Rory Vu Mather

All Publications

• Association of peripheral nerve blocks with increased postoperative pain and opioid use in orthopaedic surgery: a single-centre retrospective cohort study. British journal of anaesthesia Chung, A. R., Mather, R. V., Gutierrez, R., Liu, R., Leung, C. F., Zhang, M., Santa Cruz Mercado, L. A., Houle, T. T., Bittner, E. A., Purdon, P. L. 2025

  Abstract

  Peripheral nerve blocks have become popular in orthopaedic surgeries to improve acute postoperative pain. However, studies are mixed on their effectiveness in decreasing postoperative opioid consumption. A more comprehensive analysis is necessary to understand if peripheral nerve blocks reduce postoperative opioid exposure and risk for opioid dependence.This retrospective cohort study evaluated electronic health record data for adults undergoing orthopaedic surgery with general anaesthesia from 2016 to 2020 at the Massachusetts General Hospital. Linear models were fitted on propensity-weighted data to characterise the association between single injection peripheral nerve blocks and clinical outcomes. Our primary outcomes were maximum pain score and cumulative opioid dose, quantified in morphine milligram equivalents, administered in the PACU. Post-discharge outcomes associated with pain and opioid consumption were also evaluated.Among 22 956 patients, peripheral nerve block administration was associated with lower maximum pain scores and lower probability of opioid administration in the PACU. However, it was associated with higher maximum pain scores and a 22.7% increase in opioid consumption during the hospital stay. Peripheral nerve blocks were associated with an increase in opioid prescriptions at 30 days after discharge, but no increase at 90 or 180 days, and with decreased chronic pain diagnoses 1 yr after operation.Although single injection peripheral nerve blocks were effective in reducing immediate postoperative pain and opioid consumption, they were associated with greater opioid consumption that could increase the risk for opioid dependence. Standardised protocols to mitigate the risk for rebound pain could help minimise postoperative opioid exposure.

  View details for DOI 10.1016/j.bja.2025.05.030

  View details for PubMedID 40610285

• Intraoperative Frontal EEG Alpha Power is Associated with Post-Operative Mortality and Other Adverse Outcomes. Anesthesiology Mather, R. V., Nipp, R. D., Balanza, G., Stone, T. A., Gutierrez, R., Raje, P., Higuchi, M., Liu, R., Santa Cruz Mercado, L. A., Bittner, E. A., Kunitake, H., Purdon, P. L. 2024

  Abstract

  With estimated global post-operative mortality rates at 1-4% leading to approximately 3-12 million deaths per year, an urgent need exists for reliable measures of perioperative risk. Existing approaches suffer from poor performance, place a high burden on clinicians to gather data, or do not incorporate intraoperative data. Prior work demonstrated that intraoperative anesthetics induce prefrontal EEG oscillations in the alpha band (8-12Hz) that correlate with post-operative cognitive outcomes.We analyzed a retrospective cohort of 1,081 patients undergoing surgery with general anesthesia at Massachusetts General Hospital with intraoperative EEG recordings. The association between EEG alpha power and adverse outcomes were characterized using statistical models that were fitted on propensity weighted data. Our primary outcome was post-operative mortality, measured from date of surgery to date of death or last follow-up. Secondary outcomes included mortality within pre-specified time windows (30-days, 90-days, 180-days, and 1-year), hospital and PACU lengths of stay, discharge to long-term care, and 30-day hospital readmission.Alpha power was associated with mortality risk (HR = 0.92, 95% CI:[ 0.85, 0.99], p=0.039). Within specified time windows, alpha power was associated with 30-day mortality (OR = 0.81, 95% CI: [0.66, 0.95], p=0.010), 90-day mortality (OR = 0.68, 95% CI: [0.55, 0.79], p<0.001), 180-day mortality (OR = 0.75, 95% CI: [0.66, 0.83], p<0.001), and 1-year mortality (OR = 0.85, 95% CI: [0.79, 0.91], p<0.001). Additionally, alpha power was associated with discharge to long-term care (OR = 0.91, 95% CI: [0.86, 0.96], p<0.001). We did not find significant associations among alpha power and 30-day readmission and hospital or PACU lengths of stay.Intraoperative EEG alpha power is independently associated with post-operative mortality and adverse outcomes, suggesting it could represent a broad measure of post-operative physical resilience and provide clinicians with a low-burden, personalized measure of post-operative risk.

  View details for DOI 10.1097/ALN.0000000000005315

  View details for PubMedID 39601585

• Development and prospective validation of postoperative pain prediction from preoperative EHR data using attention-based set embeddings. NPJ digital medicine Liu, R., Gutiérrez, R., Mather, R. V., Stone, T. A., Santa Cruz Mercado, L. A., Bharadwaj, K., Johnson, J., Das, P., Balanza, G., Uwanaka, E., Sydloski, J., Chen, A., Hagood, M., Bittner, E. A., Purdon, P. L. 2023; 6 (1): 209

  Abstract

  Preoperative knowledge of expected postoperative pain can help guide perioperative pain management and focus interventions on patients with the greatest risk of acute pain. However, current methods for predicting postoperative pain require patient and clinician input or laborious manual chart review and often do not achieve sufficient performance. We use routinely collected electronic health record data from a multicenter dataset of 234,274 adult non-cardiac surgical patients to develop a machine learning method which predicts maximum pain scores on the day of surgery and four subsequent days and validate this method in a prospective cohort. Our method, POPS, is fully automated and relies only on data available prior to surgery, allowing application in all patients scheduled for or considering surgery. Here we report that POPS achieves state-of-the-art performance and outperforms clinician predictions on all postoperative days when predicting maximum pain on the 0-10 NRS in prospective validation, though with degraded calibration. POPS is interpretable, identifying comorbidities that significantly contribute to postoperative pain based on patient-specific context, which can assist clinicians in mitigating cases of acute pain.

