Constraining China's land carbon sink from emerging satellite CO2 observations: Progress and challenges

Land carbon sink is a vital component for the achievement of China's ambitious carbon neutrality goal, but its magnitude is poorly known. Atmospheric observations and inverse models are valuable tools to constrain the China's land carbon sink. Space-based CO₂ measurements from satellites form an emerging data stream for application of such atmospheric inversions. Here, we reviewed the satellite missions that is dedicated to the monitoring of CO₂ , and the recent progresses on the inversion of China's land carbon sink using satellite CO₂ measurements. We summarized the limitations and challenges in current space platforms, retrieval algorithms, and the inverse modeling. It is shown that there are large uncertainties of contemporary satellite-based estimates of China's land carbon sink. We discussed future opportunities of continuous improvements in three aspects to better constrain China's land carbon sink with space-based CO₂ measurements.

Early cryoprecipitate transfusion versus standard care in severe postpartum haemorrhage: a pilot cluster-randomised trial

There is a lack of evidence evaluating cryoprecipitate transfusion in severe postpartum haemorrhage. We performed a pilot cluster‐randomised controlled trial to evaluate the feasibility of a trial on early cryoprecipitate delivery in severe postpartum haemorrhage. Pregnant women (>24 weeks gestation), actively bleeding within 24 h of delivery and who required at least one unit of red blood cells were eligible. Women declining transfusion in advance or with inherited clotting deficiencies were not eligible. Four UK hospitals were randomly allocated to deliver either the intervention (administration of two pools of cryoprecipitate within 90 min of first red blood cell unit requested plus standard care), or the control group treatment (standard care, where cryoprecipitate is administered later or not at all). The primary outcome was the proportion of women who received early cryoprecipitate (intervention) vs. standard care (control). Secondary outcomes included consent rates, acceptability of the intervention, safety outcomes and preliminary clinical outcome data to inform a definitive trial. Between March 2019 and January 2020, 199 participants were recruited; 19 refused consent, leaving 180 for analysis (110 in the intervention and 70 in the control group). Adherence to assigned treatment was 32% (95%CI 23–41%) in the intervention group vs. 81% (95%CI 70–90%) in the control group. The proportion of women receiving cryoprecipitate at any time‐point was higher in the intervention (60%) vs. control (31%) groups; the former had fewer red blood cell transfusions at 24 h (mean difference −0.6 units, 95%CI −1.2 to 0); overall surgical procedures (odds ratio 0.6, 95%CI 0.3–1.1); and intensive care admissions (odds ratio 0.4, 95%CI 0.1–1.1). There was no increase in serious adverse or thrombotic events in the intervention group. Staff interviews showed that lack of awareness and uncertainty about study responsibilities contributed to lower adherence in the intervention group. We conclude that a full‐scale trial may be feasible, provided that protocol revisions are put in place to establish clear lines of communication for ordering early cryoprecipitate in order to improve adherence. Preliminary clinical outcomes associated with cryoprecipitate administration are encouraging and merit further investigation.

P6203Intramyocellular lipid saturation as a new metabolic biomarker

Background

Endurance trained athletic healthy volunteers (Athl-HV) and type 2 diabetes patients (T2D) have higher levels of lipids in their skeletal myocytes compared to healthy controls. Despite apparently similar metabolic storage, they are at opposite ends of insulin sensitivity and cardio-metabolic risk.

Purpose

We investigated if the degree of saturation of the IntraMyoCellular Lipids (IMCL) will differentiate Athl-HV from T2D; and explored if an exercise intervention will induce changes in the IMCL saturation.

Methods

Male, age matched Athl-HV and T2D were enrolled (n=25/group). Athl-HV had ≥5 years endurance training, T2D were sedentary. Subjects were studied at baseline and after an exercise intervention (4 week deconditioning in Athl-HV and supervised bike training at ≥65% of peakVO2, 5 hours/week x 8 weeks in T2D). All subjects underwent cardio-pulmonary exercise testing (CPET), blood sampling for insulin sensitivity (QUICKI*) and single voxel 1H-magnetic resonance spectroscopy (1H-MRS) of the right vastus lateralis. 1H-MRS was acquired on 3T Philips Achieva with a 16-channel coil, point-resolved spectroscopy, variable pulse power and optimized relaxation delay water suppression and analysed in LCModel. We derived fractional lipid mass (fLM) and fractions of saturated (fSL) and unsaturated (fUL) lipids. Data were analysed by t tests, shown as mean±SEM, statistical significance p<0.05.

