II. Criteria for Diagnosis of Hypertension and Guidelines for Follow-up

Diagnosis and Assessment

Hypertension Canada continues to emphasize the use of out-of-office measurements to rule out white coat hyper-tension in subjects with increased BP in the office . Its prevalence is estimated to be between 9% and 30%.It is more common in women, older subjects, nonsmokers, subjects with mildly elevated office BP, pregnant women, and subjects without target organ damage. Subjects with white coat hypertension have been shown to have an overall cardiovascular risk that approximates that of normotensive subjects. Thus, at present, there is no evidence to support pharmacologic treatment of subjects with white coat hypertension. Because treated and untreated subjects have long-term cardiovascular risk similar to that of treated and untreated normotensive individuals, respec-tively,it is clinically relevant to identify individuals with white coat hypertension to avoid overtreatment. In individuals with diabetes, diagnosis of hypertension is probable when OBPM is 130/80 for 3 or more mea-surements on different days; out-of-office measurements could be considered to rule out white coat hypertension, when suspected. Although the diagnostic thresholds for ABPM and HBPM (as well as for AOBP) have not yet been established in subjects with diabetes, they are probably 601 lower than those mentioned for diagnosis of hypertension in the general population.

In cases of normal BP in the office, the possibility of masked hypertension (high out-of-office BP) should be sus-pected in the following cases: older age, men, current smoking, heavy alcohol drinking, obesity, diabetes mellitus, or other traditional cardiovascular risk factors, as well as in cases of electrocardiographic left ventricular hypertrophy, and high-normal systolic and diastolic office BP.Masked hypertension is common in untreated adults, with a possible prevalence of approximately 20%, which is even higher in individuals with controlled office BP (more than 1 of 3 treated individuals).48 When suspected, masked hyperten-sion should be ruled out by performing out-of-office mea-surements. In subjects with diabetes, absence of nocturnal dipping in BP (identified using ABPM) is common and correlates with higher cardiovascular mortality. Specif-ically, although mean attended AOBP and daytime ABPM have been shown to be similar in subjects with diabetes, baseline 24-hour SBP (hazard ratio, 1.53; 95% CI, 1.28-2.03) and nighttime SBP (hazard ratio, 1.50; 95% CI, 1.26-1.89) were independent predictors of short-term cardiovas-cular outcomes. Furthermore, in diabetes the adjusted odds ratio for progression to macroalbuminuria has been shown to be more than eight-fold higher in the masked hypertension group (diagnosed with HBPM) than in the controlled BP group.

Guidelines for diagnosis of hypertension

  1. At initial presentation, patients who exhibit features of a hypertensive urgency or emergency (Supplemental Table S2) should be diagnosed as hypertensive and require immediate management (Grade D). In all other patients, at least 2 more readings should be taken during the same visit.
  2. If the visit 1 OBPM is high-normal (thresholds outlined in section I. Accurate measurement of BP, Recommendation 4. ii) the patient’s BP should be assessed at yearly intervals (Grade C).
  3. If the visit 1 mean AOBP or OBPM is high (thresholds outlined in section I. Accurate measurement of BP, Recom-mendation 4. i and ii), a history and physical examination should be performed, and, if clinically indicated, diagnostic tests to search for target organ damage (Table 2) and associated cardiovascular risk factors (Table 3) should be arranged within 2 visits. Exogenous factors that can induce or aggravate hypertension should be assessed and removed if possible (Supplemental Table S3). Visit 2 should be scheduled within 1 month (Grade D).
  4. If the visit 1 mean AOBP or OBPM SBP is 180 mm Hg or DBP is 110 mm Hg then hypertension is diagnosed (Grade D).
  5. If the visit 1 mean AOBP SBP is 135-179 mm Hg or DBP is 85-109 mm Hg or the mean OBPM SBP is 140-179 mm Hg or DBP is 90-109 mm Hg out-of-office BP measurements should be performed before visit 2 (Grade C).
    1. ABPM is the recommended out-of-office measurement method (Grade D). Patients can be diagnosed with hypertension according to the following thresholds
      1. if the mean awake SBP is 135 mm Hg or DBP is 85 mm Hg,
      2. if the mean 24-hour SBP is 130 mm Hg or DBP is 80 mm Hg (Grade C).
    2. HBPM (as outlined in section I. Accurate measurement of BP, Recommendation 4. iv) is recommended if ABPM is not tolerated, not readily available, or patient preference (Grade D). Patients can be diagnosed with hypertension if the mean SBP is 135 mm Hg or DBP is 85 mm Hg (Grade C).
    3. If the out-of-office ABPM or HBPM average is not elevated, white coat hypertension should be diagnosed and pharmacologic treatment should not be instituted (Grade C). If the mean HBPM is < 135/85 mm Hg, before diagnosing white coat hypertension, it is advisable to either: (1) perform ABPM to confirm that the mean awake BP is < 135/85 mm Hg and the mean 24-hour BP is < 130/80 mm Hg (preferred); or (2) repeat a HBPM series to confirm the home BP is < 135/85 mm Hg (Grade D).

