Risks of progression of retinopathy and vision loss related to tight blood pressure control in type 2 diabetes mellitus: UKPDS 69.
OBJECTIVE
To determine the relationship between tight blood pressure (BP) control and the different aspects of diabetic retinopathy in patients with type 2 diabetes mellitus (DM).


METHODS
Nineteen hospital-based clinics in England, Scotland, and Northern Ireland.


METHODS
Outcome of retinopathy status assessed by 4-field retinal photography related to allocation within a randomized controlled trial comparing a tight BP control policy aiming for a BP less than 150/85 mm Hg with a less tight BP control policy aiming for a BP less than 180/105 mm Hg.


METHODS
One thousand one hundred forty-eight hypertensive patients with type 2 DM were studied. These patients had type 2 DM for a mean duration of 2.6 years at the inception of the Hypertension in Diabetes Study, had a mean age of 56 years; and had a mean BP of 160/94 mm Hg. Seven hundred fifty-eight patients were allocated to a tight BP control policy with angiotensin-converting enzyme inhibitor or beta-blockers as the main therapy; 390 were allocated to a less tight BP control policy.


METHODS
Deterioration of retinopathy (>/=2-step change on a modified Early Treatment Diabetic Retinopathy Study [ETDRS] final scale), together with end points (photocoagulation, vitreous hemorrhage, and cataract extraction) and analysis of specific lesions (microaneurysms, hard exudates, and cotton-wool spots). Visual acuity was assessed at 3-year intervals using ETDRS logarithm of the minimum angle of resolution charts. Blindness was monitored as an end point with the criterion of Snellen chart assessment at 6/60 or worse.


RESULTS
By 4.5 years after randomization, there was a highly significant difference in microaneurysm count with 23.3% in the tight BP control group and 33.5% in the less tight BP control group having 5 or more microaneurysms (relative risk [RR], 0.70; P = .003). The effect continued to 7.5 years (RR, 0.66; P<.001). Hard exudates increased from a prevalence of 11.2% to 18.3% at 7.5 years after randomization with fewer lesions found in the tight BP control group (RR, 0.53; P<.001). Cotton-wool spots increased in both groups but less so in the tight BP control group which had fewer cotton-wool spots at 7.5 years (RR, 0.53; P<.001). A 2-step or more deterioration on the ETDRS scale was significantly different at 4.5 years with fewer people in the tight BP control group progressing 2 steps or more (RR, 0.75; P = .02). Patients allocated to tight BP control were less likely to undergo photocoagulation (RR, 0.65; P = .03). This difference was driven by a difference in photocoagulation due to maculopathy (RR, 0.58; P = .02). The cumulative incidence of the end point of blindness (Snellen visual acuity, >/=6/60) in 1 eye was 18/758 for the tight BP control group compared with 12/390 for less tight BP control group. These equate to absolute risks of 3.1 to 4.1 per 1000 patient-years, respectively (P = .046; RR, 0.76; 99% confidence interval, 0.29-1.99). There was no detectable difference in outcome between the 2 randomized therapies of angiotensin-converting enzyme inhibition and beta-blockade.


CONCLUSIONS
High BP is detrimental to each aspect of diabetic retinopathy; a tight BP control policy reduces the risk of clinical complications from diabetic eye disease.
Matthews
David R
DR
Oxford Centre for Diabetes, Endocrinology, and Metabolism, Churchill Hospital, England. david.matthews@ocdem.ox.ac.uk
Stratton
Irene M
IM
Aldington
Stephen J
SJ
Holman
Rury R
RR
Kohner
Eva M
EM
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D001262:Atenolol / Q000627:therapeutic use; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure / Q000187:drug effects*; D002216:Captopril / Q000627:therapeutic use; D002387:Cataract Extraction; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy*; D003930:Diabetic Retinopathy / Q000209:etiology / Q000517:prevention & control* / Q000601:surgery; D018450:Disease Progression; D005260:Female; D006801:Humans; D006977:Hypertension, Renal / Q000150:complications / Q000188:drug therapy*; D017075:Laser Coagulation; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014786:Vision Disorders / Q000209:etiology / Q000517:prevention & control* / Q000601:surgery; D014823:Vitreous Hemorrhage / Q000175:diagnosis
D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D001786:Blood Glucose; D001262:Atenolol; D002216:Captopril