Results

CPET and insulin sensitivity are presented in Table 1. T2D had higher fLM in the skeletal muscle compared to Athl-HV, at baseline (p=0.003) and after the exercise intervention (p=0.009), Figure 1A. At baseline, T2D had a different phenotype with a lower fSL and higher fUL compared to Athl-HV (82±3 vs 88±1% and 18±3 vs 12±1%, p=0.02 for both). Whilst deconditioning did not attract any significant changes in either fSL or fUL in Athl-HV (88±1 to 86±1% and 12±1 to 14±1, p=0.2), in contrast, with exercise training T2D significantly increased fSL (82±3 to 88±1%) and decreased their fUL (18±3 to 12±1%) (both p=0.01). Figure 1B and 1C.

CPET and insulin sensitivity results Athl-HV Baseline Athl-HV Deconditioning p value T2D Baseline T2D After Training p value VO2 peak, (mL/kg/min) 45.0±0.9† 41.7±0.9‡ <0.0001 23.6±0.6† 30.3±0.6‡ <0.0001 QUICKI* 0.346±0.002† 0.343±0.003‡ 0.2 0.308±0.004† 0.317±0.004‡ 0.02 *QUICKI: Quantitative Insulin Sensitivity Check Index; †Athl-HV vs T2D at baseline p≤0.001, ‡Athl-HV vs T2D after exercise intervention p≤0.001.

Figure 1

Conclusion

We demonstrate for the first time, in vivo, significant differences in the IMCL amount and saturation between Athl-HV and T2D. IMCL saturation was changed by exercise training in T2D to mirror the phenotype seen in Athl-HV uncovering a new, independent biomarker of improved cardio-metabolic health.

Acknowledgement/Funding

British Heart Foundation Project Grant no. PG/15/88/31780

Global Sources of Fine Particulate Matter: Interpretation of PM2.5 Chemical Composition Observed by SPARTAN using a Global Chemical Transport Model

Exposure to ambient fine particulate matter (PM_2.5) is a leading risk factor for the global burden of disease. However, uncertainty remains about PM_2.5 sources. We use a global chemical transport model (GEOS-Chem) simulation for 2014, constrained by satellite-based estimates of PM_2.5 to interpret globally dispersed PM_2.5 mass and composition measurements from the ground-based surface particulate matter network (SPARTAN). Measured site mean PM_2.5 composition varies substantially for secondary inorganic aerosols (2.4-19.7 μg/m³), mineral dust (1.9-14.7 μg/m³), residual/organic matter (2.1-40.2 μg/m³), and black carbon (1.0-7.3 μg/m³). Interpretation of these measurements with the GEOS-Chem model yields insight into sources affecting each site. Globally, combustion sectors such as residential energy use (7.9 μg/m³), industry (6.5 μg/m³), and power generation (5.6 μg/m³) are leading sources of outdoor global population-weighted PM_2.5 concentrations. Global population-weighted organic mass is driven by the residential energy sector (64%) whereas population-weighted secondary inorganic concentrations arise primarily from industry (33%) and power generation (32%). Simulation-measurement biases for ammonium nitrate and dust identify uncertainty in agricultural and crustal sources. Interpretation of initial PM_2.5 mass and composition measurements from SPARTAN with the GEOS-Chem model constrained by satellite-based PM_2.5 provides insight into sources and processes that influence the global spatial variation in PM_2.5 composition.

Source influence on emission pathways and ambient PM2.5 pollution over India (2015-2050)

