ANZCTR - Registration

The ANZCTR website will be unavailable from 1pm until 3pm (AEDT) on Wednesday the 30th of October for website maintenance. Please be sure to log out of the system in order to avoid any loss of data.

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers

Trial registered on ANZCTR

Registration number

ACTRN12613001382763

Ethics application status

Approved

Date submitted

8/12/2013

Date registered

17/12/2013

Date last updated

17/12/2013

Type of registration

Prospectively registered

Titles & IDs

Public title

An observational study comparing protocol estimated values to the measured values of mean arterial basal blood pressure

Scientific title

An observational study to assess the agreement between protocol estimated values and directly measured values for the basal blood pressure in a cohort of patients who recently underwent direct measurements of their resting arterial blood pressure.

Secondary ID [1]

Nil

Universal Trial Number (UTN)

U1111-1151-1657

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Patients who recently underwent ambulatory nighttime blood pressure monitoring

Condition category

Condition code

Cardiovascular

Hypertension

Intervention/exposure

Study type

Observational

Patient registry

False

Target follow-up duration

Target follow-up type

Years

Description of intervention(s) / exposure

This is a retrospective observational cohort study among patients who attended our hospital cardiology department. We will enrol only those patients who recently underwent nighttime ambulatory blood pressure (BP) monitoring (within the last 2 years). These BP measurements will be considered as direct measurements of basal arterial BP.

For all enrolled patients, a blinded study investigator who is not aware of the direct measurements, will then estimate the basal mean arterial BP according to a preset protocol, which is displayed in public notes section.

Both values, directly measured and protocol-estimated, will be then correlated for each participant.

Intervention code [1]

Not applicable

Comparator / control treatment

We will enrol only those patients who recently underwent nighttime ambulatory blood pressure monitoring (within the last 2 years). These BP readings will be considered as direct measurements of basal arterial BP. Patient list will be extracted from the cardiology database, and the hospital electronic health information system will be accessed to obtain the required data. Where the patients do not have any digital medical records, we will contact patient’s local doctors to request previous BP measurements and anti-hypertensive treatment.

Control group

Active

Outcomes

Primary outcome [1]

Agreement between the summary measures of protocol-estimated basal arterial BP and directly-measured basal arterial BP

Timepoint [1]

Direct measurement of nighttime or basal arterial BP during ambulatory BP monitoring within last two years

Secondary outcome [1]

Correlation between protocol estimated basal arterial BP and directly measured basal arterial BP

Timepoint [1]

Basal arterial BP would have been measured during nighttime ambulatory BP monitoring within the last two years

Eligibility

Key inclusion criteria

Patients with recent outpatient ambulatory BP monitoring within last 2 years AND 2 to 5 recorded BP measurements in a routine/follow up clinic BP within last three years

Minimum age

40 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Patients with end stage renal disease and/or receiving dialysis

Study design

Purpose

Screening

Duration

Longitudinal

Selection

Defined population

Timing

Retrospective

Statistical methods / analysis

R-square statistics will be used to quantify agreement between the summary measures of directly measured and protocol-estimated BP. The strength of the relationship will be reported using linear regression (assuming normality). The Bland-Altman plot will then be used to demonstrate that there was no bias in the relationship. Finally, we will incorporate covariates such as alteration in antihypertensive prescription and lability of BP.

As there is no prior data on this subject, the sample size calculation is convenience-based. We intend to enrol 100-200 patients with ambulatory BP monitoring. We believe the agreement data on this range of sample size will be a reasonable representation of the broader population. We will endeavour to collect maximum number of patients within this range if possible, as a larger sample size will provide a more precise estimate.

Recruitment

Recruitment status

Not yet recruiting

Date of first participant enrolment

Anticipated

18/12/2013

Actual

Date of last participant enrolment

Anticipated

Actual

Date of last data collection

Anticipated

Actual

Sample size

Target

150

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

NSW

Recruitment hospital [1]

John Hunter Hospital Royal Newcastle Centre - New Lambton

Recruitment postcode(s) [1]

2305 - New Lambton

Funding & Sponsors

Funding source category [1]

Hospital

Name [1]

John Hunter Hospital

Address [1]

ICU, 64 Lookout Road, John Hunter Hospital,
New Lambton, NSW 2305

Country [1]

