eating, passive transport) and bout length of sedentary behaviours were measured using accelerometry and the Multimedia Activity Recall for Children and Adolescents. Time use (total daily energy expenditure, sleep, physical activity), age, household income and Tanner stage were covariates in sex-stratified partial least squares analyses.

RESULTS

Daily energy expenditure and income were negatively associated with adiposity for both sexes. Television time was consistently positively associated with adiposity. In boys only, prolonged bouts of sedentary behaviour and time spent playing video games/computer were positively linked with adiposity. Non-screen sedentary behaviour was negatively associated with adiposity in girls. Independent of total energy expenditure, total sedentary time was only inconsistently associated with fatness.

CONCLUSIONS

These data suggest that (1) characteristics of sedentary time other than duration are associated with adiposity in children, and (2) associations may be sex-specific.

Breaking up sedentary time with seated upper body activity can regulate metabolic health in obese high-risk adults: A randomized crossover trial

AIMS

To investigate the impact of performing short bouts of seated upper body activity on postprandial blood glucose and insulin levels during prolonged sitting.

METHODS

Participants undertook two 7.5-hour experimental conditions in randomized order: (1) prolonged sitting only and (2) sitting, interspersed with 5 minutes of seated arm ergometry every 30 minutes. Blood samples were obtained while fasting and throughout the postprandial period after ingestion of two standardized meals. The incremental area under the curve (iAUC) was calculated for glucose and insulin throughout each experimental condition. A paired samples t-test was used to assess the difference in iAUC data between conditions for glucose (primary outcome) and insulin (secondary outcome).

RESULTS

Thirteen obese adults (7 women, 6 men; mean ± standard deviation [s.d.] age: 66 ± 6 years; body mass index 33.8 ± 3.8 kg/m² ) completed this investigation. Compared with the prolonged sitting-only condition, the implementation of seated arm ergometry every 30 minutes significantly reduced mean blood glucose iAUC (from 7.4 mmol/L/h [95% confidence interval {CI} 5.2, 9.5] to 3.1 mmol/L/h [95% CI 1.3, 5.0]; P = .001). Significant reductions in mean insulin iAUC (from 696 mU/L/h [95% CI 359, 1032] to 554 mU/L/h [95% CI 298, 811]; P = .047) were also observed.

CONCLUSION

Performing short bouts of arm ergometry during prolonged sitting attenuated postprandial glycaemia despite maintaining a seated posture. This may have clinical significance for those with weight-bearing difficulty who may struggle with postural change.

Evaluation of an accident and emergency teleconsultation service for north-east Scotland

We evaluated an accident and emergency teleconsultation service provided to 14 community hospitals in north-east Scotland. Each community hospital was equipped with a videoconferencing system and a document camera to allow transmission of radiographs. The network used 384 kbit/s ISDN connections. A total of 1392 teleconsultations were recorded during a 12-month study period. Seventy-seven per cent of patients ( n = 1072) were managed locally and 23% ( n = 320) were transferred to Aberdeen. The majority (95%) of teleconsultations were conducted on weekdays, and 90% of these occurred between the hours of 09:00 and 16:00. The mean delay in contacting a doctor was 9 min and the mean consultation time was 10 min. The majority of patients were suffering from fractures or suspected fractures of the limbs. Radiograph transmission was used in 75% of all teleconsultations. A high degree of satisfaction was recorded by all users of the service.

Objectively-assessed and self-reported sedentary time in relation to multiple socioeconomic status indicators among adults in England: a cross-sectional study

OBJECTIVES

To examine the associations between socioeconomic position (SEP) and multidomain self-reported and objectively-assessed sedentary time (ST).

DESIGN

Cross-sectional.

SETTING

General population households in England.

PARTICIPANTS

2289 adults aged 16-96 years who participated in the 2008 Health Survey for England.

OUTCOMES

Accelerometer-measured ST, and self-reported television time, non-television leisure-time sitting and occupational sitting/standing. We examined multivariable associations between household income, social class, education, area deprivation for each SEP indicator (including a 5-point composite SEP score computed by aggregating individual SEP indicators) and each ST indicator using generalised linear models.