India is currently experiencing degraded air quality, and future economic development will lead to challenges for air quality management. Scenarios of sectoral emissions of fine particulate matter and its precursors were developed and evaluated for 2015-2050, under specific pathways of diffusion of cleaner and more energy-efficient technologies. The impacts of individual source sectors on PM_2.5 concentrations were assessed through systematic simulations of spatially and temporally resolved particulate matter concentrations, using the GEOS-Chem model, followed by population-weighted aggregation to national and state levels. We find that PM_2.5 pollution is a pan-India problem, with a regional character, and is not limited to urban areas or megacities. Under present-day emissions, levels in most states exceeded the national PM_2.5 annual standard (40 μg m^-3). Sources related to human activities were responsible for the largest proportion of the present-day population exposure to PM_2.5 in India. About 60 % of India's mean population-weighted PM_2.5 concentrations come from anthropogenic source sectors, while the remainder are from "other" sources, windblown dust and extra-regional sources. Leading contributors are residential biomass combustion, power plant and industrial coal combustion and anthropogenic dust (including coal fly ash, fugitive road dust and waste burning). Transportation, brick production and distributed diesel were other contributors to PM_2.5. Future evolution of emissions under regulations set at current levels and promulgated levels caused further deterioration of air quality in 2030 and 2050. Under an ambitious prospective policy scenario, promoting very large shifts away from traditional biomass technologies and coal-based electricity generation, significant reductions in PM_2.5 levels are achievable in 2030 and 2050. Effective mitigation of future air pollution in India requires adoption of aggressive prospective regulation, currently not formulated, for a three-pronged switch away from (i) biomass-fuelled traditional technologies, (ii) industrial coal-burning and (iii) open burning of agricultural residue. Future air pollution is dominated by industrial process emissions, reflecting larger expansion in industrial, rather than residential energy demand. However, even under the most active reductions envisioned, the 2050 mean exposure, excluding any impact from windblown mineral dust, is estimated to be nearly 3 times higher than the WHO Air Quality Guideline.

Incident ischaemic stroke and Type 2 diabetes: trends in incidence and case fatality in Scotland 2004-2013

AIM

To describe trends in first ischaemic stroke incidence and case fatality in adults with and without a diagnosis of Type 2 diabetes prior to their ischaemic stroke event in Scotland between 2004 and 2013.

METHODS

Using population-wide hospital admission, death and diabetes datasets, we conducted a retrospective cohort study. Negative binomial and logistic regression models were used to calculate year-specific incidence and case-fatality rates for people with Type 2 diabetes and for people without diabetes.

RESULTS

During 41.0 million person-years of follow-up there were 69 757 ischaemic stroke events. Type 2 diabetes prevalence among patients who experienced ischaemic stroke increased from 13.5% to 20.3% between 2004 and 2013. Stroke incidence rates declined by 2.7% (95% CI 2.4, 3.0) annually for people with and without diabetes [diabetes/year interaction: rate ratio 0.99 (95% CI 0.98, 1.01)]. Type 2 diabetes was associated with an increased risk of ischaemic stroke in men [rate ratio 1.23 (95% CI 1.17, 1.30)] and women [rate ratio 1.41 (95% CI 1.35, 1.48)]. Case-fatality rates were 14.2% and 12.7% in people with Type 2 diabetes and without diabetes, respectively. Case fatality declined by 3.5% (95% CI 2.7, 4.5) annually [diabetes/year interaction: odds ratio 1.01 (95% CI 0.98, 1.02)].

CONCLUSIONS

Ischaemic stroke incidence declined no faster in people with a diagnosis of Type 2 diabetes than in people without diabetes. Increasing prevalence of Type 2 diabetes among stroke patients may mean that declines in case fatality over time will be less marked in the future.

Modelling the cost-effectiveness of adopting risk-stratified approaches to extended screening intervals in the national diabetic retinopathy screening programme in Scotland

AIMS

To assess the cost-effectiveness of adopting risk-stratified approaches to extended screening intervals in the national diabetic retinopathy screening programme in Scotland.

METHODS

A continuous-time hidden Markov model was fitted to national longitudinal screening data to derive transition probabilities between observed non-referable and referable retinopathy states. These were incorporated in a decision model simulating progression, costs and visual acuity outcomes for a synthetic cohort with a covariate distribution matching that of the Scottish diabetic screening population. The cost-effectiveness of adopting extended (2-year) screening for groups with no observed retinopathy was then assessed over a 30-year time horizon.

RESULTS

Individuals with a current grade of no retinopathy on two consecutive screening episodes face the lowest risk of progressing to referable disease. For the cohort as a whole, the incremental cost per quality-adjusted life year gained for annual vs. biennial screening ranged from approximately £74 000 (for those with no retinopathy and a prior observed grade of mild or observable background retinopathy) to approximately £232 000 per quality-adjusted life year gained (for those with no retinopathy on two consecutive screening episodes). The corresponding incremental cost-effectiveness ratios in the subgroup with Type 1 diabetes were substantially lower; approximately £22 000 to £85 000 per quality-adjusted life year gained, respectively.

CONCLUSIONS

Biennial screening for individuals with diabetes who have no retinopathy is likely to deliver significant savings for a very small increase in the risk of adverse visual acuity and quality of life outcomes. There is greater uncertainty regarding the long-term cost-effectiveness of adopting biennial screening in younger people with Type 1 diabetes.

