ABSTRACT
The aim of this study was to analyze the influence of the number of visits and the number of blood pressure (BP) measurements on the prevalence of high blood pressure (HBP) in adolescents. A cross-sectional epidemiologic study with 481 adolescents (14-19 years old) selected using a random cluster sampling strategy. We measured the BP three times in a first visit. Adolescents with HBP performed subsequent visits. The final calculation of BP followed four strategies: the 1st measure, mean of 1st and 2nd measurements, mean of all three measurements, and averaging the 2nd and 3rd measurements. The prevalence of HBP in the first and second visits was 6.4% and 1.9%, and the prevalence of hypertension (after three visits) was 1.7%. The prevalence of HBP varied from 8.6%-18.6% for boys and 4.6%-9.2% for girls, using the average 2nd and 3rd measurements and the 1st measurement, respectively. In all strategies, HBP and hypertension were more prevalent in boys and students attending the nocturnal shift. The number of visits and number of measurements affect the prevalence of HBP and hypertension in adolescents. Thus, clinicians and researchers should consider these aspects when assessing BP in adolescents aged 14-19 years old.
Subject(s)
Ambulatory Care/methods , Blood Pressure Determination/methods , Blood Pressure/physiology , Hypertension/epidemiology , Adolescent , Adult , Brazil/epidemiology , Circadian Rhythm/physiology , Cross-Sectional Studies , Female , Humans , Hypertension/diagnosis , Male , Prevalence , Sex Factors , Shift Work Schedule/adverse effects , Young AdultABSTRACT
BACKGROUND: To examine the reliability of heart rate variability (HRV) parameters in adolescents and to analyse the inter- and intra-observer reliability of data analysis. METHODS: The sample included 27 adolescents aged 14-19 years old. RR intervals were obtained for 10 min in the supine position on two different days (Day 1 and Day 8) with an interval of 7 days to analyse intra-individual reliability. The signals obtained on Day 1 were used to analyse the inter- and intra-observer reliability of HRV parameters. The RR intervals, standard deviation of all RR intervals (SDNN), root mean square of the squared differences between adjacent normal RR intervals (RMSSD), the percentage of adjacent intervals over 50 ms (PNN50), and low (LF) and high (HF) frequencies were obtained. Frequency-domain variables were analysed using the autoregressive (AR) and fast Fourier transform (FFT) methods. RESULTS: There were no intra-individuals difference in RR intervals between Day 1 and Day 8 (P>0·05). The intraclass correlation coefficient (ICC) ranged from 0·647 to 0·913, whereas the coefficient of variation (CV) was lower than 20% for all parameters, except PNN50 and LF/HF. The inter- and intra-observer reliability ranged from 0·915 to 0·996 and 0·990 to 0·993, respectively. In addition, the CV was lower than 20% (inter-observer) and 7% (intra-observer) to all HRV parameters. CONCLUSION: Indicators of reproducibility obtained in this study suggest that HRV can be used in adolescents; however, the analysis of HRV parameters should be performed by the same person.