RESULTS

Accelerometry-measured total ST and occupational sitting/standing were positively associated with SEP score and most of its constituent SEP indicators, while television time was negatively associated with SEP score and education level. Area-level deprivation was largely unrelated to ST. Those in the lowest composite SEP group spent 64 (95% CIs 52 to 76) and 72 (48 to 98), fewer minutes/day in total ST and occupational sitting/standing compared to those in the top SEP group, and an additional 48 (35-60) min/day watching television (p<0.001 for linear trend). Stratified analyses showed that these associations between composite SEP score and total ST were evident only among participants who were in employment.

CONCLUSIONS

Occupational sitting seems to drive the positive association between SEP and total ST. Lower SEP is linked to higher TV viewing times.

Children's and adolescents' sedentary behaviour in relation to socioeconomic position

BACKGROUND

Sedentary behaviour is an emerging cardiometabolic risk factor in young people. Little is known about how socioeconomic position (SEP) and sedentary behaviour are associated in children and adolescents. This study examines associations between SEP and sedentary behaviour in school-age children and adolescents.

METHODS

The core sample comprised 3822 Health Survey for England 2008 participants aged 5-15 years with complete information on SEP (household income, head of household occupational social class and area deprivation) and self-reported sedentary time (television viewing and other sitting during non-school times). Accelerometer-measured total sedentary time was measured in a subsample (N=587). We examined multivariable associations between SEP (including a composite SEP score) and sedentary time using generalised linear models, adjusting for age, sex, body mass index, physical activity, accelerometer wear time and mutually adjusting for the other SEP indicators.

RESULTS

Participants in the highest SEP category spent 16 min/day less (95% CI 6 to 25, p=0.003) watching TV than participants in the lowest SEP category; yet they spent 7 (2 to 16, p=0.010) and 17 (5 to 29, p<0.000) min/day more in non-TV sitting and total (accelerometry-measured) sedentary time, respectively. Associations across individual SEP components varied in strength. Area deprivation was not associated with sedentary time.

CONCLUSIONS

Low SEP is linked with higher television times but with lower total (accelerometer-measured) sedentary time, and non-TV sitting during non-school time in children and adolescents. Associations between sedentary time and SEP differ by type of sedentary behaviour. TV viewing is not a good proxy for total sedentary time in children.

Calibration and validation of wearable monitors

BACKGROUND

Wearable monitors are increasingly being used to objectively monitor physical activity in research studies within the field of exercise science. Calibration and validation of these devices are vital to obtaining accurate data. This article is aimed primarily at the physical activity measurement specialist, although the end user who is conducting studies with these devices also may benefit from knowing about this topic.

BEST PRACTICES

Initially, wearable physical activity monitors should undergo unit calibration to ensure interinstrument reliability. The next step is to simultaneously collect both raw signal data (e.g., acceleration) from the wearable monitors and rates of energy expenditure, so that algorithms can be developed to convert the direct signals into energy expenditure. This process should use multiple wearable monitors and a large and diverse subject group and should include a wide range of physical activities commonly performed in daily life (from sedentary to vigorous).

FUTURE DIRECTIONS

New methods of calibration now use "pattern recognition" approaches to train the algorithms on various activities, and they provide estimates of energy expenditure that are much better than those previously available with the single-regression approach. Once a method of predicting energy expenditure has been established, the next step is to examine its predictive accuracy by cross-validating it in other populations. In this article, we attempt to summarize the best practices for calibration and validation of wearable physical activity monitors. Finally, we conclude with some ideas for future research ideas that will move the field of physical activity measurement forward.

Risk factors for psychological distress following injury

OBJECTIVES

To identify predictors of psychological morbidity among injured patients admitted to an Emergency Department (ED).

DESIGN

A prospective cohort study.

PARTICIPANTS

Participants were consecutive male ED attenders. 210 (97.7%) patients consented to participate. At one month, 128 (61.0%) responded, at six months, 114 (54.3%), at eighteen months 96 (45.7%).

MAIN OUTCOME MEASURES

Measures immediately following injury were the Hospital Anxiety and Depression Scale, the Eysenck Personality Questionnaire and the McGill pain questionnaire. Recovery at one month was recorded using the SF-36 Health Survey, COPE scale, Perceived Stress Scale and Revised Impact of Events Scale. At six and eighteen months outcome was measured using the General Health Questionnaire (28 items) and Revised Impact of Events Scale. Multivariate analysis identified pre-morbid, accident-related and recovery factors influencing outcome at six and eighteen months.