A New Method to Jointly Estimate the Mortality Risk of Long-Term Exposure to Fine Particulate Matter and its Components

Most studies on the association between exposure to fine particulate matter (PM2.5) and mortality have considered only total concentration of PM2.5 or individual components of PM2.5, and not the combined effects of concentration and particulate composition. We sought to develop a method to estimate the risk of death from long-term exposure to PM2.5 and the distribution of its components, namely: sulphate, nitrate, ammonium, organic mass, black carbon, and mineral dust. We decomposed PM2.5 exposure into the sum of total concentration and the proportion of each component. We estimated the risk of death due to exposure using a cohort of ~2.4 million Canadians who were followed for vital status over 16 years. Modelling the concentration of PM2.5 with the distribution of the proportions of components together was a superior predictor for mortality than either total PM2.5 concentration alone, or all component concentrations modelled together. Our new approach has the advantage of characterizing the toxicity of the atmosphere in its entirety. This is required to fully understand the health benefits associated with strategies to improve air quality that may result in complex changes not only in PM2.5 concentration, but also in the distribution of particle components.

Retrospective evaluation of low long-term efficacy of antiepileptic drugs and ketogenic diet in 39 patients with CDKL5-related epilepsy

OBJECTIVE

Mutations in the CDKL5 gene cause an early-onset epileptic encephalopathy. To date, little is known about effective antiepileptic treatment in this disorder.

METHOD

Accordingly, the aim of this retrospective study was to explore the role of different antiepileptic drugs (AEDs) and the ketogenic diet (KD) in the treatment of this rare genetic disorder. We evaluated the efficacy in 39 patients with CDKL5 mutations at 3, 6 and 12 months after the introduction of each treatment. One patient was lost to follow-up after 6 and 12 months.

RESULTS

The responder rate (>50% reduction in seizure frequency) to at least one AED or KD was 69% (27/39) after 3 months, 45% (17/38) after 6 months and 24% (9/38) after 12 months. The highest rate of seizure reduction after 3 months was reported for FBM (3/3), VGB (8/25), CLB (4/17), VPA (7/34), steroids (5/26), LTG (5/23) and ZNS (2/11). Twelve patients (31%) experienced a seizure aggravation to at least one AED. Most patients showed some but only initial response to various AEDs with different modes of actions.

SIGNIFICANCE

Considering both age-related and spontaneous fluctuation in seizure frequency and the unknown impact of many AEDs or KD on cognition, our data may help defining realistic treatment goals and avoiding overtreatment in patients with CDKL5 mutations. There is a strong need to develop new treatment strategies for patients with this rare mutation.

End-stage renal disease and survival in people with diabetes: a national database linkage study

BACKGROUND

Increasing prevalence of diabetes worldwide is projected to lead to an increase in patients with end-stage renal disease (ESRD) requiring renal replacement therapy (RRT).

AIM

To provide contemporary estimates of the prevalence of ESRD and requirement for RRT among people with diabetes in a nationwide study and to report associated survival.

METHODS

Data were extracted and linked from three national databases: Scottish Renal Registry, Scottish Care Initiative-Diabetes Collaboration and National Records of Scotland death data. Survival analyses were modelled with Cox regression.

RESULTS

Point prevalence of chronic kidney disease (CKD)5 in 2008 was 1.63% of 19 414 people with type 1 diabetes (T1DM) compared with 0.58% of 167 871 people with type 2 diabetes (T2DM) (odds ratio for DM type 0.97, P = 0.77, on adjustment for duration. Although 83% of those with T1DM and CKD5 and 61% of those with T2DM and CKD5 were receiving RRT, there was no difference when adjusted for age, sex and DM duration (odds ratio for DM type 0.83, P = 0.432). Diabetic nephropathy was the primary renal diagnosis in 91% of people with T1DM and 58% of people with T2DM on RRT. Median survival time from initiation of RRT was 3.84 years (95% CI 2.77, 4.62) in T1DM and 2.16 years (95% CI: 1.92, 2.38) in T2DM.

CONCLUSION

Considerable numbers of patients with diabetes continue to progress to CKD5 and RRT. Almost half of all RRT cases in T2DM are considered to be due to conditions other than diabetic nephropathy. Median survival time for people with diabetes from initiation of RRT remains poor. These prevalence data are important for future resource planning.

