New Staging System of the Fifth Joint National Committee Report on the Detection, Evaluation, and Treatment of High Blood Pressure (JNC-V) Alters Assessment of the Severity and Treatment of Hypertension
The fifth Joint National Committee report on the detection, evaluation, and treatment of high blood pressure (JNC-V) introduced a new system of blood pressure classification that incorporated systolic blood pressure (SBP) and established new diastolic blood pressure (DBP) cut points. With the previous JNC classification, subjects were classified according to DBP alone. In this study, our purpose was to assess the effect of the new staging system on the assessment of hypertension severity and to determine whether the new JNC-V staging system better identifies individuals at risk for hypertensive target-organ damage. We compared the assessment of hypertension severity using JNC-IV with that using JNC-V in 1158 subjects enrolled in the Harlem Hospital Hypertension Clinic database from 1975 to 1992. We used pretreatment DBP to classify subjects according to JNC-IV criteria. These subjects were reclassified into one of the four stages of JNC-V. The assessment of hypertension severity and prevalence of organ damage in subjects who remained in the same category of severity in both systems was compared with damage in subjects who were upstaged. With the JNC-V classification, 321 subjects remained in the same category, and 837 were upstaged. Six hundred and four subjects moved up because of the new cut points of DBP, and 275 were upstaged because of higher SBP. Upstaged subjects had more manifestations of hypertensive target-organ damage. With the new JNC-V classification system, hypertension is assessed as severe or very severe in more individuals than with JNC-IV. Subjects who are upstaged in JNC-V are more likely to have evidence of renal disease and other target-organ damage.
The fifth Joint National Committee report on the detection, evaluation, and treatment of high BP (JNC-V) introduced a new system of BP classification that uses both systolic and diastolic measurements.1 With previous JNC reports, including JNC-IV, subjects were classified by only DBP level. Subjects with DBP less than 90 mm Hg and SBP of 160 mm Hg or greater were all classified as having isolated systolic hypertension. Subjects with elevated DBP and SBP were classified solely according to the level of DBP as mild, moderate, or severe (Table 1⇓). With JNC-V, there are four stages of SBP and four stages of DBP. If the SBP and DBP yield different stages, the higher stage is used for classification. The four stages are shown in Table 2⇓. In JNC-V, the addition of SBP to the new staging scheme acknowledges the importance of SBP to cardiovascular and renal disease risk. All stages of hypertension are associated with an increased risk of nonfatal and fatal cardiovascular events and renal disease; the higher the BP, the greater the risk. Specifically, regarding the effect of SBP, JNC-V states that risks are greater with higher levels of SBP at every level of DBP.
This is the first major revision of the classification of hypertension since the inception of the JNC in 1972. It is not known what effect this new classification system will have on the assessment of the severity or treatment of high BP in individuals or population groups. We studied the effect of the new JNC-V staging system on the assessment of hypertension severity in a cohort of hypertensive men and women.
The subjects in this study are members of a cohort of subjects enrolled in the clinical database of the Harlem Hospital Center High Blood Pressure Program and are followed in the Harlem Hospital Hypertension Clinic. The High Blood Pressure Program was founded in 1975 with the long-term goal of reducing the morbidity and mortality attributable to high BP by providing appropriate treatment for hypertension and educating hypertensive individuals regarding the importance of lowering their BP to recommended levels through proper treatment. The program includes the Inpatient Hypertension Service, which provides consulting services for all individuals with complicated hypertension admitted to Harlem Hospital; the Hypertension Clinic, which manages outpatients with hypertension; and the Community Hypertension Project, which conducts cardiovascular risk reduction education programs, BP screening, and detection and follow-up programs in the community.
The clinic population is composed almost exclusively of black men and women. Individuals are referred from several sources: the Harlem Hospital inpatient service, other Harlem Hospital clinics, community screening, community organizations, healthcare providers, and self-referral. Because of the variety of referral sources, the subjects are diverse in socioeconomic status, comorbidities, and hypertension stages. Most of the subjects are from Harlem, a community with a high prevalence of hypertension, stroke, renal failure, chronic ischemic heart disease, and congestive heart failure.
The medical records of all 1413 individuals who had been enrolled in the Hypertension Clinic between January 1, 1975, and December 31, 1992, were reviewed for inclusion in the study. Inclusion criteria required that subjects be older than 18 years, have BP data available, and not be on antihypertensive medication within 4 weeks of presentation. Pretreatment DBP was used for classification of subjects' hypertension as mild, moderate, or severe by the JNC-IV criteria. Pretreatment SBP and DBP were then used for reclassification of these subjects into one of the four stages of JNC-V. The assessment of hypertension severity by the two classification systems was compared.