RESULTS

The strongest predictors of outcome were initial levels of anxiety and depression, prior history of mental health problems, early PTSD symptoms and involvement in litigation. These factors predicted between 40-60% of the variance at six months (p<0.001), and 50-60% of the variance in psychological distress at eighteen months (p<0.001).

CONCLUSION

Factors identifying individuals at-risk from psychological distress following injury include those related to the immediate response and the recovery phases of injury. Further development is needed to convert identified predictors into a comprehensive screening tool for clinical use.

Bone vibration measurement using ultrasound: application to detection of hip prosthesis loosening

Hip prosthesis loosening can be determined in vivo using a vibration-based technique called vibrometry. In this technique, a low frequency (<1000Hz) sinusoidal vibration is applied to the femoral condyles and the resulting vibration is measured at the greater trochanter. If the prosthesis is securely fixed, the output vibration signal matches that of the input vibration, whereas if the prosthesis is loose, the output vibration signal is distorted and shows the marked presence of harmonics of the input frequency. One of the main problems with this application of this technique is in measuring the output vibration where significant amounts of soft tissue cover the measurement site. In order to circumvent this problem, an ultrasound probe, normally used for the measurement of blood flow, has been used to measure the output vibration. This has been evaluated by comparing the results obtained from the ultrasound probe with those from a conventional accelerometer in models representing a tight and loose hip prosthesis under simulated clinical conditions. The ultrasound probe was able to consistently detect the output vibration, for both the loose and secure prostheses. Under the test conditions used (which attempted to simulate a large thickness of soft tissue), the ultrasound probe was able to produce a greatly enhanced output vibration signal compared to the accelerometer. This suggests that the use of an ultrasound probe to detect mechanically induced vibration through significant amounts of soft tissue appears to be viable and could lead to enhanced detection of prosthesis loosening using this technique.

The role of angioplasty in acute myocardial infarction

Most patients in the UK with an acute myocardial infarction (MI) are treated with thrombolysis. This article discusses the role of primary coronary angioplasty as the first-line treatment for acute MI.

Minor injuries telemedicine

A minor injuries telemedicine network in Grampian connects 14 accident and emergency departments in community hospitals to a teaching hospital department. In a six-month study, 407 new telemedicine consultations met the inclusion criteria. Rates of transfer for treatment to the base hospital were used as an outcome measure. Fourteen out of a total of 19 members of medical staff gave telemedical advice. They were mainly middle-grade accident and emergency doctors. Transfer rates were 16-48% (median 29%) across staff. The rates did not seem to be affected by the base doctor's seniority, but were a reflection of that doctor's experience of and confidence in using videoconferencing equipment for clinical purposes. Transfer rates decreased as experience increased. Training for doctors undertaking the provision of specialist advice should include the clinical practicalities of making remote diagnoses.

An evaluation of a telemedicine fracture review clinic

Telemedicine is being widely used in the treatment of patients with minor injuries in north-east Scotland. A telemedicine fracture review clinic has been developed. During a one-month study period there were a total of 67 review appointments and 88 new patients. Fifty individual patients were reviewed and 10 were seen on more than one occasion. The mean number of reviews for all patients was 2.3. Thirty-six patients had initially been seen by telemedicine, six of whom (17%) had to come to Aberdeen for part of their treatment. Fourteen patients reviewed by telemedicine had initially been seen in person. All patients were safely managed and normal guidelines were followed. There is scope for significant expansion of this service, since 131 patients were seen in a fracture clinic in Aberdeen who lived close to a minor injury unit with telemedicine and X-ray facilities. The majority of these patients were likely to have had injuries suitable to be followed up using telemedicine.

A role for tele-education in the centralization of accident and emergency services

We evaluated the use of tele-education to provide an induction programme for accident and emergency senior house officers (SHOs) in three remote locations, and compared their performance with that of SHOs receiving the same induction programme in the conventional manner. Both groups of doctors performed similarly in a pre-course multiple-choice question (MCQ) paper, and showed comparable improvement following the induction programme lectures. Sound quality and levels of interactivity were identified as areas for improvement in the tele-education programme. Tele-education might allow doctors based in peripheral units similar access to high-quality teaching to that enjoyed by those in larger hospitals. Further experience and evaluation are required to optimize this method of education delivery.

The psychological burden of injury: an 18 month prospective cohort study

OBJECTIVES

To determine the prevalence of post-trauma psychological problems among a cohort of male accident and emergency department patients admitted to hospital. To identify the changes in their psychological symptoms over an 18 month follow up period.