Global chemical composition of ambient fine particulate matter for exposure assessment

Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004-2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m(3)), secondary inorganic aerosol (11.1 ± 5.0 μg/m(3)), and mineral dust (11.1 ± 7.9 μg/m(3)). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m(3) over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m(3)) could be almost as large as from fossil fuel combustion sources (17 μg/m(3)). These estimates offer information about global population exposure to the chemical components and sources of PM2.5.

Improving the economic value of photographic screening for optical coherence tomography-detectable macular oedema: a prospective, multicentre, UK study

OBJECTIVES

To determine the best photographic surrogate markers for detecting sight-threatening macular oedema (MO) in people with diabetes attending UK national screening programmes.

DESIGN

A multicentre, prospective, observational cohort study of 3170 patients with photographic signs of diabetic retinopathy visible within the macular region [exudates within two disc diameters, microaneurysms/dot haemorrhages (M/DHs) and blot haemorrhages (BHs)] who were recruited from seven study centres.

SETTING

All patients were recruited and imaged at one of seven study centres in Aberdeen, Birmingham, Dundee, Dunfermline, Edinburgh, Liverpool and Oxford.

PARTICIPANTS

Subjects with features of diabetic retinopathy visible within the macular region attending one of seven diabetic retinal screening programmes.

INTERVENTIONS

Alternative referral criteria for suspected MO based on photographic surrogate markers; an optical coherence tomographic examination in addition to the standard digital retinal photograph.

MAIN OUTCOME MEASURES

(1) To determine the best method to detect sight-threatening MO in people with diabetes using photographic surrogate markers. (2) Sensitivity and specificity estimates to assess the costs and consequences of using alternative strategies. (3) Modelled long-term costs and quality-adjusted life-years (QALYs).

RESULTS

Prevalence of MO was strongly related to the presence of lesions and was roughly five times higher in subjects with exudates or BHs or more than two M/DHs within one disc diameter. Having worse visual acuity was associated with about a fivefold higher prevalence of MO. Current manual screening grading schemes that ignore visual acuity or the presence of M/DHs could be improved by taking these into account. Health service costs increase substantially with more sensitive/less specific strategies. A fully automated strategy, using the automated detection of patterns of photographic surrogate markers, is superior to all current manual grading schemes for detecting MO in people with diabetes. The addition of optical coherence tomography (OCT) to each strategy, prior to referral, results in a reduction in costs to the health service with no decrement in the number of MO cases detected.

CONCLUSIONS

Compared with all current manual grading schemes, for the same sensitivity, a fully automated strategy, using the automated detection of patterns of photographic surrogate markers, achieves a higher specificity for detecting MO in people with diabetes, especially if visual acuity is included in the automated strategy. Overall, costs to the health service are likely to increase if more sensitive referral strategies are adopted over more specific screening strategies for MO, for only very small gains in QALYs. The addition of OCT to each screening strategy, prior to referral, results in a reduction in costs to the health service with no decrement in the number of MO cases detected.

STUDY REGISTRATION

This study has been registered as REC/IRAS 07/S0801/107, UKCRN ID 9063 and NIHR HTA 06/402/49.

SOURCE OF FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 17, No. 51. See the HTA programme website for further project information.

Factors associated with statin treatment for the primary prevention of cardiovascular disease in people within 2 years following diagnosis of diabetes in Scotland, 2006-2008

AIM

To describe characteristics associated with statin prescribing for the primary prevention of cardiovascular disease in people with newly diagnosed diabetes.

METHODS

Data from the Scottish Care Information-Diabetes Collaboration data set for 2006-2008 were used. This data set contains socio-demographic and prescribing data for over 99% of people with diagnosed diabetes in Scotland. Analyses were conducted on people aged over 40 years diagnosed with Type 1 or Type 2 diabetes between 2006 and 2008 with complete data and no previous history of cardiovascular or statin prescription. Logistic regression was used to calculate odds ratios for statin prescription in the 2 years following diagnosis of diabetes.

RESULTS

There were 7157 men and 5601 women who met the inclusion criteria, 68% of whom had a statin prescription recorded in the 2 years following diagnosis of diabetes. The proportions receiving statins were lower above 65 years of age in men and 75 years of age in women. People with Type 1 diabetes had lower odds of receiving statins than people with Type 2 diabetes [odds ratio (95% CI) 0.42 (0.29-0.61) for men and 0.48 (0.28-0.81) for women, after adjustment for age, BMI, smoking status, cholesterol level and deprivation]. Higher total cholesterol, BMI and being a current smoker were associated with greater odds of statin prescription.