We cross-tabulated the JNC-IV classification of presenting BP for all subjects in the study cohort with the JNC-V classification to detect changes in the proportion of subjects with hypertension identified as mild, moderate, severe, or very severe. Within each JNC-IV classification, using the JNC-V cut points for SBP and DBP, we cross-tabulated presenting SBPs with presenting DBPs to decide which was responsible for the new staging category.
To determine whether the new system was a more accurate assessor of risk from hypertension, we selected 198 subjects with JNC-IV mild hypertension for special analysis from the total of 558 JNC-IV mild cases. These 198 subjects were selected to include (1) all of the 66 subjects who were upstaged from the JNC-IV mild category to the JNC-V severe (stage 3) or very severe (stage 4) category and (2) two randomly chosen comparison cases for each upstaged case from the 190 who were not upstaged at all. No cases were chosen from those who were upstaged only one grade to moderate. See Fig 1⇓ for a graphic display of the selection process.
We used baseline clinical data, including medical history, physical examination, laboratory findings, electrocardiogram, echocardiogram, and chest radiograph, to determine the presence of cardiovascular, peripheral vascular, cerebrovascular, retinal, and renal damage. We compared the subjects in the mild category under both JNC-IV and JNC-V (group 1) with the subjects in JNC-IV mild who were upstaged to severe or very severe (group 2) to determine the prevalence of target-organ damage.
For continuous variables, Student's t test was used for evaluation of differences in means; between two groups for categorical variables, χ2 tests were performed. Differences were considered significant at a probability level of less than or equal to .05.
Of the total 1413 enrolled individuals, 1158 were older than 18 years and were not on antihypertensive medication within 4 weeks of presentation. The subjects who were excluded from the study were younger (46.7 versus 51.8 years); there were no significant differences in sex or source of referral.
Thirty-eight percent of the subjects were male and 98% were black. Fig 2⇓ compares the assessment of hypertension severity under the two classification systems. With the JNC-IV classification, mild was the most common class of hypertension, with 558 subjects (48.2%) so classified. With JNC-IV, 288 subjects (24.9%) were classified as having moderate, 219 (18.9%) as having severe, and 93 (8.0%) as having isolated systolic hypertension. When these 1158 subjects were reclassified with JNC-V staging, 240 (20.7%) were classified as stage 1 (mild), 404 (34.9%) as stage 2 (moderate), 329 (28.4%) as stage 3 (severe), and 185 (16.0%) as stage 4 (very severe).
Table 3⇓ shows the effect of JNC-V staging on subject classification in each JNC-IV class. When the 93 subjects with JNC-IV isolated systolic hypertension were reclassified with JNC-V criteria, 50 became JNC-V stage 1, 22 became stage 2, 18 became stage 3, and 3 became stage 4. When the 558 subjects with JNC-IV mild hypertension were reclassified with JNC-V criteria, 190 remained mild (stage 1), 302 became stage 2, 62 became stage 3, and 4 became stage 4. When the 288 subjects with JNC-IV moderate hypertension were reclassified with JNC-V criteria, 80 remained moderate (stage 2), 198 became stage 3, and 10 became stage 4. When the 219 JNC-IV severe subjects were reclassified with JNC-V criteria, 51 remained severe (stage 3) and 168 became stage 4. Overall, 321 (27.7%) of the subjects remained in the same category of severity, and 837 (72.3%) were staged higher.
Effect of Revised DBP Cut Points
The cut points for the four stages of DBP with the JNC-V classification differed from the cut points for the three classes of DBP with the JNC-IV classification. The DBP cut points for the mild category were 90 through 104 mm Hg for JNC-IV and 90 through 99 mm Hg for JNC-V stage 1; for the moderate category, 105 through 114 mm Hg for JNC-IV and 100 through 109 mm Hg for JNC-V stage 2; for the severe category, greater than or equal to 115 mm Hg for JNC-IV and 110 through 119 mm Hg for JNC-V stage 3; and for the very severe category, greater than or equal to 120 mm Hg according to JNC-V stage 4 (JNC-IV has no very severe category).
Inherent in the new JNC-V classification of DBP is the upstaging of some individuals by one category because of the lower DBP cut points; that is, subjects with DBP in the upper range of a JNC-IV class will stage one category of severity higher with JNC-V staging. Consequently, 258 subjects with DBP in the upper range of JNC-IV mild (DBP 100 to 104 mm Hg) met the criteria for stage 2, and 184 subjects in the upper range of JNC-IV moderate (DBP 110 to 114 mm Hg) met the criteria for stage 3. One hundred and sixty-two of the 219 subjects in the upper range of JNC-IV severe (DBP ≥115 mm Hg) met the criteria for JNC-V stage 4 (very severe). A total of 604 subjects (52.2%) moved up one category of severity because of the revised staging of DBP.
