Correlation Coefficients for a Study with Repeated Measures

Shan, Guogen; Zhang, Hua; Jiang, Tao

doi:10.1155/2020/7398324

Cited by 33 publications

(19 citation statements)

References 28 publications

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“…Repeated‐measures correlation assesses the linear association between two variables that is common within a group by adjusting for between‐person variability using a modified ANCOVA model (Bakdash & Marusich, 2017 ). In repeated‐measures studies, this technique avoids the pitfalls of Pearson correlation, which assumes independence of errors between paired data points and does not properly account for both within‐ and between‐individual variance (Shan et al, 2020 ), and precludes the need for data aggregation which may limit statistical power (Bakdash & Marusich, 2017 ). Within the context of the current work, however, it is important to recognize that repeated‐measures correlation relies on an estimated common slope for all participants upon which the association between the two variables is based, and a divergence from slope homogeneity results in a smaller effect size (Bakdash & Marusich, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Sex‐dependent jugular vein optical attenuation and distension during head‐down tilt and lower body negative pressure

Patterson

Amelard

Saarikoski

et al. 2022

Physiological Reports

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Non‐contact coded hemodynamic imaging (CHI) is a novel wide‐field near‐infrared spectroscopy system which monitors blood volume by quantifying attenuation of light passing through the underlying vessels. This study tested the hypothesis that CHI‐based jugular venous attenuation (JVA) would be larger in men, and change in JVA would be greater in men compared to women during two fluid shift challenges. The association of JVA with ultrasound‐based cross‐sectional area (CSA) was also tested. Ten men and 10 women completed three levels of head‐down tilt (HDT) and four levels of lower body negative pressure (LBNP). Both JVA and CSA were increased by HDT and reduced by LBNP (all p < 0.001). Main effects of sex indicated that JVA was higher in men than women during both HDT ( p = 0.003) and LBNP ( p = 0.011). Interaction effects of sex and condition were observed for JVA during HDT ( p = 0.005) and LBNP ( p < 0.001). We observed moderate repeated‐measures correlations ( r rm ) between JVA and CSA in women during HDT ( r rm = 0.57, p = 0.011) and in both men ( r r m = 0.74, p < 0.001) and women ( r rm = 0.66, p < 0.001) during LBNP. While median within‐person correlation coefficients indicated an even stronger association between JVA and CSA, this association became unreliable for small changes in CSA. As hypothesized, JVA was greater and changed more in men compared to women during both HDT and LBNP. CHI provides a non‐contact method of tracking large changes in internal jugular vein blood volume that occur with acute fluid shifts, but data should be interpreted in a sex‐dependent manner.

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Section: Discussionmentioning

confidence: 99%

Sex‐dependent jugular vein optical attenuation and distension during head‐down tilt and lower body negative pressure

Patterson

Amelard

Saarikoski

et al. 2022

Physiological Reports

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show abstract

“…Overall, a higher Pearson correlation coefficient values indicate greater direct correlation between predicted and observed measurements, whereas lower values of RMSE and AIC indicate better model fit. 17,20…”

Section: Discussionmentioning

confidence: 99%

Height Gain After Spinal Fusion for Idiopathic Scoliosis: Which Model Fits Best?