METHODS

A prospective cohort study of male accident and emergency department patients who were admitted for treatment of an injury. Baseline interview recorded demographic details and accident details. Standardised questionnaires measured baseline psychological state and personality type. Follow up at six weeks, six months, and 18 months after injury was by face to face interview or postal questionnaire and recorded progress since injury, and documented psychological status through the use of standardised questionnaires to detect psychiatric disorder and symptoms of post-traumatic stress disorder (PTSD).

RESULTS

210 male patients were recruited into the study. Psychiatric disorder was identified in 47.6% of responders at six weeks, and 43.4% at six months after injury. This improved significantly at 18 months. PTSD symptoms were moderate in 25%-30% and severe in 5%-14% and did not change significantly over the study period. A significant relation was found between previous psychiatric history and psychological symptoms at 18 months after injury. No relation was identified between injury severity and psychological status after injury.

CONCLUSION

This study finds a high prevalence of psychological distress in male accident and emergency department patients after injury. Although some symptoms resolve over the follow up period, a proportion remain and may be related to previous psychiatric history. There was no relation identified between severity of injury and psychological morbidity.

Ocular manifestations of hindbrain-related syringomyelia and outcome following craniovertebral decompression

PURPOSE

To analyse and evaluate associated ocular symptoms and signs in hindbrain-related syringomyelia and their response to treatment.

METHODS

From a database of 275 patients treated in a single institution for hindbrain hernia and syringomyelia, 39 patients (14%) had ocular symptoms and signs. Only 31 patients were included in this study; the remainder were excluded due to inadequate follow-up information. All patients had confirmed evidence of hindbrain-related syringomyelia with MRI scan or CT myelogram. Treatment included craniovertebral decompression or ventriculo-peritoneal shunting. The mean follow-up was 23 months.

RESULTS

In addition to the well-recognised sign of downbeat nystagmus, classically associated with foramen magnum abnormalities, a number of other ophthalmic features were identified. Symptoms included diplopia, oscillopsia, tunnel vision and difficulty in lateral gaze. Signs included nystagmus (downbeat, horizontal, rotatory, and combinations), strabismus, disc pallor, anisocoria, ptosis and field defect. Patients were categorised into two groups depending on whether the ocular features were manifest at first presentation (group 1, n = 14) or developed later in the course of the disease (group 2, n = 17). The delay in diagnosis from first presentation was 5 and 6 years respectively. All patients underwent surgery. Craniovertebral decompression was performed in 13 patients in group 1 and in 15 patients in group 2. Ventriculo-peritoneal shunt was inserted in 1 patient in group 1 and in 3 patients in group 2, for the associated hydrocephalus. Following surgery, 100% of patients in group 1 and 82% of patients in group 2 had complete or partial resolution of their ocular symptoms and signs.

CONCLUSIONS

The presence of unexplained ophthalmic features such as nystagmus or oscillopsia should alert one to the potential diagnosis of hindbrain-related syringomyelia. Delay in diagnosis is often associated with poorer outcome. Surgical treatment can offer excellent results for these patients.

The effect of three different educational approaches on children's drawing ability: Steiner, Montessori and traditional

BACKGROUND

Although there is a national curriculum for art education in the UK there are also alternative approaches in the private sector. This paper addresses the issue of the effect of these approaches on children's drawing ability.

AIM

To compare the drawing ability in three drawing tasks of children in Steiner, Montessori and traditional schools.

SAMPLE

The participants were 60 school children between the ages of 5;11 and 7;2. Twenty children were tested in each type of school.

METHOD

Each child completed three drawings: a free drawing, a scene and an observational drawing.

RESULTS

As predicted, the free and scene drawings of children in the Steiner school were rated more highly than those of children in Montessori and traditional schools. Steiner children's use of colour was also rated more highly, although they did not use more colours than the other children. Steiner children used significantly more fantasy topics in their free drawings. Further observation indicated that the Steiner children were better at using the whole page and organising their drawings into a scene; their drawings were also more detailed. Contrary to previous research Montessori children did not draw more inanimate objects and geometrical shapes or fewer people than other children. Also, contrary to the prediction, Steiner children were significantly better rather than worse than other children at observational drawing.

