Final Report Summary - CKD-UK (Quality of chronic kidney disease management in people with diabetes in England after the introduction of new primary care policies for diabetes and renal disease)
Background and objectives: The prevalence of diabetes is increasing in epidemic proportions worldwide. Although patients with diabetes are now increasingly surviving vascular events, cardiovascular disease (CVD) remains the leading cause of death in this patient group. As part of a national strategy to reduce CVD morbidity and mortality, a number of quality improvement initiatives were introduced in the UK health system during the last decade, with a major emphasis on comprehensive secondary prevention in high-risk groups. Despite considerable investments in primary care, the uptake of existing interventions to identify and manage CVD risk factors is often suboptimal. The objectives of the project were to assess the control of some key CVD risk factors in the UK and examine their impact on hard clinical outcomes in people with diabetes: Objective 1. To describe recent national trends in major CVD events and procedures in people with and without diabetes 2. To examine disparities in screening for chronic kidney disease (CKD) (micro-, marcoalbuminuria and creatinine testing) following the introduction of the Quality and Outcomes Framework (QOF) in UK primary care 3. To examine the association between systolic and diastolic blood pressure control and mortality in newly diagnosed patients with Type 2 diabetes. 4. To assess the effectiveness of influenza vaccine in people with diabetes against acute CVD events and death in people with diabetes.
Research Methods: Objective 1: We identified all patients aged 16 years and above with cardiovascular events in England between 2004–2005 and 2009–2010 using national Hospital Episode Statistics data. Diabetes- and non-diabetes-specific rates were calculated for each year. To test for time trend, we fitted Poisson regression models. Objective 2. We set up a primary care database through the Cutting Out Needless Deaths Using Information Technology (CONDUIT) Network. We extracted the data from GP computer systems using a Department of Health data extraction tool called Morbidity Information Query and Export Syntax (MIQUEST) and anonymised the extracted data to assess testing for kidney function and proteinuria following the introduction of QOF. Objective 3. We undertook a retrospective cohort study among newly diagnosed people with diabetes using data from the United Kingdom General Practice Research Database between 1990 and 2005. We used Cox proportional hazard regression models to estimate hazard ratios with 95% confidence intervals of all-cause mortality for groups of systolic and diastolic blood pressure, using the usual control groups as references. Objective 4. We conducted a retrospective cohort study using data from the Clinical Practice Research Database (CPRD) between 2003-2004 and 2009-2010. We estimated rates of hospitalisation for acute myocardial infarction (AMI), stroke, heart failure and pneumonia / influenza and all-cause mortality. Event rates were analysed for the pre-influenza, influenza, post-influenza and summer periods. Estimates for the summer, when influenza is not circulating, were used to assess and adjust for residual confounding.
Results: In people with diabetes, admission rates for angina, acute myocardial infarction, and coronary artery bypass graft decreased significantly by 5% (rate ratio 0.95 [95% CI 0.94–0.96]) 5% (0.95 [0.93–0.97]) and 3% (0.97 [0.95–0.98]) per year, respectively, between 2004 and 2009. Admission rates for stroke did not significantly change (0.99 [0.98–1.004]) but increased for percutaneous coronary intervention (1.01 [1.005–1.03]) in people with diabetes. People with and without diabetes had similar proportional changes for all outcomes, with no significant differences in trends between these groups. However, people with diabetes had ~3.5- to 5-fold risk of CVD events compared with people without diabetes.
In the CONDUIT sample, there was a considerable variation in serum creatinine (kidney function) testing by age, gender and ethnicity. Overall, testing was higher in women, elderly patients, south Asian and Black Caribbean patients and those with diabetes. People with diabetes were significantly more likely to have a microalbuminuria test compared to those without diabetes with over 82% recording rate. Microalbuminuria testing was higher in people with south Asian and African-Caribbean ethnicity compared to white patients in people without diabetes. In people without diabetes, testing for proteinuria or microalbuminuria was sporadic. Overall, women were more likely to have their renal function tested compared to men. The magnitude of difference compared to men was modified according to the presence of diabetes, ethnicity and age.
