Cardiovascular risk factor control in British adults with diabetes mellitus: Retrospective cohort study

Abstract Using primary care electronic medical records (the United Kingdom Health Improvement Network Database 2003‐2015), we examined the control of cardiovascular risk factors in the first year after diagnosis in British adults with diabetes mellitus. Among 292 170 individuals with diabetes receiving frequent outpatient management (median of 16 primary care visits in the prior year), control of cardiovascular risk factors a median of 354 days after diagnosis was suboptimal: 14.7% had HbA1C < 7%, SBP < 140 mm Hg, LDL cholesterol ≤1.8 mmol/L or taking a statin, and were nonsmokers (the proportion dropped to 7.5% if the SBP target was defined as <130 mm Hg). While 90.4% had an LDL cholesterol ≤1.8 mmol/L or were taking a statin, and 86.0% were nonsmokers, only 52.0% had HbA1C < 7% and 53.1% had SBP < 140 mm Hg (29.8% had SBP < 130 mm Hg) despite 71.4% taking antihypertensive agents. Thus, there is still a need for quality improvement strategies that target all atherosclerotic risk factors in individuals with diabetes and not just glycaemic control.


| Cohort selection
As described in detail elsewhere, 5  Our cohort consists of patients with newly diagnosed diabetes seen between 2003 and 2015 who had a recorded measurement of their HbA1C and systolic blood pressure (SBP) at least 6 months after they were diagnosed with diabetes but before one year. We defined the index date for assessing CV risk factor control as the time of their first HbA1C done at least 6 months after diagnosis.

| Definition of risk factor control
We defined CV risk factor control for each patient on the basis of laboratory results and physical measures recorded at least 6 months after the initial diagnosis of diabetes (in order to give physicians and patients time to implement any changes) but before one year. In the case of multiple measurements, we used those closest to the time of the index HbA1C measurement.

| Covariates
The specific variables included are detailed in the Table 1 and were based on diagnoses assigned by their primary care physician.

| Statistical analysis
Patient characteristics were reported as means and standard deviations for continuous variables (and compared using t tests and one-way ANOVA), and categorical variables were reported as proportions (and compared using chi-squared tests).

| Ethics
We were granted a waiver of informed consent by the University of Calgary Health Research Ethics Board (REB15-0203_REN3) because we used de-identified data from the THIN database obtained by the Cumming School of Medicine at the University of Calgary under license from IQVIA (IMS Quintiles VIA-see www.iqvia.com).

| RE SULTS
Of 406 649 individuals with diabetes, 292 170 (mean age 61.7 years) had both HbA1C and SBP measured 6-12 months after diabetes diagnosis and formed the sample for this study. The median time from diabetes diagnosis to the risk factor assessments we examined was 354 days, and the median number of primary care physician visits in the year prior to the assessment of risk factor control was 16 (

| D ISCUSS I ON
We found that only one seventh of patients with type 2 diabetes receiving close follow-up with UK primary care physicians had optimal risk factor profiles approximately one year after diagnosis of their diabetes. While control of lipids and nonsmoking rates were reasonably high, the frequency of SBP control was low and poorer than glycaemic control despite nearly three quarters of patients taking antihypertensive therapy. This is an important gap since SBP is the strongest driver of cardiovascular outcomes in diabetes (with quadruple the attributable risk for mortality and triple the attributable risk for cardiovascular events as hyperglycaemia in the Framingham study), 7 the benefits of lowering blood pressure 8 surpass those of lowering glucose in individuals with diabetes mellitus, 9 and antihypertensives are the most cost-effective cardiovascular prevention therapies in type 2 diabetes. 10 The suboptimal control of cardiovascular risk factors in patients with type 2 diabetes we found in UK primary care practices is actually better than those reported in the United States and European studies. 4

TA B L E 1 (Continued)
the Swedish National Diabetes Register reported that only 5% of adults with type 2 diabetes were nonsmokers, did not have albuminuria, had BP < 140/80 mm Hg, LDL cholesterol <2.5 mmol/L and HbA1C < 7.0. 13 Importantly, as the number of uncontrolled risk factors increased so did the risk of subsequent cardiovascular events. 13 However, there is clearly still room for improvement and a recent systematic review of 42 randomized trials on improving management of type 2 diabetes documented that most primary care-based interventions focused on glycaemic management rather than total CV risk. 15 However, there is a rich vein of literature on the efficacy of chronic disease management programs run by other healthcare professionals in collaboration with primary care physicians for optimizing total CV risk factor profiles in individuals with diabetes. 16,17

| Limitations
Despite the availability of detailed clinical data in a large population-

| CON CLUS ION
In conclusion, nearly half of adults in our cohort newly diagnosed with diabetes mellitus exhibited suboptimal control of glucose (HbA1C > 7%) or SBP (>140 mm Hg), and over 85% exhibited suboptimal control of at least one cardiovascular risk factor despite frequent primary care visits. Despite a recent flurry of literature suggesting that individuals with diabetes may be over-treated, our study highlights the continued need for primary care quality improvement strategies in type 2 diabetes that focus on all atherosclerotic risks and not just glycaemic control.

ACK N OWLED G EM ENTS
FM is supported by the Alberta Health Services Chair in Cardiovascular Outcomes Research at the University of Alberta.

CO N FLI C T S O F I NTE R E S T
All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_discl osure.pdf and declare: no support from any organization for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

AUTH O R S ' CO NTR I B UTI O N S
FM involved in study conception and design; BL and TW involved in data attainment and analysis; all authors involved in interpretation of data and subsequent revisions; SC and FM contributed to first draft of manuscript.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available under license from IQVIA (IMS Quintiles VIA-see www.iqvia.com) but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available.