Effect of Inclusion of SBP on JNC Staging
With the addition of four stages of SBP to the JNC-V classification, it became possible for SBP and DBP to yield different categories of severity. Table 4⇓ shows the effect of the inclusion of SBP on the assessment of hypertension severity with JNC-V staging. SBP and DBP yielded the same stage in 349 (30.1%) subjects. DBP yielded a higher category than SBP in 534 subjects (46.1%), and SBP yielded a higher category than DBP in 275 (23.7%). In the 883 subjects whose DBP yielded the same or a higher category than the category of SBP, the inclusion of SBP in the JNC-V classification did not influence the staging. However, in the 275 subjects whose SBP yielded a higher category than the DBP, the level of SBP determined the JNC-V staging of the subjects. This group of subjects included the 93 subjects who had been classified as JNC-IV isolated systolic hypertension, 142 subjects as JNC-IV mild, 34 as JNC-IV moderate, and 6 as JNC-IV severe. Table 4⇓ shows how SBP influenced the JNC-V staging of these 275 subjects whose SBP yielded a higher stage than the DBP. One hundred and ten of 300 subjects with DBP in the stage 1 range of 90 to 99 mm Hg moved to a higher category when SBP was added to the staging. The higher stages of these 110 subjects were as follows: stage 2, 76 subjects; stage 3, 31 subjects; and stage 4, 3 subjects. Fifty-six of 362 subjects with DBP in the stage 2 range of 100 to 109 mm Hg moved to a higher category when SBP was added to the staging: 55 subjects became stage 3, and 1 subject became stage 4. Sixteen of 241 subjects with DBP in the stage 3 range of 110 to 119 mm Hg became stage 4 with the addition of SBP to JNC-V staging.
Effect of Age and Sex on JNC Staging
SBP and age were closely correlated in these subjects (r=.265, P<.001), and the effect of SBP on JNC-V staging was most prominent in subjects 60 years of age and older (Table 5⇓). Of 300 subjects with DBP in the stage 1 range of 90 to 99 mm Hg, 68.0% of those older than 60 years were staged because of the level of SBP (compared with 21.0% of subjects younger than 60 years). Of 362 subjects with DBP in the stage 2 range of 100 to 109 mm Hg, 31.3% of those older than 60 years were staged because of the SBP level (compared with 10.8% of those younger than 60 years of age). Of 241 subjects with DBP in the stage 3 range of 110 to 119 mm Hg, 15.2% of those older than 60 years of age were staged because of the level of SBP (compared with 3.4% of those younger than 60 years). When the subjects whose staging was determined by SBP were compared with the subjects whose staging was determined by DBP, those in the systolic group were significantly older (mean age, 59.6 years, compared with 47.3 years in the diastolic group; P<.001) and more likely to be female (70.3% female compared with 54.1% female in the diastolic group, P<.001).
JNC-V Staging and Cardiovascular and Renal Disease Risk
A special analysis included 62 of the 66 subjects who were in the JNC-IV mild category but were upstaged to severe or very severe with the JNC-V classification (group 2) and 132 of 190 subjects in the mild category under both JNC-IV and JNC-V (group 1). Four of the upstaged cases had inadequate data for the special analysis. The 132 subjects for group 1 were not significantly different in age, sex, or referral source from the 58 subjects who were not selected for the special analysis.
Comparison of group 1 (n=132) and group 2 (n=62) showed that the subjects in group 2 were significantly older (61.6 versus 46.1 years) and had a higher prevalence of target-organ damage (Table 6⇓). Left ventricular hypertrophy was found in 40.7% of group 2 subjects and 27.8% of group 1 subjects (P=.13). Coronary artery disease, defined by occurrence of myocardial infarction, was present in 3.3% of group 2 subjects and 0.8% of group 1 subjects (P=.48). Overall, evidence of cardiovascular organ damage, defined as left ventricular hypertrophy or occurrence of myocardial infarction, was found in 36.1% of group 2 subjects and 24.8% of group 1 subjects (P=.15). An elevated serum creatinine level (>1.4 mg/dL for males, >1.2 mg/dL for females) was found in 28.6% of group 2 subjects and 11.1% of group 1 subjects (P=.01). The prevalence of cerebrovascular disease, peripheral vascular disease, and retinopathy did not differ significantly between the two groups. When all factors were taken into account, 78.7% of group 2 subjects and 61.7% of group 1 subjects had one or more manifestations of hypertensive target-organ damage (P=.03).