CONCLUSION

Approximately one third of the study population had no record of statin prescription during the 2 years after diagnosis of diabetes. Cardiovascular disease risk reduction opportunities may be missed in some of these people.

Rates of referable eye disease in the Scottish National Diabetic Retinopathy Screening Programme

AIMS

Diabetic retinopathy screening aims to detect people at risk of visual loss due to proliferative diabetic retinopathy, but also refers cases of suspected macular oedema (maculopathy). At the introduction of screening, ophthalmology was concerned that referral rates would be unmanageable. We report yield of referable disease by referral reason for the first 5 years of the programme.

METHODS

We extracted screening results from a nationwide clinical diabetes database to calculate annual referral rates to ophthalmic clinics. We used logistic regression to examine associations between clinical measures and referable disease.

RESULTS

182 397 people underwent ≥ 1successful retinal screening between 2006 and 2010. The yield of referable eye disease was highest in the first 2 years of screening (7.0% and 6.0%) before stabilising at ∼4.3%. The majority of referrals are due to maculopathy with 73% of referrals in 2010 based on a finding of maculopathy.

CONCLUSIONS

The commonest cause for referral is for suspected macular oedema (maculopathy). Referral rates for retinopathy have stabilised, as predicted, at relatively low rates. However, ophthalmology workload continues to rise as new treatment options (ie, monthly intraocular injections) have unexpectedly increased the impact on ophthalmology. A review of the screening referral path for maculopathy may be timely.

Predicted impact of extending the screening interval for diabetic retinopathy: the Scottish Diabetic Retinopathy Screening programme

AIMS/HYPOTHESIS

The aim of our study was to identify subgroups of patients attending the Scottish Diabetic Retinopathy Screening (DRS) programme who might safely move from annual to two yearly retinopathy screening.

METHODS

This was a retrospective cohort study of screening data from the DRS programme collected between 2005 and 2011 for people aged ≥12 years with type 1 or type 2 diabetes in Scotland. We used hidden Markov models to calculate the probabilities of transitions to referable diabetic retinopathy (referable background or proliferative retinopathy) or referable maculopathy.

RESULTS

The study included 155,114 individuals with no referable diabetic retinopathy or maculopathy at their first DRS examination and with one or more further DRS examinations. There were 11,275 incident cases of referable diabetic eye disease (9,204 referable maculopathy, 2,071 referable background or proliferative retinopathy). The observed transitions to referable background or proliferative retinopathy were lower for people with no visible retinopathy vs mild background retinopathy at their prior examination (respectively, 1.2% vs 8.1% for type 1 diabetes and 0.6% vs 5.1% for type 2 diabetes). The lowest probability for transitioning to referable background or proliferative retinopathy was among people with two consecutive screens showing no visible retinopathy, where the probability was <0.3% for type 1 and <0.2% for type 2 diabetes at 2 years.

CONCLUSIONS/INTERPRETATION

Transition rates to referable diabetic eye disease were lowest among people with type 2 diabetes and two consecutive screens showing no visible retinopathy. If such people had been offered two yearly screening the DRS service would have needed to screen 40% fewer people in 2009.

Type 2 diabetes, socioeconomic status and risk of cancer in Scotland 2001-2007

AIMS/HYPOTHESIS

The objective of this study was to use Scottish national data to assess the influence of type 2 diabetes on the risk of cancer at 16 different sites, while specifically investigating the role of confounding by socioeconomic status in the diabetes-cancer relationship.

METHODS

All people in Scotland aged 55-79 years diagnosed with any of the cancers of interest during the period 2001-2007 were identified and classified by the presence/absence of co-morbid type 2 diabetes. The influence of diabetes on cancer risk for each site was assessed via Poisson regression, initially with adjustment for age only, then adjusted for both age and socioeconomic status.

RESULTS

There were 4,285 incident cancers in people with type 2 diabetes. RR for any cancers (adjusted for age only) was 1.11 (95% CI 1.05, 1.17) for men and 1.33 (1.28, 1.40) for women. Corresponding values after additional adjustment for socioeconomic status were 1.10 (1.04, 1.15) and 1.31 (1.25, 1.38), respectively. RRs for individual cancer sites varied markedly.

CONCLUSIONS/INTERPRETATION

Socioeconomic status was found to have little influence on the association between type 2 diabetes and cancer.

External validity of randomized controlled trials of glycaemic control and vascular disease: how representative are participants?

AIMS

To describe the proportion of people with Type 2 diabetes living in Scotland who meet eligibility criteria for inclusion in several large randomized controlled trials of glycaemic control to inform physicians and guideline developers about the generalizibility of trial results.

