The management of pre-hypertension in primary care: Is it adequate?

Abstract

Background. Pre-hypertension (pHT) is frequently diagnosed in the primary care setting, but its management by primary care physicians (PCPs) is not well characterized. Methods. All individuals aged 30–45 years who were insured by Clalit Health services in the Tel Aviv district and had their blood pressure (BP) measured from January 2006 to December 2010 were evaluated. Individuals were divided into three groups based on their initial BP value: optimal (< 120/80 mmHg), normal (systolic BP 120–129 or diastolic 80–84 mmHg) and borderline (130–139/85–89 mmHg). Groups were compared regarding clinical and laboratory follow-up performed by their PCP. Results. Of the 20,214 individuals included in the study, 6576 (32.5%) had values in the pHT range. Of these, 2126 (32.3% of those with pHT) had BP values defined as “borderline” and 4450 (67.6% of those with pHT) had BP values defined as “normal”. The number of follow-up visits by the PCP and repeat BP measurement were similar in those with “optimal” BP and pHT. A third and fourth BP measurement were recorded more frequently in those with pHT. In those with pHT, there were more recorded BP measurements than in those with borderline BP (3.35 ± 3 vs 3.23 ± 2.6), but the time from the initial to the second measurement and a record of a third and fourth measurement were the same in the two groups. Conclusion. Identification of pHT does not lead to a significant change in follow-up by PCPs, irrespective of BP values in the pHT range.

Key Words::

• Hypertension
• pre-hypertension
• primary care

Introduction

Pre-hypertension (pHT) has been defined by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (the JNC 7 Report) as systolic blood pressure (BP) values of 120–139 mmHg or diastolic BP values of 80–89 mmHg (1). pHT is important both because BP values in this range are probably associated with increased cardiovascular morbidity and mortality (2,3) and because these individuals are at an increased risk for the development of frank hypertension (4,5). In addition, several studies found an increased prevalence of “traditional” cardiovascular risk factors in patients with pHT (6,7). It would therefore seem logical to have individuals with pHT under closer medical supervision and have their BP measured and risk factors assessed at a higher frequency compared with individuals with “optimal” BP values. Although the JNC 7 report recommended annual BP measurement in pHT as opposed to every 2 years in patients with optimal BP, it is not clear whether this recommendation is implemented in clinical practice (1). Because of the high prevalence of pHT (8,9), the follow-up of these individuals may be particularly time-consuming for the primary care physician (PCP). It is also unclear how often additional risk factors for cardiovascular disease are evaluated in these individuals. This study evaluated the follow-up of patients with pHT in a large cohort of patients managed in a primary care setting.

Patients and methods

The analysis was performed using a large unnamed database derived from a health care maintenance organization. Clalit Health Services (CHS) is the largest health organization in Israel and this study evaluated all individuals aged 30–45 years insured in CHS in the Tel Aviv district through a computerized medical database. All patients who were evaluated at least once by their PCP from January 2006 to December 2010 and had at least one BP measurement recorded in the medical file were included. To specifically evaluate the follow-up strategy of pHT, all patients with a previous diagnosis of hypertension, diabetes mellitus or ischemic heart disease were excluded from the analysis, as were patients treated with antidiabetic, antihypertensive or cardiac medications as defined by the ATC/DDD index 2010 (10).

For all eligible patients, the following data were retrieved from the computerized medical records: age, gender, initial BP values, follow-up BP values and the interval between measurements, body mass index (BMI), glucose values, lipid panel and serum creatinine. These variables were compared between two groups of patients based on JNC 7 definitions: (i) those with an initial “optimal” BP (systolic BP < 120 mmHg and diastolic BP < 80 mmHg); and (ii) those with pHT (systolic BP of 120–139 mmHg or diastolic BP of 80–89 mmHg). Those with pHT were further divided into two categories based on JNC 6 definitions: (i) those with an initial “normal” value (systolic BP of 120–129 mmHg or diastolic BP of 80–84 mmHg); and (ii) those with an initial BP in the “borderline” range (systolic BP of 130–139 mmHg or diastolic BP of 85–89 mmHg). When BP values were discordant, the patient was categorized according to the higher BP category, according to JNC 6/7 recommendations. The study was approved by the ethics committee of CHS with a waiver of informed consent.

