Four-layer technique for tracheostomy scar treatment

One important complication of the tracheostomy procedure is the depressed scar left after the tube is removed. A depressed tracheostomy scar can be aesthetically and functionally unacceptable. Tracheostomy scar treatment aims to fill lost soft tissue volume and correct tracheal skin tug. There are various techniques described to manage post-tracheostomy scars, including the use of autologous tissue or allogenic material and the creation of muscle flaps. In this article, the authors introduce a surgical method using four layers: the scar, the strap muscles, the platysma muscle, and the skin. This procedure has been used in two patients with depressed scar after prolonged tracheostomy placement. The tracheal tug was eliminated in each patient, and an imperceptible cutaneous scar remained. In each case, patient satisfaction was complete. The authors recommend this technique as a simple and effective method of closure for these troublesome tracheostomy scars.

Early-Onset Generalized Pustular Psoriasis of Pregnancy Following Hydroxychloroquine Use

Generalized pustular psoriasis of pregnancy (GPPP), characterized by widespread sterile pustules and erythematous patches with systemic symptoms such as fever, is a rare form of pustular psoriasis. GPPP typically occurs in the third trimester of pregnancy and can be triggered by various factors such as infections, hypocalcemia, and drugs including N-butyl-scopolammonium bromide. We report a rare case of new-onset GPPP in a 33-yearold multigravida female at 17 weeks’ gestation, which occurred earlier than usual, after taking hydroxychloroquine for 3 weeks to treat systemic lupus erythematosus. She stopped her medications and was treated with systemic corticosteroid, but without improvement.Her medication was changed to systemic cyclosporine; her skin lesions improved, which completely resolved after delivery. This is the first case of GPPP developed following hydroxychloroquine use for systemic lupus erythematosus, which occurred earlier than usual and completely resolved after delivery. This case demonstrates that hydroxychloroquine can induce GPPP before the third trimester of pregnancy.

Reversible Gait Disturbance Due to Vitamin B12 Deficiency

Vitamin B12 deficiency causes a variety of symptoms in the hematologic, gastrointestinal tract, and neurologic deficit. We report a rare case of progressive gait disturbance, bradykinesia and dysarthria which was that vitamin B12 deficiency was diagnosed as the cause, and symptoms improved after intramuscular cobalamin treatment. Vitamin B12, homocysteine, and methylmalonic acid tests are recommended for patients with progressive gait disturbance, even in the absence of obvious anemia symptoms.

Effects of Poly-L-Lactic Acid on Adipogenesis and Collagen Gene Expression in Cultured Adipocytes Irradiated with Ultraviolet B Rays

Background@#Poly-L-lactic acid (PLLA), a synthetic, biocompatible, and biodegradable polymer, has been safely used in several clinical applications. Recently, PLLA has been widely used in the field of dermatology to treat wrinkles in aging skin. Reportedly, PLLA directly acts on dermal fibroblasts causing a significant increase in the expression of type I collagen. However, little is known about the effect of PLLA on adipocytes. @*Objective@#This study aimed to analyze the effect of PLLA on adipocytes and examine its potential in treating deep wrinkles engendered by the loss of subcutaneous fat because of aging and photoaging. @*Methods@#To elucidate the effect of PLLA on skin photoaging, cultured 3T3-L1 adipocytes were irradiated with ultraviolet B (UVB) rays. Oil red O staining was used to detect lipid accumulation in the adipocytes. Real-time quantitative polymerase chain reaction and Western blotting were performed to detect types IV and VI collagen mRNA and protein levels, respectively, under different conditions. @*Results@#The differentiation of 3T3-L1 cells enhanced adipogenesis and the expression of types IV and VI collagens, both of which were inhibited by UVB irradiation. Following this irradiation, PLLA stimulated adipogenesis and the expression of types IV and VI collagens. @*Conclusion@#PLLA may provide the beneficial effect on adipocytes from the aspect of adipogenesis and collagen expression in the subcutaneous adipose tissues.

