Evaluation of the Omron MX3 Plus monitor for blood pressure

Eur J Pediatr DOI 10.1007/s00431-009-0936-x

ORIGINAL PAPER

Evaluation of the Omron MX3 Plus monitor for blood pressure measurement in adolescents Diego Giulliano Destro Christofaro & Juliano Casonatto & Marcos Doederlein Polito & Jefferson Rosa Cardoso & Rômulo Fernandes & Débora Alves Guariglia & Aline Mendes Gerage & Arli Ramos de Oliveira

Received: 8 December 2008 / Accepted: 27 January 2009 # Springer-Verlag 2009

Abstract This study analyzed the accuracy/agreement of the Omron MX3 monitor on 165 adolescents. Blood pressure was measured by the automatic monitor connected in Y with the mercury column (three consecutive and simultaneous measures). The independent measures were analyzed, and the mean differences between systolic and diastolic measures for both methods were calculated and compared with British Hypertension Society (BHS) and Association for the Advancement of D. G. D. Christofaro : J. Casonatto : M. D. Polito (*) : J. R. Cardoso : D. A. Guariglia : A. M. Gerage : A. R. de Oliveira Department of Physical Education, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid km 380, 86051-990 Londrina, PR, Brazil e-mail: [email protected] D. G. D. Christofaro e-mail: [email protected] J. Casonatto e-mail: [email protected] J. R. Cardoso e-mail: [email protected] D. A. Guariglia e-mail: [email protected] A. M. Gerage e-mail: [email protected] A. R. de Oliveira e-mail: [email protected] R. Fernandes Department of Physical Education, Universidade Estadual Paulista, Rua Roberto Simonsen 305, 19060-900 Presidente Prudente, SP, Brazil e-mail: [email protected]

Medical Instrumentation (AAMI) criteria. The automatic monitor received the highest degree of BHS recommendations for systolic and diastolic blood pressures according to the BHS. The median (25th and 75th) difference between the observer and the monitor measurements was −2 (−6 and 1)mmHg for systolic and 0 (−3 and1)mmHg for diastolic pressures. The monitor also satisfies the AAMI standard for the studied population. In conclusion, the Omron MX3 Plus monitor can be considered reliable and valid for clinical practice and is in accordance with BHS and AAMI criteria. Keywords Blood pressure . Validation . Adolescents

Introduction Prevalence of elevated blood pressure is currently considered as one of the main risk factors for development of cardiovascular disease [23]. Hypertension has increased in adults [5, 7, 13, 22] as well as in children and adolescents [8, 12, 19], becoming a public health problem since cardiovascular diseases are the worldwide main cause of death [23]. Precise and reliable blood pressure (BP) measures, whether in clinical practice or in epidemiological research, are indispensable for diagnosis and for the interpretation of data. The literature recommends several forms of measuring BP [18], among these the most commonly used methods are the auscultatory method, which can be measured by either aneroid sphygmomanometer or mercury column. However, this method’s accuracy may be compromised by human errors such as mistakes in the identification of Korotkoff phases, incorrect eye positioning in reading the manometer scale and excessive stethoscope pressure on the

Eur J Pediatr

brachial artery, excessive cuff inflation, and/or high speed deflation [17]. Another alternative is to measure the blood pressure automatically, which can be both auscultatory or oscillometric. The automated oscillometric method was used in this study because it avoids the common errors associated with the manual auscultatory method, as well as being both low cost and easy to use. However, this type of equipment must be evaluated according to international criteria, such as those suggested by the British Hypertension Society (BHS) [14] and the Association for the Advancement of Medical Instrumentation (AAMI) [3]. Furthermore, the majority of validation data originate from adult samples [2, 6, 16, 20, 26] information, and although several studies have been conducted with children [1, 4, 11, 21, 24, 25], there are few studies that have examined the sensitivity and specificity of these types of devices jointly with a validation of BHS [14] and AAMI [3] protocols with this population. Thus, the purpose of the present study was to evaluate the accuracy of the Omron MX3 Plus (model HEM-742-E) blood pressure monitor among adolescents according to BHS [14] and AAMI [3] standards.

