Orthostatic Hypotension Occurs Similarly Among CKD Patients With, Without DNP

Researchers from Bezmialem Vakif University in Turkey found the occurrence of orthostatic hypotension (OH) to be similar among patients with chronic kidney disease (CKD) who do or do not have comorbid diabetic nephropathy (DNP). Their study, published recently in Kidney and Blood Pressure Research, investigated the subtype of low blood pressure that occurs upon standing up after an individual has been sitting or lying on their back.

According to the authors, “Diabetic nephropathy is one of the microvascular complications of diabetes. It is also the most common cause of chronic kidney disease.” For their study, they used the American Academy of Nephrology’s definition of OH, which is a 20 mm Hg or 10 mm Hg decrease in systolic or diastolic blood pressure, respectively, in the 3 minutes after rising from either sitting or lying down.

“Studies show that OH is an important parameter affecting quality of life,” the authors wrote, but no studies have investigated a possible link between OH and DNP. “The aim of this study was to investigate and compare the presence and affecting factors of OH among patients with and without diabetic nephropathy.”

They did see a slight difference between the DNP and non-DNP groups regarding the presence of OH, but this difference was deemed not significant, at 70.5% and 61.7% (P = .181), respectively. Neither was the result of change in systolic blood pressure, at 24.00 (range, 10.00-32.00) mm Hg for the DNP cohort and 24.00 (range, 13.75-30.25) mm Hg for the non-DNP cohort.

Significant differences were seen, however, regarding change in diastolic blood pressure and occurrence of OH when CKD medication class was considered:

• Change in diastolic blood pressure: 8.00 (range, 2.00-9.00) vs 6.00 (2.00-9.00) mm Hg for the DNP and non-DNP cohorts, respectively
• Calcium channel blocker (CCB) use resulted in 73.7% of patients developing OH.
• Alpha-blocker use resulted in 80.6% of patients developing OH.

In addition, OH occurred much more often among the male patients than the female patients, at 74.7% vs 60.0% (P = .026); the mean (SD) uric acid level was determined to be significantly higher in the DNP vs non-DNP group for those with OH, at 7.18 (1.55) vs 6.36 (1.65) mg/dL (P = .017); and mean serum albumin levels were significantly higher among all patients with OH compared with those without OH, at 42.10 (3.13) vs 39.60 (3.72) g/L (P <. 001).

All patients included in this analysis were outpatients who visited the Nephrology Outpatient Clinic at Bezmialem Vakif University Hospital between February and August 2019. The 2 study groups (112 with DNP; 94 without) were matched for age, gender, and estimated glomerular filtration rate (eGFR) distributions. Overall, both groups were predominantly male (54%, DNP; 57%, without) and of equal mean (SD) age (62.56 [9.35] and 62.23 [10.08] years, respectively; P = .809). Except for insulin use in the DNP group, the top 3 most common medications used by both patient groups were diuretics (34.0% in the non-DNP group; 62.5% in the DNP group; P < .001), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (41.5% and 52.7%, respectively; P = .109), and CCBs (48.9% and 60.7%; P = .090)

“In this study, it was shown for the first time that whether the etiology of CKD is DNP or not does not influence the OH prevalence in these patients,” the authors wrote.

However, they do cite several limitations to their findings, including their small sample size, lack of data on diabetes duration among their study subjects, and that blood pressure measurements were only taken once.

They recommend that patients with comorbid CKD and diabetes be evaluated for OH at every visit, along with potential causes, “because necessary precautions should be taken to prevent future OH-related complications.”

Reference

Gamze A, Kazancıoğlub R, Elçioğlub OC, et al. Comparative evaluation of orthostatic hypotension in patients with diabetic nephropathy. Kidney Blood Press Res. 2021;1-7. doi:10.1159/000517316