Chronic kidney disease and cardiovascular risk in hypertensive type 2 diabetics: a primary care perspective

Chronic kidney disease (CKD) is associated with poor renal and cardiovascular (CV) outcome, and early identification largely depends on the general practitioners' (GPs) awareness of it. Only a few studies have evaluated the prevalence of CKD in type 2 diabetes in primary care, and no studies are available on hypertensive diabetics. Thus, the aim of this study was to assess the prevalence of CKD and its association with CV morbidity in such a population.

On the basis of an Italian national project involving GPs and nephrologists, we retrieved demographic, laboratory and clinical data regarding 7582 hypertensive type 2 diabetics (3564 men; age 25-89 years) who were selected using the diagnostic code Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) for diabetes and hypertension. Blood pressure (BP) values, serum creatinine, ECG-diagnosed left ventricular hypertrophy (LVH) and the occurrence of previous major CV events were obtained for each patient from the GPs' Health Search Database. Estimated glomerular filtration rate (GFR) was calculated according to the four-variable MDRD equation. CKD was defined as an estimated GFR < 60 mL/min/ 1.73 m2.

CKD prevalence was 26%, although renal disease was diagnosed by GPs in only 5.4% of cases. The prevalence of both LVH and major CV events was 8%. Adequate BP control was only achieved in 10.4% of patients. Patients whose GFR was <60 mL/min/1.73 m2 were older, prevalently female, had increased pulse pressure and higher prevalence of dyslipidaemia. Moreover, the prevalence of both LVH and major CV events was higher in patients with CKD as compared to patients with normal GFR. Multivariate logistic regression analysis showed that patients with CKD had a higher risk of LVH and/or CV events adjusted for eight covariates, and this risk increased by 23% with each 21 mL/min/1.73 m2 decrease in GFR.

This study shows that CKD is highly prevalent in hypertensive type 2 diabetic patients, where it is a strong predictor of CV adverse outcome. However, awareness of CKD by GPs is low. Equations for calculating estimated GFR should be included in the GPs' database in order to detect the presence of CKD and to improve CV outcome of such a high-risk population.