title: Symbolic dynamics marker of heart rate variability combined with clinical variables enhance obstructive sleep apnea screening.
abstract: Many sleep centres try to perform a reduced portable test in order to decrease the number of overnight polysomnographies that are expensive, time-consuming, and disturbing. With some limitations, heart rate variability (HRV) has been useful in this task. The aim of this investigation was to evaluate if inclusion of symbolic dynamics variables to a logistic regression model integrating clinical and physical variables, can improve the detection of subjects for further polysomnographies. To our knowledge, this is the first contribution that innovates in that strategy. A group of 133 patients has been referred to the sleep center for suspected sleep apnea. Clinical assessment of the patients consisted of a sleep related questionnaire and a physical examination. The clinical variables related to apnea and selected in the statistical model were age (p < 10(-3)), neck circumference (p < 10(-3)), score on a questionnaire scale intended to quantify daytime sleepiness (p < 10(-3)), and intensity of snoring (p < 10(-3)). The validation of this model demonstrated an increase in classification performance when a variable based on non-linear dynamics of HRV (p < 0.01) was used additionally to the other variables. For diagnostic rule based only on clinical and physical variables, the corresponding area under the receiver operating characteristic (ROC) curve was 0.907 (95% confidence interval (CI) = 0.848, 0.967), (sensitivity 87.10% and specificity 80%). For the model including the average of a symbolic dynamic variable, the area under the ROC curve was increased to 0.941 (95% = 0.897, 0.985), (sensitivity 88.71% and specificity 82.86%). In conclusion, symbolic dynamics, coupled with significant clinical and physical variables can help to prioritize polysomnographies in patients with a high probability of apnea. In addition, the processing of the HRV is a well established low cost and robust technique.
authors.affiliation: Institute for Technological Development and Innovation in Communications (IDeTIC), Universidad de Las Palmas de Gran Canaria, Las Palmas de G.C. 35017, Spain.
authors.forename: A G
authors.initials: AG
authors.lastname: Ravelo-García
authors.affiliation: Department of Mathematics. Universidad de Las Palmas de Gran Canaria, Las Palmas de G.C. 35017, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Saavedra-Santana
authors.affiliation: Pulmonary Medicine Department. Hospital Universitario de Gran Canaria Dr. Negrín, Las Palmas de G.C. 35010, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Juliá-Serdá
authors.affiliation: Institute for Technological Development and Innovation in Communications (IDeTIC), Universidad de Las Palmas de Gran Canaria, Las Palmas de G.C. 35017, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Navarro-Mesa
authors.affiliation: Pulmonary Medicine Department. Hospital Universitario de Gran Canaria Dr. Negrín, Las Palmas de G.C. 35010, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Navarro-Esteva
authors.affiliation: Pulmonary Medicine Department. Hospital Universitario de Gran Canaria Dr. Negrín, Las Palmas de G.C. 35010, Spain.
authors.forename: X
authors.initials: X
authors.lastname: Álvarez-López
authors.affiliation: Department of Physics, Humboldt-Universität zu Berlin, Berlin 10115, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Gapelyuk
authors.affiliation: Sleep Center, Charité Universitätsmedizin, Berlin 10117, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Penzel
authors.affiliation: Department of Physics, Humboldt-Universität zu Berlin, Berlin 10115, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Wessel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016001:Confidence Intervals; D019992:Databases as Topic; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017711:Nonlinear Dynamics; D012372:ROC Curve; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D014463:Ultrasonography; D055815:Young Adult