  View details for DOI 10.1038/s41746-023-00947-z

  View details for PubMedID 37973817

  View details for PubMedCentralID 8369227

• A Prospective Study Characterizing Cognitive Function in Patients with Inflammatory Bowel Disease. Clinical and translational gastroenterology Raje, P., Stone, T. A., Alkourabi, J., Mather, R. V., Liu, R., Higuchi, M., Nipp, R. D., Purdon, P. L., Kochar, B., Kunitake, H. 2026

  Abstract

  Inflammatory bowel disease (IBD) may be associated with cognitive impairment. Cognitive decline is also linked to weaker anesthesia-induced alpha wave electroencephalographic (EEG) signals. We aimed to characterize the associations between cognition and EEG alpha power in patients with IBD.In this prospective cohort study, patients with IBD and controls undergoing diagnostic or screening colonoscopies underwent preprocedural cognitive testing using the tablet-based Brain Health Assessment (BHA), intraprocedural EEG monitoring, and follow-up testing. Primary outcomes were BHA scores and EEG alpha power. Secondary outcomes included within-participant changes in cognitive performance.We enrolled 40 patients with IBD and 42 control patients. Fifteen IBD patients and 17 controls completed follow-up cognitive testing 6-18 months after endoscopy. Patients with IBD were younger (mean age 42 vs. 56 years, p<0.001), more likely to screen positively for depression (p=0.004), and had fewer years of education (16.2 vs. 17.3 years, p=0.03). Fifteen IBD patients had active endoscopic inflammation. Adjusting for demographics, education level, and depression, EEG alpha power did not differ between groups. Median BHA scores indicated moderate likelihood of cognitive impairment in both groups. However, controls demonstrated improved within-participant follow-up performance (p<0.01), while IBD patients did not (p=0.16).IBD patients and controls demonstrate preprocedural cognitive impairment on BHA, but no differences in EEG alpha power. Lack of follow-up improvement in IBD patients may suggest lower baseline cognitive function while highlighting the importance of further investigations on cognition in this population.

  View details for DOI 10.14309/ctg.0000000000001036

  View details for PubMedID 41995584

• Intraoperative Electroencephalogram Alpha Power Associated with Mortality: Reply. Anesthesiology Mather, R. V., Nipp, R. D., Balanza, G., Stone, T. A., Gutierrez, R., Raje, P., Higuchi, M., Liu, R., Mercado, L. A., Bittner, E. A., Kunitake, H., Purdon, P. L. 2025; 143 (5): 1425-1427

  View details for DOI 10.1097/ALN.0000000000005676

  View details for PubMedID 41085317

• Electroencephalogram-Guided General Anesthesia in a Pediatric Patient With Alexander's Disease: A Case Report. A&A practice Zhang, M., Mather, R. V., Chung, A. R., Leung, C. F., Ramamurthi, R. J., Purdon, P. L. 2025; 19 (1): e01910

  Abstract

  In this case, the electroencephalogram (EEG) was used to guide anesthesia care for a pediatric patient with Alexander's Disease undergoing serial intrathecal injections. Previous procedures using a standard maintenance propofol dose of up to 225 µg/kg/min led to postanesthetic recovery times of over 6 hours, requiring a neurology consult for noncoherence. The EEG assisted in guiding maintenance propofol dosing to 75 µg/kg/min, decreasing postanesthetic wash-off and postanesthesia care unit (PACU) recovery time by 50%. This highlights the potential impact of astrocyte dysfunction on anesthetic sensitivity and robustness of EEG as a biomarker of anesthetic effect, including for pediatric patients with rare neurodevelopmental diseases.

  View details for DOI 10.1213/XAA.0000000000001910

  View details for PubMedID 39831714

• Development and multicentre validation of the FLEX score: personalised preoperative surgical risk prediction using attention-based ICD-10 and Current Procedural Terminology set embeddings. British journal of anaesthesia Liu, R., Stone, T. A., Raje, P., Mather, R. V., Santa Cruz Mercado, L. A., Bharadwaj, K., Johnson, J., Higuchi, M., Nipp, R. D., Kunitake, H., Purdon, P. L. 2024

  Abstract

  BACKGROUND: Preoperative knowledge of surgical risks can improve perioperative care and patient outcomes. However, assessments requiring clinician examination of patients or manual chart review can be too burdensome for routine use.METHODS: We conducted a multicentre retrospective study of 243 479 adult noncardiac surgical patients at four hospitals within the Mass General Brigham (MGB) system in the USA. We developed a machine learning method using routinely collected coding and patient characteristics data from the electronic health record which predicts 30-day mortality, 30-day readmission, discharge to long-term care, and hospital length of stay.RESULTS: Our method, the Flexible Surgical Set Embedding (FLEX) score, achieved state-of-the-art performance to identify comorbidities that significantly contribute to the risk of each adverse outcome. The contributions of comorbidities are weighted based on patient-specific context, yielding personalised risk predictions. Understanding the significant drivers of risk of adverse outcomes for each patient can inform clinicians of potential targets for intervention.CONCLUSIONS: FLEX utilises information from a wider range of medical diagnostic and procedural codes than previously possible and can adapt to different coding practices to accurately predict adverse postoperative outcomes.

  View details for DOI 10.1016/j.bja.2023.11.039

  View details for PubMedID 38184474