Tahlia Kerridge

Dr Tahlia Kerridge MBChB, CertHSc
- Resident Medical Officer, Whakatane Hospital

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Nocturnal Dipping Pattern In 24-hour Ambulatory Blood Pressure Recordings Of Hypertensive Individuals In The Bay Of Plenty ​

AIMS: 24-Hour Ambulatory blood pressure monitoring (ABPM) is gold standard for diagnosis/management of hypertension (HT). Untreated and poorly controlled HT leads to increased rates of cerebrovascular, cardiovascular, and renal disease. Data is lacking on dipping patterns in different ethnicities of New Zealand (NZ). The primary aim was to compare nocturnal dipping pattern between Maori and Non-Maori ethnicities. Secondary aims included comparison of nocturnal HT, morning surge index (MSI) and ambulatory arterial stiffness index (AASI) amongst them and comparison as per socio-economic deprivation index (NZDep 2018).

METHODS: ABPM data of hypertensive adults >18 years of age (on antihypertensives) in EBOP was collected retrospectively from Midland Clinical Portal from 1st December 2018 to 31st July 2021. Duplicates or unsuccessful ABPM results were excluded from the analysis. Normal dipping was defined as 10-20%, non-dipping being 0-<10%, reverse dipping <0% and extreme dipping >20%. Statistics were processed using Excel. 

RESULTS: Of 213 ABPMs analysed, 20% were Maori. 39.5% of Maori were non-dippers and 9.3% were reverse dippers. Amongst Non-Maori, 34.1% were non-dippers and 13.5% were reverse dippers (p=0.840). Uncontrolled nocturnal HT was more likely in Maori (60.5%) as compared to Non-Maoris (54.1%), though not significant (p=0.454). AASI was significantly higher (p=0.001) in Non-Maori, though MSI was not different (p=0.865). Lower socio-economic demographic individuals or Maori are less likely to receive ABPM.

CONCLUSIONS: There was no statistical difference between dipping status of Maori and Non-Maori. However, it is evident up to 55% of patients in this data set have uncontrolled nocturnal HT suggesting that EBOP is receiving subtherapeutic management of their HT. Therefore, all hypertensives should have ABPM in NZ to manage HT. As HT is more prevalent in Maori, researchers recommend a commitment from Bay of Plenty District Health Board to address this inequity to improve cardiac, cerebrovascular and renal health.