Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach

BackgroundAcute pain management is critical in postoperative care, especially in vulnerable patient populations that may be unable to self-report pain levels effectively. Current methods of pain assessment often rely on subjective patient reports or behavioral pain observatio...

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Main Authors: Ajan Subramanian, Rui Cao, Emad Kasaeyan Naeini, Seyed Amir Hossein Aqajari, Thomas D Hughes, Michael-David Calderon, Kai Zheng, Nikil Dutt, Pasi Liljeberg, Sanna Salanterä, Ariana M Nelson, Amir M Rahmani
Format: Article
Language:English
Published: JMIR Publications 2025-01-01
Series:JMIR Formative Research
Online Access:https://formative.jmir.org/2025/1/e67969
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author Ajan Subramanian
Rui Cao
Emad Kasaeyan Naeini
Seyed Amir Hossein Aqajari
Thomas D Hughes
Michael-David Calderon
Kai Zheng
Nikil Dutt
Pasi Liljeberg
Sanna Salanterä
Ariana M Nelson
Amir M Rahmani
author_facet Ajan Subramanian
Rui Cao
Emad Kasaeyan Naeini
Seyed Amir Hossein Aqajari
Thomas D Hughes
Michael-David Calderon
Kai Zheng
Nikil Dutt
Pasi Liljeberg
Sanna Salanterä
Ariana M Nelson
Amir M Rahmani
author_sort Ajan Subramanian
collection DOAJ
description BackgroundAcute pain management is critical in postoperative care, especially in vulnerable patient populations that may be unable to self-report pain levels effectively. Current methods of pain assessment often rely on subjective patient reports or behavioral pain observation tools, which can lead to inconsistencies in pain management. Multimodal pain assessment, integrating physiological and behavioral data, presents an opportunity to create more objective and accurate pain measurement systems. However, most previous work has focused on healthy subjects in controlled environments, with limited attention to real-world postoperative pain scenarios. This gap necessitates the development of robust, multimodal approaches capable of addressing the unique challenges associated with assessing pain in clinical settings, where factors like motion artifacts, imbalanced label distribution, and sparse data further complicate pain monitoring. ObjectiveThis study aimed to develop and evaluate a multimodal machine learning–based framework for the objective assessment of pain in postoperative patients in real clinical settings using biosignals such as electrocardiogram, electromyogram, electrodermal activity, and respiration rate (RR) signals. MethodsThe iHurt study was conducted on 25 postoperative patients at the University of California, Irvine Medical Center. The study captured multimodal biosignals during light physical activities, with concurrent self-reported pain levels using the Numerical Rating Scale. Data preprocessing involved noise filtering, feature extraction, and combining handcrafted and automatic features through convolutional and long-short-term memory autoencoders. Machine learning classifiers, including support vector machine, random forest, adaptive boosting, and k-nearest neighbors, were trained using weak supervision and minority oversampling to handle sparse and imbalanced pain labels. Pain levels were categorized into baseline and 3 levels of pain intensity (1-3). ResultsThe multimodal pain recognition models achieved an average balanced accuracy of over 80% across the different pain levels. RR models consistently outperformed other single modalities, particularly for lower pain intensities, while facial muscle activity (electromyogram) was most effective for distinguishing higher pain intensities. Although single-modality models, especially RR, generally provided higher performance compared to multimodal approaches, our multimodal framework still delivered results that surpassed most previous works in terms of overall accuracy. ConclusionsThis study presents a novel, multimodal machine learning framework for objective pain recognition in postoperative patients. The results highlight the potential of integrating multiple biosignal modalities for more accurate pain assessment, with particular value in real-world clinical settings.