METHODS

A literature review was performed to identify large trials assessing the impact of glycaemic control on risk of macrovascular disease. Inclusion and exclusion criteria from each trial were applied to data on the population of people with a diagnosis of Type 2 diabetes living in Scotland in 2008 (n = 180,590) in a population-based cross-sectional study and the number and proportion of people eligible for each trial was determined.

RESULTS

Seven trials were identified. The proportion of people with Type 2 diabetes who met the eligibility criteria for the trials ranged from 3.5 to 50.7%. Trial participants were younger at age of diagnosis of diabetes and at time of trial recruitment than in the Scottish study population. The application of upper age criteria excluded the largest proportion of patients, with up to 39% of people with Type 2 diabetes ineligible for a trial with the most stringent criteria based on age alone.

CONCLUSIONS

We found that many of the large trials of glycaemic control among people with Type 2 diabetes have limited external validity when applied to a population-based cohort of people with Type 2 diabetes. In particular, the age distribution of trial participants often does not reflect that of people with Type 2 diabetes in a contemporary British population.

Hospitalised hip fracture risk with rosiglitazone and pioglitazone use compared with other glucose-lowering drugs

AIMS/HYPOTHESIS

Current drug labels for thiazolidinediones (TZDs) warn of increased fractures, predominantly for distal fractures in women. We examined whether exposure to TZDs affects hip fracture in women and men and compared the risk to that found with other drugs used in diabetes.

METHODS

Using a nationwide database of prescriptions, hospital admissions and deaths in those with type 2 diabetes in Scotland we calculated TZD exposure among 206,672 individuals. Discrete-time failure analysis was used to model the effect of cumulative drug exposure on hip fracture during 1999-2008.

RESULTS

There were 176 hip fractures among 37,479 exposed individuals. Hip fracture risk increased with cumulative exposure to TZD: OR per year of exposure 1.18 (95% CI 1.09, 1.28; p = 3 × 10(-5)), adjusted for age, sex and calendar month. Hip fracture increased with cumulative exposure in both men (OR 1.20; 95% CI 1.03, 1.41) and women (OR 1.18; 95% CI 1.07, 1.29) and risks were similar for pioglitazone (OR 1.18) and rosiglitazone (OR 1.16). The association was similar when adjusted for exposure to other drugs for diabetes and for other potential confounders. There was no association of hip fracture with cumulative exposure to sulfonylureas, metformin or insulin in this analysis. The 90-day mortality associated with hip fractures was similar in ever-users of TZD (15%) and in never-users (13%).

CONCLUSIONS/INTERPRETATION

Hip fracture is a severe adverse effect with TZDs, affecting both sexes; labels should be changed to warn of this. The excess mortality is at least as much as expected from the reported association of pioglitazone with bladder cancer.

Diabetic retinopathy at diagnosis of type 2 diabetes in Scotland

AIMS/HYPOTHESIS

The aim of this study was to examine the prevalence of and risk factors for diabetic retinopathy in people with newly diagnosed type 2 diabetes mellitus, using Scottish national data.

METHODS

We identified individuals diagnosed with type 2 diabetes mellitus in Scotland between January 2005 and May 2008 using data from the national diabetes database. We calculated the prevalence of retinopathy and ORs for risk factors associated with retinopathy at first screening.

RESULTS

Of the 51,526 people with newly diagnosed type 2 diabetes mellitus identified, 91.4% had been screened by 31 December 2010. The median time to first screening was 315 days (interquartile range [IQR] 111-607 days), but by 2008 the median was 83 days (IQR 51-135 days). The prevalence at first screening of any retinopathy was 19.3%, and for referable retinopathy it was 1.9%. For individuals screened after a year the prevalence of any retinopathy was 20.5% and referable retinopathy was 2.3%. Any retinopathy at screening was associated with male sex (OR 1.19, 95% CI 1.14, 1.25), HbA(1c) (OR 1.07, 95% CI 1.06, 1.08 per 1% [11 mmol/mol] increase), systolic BP (OR 1.06, 95% CI 1.05, 1.08 per 10 mmHg increase), time to screening (OR for screening >1 year post diagnosis = 1.12, 95% CI 1.07, 1.17) and obesity (OR 0.87, 95% CI 0.82, 0.93) in multivariate analysis.