Statistical analysis

Statistical analyses were performed using SPSS version 21 software (SPSS, Chicago, IL, USA). Continuous variables are presented as averages ± standard deviations in the tables. To test differences in continuous variables between the two groups, the independent samples t test or the Mann–Whitney U test was performed. Associations between dichotomous variables were assessed with the Pearson chi-squared test.

Results

From January 2006 to December 2010, 30,420 individuals aged 30–45 years were eligible for evaluation in CHS in the Tel Aviv district. Of these, 20,214 were evaluated by their PCP and had their BP measured on at least one occasion, 2707 were evaluated by their PCP but their BP was not recorded, and 7499 met exclusion criteria.

Of the 20,214 individuals who were evaluated by their PCP and had their BP measured, 13,638 (67.5% of the total cohort) had BP values defined as optimal and 6576 (32.5% of total cohort) had initial BP values in the pHT range. Of these, 2126 (32.3% of those with pHT) had BP values defined as borderline and 4450 (67.6% of those with pHT) had BP values defined as normal. Demographic and laboratory variables of all three groups are presented in Tables I and II. Individuals with pHT had higher glucose, higher low-density lipoprotein (LDL)-cholesterol, lower high-density lipoprotein (HDL)-cholesterol, higher triglycerides and higher creatinine concentrations compared with those with optimal BP (Table I). Those with borderline BP values had a higher BMI and higher triglyceride values compared with those with normal BP values (Table II).

Table I. Baseline characteristics of individuals with optimal blood pressure (BP) compared with pre-hypertension (pHT).

	Optimal BP (n = 13,638)	pHT (n = 6576)	p
Age (years)	32.7 ± 4.5	33.6 ± 4.7	< 0.01
Gender, M/F	8622/5016	2332/4244
Systolic blood pressure (mmHg)	106 ± 8	123.9 ± 5.1	< 0.01
Diastolic blood pressure (mmHg)	67.2 ± 6	80.9 ± 2	< 0.01
Body mass index (kg/m^2)	23.6 ± 4.3	26 ± 5	< 0.01
Glucose (mg/dl)	85.4 ± 11.1	88.3 ± 12	< 0.01
LDL-cholesterol (mg/dl)	110.3 ± 31.4	117.1 ± 32.5	< 0.01
HDL-cholesterol (mg/dl)	51.2 ± 12.8	47.1 ± 12	< 0.01
Triglycerides (mg/dl)	109.1 ± 59.1	132.5 ± 75	< 0.01
Creatinine (mg/dl)	0.76 ± 0.2	0.82 ± 0.2	< 0.01

M, male; F, female; LDL, low-density lipoprotein; HDL, high-density lipoprotein.

Table II. Baseline characteristics of the two subgroups comprising the pre-hypertension (pHT) group.

	Borderline BP (n = 2126)	Normal BP (n = 4450)	p
Age (years)	34.2 ± 4.7	33.3 ± 4.6	NS
Gender, M/F	1479/647	2765/1685
Systolic blood pressure (mmHg)	130.1 ± 4	121 ± 2.1	< 0.05
Diastolic blood pressure (mmHg)	82.4 ± 2.9	80.2 ± 0.7	< 0.05
Body mass index (kg/m^2)	26.9 ± 5.3	25.5 ± 4.8	< 0.05
Glucose (mg/dl)	89 ± 12.1	88 ± 9.5	NS
LDL-cholesterol (mg/dl)	120.8 ± 32.6	115.3 ± 32.3	NS
HDL-cholesterol (mg/dl)	46.3 ± 11.7	47.6 ± 12.1	NS
Triglycerides (mg/dl)	140.6 ± 77	128.6 ± 73.7	< 0.05
Creatinine (mg/dl)	0.84 ± 0.2	0.82 ± 0.2	NS

BP, blood pressure; M, male; F, female; LDL, low-density lipoprotein; HDL, high-density lipoprotein; NS, not significant.