Cases of Pernio-Like Lesions after mRNA-1273 Vaccination with Clinical and Pathological Features: A Single-Center Experience

The currently available coronavirus disease 2019 (COVID-19) vaccines in South Korea include mRNA (Moderna® and Pfizer®) and adenoviral vector (AstraZeneca® and Janssen® ) vaccines. Dermatologic side effects of COVID-19 vaccines range from local injection site reactions to systemic eruptions, including morbilliform rashes or erythema multiforme. Pernio-like lesions, one of the most common cutaneous manifestations of COVID-19, have been rarely reported post-vaccination. Herein, we report four cases of pernio-like lesions, which were detected in a single tertiary hospital within 2 months, after the first dose of mRNA-1273 (Moderna® ) vaccination was administered. In this study, we discuss the clinical and pathological features of our cases and compare them with those of previously reported cases of pernio-like lesions after COVID-19 vaccination. It is pivotal to realize that perniolike lesions can be a possible side effect of COVID-19 vaccination and that the number of patients experiencing this side effect is bound to be quite high in real-world clinical settings.

Clinical Usefulness of Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Low Serum Testosterone Measurement

Background@#Mass spectrometry methods exhibit higher accuracy and lower variability than immunoassays at low testosterone concentrations. We developed and validated an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay for quantifying serum total testosterone. @*Methods@#We used an ExionLC UPLC (Sciex, Framingham, MA, USA) system and a Sciex Triple Quad 6500+ (Sciex) MS/MS system in electrospray ionization and positive ion modes with multiple reaction monitoring transitions to evaluate precision, accuracy, linearity, lower limit of quantitation (LLOQ), carryover, ion suppression, stability, and reference intervals. For method comparison, we measured serum testosterone concentrations using this method in 40 subjects whose testosterone concentrations ranged from 0.14 to 55.48 nmol/L as determined using the Architect i2000 immunoassay (Abbott Diagnostics, Abbott Park, IL, USA) and in an additional 160 sera with testosterone concentrations <1.67 nmol/L. @*Results@#The intra- and inter-run precision CVs were <2.81%, and the accuracy bias values were <3.85%, which were all acceptable. The verified linear interval was 0.03–180.84 nmol/L; the LLOQ was 0.03 nmol/L. No significant carryover and ion suppression were observed. The testosterone in serum was stable at 4°C, at –20°C, and after three freeze-thaw cycles. The reference intervals were successfully verified. The correlation was good at testosterone concentrations of 0.14–55.48 nmol/L; however, the Architect assay showed positive percent bias at concentrations <1.67 nmol/L. @*Conclusions@#The UPLC-MS/MS assay shows acceptable performance, with a lower LLOQ than the immunoassay. This method will enable the quantitation of low testosterone concentrations.

Evaluation of Cellular Responses to ChAdOx1-nCoV-19 and BNT162b2 Vaccinations

While numerous studies have evaluated humoral responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines, data on the cellular responses to these vaccines remain sparse. We evaluated T cell responses to ChAdOx1-nCoV-19 and BNT162b2 vaccinations using an interferon gamma (IFN-γ) release assay (IGRA). ChAdOx1-nCoV-19- and BNT162b2-vaccinated participants initially showed stronger T cell responses than unvaccinated controls. The T cell response decreased over time and increased substantially after the administration of a BNT162b2 booster dose. Changes in the T cell response were less significant than those in the anti-receptor-binding domain IgG antibody titer. The study results can serve as baseline data for T cell responses after SARS-CoV-2 vaccination and suggest that the IGRA can be useful in monitoring immunogenicity.

A New Strategy for Evaluating the Quality of Laboratory Results for Big Data Research: Using External Quality Assessment Survey Data (2010–2020)

Background@#To ensure valid results of big data research in the medical field, the input laboratory results need to be of high quality. We aimed to establish a strategy for evaluating the quality of laboratory results suitable for big data research. @*Methods@#We used Korean Association of External Quality Assessment Service (KEQAS) data to retrospectively review multicenter data. Seven measurands were analyzed using commutable materials: HbA1c, creatinine (Cr), total cholesterol (TC), triglyceride (TG), alpha-fetoprotein (AFP), prostate-specific antigen (PSA), and cardiac troponin I (cTnI). These were classified into three groups based on their standardization or harmonization status. HbA1c, Cr, TC, TG, and AFP were analyzed with respect to peer group values. PSA and cTnI were analyzed in separate peer groups according to the calibrator type and manufacturer, respectively. The acceptance rate and absolute percentage bias at the medical decision level were calculated based on biological variation criteria. @*Results@#The acceptance rate (22.5%–100%) varied greatly among the test items, and the mean percentage biases were 0.6%–5.6%, 1.0%–9.6%, and 1.6%–11.3% for all items that satisfied optimum, desirable, and minimum criteria, respectively. @*Conclusions@#The acceptance rate of participants and their external quality assessment (EQA) results exhibited statistically significant differences according to the quality grade for each criterion. Even when they passed the EQA standards, the test results did not guarantee the quality requirements for big data. We suggest that the KEQAS classification can serve as a guide for building big data.