Materials and methods The BHS [15] protocol recommends that 30 participants be included in a formal validation study in children and adolescents. Brazilian children are a largely heterogeneous population in terms of height, body size, and ethnicity. Therefore, given the availability of a large number of children participating in the present study, we preferred to include a larger sample. The study sample was taken from a single public middle school and was composed of 165 (84 boys and 81 girls) adolescents of both genders and ranged in age from 10 to 15 years old. Prior diagnosis of any cardiac problem was considered the exclusion criteria, and additionally, no adolescent with any reported renal problem was detected. All the students who were invited to participate received a written informed consent form, which was filled out by both the parents and the adolescents before they took part in the survey. The study was approved by the Ethics Committee on Human Experimentation of the Institution involved (0281.0.268.000-07). Anthropometric measures The adolescents’ chronological age was obtained. Body mass and stature were measured for sample characterization, by means of a digital scale and a metal stadiometer. The adolescents were barefoot and dressed in light clothes for the measurements, in agreement with the protocol

Table 1 Criteria used by British Hypertension Society [14] for differences between monitor and mercury column Classification

Monitor variation in comparison to mercury column ≤5mmHg

Degree Degree Degree Degree

A B C D

≤10mmHg

60% 85% 50% 75% 40% 65% Inferior to the degree C

≤15mmHg 95% 90% 85%

suggested by Gordon et al. [10]. From this information, body mass index (BMI) was calculated, being expressed in kilograms per square meter. Blood pressure measures For BP measurement, two types of cuffs were used according to the arm circumference (6 mm × 12 mm [prepubertal children] and 9 mm×18 mm [adolescents]), following the recommendations of the American Heart Association (AHA) [18]. To determine which cuff would be used, the circumference of the arm of each child was measured, and the cuff that had approximately 40% of the width of arm circumference and 80% of length was used, according to AHA recommendations. After these procedures, the Omron MX3 Plus monitor was connected in Y with the mercury column, and the inflation mechanism of the monitor was activated; thus, blood pressure was measured simultaneously by the oscillometric device and the mercury column. Before gauging the BP, the subjects rested in a seated position for 5 min. The measurement of the BP was taken at the individuals’ right arm, and the observer who registered the values of the mercury column did not have access to the values of the Omron monitor. Table 2 Subjects' physical characteristics grouped by gender Variables

Male (n=84) Mean (SD)

Female (n=81) Mean (SD)

Age (years) Weight (kg) Height (cm) BMI (kg/m2) Auscutatory SBP (mmHg) DBP (mmHg) Omron MX3 Plus SBP (mmHg) DBP (mmHg)

12.8 48.1 1.56 19.7

12.7 49.4 1.56 20.1

(1.3) (11.7) (0.08) (3.1)

(1.3) (10.1) (0.07) (2.9)

110.2 (7.2) 64.5 (4.1)

110.4 (8.4) 65.3 (4.6)

112.6 (7.1) 65.6 (3.9)

112.3 (8.1) 65.8 (4.9)

SD standard deviation, SBP systolic blood pressure, DBP diastolic blood pressure

Eur J Pediatr Table 3 Comparison between Omron MX3 Plus and mercury column according to BHS procedures [14]

Evaluations

SBP DBP

Variation monitor tests in comparison with mercury column

495 495

≤5mmHg

≤10mmHg

≤15mmHg

66.8% (331) 69.8% (346)

88.0% (436) 91.1% (451)

96.7% (479) 97.3% (482)

Three consecutive and simultaneous measures were taken between the monitor and the mercury column for each subject, with an interval of 2 min between each. The independent measures were analyzed; the mean differences between the systolic and diastolic, as well as the standard deviation (SD) of those differences, were calculated. Device classification was based on the differences between the mercury column and the automatic monitor and classified in accordance with BHS [14] and AAMI [3] protocols. All the measures were taken by experienced observers. Validation criteria The BHS [14] criteria specifies that for a device to be validated, it must recive a degree of B. This means that, among the population measured, there can be no deviation above 5 mmHg for 50% of the subjects, above 10 mmHg in 75% of the subjects, and above 15 mmHg in 90% of the subjects (Table 1). The established criteria for AAMI [3] protocol indicates that the differences between averages of the measures with the tested monitor and the mercury column should be ≤5 mmHg and that the standard deviation of the differences of the averages is not larger than 8 mmHg. Statistical procedures The variables (anthropometric and BP values) were tested for normal distribution and are presented in a descriptive form (mean and standard deviation). Both paired Student t test and ANOVA for repeated measures were used to compare the mean of the numerical values. Intraclass Table 4 Comparison of the monitors for blood pressure assessment

SD standard deviation, ICC intraclass correlation coeficient, 95%CI 95% confidence interval, SBP systolic blood pressure, DBP diastolic blood pressure