CONCLUSION

The results suggest that the approach to art education in Steiner schools is conducive not only to more highly rated imaginative drawings in terms of general drawing ability and use of colour but also to more accurate and detailed observational drawings.

Post-traumatic stress disorder

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Nephrotic syndrome associated with N-hydroxyureas, inhibitors of 5-lipoxygenase

The N-hydroxyurea derivatives 70C ((E)-N-[3-[3- (4-fluorophenoxy)phenyl[-1-(R,S)-methylprop-2-enyl]-N-hydroxyurea) and its (R) 225C and (S) 404C enantiomers, which were being developed as 5-lipoxygenase inhibitors for the treatment of certain allergic and inflammatory conditions, were found to cause severe glomerulonephropathy in the rat. The lesion appeared to be of greater severity in female rats compared with male rats. In addition, 70C and 225C treated animals appeared more severely affected than 404C treated animals. Detailed examination of the lesion in animals dosed with 225C showed that there was a clear relationship between the onset of the lesion and the dose given, i.e. the higher the dose the sooner the lesion developed. The earliest changes detected in the kidney by transmission electron microscopy were noted in the glomeruli, in which the visceral cells appeared enlarged and showed varying degrees of foot process loss. In the more advanced lesion, the degree of foot process loss became more obvious and changes in the kidney tubules were seen by light microscopy. The morphological changes were mirrored by a dose-related increase in water consumption, an increased kidney to body weight ratio and gastrointestinal oedema, suggesting impaired renal function. Shortly after the onset of foot process loss, decreases in the total plasma protein and albumin and increases in the plasma cholesterol, triglycerides, urea and creatinine were recorded. These changes, particularly the foot-process loss, together with increased proteinuria, hypoalbuminaemia, hypercholesterolaemia and lipaemia, are all characteristic of "minimal change nephrotic syndrome". Because of the serious nature of the kidney lesion caused by these N-hydroxyureas in the rat, it was considered that it precluded their development as therapeutic agents for use in man.

Comparison of sexual behaviour and risk of HIV transmission of Scottish inmates, with or without a history of intravenous drug use

The sexual behaviour and intravenous drug use (IVDU) of a sample of 559 inmates (480 males and 79 females) was investigated. Sexual behaviour and IVDU prior to imprisonment, during imprisonment, and that expected after release, was assessed. Alterations in sexual behaviour as a means of HIV risk reduction was also assessed in relation to IVDU status. Prior to imprisonment most IVDUs and non-IVDUs engaged in unprotected intercourse. Sexual behaviour during imprisonment, as reported by inmates, was almost negligible for both groups. Expected sexual behaviour after imprisonment differed little from that before imprisonment for both IVDUs and non-IVDUs. Selecting partners more carefully and reducing their number was the most common method of HIV risk reduction for both IVDUs and non-IVDUs prior to imprisonment and was expected to be increasingly so after release. There was little difference in the sexual behaviour of IVDUs and non-IVDUs prior to imprisonment, during imprisonment, and as expected after release. However, IVDU inmates were more likely to have had an IVDU sexual partner than did non-IVDU inmates. Those IVDU inmates who had an HIV test, and those who had an IVDU sexual partner, were more likely to expect to continue IVDU after imprisonment. IVDU inmates, who had an IVDU sexual partner, were also more likely to have shared injected equipment but no more likely to have sterilized injecting equipment than did IVDU inmates whose sexual partner was not involved with IVDU. Results are discussed in relation to risk of HIV transmission for IVDUs and their sexual partners.

Intravenous drug use and HIV transmission amongst inmates in Scottish prisons

The intravenous drug use behaviour and HIV risk reduction strategies used by a group of Scottish inmates prior to prison, during imprisonment and as expected after release was investigated. From a sample of 559 inmates (480 males and 79 females) 27.5% were involved in IVDU prior to imprisonment, 7.7% on at least one occasion during a period of imprisonment and 14.7% expected to do so after release. Prior to imprisonment 17.3% had shared needles, 5.7% at some time during imprisonment and 4.3% expected to do so after release. Some form of HIV risk reduction strategies were practised by the majority of IVDU inmates prior to imprisonment, during imprisonment and were expected to continue after release. The most at risk inmates were those who continued to share injecting equipment without reduction and without sterilizing. The reduction in IVDU and needle sharing during imprisonment in comparison to prior to imprisonment was paralleled by a self-perceived reduction of personal risk from HIV during imprisonment.