Individuals with optimal BP were followed for 1271.8 ± 610.4 days, whereas those with pHT were followed for 1333.3 ± 605.6 days. In those with pHT, individuals with normal BP and borderline BP were followed for 1342.4 ± 601.9 days and 1314.3 ± 613.2 days, respectively. Follow-up examinations for those with optimal BP compared with pHT are presented in Tables III and IV. Re-evaluation by the PCP and repeat BP measurement were similar in those with pHT and those with optimal BP. The number of BP measurements per year of follow-up was slightly but significantly higher in those with optimal BP. Lipid panel and glucose were measured more often in those with pHT, whereas serum creatinine was measured more frequently in those with optimal BP. The time to performance of the second BP measurement following the initial one was longer in the pHT group (514.4 ± 418 days vs 493.6 ± 419 days) but this difference was not statistically significant. A third and fourth BP measurement were recorded more often in those with pHT.

Table III. Follow-up of patients with “optimal” blood pressure (BP) compared with pre-hypertension (pHT).

	Optimal BP	pHT	p
No. of office visits	4.34 ± 4.1	4.21 ± 4.1	NS
No. of BP measurements	3.15 ± 2.9	3.27 ± 2.7	NS
No. of BP measurements/years of follow-up	1.05 ± 1	1.01 ± 0.9	< 0.01
No. of blood glucose measurements	2.84 ± 2.5	2.64 ± 2.1	0.01
No. of LDL-cholesterol measurements	2.24 ± 1.7	2.35 ± 1.8	< 0.01
No. of HDL-cholesterol measurements	2.24 ± 1.7	2.35 ± 1.8	< 0.01
No. of blood triglyceride measurements	2.36 ± 1.8	2.46 ± 1.9	< 0.01
No. of blood creatinine measurements	2.61 ± 2.5	2.52 ± 2	0.05
Time to second BP measurement (days)	493.6 ± 419	514.4 ± 418	NS
Presence of third BP measurement (% of patients)	45.4	48.8	< 0.01
Presence of fourth BP measurement (% of patients)	30.2	33.4	< 0.01

LDL, low-density lipoprotein; HDL, high-density lipoprotein; NS, not significant.

Table IV. Follow-up of patients with “normal” blood pressure (BP) compared with “borderline” BP.

	Normal BP	Borderline BP	p
No. of office visits	4.23 ± 4.1	4.17 ± 4.2	NS
No. of BP measurements	3.23 ± 2.6	3.35 ± 3	0.01
No. of BP measurements/years of follow-up	0.99 ± 0.8	1.06 ± 1	0.01
No. of blood glucose measurements	2.64 ± 2.1	2.63 ± 2.1	NS
No. of LDL-cholesterol measurements	2.31 ± 1.8	2.42 ± 1.9	< 0.01
No. of HDL-cholesterol measurements	2.32 ± 1.8	2.42 ± 1.8	< 0.01
No. of blood triglyceride measurements	2.43 ± 1.9	2.53 ± 2	0.02
No. of blood creatinine measurements	2.5 ± 2	2.55 ± 2	NS
Time to second BP measurement (days)	527.15 ± 418	487.6 ± 418	NS
Presence of third BP measurement (% of patients)	48.9	48.8	NS
Presence of fourth BP measurement (% of patients)	33.5	33.3	NS

LDL, low-density lipoprotein; HDL, high-density lipoprotein; NS, not significant.

In individuals with pHT, there were more recorded BP measurements in those with borderline BP (3.35 ± 3, 0.99 ± 0.84 per year vs 3.23 ± 2.6, 1.06 ± 0.99 per year, p = 0.01 for both), but the time from the initial to the second measurement as well as the presence of a third and fourth measurement were not different between the two groups (Table IV).

Of those who had initial BP measurements in the pHT range, 4444 (68%) had a record of a second BP. Of these, in 1144 (25.7%) individuals the second BP was in the optimal range and in 3300 (74.2%) it was in the pHT range. Follow-up was similar in those who had pHT recorded on two measurements and in those in whom it was recorded only once (Table V).

Table V. Follow-up of patients with reproducible pre-hypertension (pHT) compared with those with a single measurement of pHT.