SBP I SBP II SBP III ANOVA DBP I DBP II DBP III ANOVA

correlation coefficient (ICC; random effect one factor) and the agreement test of Bland and Altman were used to obtain intraobserver reliability data. An ICC of 1 indicates high reliability (i.e., errors are considered to be absent), while ICC = 0 indicates no reproducibility. The 95% confidence interval for each ICC value was calculated. The Bland and Altman agreement test was also utilized to examine the mean difference between the measures ( d ) and their respective reliability intervals of 95% (IC 95% for d ), the standard deviation of the difference of the average (SD of d ), and the agreement limits. The closer the distribution of the values of the Bland and Altman test is to zero, the higher is the agreement. Furthermore, the receiver operating characteristic (ROC) curve was used to analyze the accuracy of the Omron MX3 Plus in the identification of elevated BP values in the sample. The significance was set at 5%.

Results Characteristics of the analyzed subjects are described in Table 2. There were no statistical differences among the age groups for weight and height. In Table 3, values recorded by the Omron MX3 Plus monitor are compared with those of the BHS [14]. According to this protocol, the tested monitor acquired a degree of A, in both diastolic and systolic BP. The median (25th and 75th) difference between the observer and the monitor measurements was −2 (−6 and 1)mmHg for systolic and 0 (−3 and1)mmHg for diastolic pressures. The measure of the differences between two types of equipment proposed by AAMI is normally presented in mean and SD. Our values

Omron MX3 Plus Mean (SD)

Mercury Collum Mean (SD)

ICC (95%CI)

112.5 (8.2) 112.3 (8.4) 112.5 (8.6) F=0.196; p=0.812 66.1 (6.8) 65.1 (6.2) 66.2 (6.4) F=1.975; p=0.145

110.1 (9.1) 110.7 (8.6) 110.3 (8.8) F=0.573; p=0.557 64.8 (6.6) 64.4 (6.1) 65.5 (6.3) F=1.731; p=0.183

0.80 (0.74–0.85) 0.87 (0.83–0.90) 0.78 (0.72–0.84) 0.71 (0.63–0.78) 0.62 (0.52–0.70) 0.64 (0.54–0.72)

Eur J Pediatr Table 5 Sensibility and specificity of the Omron MX3 Plus in identification of elevated blood pressure values among adolescents

PPV positive predictive value, PNV negative predictive value

ROC parameters

Measure I Measure II Measure III

Sensitivity

Specificity

AUC (95%CI)

PPV

PNV

100 100 100

100 98.7 100

100±0.000 (100–100) 99.3±0.006 (98.3–100) 100±0.000 (100–100)

100 100 100

100 100 100

satisfactory concurrence between the measures for both SBP and DBP.

for these criteria are 2.14 (SD=5.16)mmHg for systolic and 0.79 (SD=5.27)mmHg for diastolic BP. Table 4 shows the comparisons between SBP and DBP for both instruments. Although a high ICC has been observed (for both genders), there were differences for SBP values among the methods of blood pressure assessment, as well as for DBP in the first measure. For both SBP and BDP, in the two methods, there were no differences among the three measures made with the same instruments. The ROC curve indicated high values of sensitivity and specificity in all the three measures (Table 5). The values of sensitivity were 100%, and the specificity ranged from 98.7% to 100%; these high values influenced the area under curve (AUC), which was higher than 95% and with very low confidence intervals. Furthermore, the probability of an individual having either elevated (predictive positive value [PPV]) or normal (predictive negative value [PNV]) BP values as indicated by the electronic monitor was 100%. The Bland–Altman plot is demonstrated in Figs. 1 and 2. Satisfactory concurrence between the measures is observed. The Bland–Altman plot is demonstrated in Figs. 1 and 2. Among all 495 measures (three for each individual), few cases were out of the 95%CI computed, indicating a

During the last decade, the increase in the use of automatic and semiautomatic monitors has been well documented. This is due to technological progress in electronics. This equipment, which works through automatic inflation and deflation, is light, portable, and both easy to use and interpret, reducing the occurrence of reading mistakes by the observer, which are common in the auscultatory method. Therefore, the use of this equipment would seem to be a worthwhile strategy for BP evaluation, principally for layuse in home testing of hypertension. However, the majority of validations of automatic electronic monitors have been carried out among adults [2, 6, 16, 20], and such validation is also necessary for special populations. Therefore, the validation of such equipment for use with children and adolescents is of great importance, and although several studies have been conducted with children [1, 4, 9, 11, 21, 24, 25], there are few studies that have evaluated the sensitivity and specificity of these devices together with their validation in this population.

