Comparison of Blood Pressure Lowering with Hydrochlorothiazide and ChlorthalidoneKurt A. Wargo, Pharm.D., BCPS, Thomas M. English, Ph.D., Anna J. Aaron, Pharm.D. Candidate

Auburn University Harrison School of Pharmacy and University of Alabama School of Medicine, Huntsville Regional Medical Campus

Objective Results Results DiscussionJNC-VII guidelines recommend thiazide diuretics as first line agents to treat hypertension. Unfortunately, for clinicians, specific recommendation on which thiazide diuretic to use is not provided. A plethora of evidence suggests chlorthalidone lowers blood pressure more effectively than hydrochlorothiazide (HCTZ) and this lowering of blood pressure has been proposed to lead to decreased morbidity and mortality. Therefore, the purpose of this study was to determine if the blood pressure lowering exhibited with HCTZ was similar to that of chlorthalidone, and if so this could justify the use of HCTZ as first line.

Methods

Conclusions

Disclosure

Institutional Review Board approvedRetrospective, observational analysis

Inclusion criteria:• Initiated on hydrochlorothiazide or chlorthalidone from

January 1, 2009 until December 31, 2010Exclusion criteria:• Less than 19 years of ageProcedure:• Patients were identified using a search engine for

those initiated on one of the study medications from January 1, 2009 until December 31, 2010

• The following data was collected: • Age, sex, height, weight, vital signs (blood pressure

and heart rate), laboratory values (sodium, potassium, BUN, creatinine, glucose), concurrent disease states, doses of study medications and concurrent antihypertensive agents utilized

Analysis:• Statistical analysis is to be completed• Results listed are preliminary raw data

Table 1. Baseline Demographics

Kurt A. Wargo, Thomas M. English, and Anna J. Aaron have no financial or personal relationships with any commercial entities to disclose

Chlorthalidone (n=72)

HCTZ (n=805)

Mean Age, yrs ( SD) 55.84 14.79 53.03 15.09

Mean BMI ( SD) 33.58 7.48 33.05 9.11

Mean systolic BP ( SD) 158.93 23.90 154.25 21.55

Mean diastolic BP ( SD) 89.66 13.67 89.91 12.11

Heart rate (BPM) 78.08 15.84 82.44 15.88

Sodium (mEq/L) 138.64 3.57 139.39 2.64

Potassium (mEq/L) 4.12 0.5 4.16 0.41

BUN (mg/dL) 17.35 8.78 15.03 6.9

Serum Creatinine (mg/dL) 1.04 0.34 0.96 0.29

Glucose (mg/dL) 123.89 78.03 118.87 89.78

Comorbid disease statesDiabetes (n, %)Chronic kidney diseaseHyperlipidemiaAtrial fibrillationCoronary artery diseaseMyocardial infarction or Heart failureStroke/TIA

16 (22.2) 5 (6.9)

23 (32.9)1 (1.4)4 (5.6)2 (2.8)

2 (2.8)

201 (25)60 (7.4)

295 (36.6)9 (1.1)40 (5)

29 (3.6)

31 (3.9)

Mean number of medications other than thiazide diuretics* 1.51 1.58 1.18 1.02

•Figure 1 demonstrates that patients taking chlorthalidone may experience a greater percent change reduction in systolic blood pressure compared to patients taking HCTZ

•Patients taking chlorthalidone had an average percent decrease in SBP of 13.51% ± 11.09 versus HCTZ, which had a decrease of 9.09 ± 12.12

•Figure 2 demonstrates that a greater percentage of patients reached their goal blood pressure in the chlorthalidone group (56.9%) compared to HCTZ (46.5%)

•After treatment, the average potassium level in the chlorthalidone group was 4.04 0.43 mEq/L (a decrease of 2% from baseline), whereas the potassium level remained unchanged in the HCTZ group

•Thiazide diuretics are recommended as first line agents in the treatment of hypertension

•Currently no specific thiazide diuretic is recommended over another

•This study demonstrates that chlorthalidone may result in improved blood pressure control compared to HCTZ

•Chlorthalidone use was not associated with a significant reduction in potassium levels

•We recommend further studies be conducted in order to demonstrate chlorthalidone should be the preferred thiazide diuretic to use in the treatment of hypertension

Figure 1. Percentage change in systolic blood pressure (SBP)

Figure 2. Percentage of patients reaching BP control

*Medications allowed: ACEI/ARB, DHP CCB, non-DHP CCB, Beta blockers, Spironolactone, Loop diuretics

Most common medications in each group were ACEI/ARB followed by beta blockers.

-14%

-9%

-16%

-14%

-12%

-10%

-8%

-6%

-4%

-2%

0%

46%

57%

0%

10%

20%

30%

40%

50%

60%

Chlorthalidone Hydrochlorothiazide

Chlorthalidone Hydrochlorothiazide