• Ethnicity and differences between clinic and ambulatory blood pressure measurements

      Martin, U.; Haque, M.S.; Wood, S.; Greenfield, S.M.; Gill, P.S.; Mant, J.; Mohammed, Mohammed A.; Heer, G.; Johal, A.; Kaur, R.; et al. (2015)
      This study investigated the relationship of ethnicity to the differences between blood pressure (BP) measured in a clinic setting and by ambulatory blood pressure monitoring (ABPM) in individuals with a previous diagnosis of hypertension (HT) and without a previous diagnosis of hypertension (NHT). A cross-sectional comparison of BP measurement was performed in 770 participants (white British (WB, 39%), South Asian (SA, 31%), and African Caribbean (AC, 30%)) in 28 primary care clinics in West Midlands, United Kingdom. Mean differences between daytime ABPM, standardized clinic (mean of 3 occasions), casual clinic (first reading on first occasion), and last routine BP taken at the general practitioner practice were compared in HT and NHT individuals. Daytime systolic and diastolic ABPM readings were similar to standardized clinic BP (systolic: 128 (SE 0.9) vs. 125 (SE 0.9) mm Hg (NHT) and 132 (SE 0.7) vs. 131 (SE 0.7) mm Hg (HT)) and were not associated with ethnicity to a clinically important extent. When BP was taken less carefully, differences emerged: casual clinic readings were higher than ABPM, particularly in the HT group where the systolic differences approached clinical relevance (131 (SE 1.2) vs. 129 (SE 1.0) mm Hg (NHT) and 139 (SE 0.9) vs. 133 (SE 0.7) mm Hg (HT)) and were larger in SA and AC hypertensive individuals (136 (SE 1.5) vs. 133 (SE 1.2) mm Hg (WB), 141 (SE 1.7) vs. 133 (SE 1.4) mm Hg (SA), and 142 (SE 1.6) vs. 134 (SE 1.3) mm Hg (AC); mean differences: 3 (0-7), P = 0.03 and 4 (1-7), P = 0.01, respectively). Differences were also observed for the last practice reading in SA and ACs. BP differences between ethnic groups where BP is carefully measured on multiple occasions are small and unlikely to alter clinical management. When BP is measured casually on a single occasion or in routine care, differences appear that could approach clinical relevance.
    • Influence of ethnicity on acceptability of method of blood pressure monitoring: a cross-sectional study in primary care.

      Wood, S.; Greenfield, S.M.; Haque, M.S.; Martin, U.; Gill, P.S.; Mant, J.; Mohammed, Mohammed A.; Heer, G.; Johal, A.; Kaur, R.; et al. (2016)
      Background: Ambulatory and/or home monitoring are recommended in the UK and North America for the diagnosis of hypertension but little is known about acceptability. Aim: To determine the acceptability of different methods of measuring blood pressure to people from different ethnic minority groups. Design and setting : Cross sectional study with focus groups in primary care. Methods: People with and without hypertension of different ethnicities were assessed for acceptability of clinic, home and ambulatory blood pressure measurement using completion rate, questionnaire and focus groups. Results: 770 participants were included comprising white British (n=300), South Asian (n=241) and African Caribbean (n=229). White British participants had significantly higher successful completion rates across all monitoring modalities compared to the other ethnic groups, especially for ambulatory monitoring: white British (277 completed, 92%[89-95%]) vs South Asian (171, 71%[65-76%], p<0.001 and African Caribbean (188, 82%[77-87%], p<0.001) respectively. There were significantly lower acceptability scores for minority ethnic participants across all monitoring methods compared to white British. Focus group results highlighted self-monitoring as most acceptable and ambulatory monitoring least without consistent differences by ethnicity. Clinic monitoring was seen as inconvenient and anxiety provoking but with the advantage of immediate professional input. Conclusions: Reduced acceptability and completion rates amongst minority ethnic groups raise important questions for the implementation and interpretation of blood pressure monitoring in general and ambulatory monitoring in particular. Selection of method for blood pressure monitoring should take into account clinical need and patient preference as well as consideration of potential cultural barriers to monitoring.
    • Inter-arm difference in systolic blood pressure in different ethnic groups and relationship to the “white coat effect”: a cross sectional study

      Schwartz, C.L.; Clark, C.E.; Koshiaris, C.; Gill, P.S.; Greenfield, S.M.; Haque, M.S.; Heer, G.; Johal, A.; Kaur, R.; Mant, J.; et al. (2017-09)
      Background: Inter-arm differences (IAD) ≥10mmHg in systolic blood pressure (BP) are associated with greater incidence of cardiovascular disease. The effect of ethnicity and the white coat effect (WCE) on significant systolic inter-arm differences (ssIADs) are not well understood. Methods: Differences in BP by ethnicity for different methods of BP measurement were examined in 770 people (300 White British, 241 South Asian, 229 African-Caribbean). Repeated clinic measurements were obtained simultaneously in the right and left arm using two BP-Tru monitors and comparisons made between the first reading, mean of second and third and mean of second to sixth readings for patients with, and without known hypertension. All patients had ambulatory monitoring (ABPM). WCE was defined as systolic Clinic BP ≥10mmHg higher than daytime ABPM. Results: No significant differences were seen in the prevalence of ssIAD between ethnicities whichever combinations of BP measurement were used and regardless of hypertensive status. ssIADs fell between the 1st measurement (161, 22%), 2nd/3rd (113, 16%) and 2nd-6th (78, 11%) (1st vs 2nd/3rd and 2nd-6th, p<0.001). Hypertensives with a WCE were more likely to have ssIADs on 1st, (OR 1.73 (95% CI 1.04-2.86), 2nd/3rd, (OR 3.05 (1.68-5.53) and 2nd-6th measurements, (OR 2.58 (1.22-5.44). Non-hypertensive participants with a WCE were more likely to have a ssIAD on their first measurement (OR 3.82 (1.77 -8.25) only. Conclusion: ssIAD prevalence does not vary with ethnicity regardless of hypertensive status but is affected by the number of readings, suggesting the influence of WCE. Multiple readings should be used to confirm ssIADs.