Fig. 1 Bland–Altman plot demonstrating the mean difference between the monitor and the mercury column of SBP. Black line is the mean of the differences; dotted lines are both lower and upper 95% confidence interval

Fig. 2 Bland–Altman plot demonstrating the mean difference between the monitor and the mercury column of DBP. Black line is the mean of the differences; dotted lines are both lower and upper 95% confidence interval

Discussion

Eur J Pediatr

In adolescents, the need to adapt cuff size to the circumference of the arm occassionally requires alterations to the equipment, which makes this validation even more necessary. However, to be used for specific populations, a device must first be validated for adults, according to BHS regulations [14], as is the case of the tested equipment [6]. The present study’s evaluation of the Omron MX3 Plus monitor in an adolescent population demonstrated that the equipment reached the established criteria for BHS [14], obtaining a degree of A (highest level) for systolic and diastolic BP measures. Nevertheless, the BHS protocol [14] recommends that a high range of values be assessed for systolic (from 100 to 240 mmHg) and diastolic (from 60 to 120 mmHg). In our study, the values found for systolic BP (from 98 to 136 mmHg) and diastolic BP (from 52 to 93 mmHg) did not reach the suggested values. That is apparently justified by a lower prevalence of arterial hypertension in adolescents in relation to the adult population. In the present investigation, the mean difference between the tested equipment and AAMI [3] norms were 2.1 mmHg and 0.79 mmHg for systolic BP and diastolic BP, respectively, and therefore lower than the limit of 5 mmHg. The standard deviation was 5.16 mmHg to systolic BP and 5.27 mmHg for diastolic BP versus the 8 mmHg SD imposed by AAMI [3], which are differences of 2.84 and 2.73, respectively, and fall well within the recommendations. These results indicate that the Omron MX3 Plus reached the criteria proposed by AAMI [3]. Additionally, the ICC was utilized to indicate the relationship among the values and also applied the ROC curve to indicate de accuracy. The presented data indicated that the Omron MX3 Plus obtained highly accurate values of SBP in all measurements and of DBP in the first assessment when compared with the mercury sphygmomanometry. The ICC indicated the occurrence of high relationship among the values of both SBP and DBP provided by the two methods for the assessment of BP. The Bland–Altman plot was used to indicate the agreement of the numeric values provided by both methods for BP measurement. There was a high agreement level in which a reduced number of subjects presented variations under/ above of the calculated 95% CI. Furthermore, this interval was relatively low. The existence of a strong relationship among the mean values provided by these two methods is a positive indicator for utilization of the Omron MX3 Plus in clinical practice. This device as an identifier of elevated BP was verified accord to the parameters of the ROC curve sensitivity (efficiency on identification of the elevated blood pressure presence), specificity (efficiency in identification of the elevated blood pressure absence), and AUC (interaction between sensitivity and specificity). The results

presented both high sensitivity and specificity, as well as elevated AUC, and represent solid evidence of the utility of this equipment on elevated BP identification on clinical settings. In conclusion, the results of this study suggest that the Omron MX3 Plus monitor can be used with confidence in clinical practice and epidemiological contexts since it is in agreement with international BHS [14] and AAMI [3] recommendations. Furthermore, the monitor also presented high sensitivity and specificity in the diagnosis of elevated BP in youth. However, the efficiency of the Omron MX3 Plus monitor was proven for the age group of 10–15 years, and further studies are required to evaluate its effectiveness in children under 10. Conflict of interest interest in this paper.