CONCLUSIONS/INTERPRETATION

The prevalence of retinopathy at first screening is lower than in previous UK studies, consistent with earlier diagnosis of diabetes. Most newly diagnosed type 2 diabetic patients in Scotland are screened within an acceptable interval and the prevalence of referable disease is low, even in those with delayed screening.

External quality assurance for image grading in the Scottish Diabetic Retinopathy Screening Programme

AIMS

To develop and evaluate an image grading external quality assurance system for the Scottish Diabetic Retinopathy Screening Programme.

METHOD

A web-based image grading system was developed which closely matches the current Scottish national screening software. Two rounds of external quality assurance were run in autumn 2008 and spring 2010, each time using the same 100 images. Graders were compared with a consensus standard derived from the top-level graders' results. After the first round, the centre lead clinicians and top-level graders reviewed the results and drew up guidance notes for the second round.

RESULTS

Grader sensitivities ranged from 60.0 to 100% (median 92.5%) in 2008, and from 62.5 to 100% (median 92.5%) in 2010. Specificities ranged from 34.0 to 98.0% (median 86%) in 2008, and 54.0 to 100% (median 88%) in 2010. There was no difference in sensitivity between grader levels, but first-level graders had a significantly lower specificity than level-two and level-three graders. In 2008, one centre had a lower sensitivity but higher specificity than the majority of centres. Following the feedback from the first round, overall agreement improved in 2010 and there were no longer any significant differences between centres.

CONCLUSIONS

A useful educational tool has been developed for image grading external quality assurance.

Bone metastases from prostate, breast and multiple myeloma: differences in lesion conspicuity at short-tau inversion recovery and diffusion-weighted MRI

OBJECTIVES

The objective of this study was to compare the relative conspicuity of bone metastases on short-tau inversion recovery (STIR) and diffusion-weighted MRI (DWI) whole-body MR sequences for breast, prostate and myeloma malignancies.

METHODS

44 whole-body MRI scans were reviewed retrospectively (coronal T(1) weighted, STIR and DWI with b=800). On each scan, up to four of the largest bone lesions were identified on T(1) weighting, and the region of interest signal intensity was measured on STIR and DWI, as well as the background signal intensity. The mean lesion signal to background ratio was calculated for each patient and then for each malignancy group.

RESULTS

In prostate cancer patients, the DWI signal/background ratio was greater than that of STIR in 22 out of 24 patients (mean DWI lesion/background ratio 3.91, mean STIR lesion/background ratio 2.31; p=0.0001). In multiple myeloma, the DWI ratio was higher in 6/7 patients (DWI group mean ratio 7.59, STIR group mean ratio 3.7; p=0.0366). In 13 breast cancer patients, mean STIR and DWI signal/background were similar (DWI group mean ratio 4.13, group mean STIR ratio 4.26; p=0.8587).

CONCLUSION

Bone lesion conspicuity measured by lesion/background signal intensity was higher on DWI b=800 than on STIR in patients with prostate cancer and multiple myeloma. DWI should be used in whole-body MR oncology protocols in these conditions to maximise lesion detection.

Do men develop type 2 diabetes at lower body mass indices than women?

AIMS/HYPOTHESIS

To describe the associations between age, sex and BMI at diagnosis of type 2 diabetes, and test the hypothesis that men are diagnosed with diabetes at lower average BMI than women of similar age.

METHODS

Linear regression was used to estimate and compare the relationship between age and BMI at diagnosis among 51,920 men and 43,137 women included in a population-based diabetes register in Scotland for whom an index BMI measurement was taken within 1 year of diabetes diagnosis. We also examined HbA(1c) values by sex within the same timescale.

RESULTS

Mean BMI closest to date of diagnosis of type 2 diabetes mellitus was 31.83 kg/m(2) (SD 5.13) in men and 33.69 kg/m(2) (SD 6.43) in women. The inverse relationship between age and BMI at diagnosis of type 2 diabetes mellitus was significantly steeper in women than in men (slope estimate in men -0.12 kg/m(2) per year [95% CI -0.13, -0.12] women -0.18 kg/m(2) per year [95% CI -0.18, -0.17], p < 0.0001 for formal test of interaction). Mean BMI difference was most marked at younger ages and narrowed with advancing age. However, HbA(1c) levels within 1 year of diagnoses were broadly similar in men and women.

CONCLUSIONS/INTERPRETATION

Men are diagnosed with type 2 diabetes at lower BMI than women across the age range. This observation may help explain why type 2 diabetes is more common among middle-aged men in populations of European extraction. Whether the same pattern is also observed in other ethnic groups requires confirmation.