Patients with diabetes and CVD, tight control of systolic blood pressure (SBP, below 110 mm Hg) and diastolic blood pressure (DBP, below 75 mm Hg) were associated with significantly increased risk of all-cause mortality after adjustment for baseline characteristics (age at diagnosis, sex, practice level clustering, deprivation score, body mass index, smoking, HbA1c and cholesterol levels, and blood pressure). In patients with diabetes without established CVD, SBP below 120 mm Hg and DBP below 75 mm Hg were associated with a significant increased risk of mortality. These associations persisted when we restricted our analyses to patients who received treatment for hypertension and to those who had a diagnosis of hypertension at baseline.
In the CPRD sample, there were 124,503 patients with Type 2 diabetes contributing to 623,591 person-years of observation during the seven study periods. Influenza vaccine recipients were older and had more co-comorbid conditions compared with non-recipients. After adjustment for covariates and residual confounding, vaccination was associated with significant reductions ranging from 15-30% (IRR 0.70 (0.53-0.91) and IRR 0.85 (0.74-0.99)) in hospitalisation rates for AMI, stroke, heart failure, reduction for pneumonia or influenza and all-cause mortality.
Conclusions and societal implications:
Although there was a considerable recent decline in admissions for major cardiovascular diseases, people with diabetes still are at an ~3.5- to 5-fold risk of CVD events compared with those without diabetes. These findings emphasize the ongoing need for aggressive risk reduction and primary prevention of CVD in people with diabetes. Our results also show unequal screening for chronic kidney disease (CKD) in UK primary care across different age, gender and ethnic groups despite increasing focus on early detection of CKD in high-risk patients. Social and policy implications include that described disparities in testing do not always follow increased risk with a prospect of widening health inequalities between more and less tested groups. Trainings, educational programmes and other interventions might be needed to align screening with need.
Blood pressure control is a major predictor of CVD morbidity and mortality. However, our observational study showed that low blood pressure, particularly below 110/75 mm Hg, was associated with increased risk for poor outcomes. Although causal associations cannot be implied from these results, our findings extend previous findings suggesting that lower levels of blood pressure maintained during the first year after diagnosis of diabetes identify a subset of patients with significantly increased risk of death. Influenza infection triggers CVD events particularly in high-risk patients. Influenza vaccination was associated with reductions in hospitalisation rates for major acute cardiovascular and respiratory conditions and all-cause mortality in people with Type 2 diabetes. Policy implications are that whilst the development and approval of new vaccines and new approaches are in progress, efforts should be focused on improvements in vaccine uptake in this high priority group.
Research Methods: Objective 1: We identified all patients aged 16 years and above with cardiovascular events in England between 2004–2005 and 2009–2010 using national Hospital Episode Statistics data. Diabetes- and non-diabetes-specific rates were calculated for each year. To test for time trend, we fitted Poisson regression models. Objective 2. We set up a primary care database through the Cutting Out Needless Deaths Using Information Technology (CONDUIT) Network. We extracted the data from GP computer systems using a Department of Health data extraction tool called Morbidity Information Query and Export Syntax (MIQUEST) and anonymised the extracted data to assess testing for kidney function and proteinuria following the introduction of QOF. Objective 3. We undertook a retrospective cohort study among newly diagnosed people with diabetes using data from the United Kingdom General Practice Research Database between 1990 and 2005. We used Cox proportional hazard regression models to estimate hazard ratios with 95% confidence intervals of all-cause mortality for groups of systolic and diastolic blood pressure, using the usual control groups as references. Objective 4. We conducted a retrospective cohort study using data from the Clinical Practice Research Database (CPRD) between 2003-2004 and 2009-2010. We estimated rates of hospitalisation for acute myocardial infarction (AMI), stroke, heart failure and pneumonia / influenza and all-cause mortality. Event rates were analysed for the pre-influenza, influenza, post-influenza and summer periods. Estimates for the summer, when influenza is not circulating, were used to assess and adjust for residual confounding.
