Shawn Kok

Dr. Shawn Kok

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 February 2024 in Annals of Coloproctology
Verified
Journal Article
Open access
PDF file
JWJingting Wu
Jingting Wu
HCHannah Chi
Hannah Chi
SKShawn Kok
Shawn Kok
JCJason M.W. Chua
Jason M.W. Chua
XHXi-Xiao Huang
Xi-Xiao Huang
FKFrederick H Koh
Frederick H Koh
Sarcopenia, which is characterized by progressive and generalized loss of skeletal muscle mass and strength, has been well described to be associated with numerous poor postoperative outcomes, such as increased perioperative mortality, postoperative sepsis, prolonged length of stay, increased cost of care, decreased functional outcome, and poorer oncological outcomes in cancer surgery. Multimodal prehabilitation, as a concept that involves boosting and optimizing the preoperative condition of a patient prior to the upcoming stressors of a surgical procedure, has the purported benefits of reversing the effects of sarcopenia, shortening hospitalization, improving the rate of return to bowel activity, reducing the costs of hospitalization, and improving quality of life. This review aims to present the current literature surrounding the concept of sarcopenia, its implications pertaining to colorectal cancer and surgery, a summary of studied multimodal prehabilitation interventions, and potential future advances in the management of sarcopenia.

20 August 2024 in Nutrients
Verified
Journal Article
Open access
PDF file
VYVanessa Yik
Vanessa Yik
SKShawn Kok
Shawn Kok
ECEsther Chean
Esther Chean
YLYi-En Lam
Yi-En Lam
WCWei-Tian Chua
Wei-Tian Chua
FKFrederick H Koh
Frederick H Koh
Background: Sarcopenia has been recognized as a determining factor in surgical outcomes and is associated with an increased risk of postoperative complications and readmission. Diagnosis is currently based on clinical guidelines, which includes assessment of skeletal muscle mass but not quality. Ultrasound has been proposed as a useful point-of-care diagnostic tool to assess muscle quality, but no validated cut-offs for sarcopenia have been reported. Using novel automated artificial intelligence (AI) software to interpret ultrasound images may assist in mitigating the operator-dependent nature of the modality. Our study aims to evaluate the fidelity of AI-aided ultrasound as a reliable and reproducible modality to assess muscle quality and diagnose sarcopenia in surgical patients. Methods: Thirty-six adult participants from an outpatient clinic were recruited for this prospective cohort study. Sarcopenia was diagnosed according to Asian Working Group for Sarcopenia (AWGS) 2019 guidelines. Ultrasonography of the rectus femoris muscle was performed, and images were analyzed by an AI software (MuscleSound® (Version 5.69.0)) to derive muscle parameters including intramuscular adipose tissue (IMAT) as a proxy of muscle quality. A receiver operative characteristic (ROC) curve was used to assess the predictive capability of IMAT and its derivatives, with area under the curve (AUC) as a measure of overall diagnostic accuracy. To evaluate consistency between ultrasound users of different experience, intra- and inter-rater reliability of muscle ultrasound parameters was analyzed in a separate cohort using intraclass correlation coefficients (ICC) and Bland–Altman plots. Results: The median age was 69.5 years (range: 26–87), and the prevalence of sarcopenia in the cohort was 30.6%. The ROC curve plotted with IMAT index (IMAT% divided by muscle area) yielded an AUC of 0.727 (95% CI: 0.551–0.904). An optimal cut-off point of 4.827%/cm2 for IMAT index was determined with a Youden’s Index of 0.498. We also demonstrated that IMAT index has excellent intra-rater reliability (ICC = 0.938, CI: 0.905–0.961) and good inter-rater reliability (ICC = 0.776, CI: 0.627–0.866). In Bland–Altman plots, the limits of agreement were from −1.489 to 1.566 and −2.107 to 4.562, respectively. Discussion: IMAT index obtained via ultrasound has the potential to act as a point-of-care evaluation for sarcopenia screening and diagnosis, with good intra- and inter-rater reliability. The proposed IMAT index cut-off maximizes sensitivity for case finding, supporting its use as an easily implementable point-of-care test in the community for sarcopenia screening. Further research incorporating other ultrasound parameters of muscle quality may provide the basis for a more robust diagnostic tool to help predict surgical risk and outcomes.

1 April 2020 in Radiology: Cardiothoracic Imaging
Verified
Journal Article
Open access
BTBien Peng Tan
Bien Peng Tan
KLKheng Choon Lim
Kheng Choon Lim
YGYonggeng Goh
Yonggeng Goh
SKShawn Kok
Shawn Kok
STSze Yiun Teo
Sze Yiun Teo
LCLai Peng Chan
Lai Peng Chan
The coronavirus disease 2019 (COVID-19) pandemic presents an unprecedented challenge to the healthcare systems of the world. In Singapore, the Radiology community’s early experience on managing thi...

