Lower extremity amputation in people with diabetes: Trends and determinants

Introduction: The prevalence of diabetes is rising rapidly. Assessing quality of diabetes care is difficult. Lower Extremity Amputation (LEA) is recognised as a marker of the quality of diabetes care. The focus of this thesis was first to describe the trends in LEA rates in people with and without diabetes in the Republic of Ireland (RoI) in recent years and then, to explore the determinants of LEA in people with diabetes. While clinical and socio-demographic determinants have been well-established, the role of service-related factors has been less well-explored. Methods: Using hospital discharge data, trends in LEA rates in people with and without diabetes were described and compared to other countries. Background work included concordance studies exploring the reliability of hospital discharge data for recording LEA and diabetes and estimation of diabetes prevalence rates in the RoI from a nationally representative study (SLAN 2007). To explore determinants, a systematic review and meta-analysis assessed the effect of contact with a podiatrist on the outcome of LEA in people with diabetes. Finally, a case-control study using hospital discharge data explored determinants of LEA in people with diabetes with a particular focus on the timing of access to secondary healthcare services as a risk factor. Results: There are high levels of agreement between hospital discharge data and medical records for LEA and diabetes. Thus, hospital discharge data was deemed sufficiently reliable for use in this PhD thesis. A decrease in major diabetes-related LEA rates in people with diabetes was observed in the RoI from 2005-2012. In 2012, the relative risk of a person with diabetes undergoing a major LEA was 6.2 times (95% CI 4.8-8.1) that of a person without diabetes. Based on the systematic review and meta-analysis, contact with a podiatrist did not significantly affect the relative risk (RR) of LEA in people with diabetes. Results from the case-control study identified being single, documented CKD and documented hypertension as significant risk factors for LEA in people with diabetes whilst documented retinopathy was protective. Within the seven year time window included in the study, no association was detected between LEA in patients with diabetes and timing of patient access to secondary healthcare for diabetes management. Discussion: Many countries have reported reduced major LEA rates in people with diabetes coinciding with improved organisation of healthcare systems. Reassuringly, these first national estimates in people with diabetes in the RoI from 2005 to 2012 demonstrated reducing trends in major LEA rates. This may be attributable to changes in diabetes care and also, secular trends in smoking, dyslipidaemia and hypertension. Consistent with international practice, LEA trends data in Ireland can be used to monitor quality of care. Quantifying this improvement precisely, though, is problematic without robust denominator data on the prevalence of diabetes. However, a reduction in major diabetes-related LEA rates suggests improved quality of diabetes care. Much controversy exists around the reliability of hospital discharge data in the RoI. This thesis includes the first multi-site study to explore this issue and found hospital discharge data reliable for the reporting of the procedure of LEA and diagnosis of diabetes. This project did not detect protective effects of access to services including podiatry and secondary healthcare for LEA in people with diabetes. A major limitation of the systematic review and meta-analysis was the design and quality of the included studies. The data available in the area of effect of contact with a podiatrist on LEA risk are too sparse to say anything definitive about the efficacy of podiatry on LEA. Limitations of the case-control study include lack of a diabetes register in Ireland, restricted information from secondary healthcare and lack of data available from primary healthcare. Due to these issues, duration of disease could not be accounted for in the study which limits the conclusions that can be drawn from the results. The model of diabetes care in the RoI is currently undergoing a re-configuration with plans to introduce integrated care. In the future, trends in LEA rates should be continuously monitored to evaluate the effectiveness of changes to the healthcare system. Efforts are already underway to improve the availability of routine data from primary healthcare with the recent development of the iPCRN (Irish Primary Care Research Network). Linkage of primary and secondary healthcare records with a unique patient identifier should be the goal for the future.