Results: In people with diabetes, admission rates for angina, acute myocardial infarction, and coronary artery bypass graft decreased significantly by 5% (rate ratio 0.95 [95% CI 0.94–0.96]) 5% (0.95 [0.93–0.97]) and 3% (0.97 [0.95–0.98]) per year, respectively, between 2004 and 2009. Admission rates for stroke did not significantly change (0.99 [0.98–1.004]) but increased for percutaneous coronary intervention (1.01 [1.005–1.03]) in people with diabetes. People with and without diabetes had similar proportional changes for all outcomes, with no significant differences in trends between these groups. However, people with diabetes had ~3.5- to 5-fold risk of CVD events compared with people without diabetes.
In the CONDUIT sample, there was a considerable variation in serum creatinine (kidney function) testing by age, gender and ethnicity. Overall, testing was higher in women, elderly patients, south Asian and Black Caribbean patients and those with diabetes. People with diabetes were significantly more likely to have a microalbuminuria test compared to those without diabetes with over 82% recording rate. Microalbuminuria testing was higher in people with south Asian and African-Caribbean ethnicity compared to white patients in people without diabetes. In people without diabetes, testing for proteinuria or microalbuminuria was sporadic. Overall, women were more likely to have their renal function tested compared to men. The magnitude of difference compared to men was modified according to the presence of diabetes, ethnicity and age.
Patients with diabetes and CVD, tight control of systolic blood pressure (SBP, below 110 mm Hg) and diastolic blood pressure (DBP, below 75 mm Hg) were associated with significantly increased risk of all-cause mortality after adjustment for baseline characteristics (age at diagnosis, sex, practice level clustering, deprivation score, body mass index, smoking, HbA1c and cholesterol levels, and blood pressure). In patients with diabetes without established CVD, SBP below 120 mm Hg and DBP below 75 mm Hg were associated with a significant increased risk of mortality. These associations persisted when we restricted our analyses to patients who received treatment for hypertension and to those who had a diagnosis of hypertension at baseline.
In the CPRD sample, there were 124,503 patients with Type 2 diabetes contributing to 623,591 person-years of observation during the seven study periods. Influenza vaccine recipients were older and had more co-comorbid conditions compared with non-recipients. After adjustment for covariates and residual confounding, vaccination was associated with significant reductions ranging from 15-30% (IRR 0.70 (0.53-0.91) and IRR 0.85 (0.74-0.99)) in hospitalisation rates for AMI, stroke, heart failure, reduction for pneumonia or influenza and all-cause mortality.
Conclusions and societal implications:
Although there was a considerable recent decline in admissions for major cardiovascular diseases, people with diabetes still are at an ~3.5- to 5-fold risk of CVD events compared with those without diabetes. These findings emphasize the ongoing need for aggressive risk reduction and primary prevention of CVD in people with diabetes. Our results also show unequal screening for chronic kidney disease (CKD) in UK primary care across different age, gender and ethnic groups despite increasing focus on early detection of CKD in high-risk patients. Social and policy implications include that described disparities in testing do not always follow increased risk with a prospect of widening health inequalities between more and less tested groups. Trainings, educational programmes and other interventions might be needed to align screening with need.
Blood pressure control is a major predictor of CVD morbidity and mortality. However, our observational study showed that low blood pressure, particularly below 110/75 mm Hg, was associated with increased risk for poor outcomes. Although causal associations cannot be implied from these results, our findings extend previous findings suggesting that lower levels of blood pressure maintained during the first year after diagnosis of diabetes identify a subset of patients with significantly increased risk of death. Influenza infection triggers CVD events particularly in high-risk patients. Influenza vaccination was associated with reductions in hospitalisation rates for major acute cardiovascular and respiratory conditions and all-cause mortality in people with Type 2 diabetes. Policy implications are that whilst the development and approval of new vaccines and new approaches are in progress, efforts should be focused on improvements in vaccine uptake in this high priority group.