Different time points, different blood pressures: complexity of blood pressure measurement in hemodialysis patients

We used our established database to investigate predialysis blood pressure (BP) measurements at different time points.

Our study period spanned from 1 January 2019 to 31 December 2019. The different time points included: the long interdialytic interval versus the short interdialytic interval; different hemodialysis shifts. Multiple linear regression was used to explore the association between BP measurements and different time points.

A total of 37 081 cases of hemodialysis therapies were included. After a long interdialytic interval, predialysis SBP and DBP were significantly elevated. Predialysis BP was 147.72/86.73 mmHg on Monday and 148.26/86.52 mmHg on Tuesday, respectively. Both predialysis SBP and DBP were higher in the a.m. shift. The mean BP in the a.m. and p.m. shifts were 147.56/87 mmHg and 144.83/84.64 mmHg, respectively. In both diabetic nephropathy and non-diabetic nephropathy patients, higher SBP measurements after a long interdialytic interval were observed; however, in diabetic nephropathy patients, we did not find significant differences in DBP among different dates. In diabetic nephropathy and non-diabetic nephropathy patients, we observed that the effect of different shifts on BP was similar. In Monday, Wednesday and Friday subgroups, the long interdialytic interval was also associated with BP; however, in Tuesday, Thursday and Saturday subgroups, different shifts but not the long interdialytic interval was associated with BP.

The long interdialytic interval and different hemodialysis shifts have a significant effect on predialysis BP in patients with hemodialysis. When interpreting BP in patients with hemodialysis, different time points is a confounder.