Childhood obesity in Ireland: recent trends and modifiable determinants

Background: Childhood obesity is a global epidemic posing a significant threat to the health and wellbeing of children. To reverse this epidemic, it is essential that we gain a deeper understanding of the complex array of driving factors at an individual, family and wider ecological level. Using a social-ecological framework, this thesis investigates the direction, magnitude and contribution of risk factors for childhood overweight and obesity at multiple levels of influence, with a particular focus on diet and physical activity. Methods: A systematic review was conducted to describe recent trends (from 2002-2012) in childhood overweight and obesity prevalence in Irish school children from the Republic of Ireland. Two datasets (Cork Children’s Lifestyle [CCLaS] Study and the Growing Up in Ireland [GUI] Study) were used to explore determinants of childhood overweight and obesity. Individual lifestyle factors examined were diet, physical activity and sedentary behaviour. The determinants of physical activity were also explored. Family factors examined were parental weight status and household socio-economic status. The impact of food access in the local area on diet quality and body mass index (BMI) was investigated as an environmental level risk factor. Results: Between 2002 and 2012, the prevalence of childhood overweight and obesity in Ireland remained stable. There was some evidence to suggest that childhood obesity rates may have decreased slightly though one in four Irish children remained either overweight or obese. In the CCLaS study, overweight and obese children consumed more unhealthy foods than normal weight children. A diet quality score was constructed based on a previously validated adult diet score. Each one unit increase in diet quality was significantly associated with a decreased risk of childhood overweight and obesity. Individual level factors (including gender, being a member of a sports team, weight status) were more strongly associated with physical activity levels than family or environmental factors. Overweight and obese children were more sedentary and less active than normal weight children. There was a dose response relationship between time spent at moderate to vigorous physical activity (MVPA) and the risk of childhood obesity independent of sedentary time. In contrast, total sedentary time was not associated with the risk of childhood obesity independent of MVPA though screen time was associated with childhood overweight and obesity. In the GUI Study, only one in five children had 2 normal weight parents (or one normal weight parent in the case of single parent families). Having overweight and obese parents was a significant risk factor for overweight and obesity regardless of socio-economic characteristics of the household. Family income was not associated with the odds of childhood obesity but social class and parental education were important risk factors for childhood obesity. Access to food stores in the local environment did not impact dietary quality or the BMI of Irish children. However, there was some evidence to suggest that the economic resources of the family influenced diet and BMI. Discussion: Though childhood overweight and obesity rates appear to have stabilised over the previous decade, prevalence rates are unacceptably high. As expected, overweight and obesity were associated with a high energy intake and poor dietary quality. The findings also highlight strong associations between physical inactivity and the risk of overweight and obesity, with effect sizes greater than what have been typically found in adults. Important family level determinants of childhood overweight and obesity were also identified. The findings highlight the need for a multifaceted approach, targeting a range of modifiable determinants to tackle the problem. In particular, policies and interventions at the shared family environment or community level may be an effective mean of tackling this current epidemic.

Trends in blindness due to diabetic retinopathy among adults aged 18-69 years over a decade in Ireland

Aims: To describe trends in the incidence of visual impairment and blindness due to diabetic retinopathy among adults aged 18–69 years in Ireland between 2004 and 2013. Methods: Data on visual impairment due to diabetic retinopathy in adults aged 18–69 years or over who are registered with the National Council for the Blind of Ireland, (2004–2013) were analysed. Annual incidence rates were calculated for the adult population and the population with diagnosed diabetes. Poisson regression was used to test for changes in rates over time. The relative, attributable and population risk of blindness and visual impairment due to diabetic retinopathy were calculated for 2013. Results: Over the decade, the prevalence of diagnosed diabetes increased from 2.1% to 3.6%. Among people with diagnosed diabetes, the incidence of visual impairment due to diabetic retinopathy increased from 6.4 (95% CI 2.4–13.9) per 100,000 in 2004 to 11.7 (95% CI 5.9–21.0) per 100,000 in 2013. The incidence of blindness due to diabetic retinopathy varied from 31.9 per 100,000 (95% CI 21.6–45.7) in 2004 to 14.9 per 100,000 (95% CI 8.2–25.1) in 2013. Conclusions: Our findings indicate the need for increased attention to preventive measures for microvascular complications among adults with diabetes in Ireland. Retinopathy screening has been standardised in Ireland, these findings provide useful baseline statistics to monitor the impact of this population-based screening programme.

Worldwide trends in blood pressure from 1975 to 2015: a pooled analysis of 1479 population-based measurement studies with 19·1 million participants

