Patterns in blood pressure medication use in US incident dialysis patients over the first 6 months

Abstract

Background: Several observational studies have evaluated the effect of a single exposure window with blood pressure (BP) medications on outcomes in incident dialysis patients, but whether BP medication prescription patterns remain stable or a single exposure window design is adequate to evaluate effect on outcomes is unclear.

Methods: We described patterns of BP medication prescription over 6 months after dialysis initiation in hemodialysis and peritoneal dialysis patients, stratified by cardiovascular comorbidity, diabetes, and other patient characteristics. The cohort included 13,072 adult patients (12,159 hemodialysis, 913 peritoneal dialysis) who initiated dialysis in Dialysis Clinic, Inc., facilities January 1, 2003-June 30, 2008, and remained on the original modality for at least 6 months. We evaluated monthly patterns in BP medication prescription over 6 months and at 12 and 24 months after initiation.

Results: Prescription patterns varied by dialysis modality over the first 6 months; substantial proportions of patients with prescriptions for beta-blockers, renin angiotensin system agents, and dihydropyridine calcium channel blockers in month 6 no longer had prescriptions for these medications by month 24. Prescription of specific medication classes varied by comorbidity, race/ethnicity, and age, but little by sex. The mean number of medications was 2.5 at month 6 in hemodialysis and peritoneal dialysis cohorts.

Conclusions: This study evaluates BP medication patterns in both hemodialysis and peritoneal dialysis patients over the first 6 months of dialysis. Our findings highlight the challenges of assessing comparative effectiveness of a single BP medication class in dialysis patients. Longitudinal designs should be used to account for changes in BP medication management over time, and designs that incorporate common combinations should be considered.

Figure 1

Flow diagram for patients included and excluded from the study. DCI, Dialysis Clinic, Inc; HD, hemodialysis; PD, peritoneal dialysis; USRDS, United States Renal Data System; patients were evaluated for exclusion criteria in the 6-month period after dialysis initiation.

Figure 2

Percentages of hemodialysis and peritoneal dialysis patients prescribed blood pressure medication classes or specific agents over the first 6 months after dialysis initiation. BP, blood pressure; CCB, calcium channel blocker; Cent Alpha 2 Ag, central alpha 2 agonist; DHP, dihydropyridine; diuretic, any including thiazides, thiazide-like, loop, potassium-sparing; HD, hemodialysis; NDHP, non-dihydropyridine; PD, peritoneal dialysis; RAS, renin angiotensin system agent (angiotensin converting enzyme inhibitor or angiotensin receptor blocker).

Figure 3

Blood pressure medications (single or in combination) prescribed for ≥ 5% of hemodialysis or peritoneal dialysis patients with at least one blood pressure medication prescription. BB, beta blocker; BP, blood pressure; DHP, dihydropyridine; diuretic, any including thiazides, thiazide-like, loop, potassium-sparing; RAS, renin angiotensin system agent (angiotensin converting enzyme inhibitor or angiotensin receptor blocker).

Figure 4

Blood pressure medication combinations prescribed for ≥ 10% of hemodialysis or peritoneal dialysis patients with at least one blood pressure medication prescription. BB, beta blocker; BP, blood pressure; RAS, renin angiotensin system agent (angiotensin converting enzyme inhibitor or angiotensin receptor blocker).