The clinical implication of the new JNC-V classification on the assessment of the severity and management of hypertensive individuals has not been studied. In this study, we found that the JNC-V classification had a significant effect on the assessment of hypertension severity in a cohort of hypertensive subjects. In contrast to earlier data,2 the mild category was no longer the most common. Only 21% of subjects remained in the mild category with restaging; 35% of the subjects were staged as moderate; and 44% were staged as severe or very severe. Overall, more than half of the subjects were staged in a higher category of severity with the new JNC-V staging. The subjects in this study were staged higher because the classification system for diastolic hypertension has been shifted toward lower levels and a new aggressive classification system for systolic hypertension has been introduced. The subjects whose higher staging resulted from the revised cut points of DBP in JNC-V moved up by one category of severity. The subjects who were upstaged as a result of the addition of SBP to the staging process moved up as many as three levels of severity. For example, a subject with a BP of 212/90 mm Hg would be classified as mild under the JNC-IV classification and as stage 4 (very severe) under the JNC-V classification.
The JNC reports have had a far-reaching influence on the diagnosis, evaluation, and treatment of high BP since the formation of the committee in 1972. The second JNC report in 1980 introduced a BP classification system according to the level of DBP, with subjects classified as mild, moderate, or severe.3 This classification was used in all subsequent reports until JNC-V in 1993.3 4 5 This classification has been widely used in the determination of hypertension severity in individuals with elevated BP, and this severity classification has been used to decide the indications for and efficacy of antihypertensive therapy. In addition, epidemiological studies of the association of hypertension severity with target-organ damage have been based on the JNC classification of hypertension.
The fact that the new staging system of JNC-V alters the assessment of hypertension severity among some individuals may provide insight into several unexplained epidemiological and clinical observations. For example, it has been noted that despite the favorable effect of hypertension treatment on stroke and total cardiovascular mortality, the effect of hypertension treatment on coronary heart disease has been less favorable than expected.6 7 One possibility is that the exclusion of SBP from the clinical assessment and treatment goals of patients led to an inaccurate assessment of the severity and/or adequacy of treatment of hypertension in some of these patients. It is noteworthy that 70% of the subjects in the present study had a disparity between the JNC-V stages yielded by SBP and DBP. In the subjects whose SBP and DBP fell into different categories, SBP yielded a higher stage in 30%. When one considers that SBP is at least as important a predictor of cardiovascular complications as DBP,8 9 the results of this study would suggest that the previous JNC classification systems were likely to underestimate the risk associated with hypertension in more than a fifth of hypertensive individuals.
Several studies have shown that black subjects with mild hypertension have a greater prevalence of hypertensive complications than white subjects with similar BP levels.10 11 12 13 Although the reason for this disparity has not been determined, one possible explanation is that the black and white subjects may not be truly comparable in their severity of hypertension. For example, if black subjects with mild hypertension (based on DBP) have higher SBP than white subjects with similar levels of DBP, a difference in clinical outcomes might be explained. It should be noted that during screening for the Systolic Hypertension in the Elderly Program, blacks and women were more likely to have a disproportionate elevation of SBP compared with DBP.14 Our subject population was almost completely black, so we were unable to compare whites and blacks in the present study. However, our population can serve as a valuable comparison group for studies with white populations.
In summary, the new JNC staging will have a significant effect on the assessment of hypertension severity in individuals and population groups, especially in women and the elderly. The revised JNC-V classification, by placing individuals in a higher category of severity, will influence how hypertensive individuals are treated. The person who moves from JNC-IV mild to JNC-V stage 4 will be started on antihypertensive drugs sooner and will have a shorter interval between changes in the drug regimen. The upstaged individual may start treatment with more than one medication and have an increase in the maximum dosage of some drugs.
This study also confirms that the use of SBP and DBP in the classification schema provides a more accurate assessment of the individual's risk of hypertensive complications than the previous classification. Subjects who are upstaged because of the addition of SBP to the new classification system have more hypertensive target-organ damage. This finding supports the validity and usefulness of the new classification system in the assessment of hypertensive individuals. Whether this new staging will lead to an improved outcome is yet to be determined.
Selected Abbreviations and Acronyms
|DBP||=||diastolic blood pressure|
|JNC||=||Joint National Committee|
|JNC-IV||=||Fourth Joint National Committee Report on the Detection, Evaluation, and Treatment of High Blood Pressure|
|JNC-V||=||Fifth Joint National Committee Report on the Detection, Evaluation, and Treatment of High Blood Pressure|
|SBP||=||systolic blood pressure|
This study was supported in part by American Health Care Policy and Research grant No. HS0-7399. The authors thank Dr Gerald E. Thomson and Dr George Branche who established the Harlem Hospital hypertension database, Dr Alfred Ashford for his review of the manuscript, and Katherine Aponte for expert administrative assistance.
- Received April 17, 1996.
- Revision received May 8, 1996.
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