The authors declare there is no conflict of

References 1. Alpert BC (1996) Validation of CAS model 9010 automated blood pressure monitor:children/adult and neonatal studies. Blood Press Monit 1:69–73 2. Altunkan S, Ilman N, Kayatürk N, Altunkan E (2007) Validation of the Omron M6 (HEM-7001-E) upper-arm blood pressure measuring device according to the international protocol in adults and obese adults. Blood Press Monit 12:219–225 3. Association for the Advancement of Medical Instrumentation (1993) American national standard. Electronic or automated sphygmomanometers. AAMI, Arlington, Virginia 4. Barker ME, Shiell AW, Law CM (2000) Evaluation of the Dinamap 8100 and Omron M1 blood pressure monitors for use in children. Paediatr Perinat Epidemiol. 14:179–186 5. Barquera S, Durazo-Arvizu RA, Luke A et al (2008) Hypertension in Mexico and among Mexican Americans: prevalence and treatment patterns. J Hum Hypertens 9:617–626 6. Coleman A, Freeman P, Steel S, Shennan A (2005) Validation of the Omron MX3 Plus oscillometric blood pressure monitoring device according to the European Society of Hypertension international protocol. Blood Press Monit 10:165–168 7. Cooper RS, Wolf-Maier K, Luke A et al (2005) An international comparative study of blood pressure in populations of European vs. African descent. BMC Med [electronic resource] 3 8. Din-Dzietham R, Liu Y, Bielo MV, Shamsa F (2007) High blood pressure trends in children and adolescents in national surveys, 1963 to 2002. Circulation 116:1488–1496 9. Furusawa EA, Ruiz MF, Saito MI, Koch VH (2005) Evaluation of the Omron 705-CP blood pressure measuring device for use in adolescents and young adults. Arq Bras Cardiol 84:367–370 10. Gordon CC, Chumlea WC, Roche AF (1988) Stature, recumbent length and weight. In: Lohman TG, Roche AF, Martorel R (eds) Anthropometric standardization reference manual. Human Kinetics Books, Champaign, pp 3–8 11. Ling J, Ohara Y, Orime Y et al (1995) Clinical evaluation of the oscillometric blood pressure monitor in adults and children based on the 1992 AAMI SP-10 standards. J Clin Monit 11:123–130 12. McGavock JM, Torrance B, McGuire KA et al (2007) The relationship between weight gain and blood pressure in children and adolescents. Am J Hypertens 20:1038–1044

Eur J Pediatr 13. Nijdam ME, Plantinga Y, Hulsen HT et al (2008) Pulse pressure amplification and risk of cardiovascular disease. Am J Hypertens 21:388–392 14. O’Brien E, Petrie J, Littler W (1990) The British Hypertension society protocol for the evaluation of automated and semiautomated blood pressure measuring devices with special reference to ambulatory systems. J Hypertens 8:607–619 15. O’Brien E, Petrie J, Littler WA et al (1993) The British Hypertension Society Protocol for the evaluation of blood pressure measuring devices. J Hypertens 11(Suppl 2):43–62 16. O’Brien E, Asmar R, Beilin L et al (2003) European Society of Hypertension Working Group on Blood Pressure Monitoring. European Society of Hypertension recommendations for conventional, ambulatory and home blood pressure measurement. J Hypertens 21:821–848 17. Perloff D, Grim C, Flack J et al (1993) Human blood pressure determination by sphygmomanometry. Circulation 88:2460–2470 18. Pickering TG, Hall JE, Appel LJ et al (2005) Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Recommendations for blood pressure measurement in humans and experimental animals: Part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Hypertension 45:142–161 19. Sinha MD, Reid CJ (2007) Evaluation of blood pressure in children. Curr Opin Nephrol Hypertens 16:577–584

20. Stergiou GS, Tzamouranis D, Nasothimiou EG, Protogerou AD (2008) Can an electronic device with a single cuff be accurate in a wide range of arm size? Validation of the Visomat Comfort 20/40 device for home blood pressure monitoring. J Hum Hypertens 22:796–800. doi:10.1038/jhh.2008.70 21. Stergiou GS, Yiannes NG, Rarra VC (2006) Validation of the Omron 705 IT oscillometric device for home blood pressure measurement in children and adolescents: the Arsakion School Study. Blood Press Monit 11:229–234 22. Thorogood M, Connor M, Tollman S et al (2007) A crosssectional study of vascular risk factors in a rural South African population: data from the Southern African Stroke Prevention Initiative (SASPI). BMC Public Health 13:317–326 23. VII JNC (2003) Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure 24. Wattigney WA, Webber LS, Lawrence MD, Berenson GS (1996) Utility of an automatic instrument for blood pressure measurement in children. The Bogalusa Heart Study. Am J Hypertens 9:256– 262 25. Wong SN, Tz Sung RY, Leung LC (2006) Validation of three oscillometric blood pressure devices against auscultatory mercury sphygmomanometer in children. Blood Press Monit 11:281–291 26. Zaetta V, Daniele L, Perkovic D et al (2007) Validation of the SAA-102 home blood pressure monitor according to the protocols of the European Society of Hypertension, the Association for the Advancement of Medical Instrumentation and the British Society of Hypertension. Blood Press Monit 12:363–368