Australia

Primary sponsor type

Hospital

Name

John Hunter Hospital

Address

ICU, 64 Lookout Road, John Hunter Hospital,
New Lambton, NSW 2305

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Hunter New England Human Research Ethics Committee

Ethics committee address [1]

Locked Bag 1
New Lambton, NSW 2305

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

03/12/2013

Approval date [1]

16/12/2013

Ethics approval number [1]

Summary

Brief summary

Few patients admitted to the intensive care unit (ICU) have a previous record of directly measured BP during nighttime or resting (hereto referred as basal) state. Therefore, the usual hemodynamic targets in ICU are broadly based on values relevant to the general population. Individualising these targets could vastly improve management of critically ill patients. A validated protocol to estimate a patient’s baseline BP would enable this tailored therapy for the patients. 

The main purpose of this study is to assess the agreement (or the difference) between a protocol-estimated value and a directly measured value for the resting BP in a cohort of patients who recently underwent direct measurements of their resting arterial BP.

In this study, we hypothesise that the directly measured and protocol-estimated BP values will correlate well with minimal bias.

Trial website

Trial related presentations / publications

Public notes

Data will be collected on age, gender, previous clinic arterial BP, measured arterial BP and any major co-morbidities. All information collected for the study will be rendered unidentifiable before data is exported for further analysis. Participants’ data will be recorded directly in an Excel spread sheet and identified only by patient initials and the assigned study number.

The final study report will not contain any identifiable data of the participants. Where there is no record of previous BP measurements in the digital medical records, then a written/verbal request will be made to the patient’s local doctor. In case no previous BP measurements of a patient can be traced, then, since we cannot estimate basal BP for such a patient, he/she will be excluded from the study.

Participants: We anticipate enrolling approximately 100-200 patients for arterial BP assessment. This is a convenience-based sample size as there is no previous data in literature to determine appropriate sample size for such a study.

The preset protocol to estimate basal MAP is as follows:

Step 1: Find preferably up to five or at least two pre-morbid MAP (or BP) measurements, recorded at least 12 hours apart, starting with the most recent reading available within the last 3 years. The selected MAP (or BP) readings should be from a period when the patient met following criteria: was not admitted to ICU, was at least two weeks following any surgery, was not in renal failure, was not pregnant, was not receiving intravenous anti-hypertensive drugs, diuretics, or analgesics on that day, and was not transferred to another health care facility within the next two days. 

1.1 Find pre-morbid MAP (or BP) measurements recorded during outpatient visits, pre-admission assessment or during a non-invasive cardiac investigation. If unavailable, then

1.2 Find pre-morbid MAP (or BP) recorded on the observation charts from the last 48 hrs of a previous hospitalization. If multiple BP readings are available during the night, record the median BP during the last night of previous hospital stay. Then, record BP measurements that were done closest to the 12-hour interval from the selected median BP reading.


Step 2: Derive pre-morbid basal MAP as follows:

2.1 Convert BP readings that are recorded in SBP/DBP format to MAP as per the equation: MAP = DBP + 1/3(SBP-DBP)

2.2 Subtract 15% from the daytime MAP values to estimate nighttime (basal) MAP to account for the nighttime fall in BP in accordance with published data on 24h ambulatory BP in previous studies. 

2.3 Consider the mean of these estimated pre-morbid nighttime MAP values as basal-MAP.

Contacts

Principal investigator

Name

Dr Rakshit Panwar

Address

ICU, 64 Lookout Road, John Hunter Hospital,
New Lambton, NSW 2305

Country

Australia

Phone

+61412018808

Fax

[email protected]

Contact person for public queries

Name

Rakshit Panwar

Address

ICU, 64 Lookout Road, John Hunter Hospital,
New Lambton, NSW 2305

Country

Australia

Phone

+61410218808

Fax

[email protected]

Contact person for scientific queries

Name

Rakshit Panwar

Address

ICU, 64 Lookout Road, John Hunter Hospital,
New Lambton, NSW 2305

Country

Australia

Phone

+61410218808

Fax

[email protected]

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Validity of a protocol to estimate patients' pre-morbid basal blood pressure*.	2018	https://dx.doi.org/10.1080/08037051.2017.1358055

N.B. These documents automatically identified may not have been verified by the study sponsor.

Trial Review

Documents added manually

Documents added automatically