	Reproducible pHT	Single pHT	p
No. of office visits	4.6 ± 4.5	4.72 ± 4.3	NS
No. of BP measurements	4.08 ± 2.7	4.13 ± 2.8	NS
No. of blood glucose measurements	2.79 ± 2.2	2.91 ± 2.2	NS
No. of LDL-cholesterol measurements	2.5 ± 1.9	2.45 ± 1.8	NS
No. of HDL-cholesterol measurements	2.51 ± 1.85	2.47 ± 1.8	NS
No. of blood triglyceride measurements	2.63 ± 2	2.59 ± 1.9	NS
No. of blood creatinine measurements	2.66 ± 2.1	2.75 ± 2.1	NS
Time from second to third BP measurement (days)	391 ± 315.6	379.77 ± 335	NS
Presence of third BP measurement (% of patients)	66.7	66.4	NS
Presence of fourth BP measurement (% of patients)	45.7	45.2	NS

BP, blood pressure; LDL, low-density lipoprotein; HDL, high-density lipoprotein; NS, not significant.

Discussion

The prevalence of pHT in this cohort was similar to that reported in several previous studies (11,12). Two previous reports from Israel in which individuals of a similar age group as in our cohort were evaluated reported a much higher prevalence of pHT (13,14). A possible explanation for this difference is the fact that the two other reports from Israel were performed in military personnel, in which the stress associated with the examination and its consequences on future employment may have resulted in higher measured BP values; a previous study in older individuals from Israel reported pHT prevalence that was similar to our study (8).

Individuals who initially had pHT were more likely to harbor other characteristics associated with the metabolic syndrome, as has been previously reported (14–16). Although most baseline characteristics were similar between those with normal BP and borderline BP, BMI was higher in those with borderline BP. Despite the fact that there are no reports on the association of BMI with borderline hypertension, previous reports did find an association between BMI and pHT (17). The number of office visits and BP measurements during the follow-up period as well as the time interval between the initial BP measurement and the second measurement were similar in those with optimal BP and those with pHT. Acquiring two BP measurements compatible with pHT did not lead to a different follow-up compared with a single BP measurement of pHT.

This study reveals that the follow-up recommended by the JNC 7 committee for those with pHT is not implemented in routine practice and this persisted even when pHT was recorded in two measurements. Although those with pHT had more laboratory tests performed during follow-up and had a higher rate of a third and fourth BP recorded compared with those with pHT, it seems that single or repeated BP measurements in the pHT range did not result in a substantially different follow-up strategy among PCPs. In addition, the second BP measurement was performed on average 493.6 ± 419 days following the initial BP measurement in those with optimal BP and 514.4 ± 418 days following the initial BP measurement in those with pHT. This time-lag is in accordance with the JNC 7 recommendations for optimal BP (2 years) but is longer than the recommended 1 year for follow-up of pHT. This serves as additional evidence for the lack of maintaining guideline recommendations in those with pHT and emphasizes the importance of better defining the population requiring follow-up and of the creation of control mechanisms to ensure adequate follow-up of those with pHT.

In the pHT group, BP was measured more often in those with borderline hypertension despite the fact that these patients did not attend the primary care clinic more often. Yet, the time from the initial measurement to the second measurement as well as the presence of a third and fourth measurement were not different between these two groups. There are no studies comparing the natural history of normal and borderline hypertension and thus at present the recommendations for follow-up for these conditions are similar. As the follow-up of patients with normal and borderline BP was similar in this cohort, the classification of pHT into these subcategories probably has little influence on the management of pHT by PCPs.

This study has several limitations. A large number of patients was excluded from the original cohort. This was done in order to isolate the management of pHT by PCPs. Even after this exclusion process, we still had a high percentage of individuals with overweight in the final analysis and it is possible that factors other than pHT contributed to the follow-up of these patients. Yet, we believe that this was the best method to evaluate the follow-up of individuals with pHT. The study was performed in young individuals in order to identify patients without significant comorbidities. Thus, its results may not be applicable to an older population with more comorbidities in whom compliance with follow-up may be different. In addition, patients were followed up for different periods because BP was measured at different times and the study was performed at a single time-point. Yet, the length of follow-up was similar in those with optimal BP and those with pHT, and in those with normal and borderline BP, and thus the length of follow-up probably did not influence the results. Despite these limitations, this is the largest “real-life” analysis of the management and follow-up of pHT by PCPs.

Conclusions

Real-life follow-up of patients with pHT is not in accordance with recommended guidelines and is similar in those with normal BP and borderline BP. The clinical significance of pHT should thus be emphasized to PCPs, and policy makers should create control mechanisms to ensure adequate follow-up of this at-risk population.

Declaration of interest: None.