Uncontrolled and apparent treatment resistant hypertension in the United States, 1988 to 2008

Abstract

Background: Despite progress, many hypertensive patients remain uncontrolled. Defining characteristics of uncontrolled hypertensives may facilitate efforts to improve blood pressure control.

Methods and results: Subjects included 13,375 hypertensive adults from National Health and Nutrition Examination Surveys (NHANESs) subdivided into 1988 to 1994, 1999 to 2004, and 2005 to 2008. Uncontrolled hypertension was defined as blood pressure ≥140/≥90 mm Hg and apparent treatment-resistant hypertension (aTRH) when subjects reported taking ≥3 antihypertensive medications. Framingham 10-year coronary risk was calculated. Multivariable logistic regression was used to identify clinical characteristics associated with untreated, treated uncontrolled on 1 to 2 blood pressure medications, and aTRH across all 3 survey periods. More than half of uncontrolled hypertensives were untreated across surveys, including 52.2% in 2005 to 2008. Clinical factors linked with untreated hypertension included male sex, infrequent healthcare visits (0 to 1 per year), body mass index <25 kg/m2, absence of chronic kidney disease, and Framingham 10-year coronary risk <10% (P<0.01). Most treated uncontrolled patients reported taking 1 to 2 blood pressure medications, a proxy for therapeutic inertia. This group was older, had higher Framingham 10-year coronary risk than patients controlled on 1 to 2 medications (P<0.01), and comprised 34.4% of all uncontrolled and 72.0% of treated uncontrolled patients in 2005 to 2008. We found that aTRH increased from 15.9% (1998-2004) to 28.0% (2005-2008) of treated patients (P<0.001). Clinical characteristics associated with aTRH included ≥4 visits per year, obesity, chronic kidney disease, and Framingham 10-year coronary risk >20% (P<0.01).

Conclusion: Untreated, undertreated, and aTRH patients have consistent characteristics that could inform strategies to improve blood pressure control by decreasing untreated hypertension, reducing therapeutic inertia in undertreated patients, and enhancing therapeutic efficiency in aTRH.

Figure 1

The percentages are depicted of hypertensive patients that reported taking 0, 1, 2, and ≥3 antihypertensive medications for (A) all (B) all uncontrolled (C) treated uncontrolled (D) treated controlled patients in the different NHANES. Symbols over a trio of columns indicate significant changes in the percentage of patients reportedly taking a given number of antihypertensive medications across the three NHANES time periods. ** p<0.01; *** p<0.001.

Figure 2

The independent relationship between selected clinical variables and the dependent variable untreated hypertension are shown as multivariable odds ratios and 95% confidence intervals for each of the three NHANES periods. The reference group for comparison is all uncontrolled hypertensive patients. Confidence intervals that do not cross the line of identity (1.0) are considered statistically significant.

Figure 3

The independent relationship between selected clinical variables including class of antihypertensive medications and the dependent variable uncontrolled hypertension on 1–2 antihypertensive medications are shown as multivariable odds ratios and 95% confidence intervals for each of the three NHANES periods. The reference group is all hypertensive patients that reported taking 1–2 BP medications. Confidence intervals that do not cross the line of identity (1.0) are considered statistically significant.

Figure 3

The independent relationship between selected clinical variables including class of antihypertensive medications and the dependent variable uncontrolled hypertension on 1–2 antihypertensive medications are shown as multivariable odds ratios and 95% confidence intervals for each of the three NHANES periods. The reference group is all hypertensive patients that reported taking 1–2 BP medications. Confidence intervals that do not cross the line of identity (1.0) are considered statistically significant.

Figure 4

The independent relationship between selected clinical variables and the dependent variable apparent treatement resistant hypertension (aTRH, [uncontrolled on ≥3 BP medications]) are shown as multivariable odds ratios and 95% confidence intervals for the three NHANES periods. The reference group is all uncontrolled hypertensive patients. Confidence intervals that do not cross the line of identity (1.0) are considered statistically significant.

Figure 5

The percentage of controlled and uncontrolled hypertensive patients taking various classes of antihypertensive medications are depicted for NHANES 2005–2008 only. The percentages of patients within each bar are further subdivided by those who are taking the medication class indicated as monotherapy or as part of a 2 or ≥3 antihypertensive medication regimen. The denominator is all controlled or uncontrolled patients within each NHANES period. ‡ p<0.01 between controlled and uncontrolled patients for the medication class indicated. ARB=angiotensin receptor blocker; ACEI=angiotensin converting enzyme inhibitor; nd=nondihyrdopyridine, d = dihyrdropryidine; TD = thiazide diuretic, LD = loop diuretic, KSD = K+-sparing diuretic.