28 February 2025 in Annals of Coloproctology
Verified
Journal Article
Open access
SAShi Wei Ang
Shi Wei Ang
JLJacqueline Liew
Jacqueline Liew
VDVanessa Malishree Dharmaratnam
Vanessa Malishree Dharmaratnam
VYVanessa Yik
Vanessa Yik
SKShawn Kok
Shawn Kok
FKFrederick H Koh
Frederick H Koh
Purpose: Diagnosing sarcopenia necessitates the measurement of skeletal muscle mass. However, guidelines lack a standardized imaging modality with thresholds validated among Asians. This systematic review compared ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and bioelectrical impedance analysis (BIA)/body composition monitoring in the detection of sarcopenia within Asian populations.Methods: PubMed and Embase were systematically searched for studies analyzing ultrasonography, CT, MRI, and BIA in diagnosing sarcopenia among Asians. Study quality was assessed using the Newcastle-Ottawa scale.Results: Pooled findings from 21,598 patients across 25 studies were examined. In receiver operating characteristic analysis, ultrasound displayed a pooled mean area under the curve (AUC) of 0.767 (95% confidence interval [CI], 0.709–0.806), with mean sensitivity of 81.1% (95% CI, 0.744–0.846) and specificity of 73.1% (95% CI, 0.648–0.774), for detecting sarcopenia in Asian populations. CT exhibited an AUC of 0.720 (sensitivity, 54.0%; specificity, 92.0%). MRI demonstrated an AUC of 0.839 (sensitivity, 67.0%; specificity, 66.0%). BIA displayed an AUC of 0.905 (95% CI, 0.842–0.968), 80.7% sensitivity (95% CI, 0.129–0.679), and 82.4% specificity (95% CI, 0.191–0.633).Conclusion: Various modalities aid in diagnosing sarcopenia, and selection should be individualized. Although only BIA and dual-energy x-ray absorptiometry are recommended by the Asian Working Group for Sarcopenia and the European Working Group on Sarcopenia in Older People, ultrasound imaging may hold diagnostic value for sarcopenia in the Asian population. In certain groups, diagnostic use of CT and MRI is warranted. Future research can standardize and validate modality-specific thresholds and protocols within Asian populations.

17 December 2024 in Nutrients
Verified
Journal Article
Open access
PDF file
FKFrederick H Koh
Frederick H Koh
VYVanessa Yik
Vanessa Yik
SCShuen-Ern Chin
Shuen-Ern Chin
SKShawn Kok
Shawn Kok
HLHui-Bing Lee
Hui-Bing Lee
FFFung Joon Foo
Fung Joon Foo
Background: Multimodal prehabilitation programs, which may incorporate nutritional supplementation and exercise, have been developed to combat sarcopenia in surgical patients to enhance post-operative outcomes. However, the optimal regime remains unknown. The use of beta-hydroxy beta-methylbutyrate (HMB) has beneficial effects on muscle mass and strength. However, its effect on muscle quality in the perioperative setting has yet to be established. This study aims to explore the impact of a multimodal prehabilitation program using a bundle of care that includes high-protein oral nutritional supplementation (HP ONS) with HMB and resistance exercise on muscle quality and functional outcomes in sarcopenic surgical patients. Methods: Sarcopenic adult patients undergoing elective major gastrointestinal surgeries were recruited for this pilot interventional cohort study. They were enrolled in a 2–4-week multimodal prehabilitation program comprising resistance exercise, nutritional supplementation, vitamin supplementation, comorbid optimization and smoking cessation. Participants were provided three units of HP ONS with HMB per day pre-operatively. The primary outcome was changes in intramuscular adipose tissue (IMAT) as a proxy of muscle quality, assessed using Artificial Intelligence (AI)-aided ultrasonography. Secondary outcomes include changes in anthropometric measurements and functional characteristics. Outcomes were measured before prehabilitation, after prehabilitation and 1 month post-operatively. Results: A total of 36 sarcopenic patients, with a median age of 71.5 years, were included in this study. There was an increase in the IMAT index after two weeks of prehabilitation (p = 0.032) to 1 month after surgery (p = 0.028). Among functional parameters, improvement was observed in gait speed (p = 0.01) after two weeks of prehabilitation, which returned to baseline post-operatively. The median length of hospital stay was 7 (range: 2–75) days. Conclusions: The increase in the IMAT index in a sarcopenic surgical cohort undergoing prehabilitation may be due to altered muscle metabolism in elderly sarcopenic patients. A prehabilitation regime in sarcopenic patients incorporating HP ONS with HMB and resistance exercise is feasible and is associated with increased gait speed.

14 July 2023 in Radiology Case Reports
Verified
Journal Article
Open access
EXEsther Tan Wan Xian
Esther Tan Wan Xian
SKShawn Kok
Shawn Kok
YMYeap Phey Ming
Yeap Phey Ming
Gout is a common metabolic disease characterized by the deposition of monosodium urate (MSU) crystals and typically affects the peripheral joint, rarely involving the axial skeleton. We present a rare case of acute tophaceous gout in the lumbar spine causing cauda equina syndrome. A 60-year-old man with a history of gout and prior admissions for polyarticular gout flare presented with acute onset of bilateral lower limb numbness and weakness. He underwent surgical decompression with drainage of the epidural collection, with histology consistent with tophaceous gout. The patient made a full recovery postoperatively and was discharged uneventfully. Due to the high initial suspicion for gout, early spinal decompression surgery was performed, and the patient was started on medical therapy. Spinal tophaceous should be considered in the list of different diagnoses of spinal epidural masses especially in the context of a history of gouty arthritis.