Comparison of Treatment Satisfaction and Perception in Psoriasis Patients with Biologics or Oral Agents: A Single Center Study / 대한피부과학회지

Background@#Many aspects are considered when selecting psoriasis treatments, such as psoriasis severity. In particular, patients’ subjective aspects, such as quality of life and treatment satisfaction, are important when planning treatment, and several studies on these aspects exist. However, studies on the direct thoughts of Korean patients with psoriasis, such as what patients value the most, are limited. @*Objective@#This study aimed to evaluate treatment satisfaction and perceptions regarding the importance or subjective achievement of goals in Korean patients with psoriasis treated with biologics or oral agents. @*Methods@#A total of 59 patients with psoriasis treated with biologics or oral agents for ＞16 weeks completed the questionnaire. The questionnaire consisted of four main parts: patient information, past history and treatment experience associated with psoriasis, treatment satisfaction, and subjective importance and degree of achievement of treatment goals in daily life. @*Results@#Treatment satisfaction in the biologics group was higher in terms of effectiveness, improvement in symptoms, speed of improvement, method of administration, frequency of administration, and comprehensive aspects than that in the oral agents group (p＜0.05). However, in both groups, the degree of improvement did not reach the patients’ subjective importance, and “concerned with other people’s eyes due to lesions in exposed area” had the biggest difference. @*Conclusion@#Although biologics had higher treatment satisfaction than oral agents, in some parts of daily life, the degree of improvement did not reach the patients’ subjective importance; therefore, some points still needs to be improved.

Temporomandibular joint morphology in Korean using cone-beam computed tomography: influence of age and gender / 대한악안면성형재건외과학회지

Objectives@#The purpose of this study was to investigate the condylar morphology and position of Koreans using cone-beam computed tomography (CBCT) images. Analyzing the mean values of this study with reference to left and right sides, gender, and age will help to understand the size of the condyle and glenoid fossa, condylar morphology, and temporomandibular joint (TMJ) symmetry for establishing the standard temporomandibular joint structures of Koreans and then design the standard temporomandibular joint prosthesis for Koreans. @*Results@#There was no significant result in the condyle size, condyle axis angle, joint space, fossa depth, and mandibular body size between the left and right sides (p > 0.05). On the other hand, the mediolateral width of the condyle and mandibular body size show significantly different with the gender (P < 0.05). Also, significant differences were found in condyle size, joint space, fossa depth, and mandibular body size according to age groups (P < 0.05). @*Conclusions@#Condylar position and morphology vary according to side, age, and gender. The results of this study are expected to help in customizing a treatment for the patients who need TMJ reconstruction by predicting the TMJ morphology according to age and gender and design the standard temporomandibular joint prosthesis for the Koreans.

Collagenous Fibroma at the Surgical Site after Thyroidectomy for Papillary Thyroid Carcinoma / 대한이비인후과학회지

Collagenous fibroma (CF) is a rare benign tumor that occurs at various anatomical sites including the head and neck. CFs are often omitted from differential diagnosis before surgery. We describe a case of CF in a 54-year-old male who presented with a growing neck mass of 1-year duration at the site of previous right hemithyroidectomy for papillary thyroid carcinoma (PTC). Although radiologic findings demonstrated a benign tumor, surgical excision was carried out per patient’s preference and to rule out recurrent thyroid cancer. The mass was severely adherent to the surrounding muscles, but was resected completely without any injury to the adjacent structures. Histological studies revealed CF. The postoperative course was uneventful without vocal fold paralysis. CFs can be a diagnostic challenge in preoperative evaluation. Conservative excision was sufficient in most cases without recurrence. Clinicians should be aware of CFs in diagnosis, especially in postoperative site.