Background: Raised blood pressure is an important risk factor for cardiovascular diseases and chronic kidney disease. We estimated worldwide trends in mean systolic and mean diastolic blood pressure, and the prevalence of, and number of people with, raised blood pressure, defined as systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher. Methods: For this analysis, we pooled national, subnational, or community population-based studies that had measured blood pressure in adults aged 18 years and older. We used a Bayesian hierarchical model to estimate trends from 1975 to 2015 in mean systolic and mean diastolic blood pressure, and the prevalence of raised blood pressure for 200 countries. We calculated the contributions of changes in prevalence versus population growth and ageing to the increase in the number of adults with raised blood pressure. Findings: We pooled 1479 studies that had measured the blood pressures of 19·1 million adults. Global age-standardised mean systolic blood pressure in 2015 was 127·0 mm Hg (95% credible interval 125·7–128·3) in men and 122·3 mm Hg (121·0–123·6) in women; age-standardised mean diastolic blood pressure was 78·7 mm Hg (77·9–79·5) for men and 76·7 mm Hg (75·9–77·6) for women. Global age-standardised prevalence of raised blood pressure was 24·1% (21·4–27·1) in men and 20·1% (17·8–22·5) in women in 2015. Mean systolic and mean diastolic blood pressure decreased substantially from 1975 to 2015 in high-income western and Asia Pacific countries, moving these countries from having some of the highest worldwide blood pressure in 1975 to the lowest in 2015. Mean blood pressure also decreased in women in central and eastern Europe, Latin America and the Caribbean, and, more recently, central Asia, Middle East, and north Africa, but the estimated trends in these super-regions had larger uncertainty than in high-income super-regions. By contrast, mean blood pressure might have increased in east and southeast Asia, south Asia, Oceania, and sub-Saharan Africa. In 2015, central and eastern Europe, sub-Saharan Africa, and south Asia had the highest blood pressure levels. Prevalence of raised blood pressure decreased in high-income and some middle-income countries; it remained unchanged elsewhere. The number of adults with raised blood pressure increased from 594 million in 1975 to 1·13 billion in 2015, with the increase largely in low-income and middle-income countries. The global increase in the number of adults with raised blood pressure is a net effect of increase due to population growth and ageing, and decrease due to declining age-specific prevalence. Interpretation: During the past four decades, the highest worldwide blood pressure levels have shifted from high-income countries to low-income countries in south Asia and sub-Saharan Africa due to opposite trends, while blood pressure has been persistently high in central and eastern Europe.

Worldwide trends in diabetes since 1980: a pooled analysis of 751 population-based studies with 4·4 million participants

Background: One of the global targets for non-communicable diseases is to halt, by 2025, the rise in the age-standardised adult prevalence of diabetes at its 2010 levels. We aimed to estimate worldwide trends in diabetes, how likely it is for countries to achieve the global target, and how changes in prevalence, together with population growth and ageing, are affecting the number of adults with diabetes. Methods: We pooled data from population-based studies that had collected data on diabetes through measurement of its biomarkers. We used a Bayesian hierarchical model to estimate trends in diabetes prevalence - defined as fasting plasma glucose of 7·0 mmol/L or higher, or history of diagnosis with diabetes, or use of insulin or oral hypoglycaemic drugs - in 200 countries and territories in 21 regions, by sex and from 1980 to 2014. We also calculated the posterior probability of meeting the global diabetes target if post-2000 trends continue. Findings: We used data from 751 studies including 4 372 000 adults from 146 of the 200 countries we make estimates for Global age-standardised diabetes prevalence increased from 4·3% (95% credible interval 2·4-7·0) in 1980 to 9·0% (7·2-11·1) in 2014 in men, and from 5·0% (2·9-7·9) to 7·9% (6·4-9·7) in women. The number of adults with diabetes in the world increased from 108 million in 1980 to 422 million in 2014 (28·5% due to the rise in prevalence, 39·7% due to population growth and ageing, and 31·8% due to interaction of these two factors). Age-standardised adult diabetes prevalence in 2014 was lowest in northwestern Europe, and highest in Polynesia and Micronesia, at nearly 25%, followed by Melanesia and the Middle East and north Africa. Between 1980 and 2014 there was little change in age-standardised diabetes prevalence in adult women in continental western Europe, although crude prevalence rose because of ageing of the population. By contrast, age-standardised adult prevalence rose by 15 percentage points in men and women in Polynesia and Micronesia. In 2014, American Samoa had the highest national prevalence of diabetes (>30% in both sexes), with age-standardised adult prevalence also higher than 25% in some other islands in Polynesia and Micronesia. If post-2000 trends continue, the probability of meeting the global target of halting the rise in the prevalence of diabetes by 2025 at the 2010 level worldwide is lower than 1% for men and is 1% for women. Only nine countries for men and 29 countries for women, mostly in western Europe, have a 50% or higher probability of meeting the global target. Interpretation Since 1980, age-standardised diabetes prevalence in adults has increased, or at best remained unchanged, in every country. Together with population growth and ageing, this rise has led to a near quadrupling of the number of adults with diabetes worldwide. The burden of diabetes, both in terms of prevalence and number of adults aff ected, has increased faster in low-income and middle-income countries than in high-income countries.