The Impact of Systolic Blood Pressure, Pulse Pressure, and Their Variability on Diabetes Retinopathy among Patients with Type 2 Diabetes
Qingqing Lou, Xue Chen, Kun Wang, Huanhuan Liu, Zongjun Zhang, Yaujiunn Lee
Abstract
Objectives. To evaluate the effects of variations in systolic blood pressure (SBP) and pulse pressure (PP) on diabetic retinopathy (DR) in patients with type 2 diabetes. Methods. A total of 3275 type 2 diabetes patients without DR at Taiwan Lee’s United Clinic from 2002 to 2014 were enrolled in the study. The average age of the patients was 65.5 (±12.2) years, and the follow-up period ranged from 3 to 10 years. Blood pressure variability was defined as the standard deviation (SD) of the average blood pressure values over the entire study period and was calculated for each patient. The mean SD for SBP was 11.16, and a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mtext>SBP</a:mtext> <a:mo>≥</a:mo> <a:mn>130</a:mn> <a:mtext> </a:mtext> <a:mtext>mmHg</a:mtext> </a:math> ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:mn>1</c:mn> <c:mtext> </c:mtext> <c:mtext>mmHg</c:mtext> <c:mo>=</c:mo> <c:mn>0.133</c:mn> <c:mtext> </c:mtext> <c:mtext>kPa</c:mtext> </c:math> ) was defined as high SBP. Based on these data, patients were divided into four groups as follows: group 1 (G1, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:mtext>mean</e:mtext> <e:mtext> </e:mtext> <e:mtext>SBP</e:mtext> <e:mo><</e:mo> <e:mn>130</e:mn> <e:mtext> </e:mtext> <e:mtext>mmHg</e:mtext> </e:math> , <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M4"> <g:mtext>SD</g:mtext> <g:mtext> </g:mtext> <g:mtext>of</g:mtext> <g:mtext> </g:mtext> <g:mtext>SBP</g:mtext> <g:mo><</g:mo> <g:mn>11.16</g:mn> <g:mtext> </g:mtext> <g:mtext>mmHg</g:mtext> </g:math> ), group 2 (G2, <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" id="M5"> <i:mtext>mean</i:mtext> <i:mtext> </i:mtext> <i:mtext>SBP</i:mtext> <i:mo><</i:mo> <i:mn>130</i:mn> <i:mtext> </i:mtext> <i:mtext>mmHg</i:mtext> </i:math> , <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" id="M6"> <k:mtext>SD</k:mtext> <k:mo>≥</k:mo> <k:mn>11.16</k:mn> <k:mtext> </k:mtext> <k:mtext>mmHg</k:mtext> </k:math> ), group 3 (G3, <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" id="M7"> <m:mtext>mean</m:mtext> <m:mtext> </m:mtext> <m:mtext>SBP</m:mtext> <m:mo>≥</m:mo> <m:mn>130</m:mn> <m:mtext> </m:mtext> <m:mtext>mmHg</m:mtext> </m:math> , <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" id="M8"> <o:mtext>SD</o:mtext> <o:mtext> </o:mtext> <o:mtext>of</o:mtext> <o:mtext> </o:mtext> <o:mtext>SBP</o:mtext> <o:mo><</o:mo> <o:mn>11.16</o:mn> <o:mtext> </o:mtext> <o:mtext>mmHg</o:mtext> </o:math> ), and group 4 (G4, <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" id="M9"> <q:mtext>mean</q:mtext> <q:mtext> </q:mtext> <q:mtext>SBP</q:mtext> <q:mo>≥</q:mo> <q:mn>130</q:mn> <q:mtext> </q:mtext> <q:mtext>mmHg</q:mtext> </q:math> , <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" id="M10"> <s:mtext>SD</s:mtext> <s:mo>≥</s:mo> <s:mn>11.16</s:mn> <s:mtext> </s:mtext> <s:mtext>mmHg</s:mtext> </s:math> ). Based on a mean PP of 80 mmHg with a pulse pressure SD of 6.53 mmHg, the patients were regrouped into four groups designated G1 <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" id="M11"> <u:msup> <u:mrow/> <u:mrow> <u:mo>′</u:mo> </u:mrow> </u:msup> </u:math> -G4 <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" id="M12"> <w:msup> <w:mrow/> <w:mrow> <w:mo>′</w:mo> </w:mrow> </w:msup> </w:math> . Results. After adjusting for patient age, sex, and disease course, Cox regression showed that the mean and SD of SBP, pulse pressure, and their SDs were risk factors for DR. After stratifying the patients based on the mean and SD of the SBP, we found that the patients in the G4 group had the highest risk of DR ( <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" id="M13"> <y:mtext>hazard</y:mtext> <y:mtext> </y:mtext> <y:mtext>ratio</y:mtext> <y:mtext> </y:mtext> <y:mfenced open="(" close=")"> <y:mrow> <y:mtext>HR</y:mtext> </y:mrow> </y:mfenced> <y:mo>=</y:mo> <y:mn>1.980</y:mn> </y:math> , 95% CI: 1.716~2.285, <cb:math xmlns:cb="http://www.w3.org/1998/Math/MathML" id="M14"> <cb:mi>P</cb:mi> <cb:mo><</cb:mo> <cb:mn>0.01</cb:mn> </cb:math> ) and patients in the G1 group had the lowest risk. Patients in the G3 group ( <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" id="M15"> <eb:mtext>HR</eb:mtext> <eb:mo>=</eb:mo> <eb:mn>1.409</eb:mn> </eb:math> , 95% CI: 1.284~1.546, <gb:math xmlns:gb="http://www.w3.org/1998/Math/MathML" id="M16"> <gb:mi>P</gb:mi> <gb:mo><</gb:mo> <gb:mn>0.01</gb:mn> </gb:math> ) had a higher risk of DR compared to those in the G2 group ( <ib:math xmlns:ib="http://www.w3.org/1998/Math/MathML" id="M17"> <ib:mtext>HR</ib:mtext> <ib:mo>=</ib:mo> <ib:mn>1.353</ib:mn> </ib:math> , 95% CI: 1.116~1.640, <kb:math xmlns:kb="http://www.w3.org/1998/Math/MathML" id="M18"> <kb:mi>P</kb:mi> <kb:mo><</kb:mo> <kb:mn>0.01</kb:mn> </kb:math> ). After the restratification of patients based on the mean and SD of the pulse pressures, it was found that patients in the G2 <mb:math xmlns:mb="http://www.w3.org/1998/Math/MathML" id="M19"> <mb:msup> <mb:mrow/> <mb:mrow> <mb:mo>′</mb:mo> </mb:mrow> </mb:msup> </mb:math> group had the highest risk of DR ( <ob:math xmlns:ob="http://www.w3.org/1998/Math/MathML" id="M20"> <ob:mtext>HR</o