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spelling doaj-art-69a0eda3b0db4d5881bfb320797965aa2025-01-27T21:01:04ZengJMIR PublicationsJMIR Formative Research2561-326X2025-01-019e6796910.2196/67969Multimodal Pain Recognition in Postoperative Patients: Machine Learning ApproachAjan Subramanianhttps://orcid.org/0000-0003-3253-1300Rui Caohttps://orcid.org/0000-0001-9295-8299Emad Kasaeyan Naeinihttps://orcid.org/0000-0002-7438-2641Seyed Amir Hossein Aqajarihttps://orcid.org/0000-0003-1747-6980Thomas D Hugheshttps://orcid.org/0000-0002-0651-9394Michael-David Calderonhttps://orcid.org/0000-0001-6824-6945Kai Zhenghttps://orcid.org/0000-0003-4121-4948Nikil Dutthttps://orcid.org/0000-0002-3060-8119Pasi Liljeberghttps://orcid.org/0000-0002-9392-3589Sanna Salanterähttps://orcid.org/0000-0003-2529-6699Ariana M Nelsonhttps://orcid.org/0000-0003-1575-1635Amir M Rahmanihttps://orcid.org/0000-0003-0725-1155 BackgroundAcute pain management is critical in postoperative care, especially in vulnerable patient populations that may be unable to self-report pain levels effectively. Current methods of pain assessment often rely on subjective patient reports or behavioral pain observation tools, which can lead to inconsistencies in pain management. Multimodal pain assessment, integrating physiological and behavioral data, presents an opportunity to create more objective and accurate pain measurement systems. However, most previous work has focused on healthy subjects in controlled environments, with limited attention to real-world postoperative pain scenarios. This gap necessitates the development of robust, multimodal approaches capable of addressing the unique challenges associated with assessing pain in clinical settings, where factors like motion artifacts, imbalanced label distribution, and sparse data further complicate pain monitoring. ObjectiveThis study aimed to develop and evaluate a multimodal machine learning–based framework for the objective assessment of pain in postoperative patients in real clinical settings using biosignals such as electrocardiogram, electromyogram, electrodermal activity, and respiration rate (RR) signals. MethodsThe iHurt study was conducted on 25 postoperative patients at the University of California, Irvine Medical Center. The study captured multimodal biosignals during light physical activities, with concurrent self-reported pain levels using the Numerical Rating Scale. Data preprocessing involved noise filtering, feature extraction, and combining handcrafted and automatic features through convolutional and long-short-term memory autoencoders. Machine learning classifiers, including support vector machine, random forest, adaptive boosting, and k-nearest neighbors, were trained using weak supervision and minority oversampling to handle sparse and imbalanced pain labels. Pain levels were categorized into baseline and 3 levels of pain intensity (1-3). ResultsThe multimodal pain recognition models achieved an average balanced accuracy of over 80% across the different pain levels. RR models consistently outperformed other single modalities, particularly for lower pain intensities, while facial muscle activity (electromyogram) was most effective for distinguishing higher pain intensities. Although single-modality models, especially RR, generally provided higher performance compared to multimodal approaches, our multimodal framework still delivered results that surpassed most previous works in terms of overall accuracy. ConclusionsThis study presents a novel, multimodal machine learning framework for objective pain recognition in postoperative patients. The results highlight the potential of integrating multiple biosignal modalities for more accurate pain assessment, with particular value in real-world clinical settings.https://formative.jmir.org/2025/1/e67969
spellingShingle Ajan Subramanian
Rui Cao
Emad Kasaeyan Naeini
Seyed Amir Hossein Aqajari
Thomas D Hughes
Michael-David Calderon
Kai Zheng
Nikil Dutt
Pasi Liljeberg
Sanna Salanterä
Ariana M Nelson
Amir M Rahmani
Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach
JMIR Formative Research
title Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach
title_full Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach
title_fullStr Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach
title_full_unstemmed Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach
title_short Multimodal Pain Recognition in Postoperative Patients: Machine Learning Approach
title_sort multimodal pain recognition in postoperative patients machine learning approach
url https://formative.jmir.org/2025/1/e67969
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