Ikwuezunma

Wang

Raymond

et al. 2022

Journal of Pediatric Orthopaedics

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Background: Patients will often inquire about the magnitude of height gain after scoliosis surgery. Several published models have attempted to predict height gain using preoperative variables. Many of these models reported good internal validity but have not been validated against an external cohort. We attempted to test the validity of 5 published models against an external cohort from our institution. Models included were Hwang, Van Popta, Spencer, Watanabe, and Sarlak models. Methods: We retrospectively queried our institution’s records from 2006 to 2019 for patients with adolescent idiopathic scoliosis treated with posterior spinal fusion. We recorded preoperative and postoperative variables including clinical height measurements. We also performed radiographic measurements on preoperative and postoperative radiographic studies. We then tested the ability of the models to predict height gain by evaluating Pearson correlation coefficient, root mean square error, Akaike Information Criterion for each model. Results: A total of 387 patients were included. Mean clinical height gain was 3.1 (±1.7) cm. All models demonstrated a moderate positive Pearson correlation coefficient, except the Hwang model, which demonstrated a weak correlation. The Spencer model was the only model with acceptable root mean square error (≤0.5) and was also the best fitting with the lowest Akaike Information Criterion (−308). The mean differences in height gain predictions between all models except the Hwang model was ≤1 cm. Conclusions: Four of the 5 models demonstrated moderate correlation and had good external validity compared with their development cohorts. Although the Spencer model was the best fitting, the clinical significance of the difference in height predictions compared with other models was low. The Watanabe model was the second best fitting and had the simplest formula, making it the most convenient to use in a clinical setting. We offer a simplified equation to use in a preoperative clinical setting based on this data—ΔHeight (mm)=0.77*(preoperative coronal angle−postoperative coronal angle). Level of Evidence: Not Applicable.

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“…Additionally, repeated measure correlation was used to assess the agreement between the estimated and reference signals from the subjects in the test set. 26 , 27 Repeated measure correlation is a statistical technique to relax the independence assumption of the convectional Pearson correlation allowing one to analyze multiple measurements from each of the subjects and estimate a common regression value, which reflected the shared agreement among subjects. We reported the repeated measurement correlation for apneas, hypopneas, and normal breathing during sleep and wakefulness, separately.…”

Section: Methodsmentioning

confidence: 99%

Respiratory Motion and Airflow Estimation During Sleep Using Tracheal Movement and Sound

Ghahjaverestan¹,

Wang²,

Aguiar³

et al. 2022

NSS

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Purpose Due to lack of access and high cost of polysomnography, portable sleep apnea testing has been developed to diagnose sleep apnea. Despite being less expensive, and having fewer sensors and reasonable accuracy in identifying sleep apnea, such devices can be less accurate than polysomnography in detecting apneas/hypopneas. To increase the accuracy of apnea/hypopnea detection, an accurate airflow estimation is required. However, current airflow measurement techniques employed in portable devices are inconvenient and subject to displacement during sleep. In this study, algorithms were developed to estimate respiratory motion and airflow using tracheo-sternal motion and tracheal sounds. Patients and Methods Adults referred for polysomnography were included. Simultaneous to polysomnography, a patch device with an embedded 3-dimensional accelerometer and microphone was affixed to the suprasternal notch to record tracheo-sternal motion and tracheal sounds, respectively. Tracheo-sternal motion was used to train two mathematical models for estimating changes in respiratory motion and airflow compared to simultaneously measured thoracoabdominal motion and nasal pressure from polysomnography. The amplitude of the estimated airflow was then adjusted by the tracheal sound envelope in segments with unstable breathing. Results Two hundred and fifty-two subjects participated in this study. Overall, the algorithms provided highly accurate estimates of changes in respiratory motion and airflow with mean square errors (MSE) of 3.58 ± 0.82% and 2.82 ± 0.71%, respectively, compared to polysomnographic signals. The estimated motion and airflow from the patch signals detected apneas and hypopneas scored on polysomnography in 63.9% and 88.3% of cases, respectively. Conclusion This study presents algorithms to accurately estimate changes in respiratory motion and airflow, which provides the ability to detect respiratory events during sleep. Our study suggests that such a simple and convenient method could be used for portable monitoring to detect sleep apnea. Further studies will be required to test this possibility.

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Correlation Coefficients for a Study with Repeated Measures

Cited by 33 publications

References 28 publications

Sex‐dependent jugular vein optical attenuation and distension during head‐down tilt and lower body negative pressure

Sex‐dependent jugular vein optical attenuation and distension during head‐down tilt and lower body negative pressure

Height Gain After Spinal Fusion for Idiopathic Scoliosis: Which Model Fits Best?

Respiratory Motion and Airflow Estimation During Sleep Using Tracheal Movement and Sound

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