  6. If the out-of-office measurement, although preferred, is not performed after visit 1, then patients can be diagnosed as hypertensive using serial OBPM visits if any of the following conditions are met:
    1. At visit 2, the mean OBPM (averaged across all visits) is 140 mm Hg SBP and/or 90 mm Hg DBP in pa-tients with macrovascular target organ damage, diabetes mellitus, or chronic kidney disease (glomerular filtration rate [GFR] < 60 mL/min/1.73 m2; Grade D);
    2. At visit 3, the mean OBPM (averaged across all visits) is 160 mm Hg SBP or 100 mm Hg DBP; and
    3. At visit 4 or 5, the mean OBPM (averaged across all visits) is 140 mm Hg SBP or 90 mm Hg DBP
  7. Investigations for secondary causes of hypertension should be initiated in patients with clinical and/or laboratory features indicative of hypertension (outlined in sections III. Routine and optional laboratory tests for the investigation of patients with hypertension, XVI. Assessment for renovas-cular hypertension, XVII. Treatment of hypertension in asso-ciation with renovascular disease, XVIII. Assessment for endocrine hypertension, and XIX. Treatment of secondary hypertension due to endocrine causes; Grade D).

Guidelines for follow-up of hypertension

  1. If at the last diagnostic visit the patient is not diagnosed as hypertensive and has no evidence of macrovascular target organ damage, the patient’s BP should be assessed at yearly intervals (Grade D)
  2. Hypertensive patients actively modifying their health be-haviours should be followed-up at 3- to 6-month intervals. Shorter intervals (every 1 or 2 months) are needed for patients with higher BP (Grade D).
  3. Patients receiving antihypertensive drug treatment should be seen monthly or every 2 months, depending on the level of BP, until readings on 2 consecutive visits are below their target (Grade D). Shorter intervals between visits will be needed for symptomatic patients and those with severe hypertension, intolerance to antihypertensive drugs, or target organ damage (Grade D). When the target BP has been reached, patients should be seen at 3- to 6-month intervals (Grade D).
  4. Standard OBPM should be used for follow-up. Measure-ment using electronic (oscillometric) upper arm devices is preferred over auscultation (Grade C).
  5. ABPM or HBPM is recommended for follow-up of pa-tients with demonstrated white coat effect (Grade D).

ABPM

A suggested protocol for ABPM is presented in Supplemental Table S1.

Recommendations

  1. In addition to a general recommendation for hypertensive patients (in section II. Diagnosis of hypertension and follow-up, 5), ABPM should be considered when an office-induced increase in BP is suspected in treated patients with:
    1. BP that is not below target despite receiving appro-priate chronic antihypertensive therapy (Grade C);
    2. symptoms suggestive of hypotension (Grade C); or
    3. fluctuating office BP readings (Grade D).
  2. The magnitude of changes in nocturnal BP should be taken into account in any decision to prescribe or withhold drug therapy on the basis of ABPM (Grade C) because a decrease in nocturnal BP of < 10% is associated with increased risk of cardiovascular events.

HBPM

    A suggested protocol for HBPM is presented in Supplemental Table S1.

    Recommendations

    1. The use of HBPM on a regular basis should be considered for patients with hypertension, particularly those with:
      1. Inadequately controlled hypertension (Grade B; revised recommendation);
      2. Diabetes mellitus (Grade D);
      3. Chronic kidney disease (Grade C);
      4. Suspected nonadherence (Grade D);
      5. Demonstrated white coat effect (Grade C); or
      6. BP controlled in the office but not at home (masked hypertension; Grade C).
    2. Health care professionals should ensure that patients who measure their BP at home have adequate training, and if necessary, repeat training in measuring their BP. Patients should be observed to determine that they measure BP correctly and should be given adequate information about interpreting these readings (Grade D).