5G-03 - Interaction of Antihypertensive Drugs and Ambient Temperature on the Risk of Intradialytic Hypotension

Background: Intradialytic hypotension (IDH) is a common and severe complication in hemodialysis patients. Antihypertensive agents directly affect blood pressure, while ambient temperature has also been linked to blood pressure fluctuations. However, the interaction between antihypertensive use and ambient temperature on IDH risk remains unclear.

Objectives: To evaluate whether an interaction exists between antihypertensive use and ambient temperature in modifying IDH risk among hemodialysis patients.

Methods: We conducted a retrospective cohort study at National Cheng Kung University Hospital, including new dialysis patients (≥20 years) who received antihypertensive drugs between 2016 and 2021. All hemodialysis sessions within three years from dialysis initiation were identified, excluding the first 90 days. IDH was defined as systolic blood pressure (SBP) < 90 mmHg or a blood pressure fall of 40 mmHg during hemodialysis. Antihypertensive exposure on the dialysis date included alpha-blockers (AB), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEI/ARB), beta-blockers (BB), and dihydropyridine calcium channel blockers (DHP-CCB). Ambient temperature was linked via national weather data. A generalized linear mixed model was applied to estimate odds ratios (OR) and 95% confidence intervals (CI) for IDH risk, incorporating an interaction term for antihypertensives and ambient temperature, adjusting for demographics, comorbidities, dialysis parameters, and co-medications.

Results: A total of 115 patients with 39,371 hemodialysis sessions were included (mean age: 61.4 years, 60% male). A significant interaction was observed between ambient temperature and alpha-blockers (AB) (p=0.0312) and dihydropyridine calcium channel blockers (DHP-CCB) (p=0.0296), with IDH risk increasing by 7% and 3% per 1°C rise, respectively. For AB, the estimated odds ratio (OR) was 0.26 (95% CI: 0.12–0.57) at 14°C and 0.85 (95% CI: 0.55–1.31) at 31°C, indicating a reduced protective effect at higher temperatures. For DHP-CCB, the OR was 0.47 (95% CI: 0.34–0.66) at 14°C and 0.80 (95% CI: 0.63–1.02) at 31°C. No significant interactions were found for ACEI/ARB (p=0.3205) or beta-blockers (p=0.8853). Similar trends were observed when defining the event as Fall40.

Conclusions: Ambient temperature modifies the effect of alpha-blockers and DHP-CCB on IDH risk, weakening their protective effects as temperature increases. These findings highlight the need for temperature-sensitive antihypertensive management in hemodialysis patients.