A randomized n-of-1 study comparing blood pressure measured on a clothed arm and on an arm with a rolled-up sleeve

ABSTRACT

Background

Blood pressure [BP] should be measured using a bare upper arm with an appropriately sized cuff. In practice, it is more convenient to measure BP on a bare arm below a rolled-up sleeve or on a sleeved arm.

Aim

A n-of-1 randomized controlled trial was performed to assess the difference between BP measurements over a sleeve or below a rolled-up sleeve.

Methods

The study subject was male, white, 72 years old, BMI 26 kg/m2, arm circumference 29 cm, and under stable antihypertensive treatment. The mean of three BP measurements over a thin sleeve was compared with measurements below a rolled-up sleeve. Additional measurements on a completely bare arm, with thicker sleeves and up to three layers were performed. The order of measurements was determined by chance and two oscillometric devices were used. Descriptive statistics, Bland-Altman test and 2-side T test were used for comparisons.

Results

504 measurements were performed: 50 % over the sleeve and 50 % below the rolled-up sleeve. The mean systolic blood pressure (SBP) was respectively 116.9 ± 9. 2 [95% CI 115.7–118.0, range 96–135] and 122.8 ± 9.2 [95% CI 121.7–124.0, range 103–139, p = 0.001] mm Hg. The mean diastolic blood pressure [DBP] was respectively 67.6 ± 6.8 [95% CI 66.8–68.4, range 52–84] and 71.8 ± 6.8 [95% CI 71.0–72.7, range 55–85, p = 0.001] mm Hg. There was no significant difference between the measurements over the sleeve and on the completely bare arm [n = 94, p = 0.97]. Sleeve thickness with 2 layers up to 3 mm thick did not affect the results.

Conclusions

Blood pressure measurements over a thin sleeve were significantly lower than measurements below a rolled-up sleeve and match measurements on a completely bare arm.

KEYWORDS:

• Hypertension
• blood pressure measurement
• clothing
• N-of-1 trial

Disclosure statement

No potential conflict of interest was reported by the author.

Ethics approval

No ethical approval is required as this is an observational study using data collected during real life day-to-day work in one participant, who is also the investigator and the author of the paper.

Data availability statement

data are available upon simple request from the author

Additional information

Funding

The author did not receive support from any organization for the submitted work.