Assessment of the Test-Retest Reliability of Level III Polysomnography: Comparison of Results Using Difference of Apnea-Hypopnea Index Score and Severity of Obstructive Sleep Apnea / 대한이비인후과학회지

Background and Objectives@#Although studies of test-retest reliability of the standard polysomnography has been reported numerous times, studies of portable sleep devices have been reported in very few cases to date. The purpose of this study is to investigate the test-retest reliability of level III devices, to examine the characteristics of patients with tendency of underestimation and to determine whether there are factors that can predict when retest is needed. Subjects and Method We enrolled 74 patients for this study from April 2014 to March 2019. Two indicators were used to assess night to night variability. If the difference of apneahypopnea index (AHI) score was less than 10 or there is no difference of severity of obstructive sleep apnea (OSA) between two nights, we decided that the results have a reliability. @*Results@#Seventeen out of 57 patients with an AHI difference of less than 10 showed unreliable results based on severity, and 3 out of 17 patients with the AHI difference more than 10 showed reliable results based on severity. Eight out of 74 patients were diagnosed at Night 2 but not at Night 1. In other words, about 11% of the subjects needed retest. Based on the change in severity of OSA, subjective sleep scores showed a statistically significant difference, indicating that the subjective sleep score should be considered when deciding a retest. AHI differed by more than 10 in about 23% of the subjects in this study, falling within “15%- 32%,” which has been reported in the literature on the level I test. @*Conclusion@#This suggests that there is no significant difference in reliability between level I and III.

Effectiveness of Plasma and Urine Neutrophil Gelatinase-Associated Lipocalin for Predicting Acute Kidney Injury in High-Risk Patients

Background@#Neutrophil gelatinase-associated lipocalin (NGAL) is a useful biomarker for acute kidney injury (AKI) prediction. However, studies on whether using both plasma NGAL (PNGAL) and urine NGAL (UNGAL) can improve AKI prediction are limited. We investigated the best approach to predict AKI in high-risk patients when using PNGAL and UNGAL together. @*Methods@#We enrolled 151 AKI suspected patients with one or more AKI risk factors. We assessed the diagnostic performance of PNGAL and UNGAL for predicting AKI according to chronic kidney disease (CKD) status by determining the areas under the receiver operating curve (AuROC). Independent predictors of AKI were assessed using univariate and multivariate logistic regression analyses. @*Results@#In the multivariate logistic regression analysis for all patients (N = 151), Model 2 and 3, including PNGAL (P = 0.012) with initial serum creatinine (S-Cr), showed a better AKI prediction power (R2 = 0.435, both) than Model 0, including S-Cr only (R2 = 0.390). In the non-CKD group (N = 135), the AuROC of PNGAL for AKI prediction was larger than that of UNGAL (0.79 vs 0.66, P = 0.010), whereas in the CKD group (N = 16), the opposite was true (0.94 vs 0.76, P = 0.049). @*Conclusions@#PNGAL may serve as a useful biomarker for AKI prediction in high-risk patients. However, UNGAL predicted AKI better than PNGAL in CKD patients. Our findings provide guidance for selecting appropriate specimens for NGAL testing according to the presence of CKD in AKI high-risk patients.

Recent Trends in Creatinine Assays in Korea: LongTerm Accuracy-Based Proficiency Testing Survey Data by the Korean Association of External Quality Assessment Service (2011–2019)

Background@#Accurate serum creatinine (Cr) concentration measurement is essential for evaluating kidney function. In 2011, the Korean Association of External Quality Assessment Service (KEQAS) launched an accuracy-based Cr proficiency testing (ABCr PT) survey. We analyzed long-term data of the KEQAS ABCr PT survey collected between 2011 and 2019 to assess recent trends in Cr assays in Korea. @*Methods@#The ABCr PT survey including three commutable fresh-frozen serum samples was performed twice a year. The target Cr concentration was assigned using isotope-dilution mass spectrometry. We analyzed data obtained from the participating laboratories, calculated the yearly bias, and evaluated bias trends for the major reagents and instruments. Outliers were excluded from all analysis. @*Results@#The mean percentage bias based on the total data of all participating laboratories was 10.8% in the 2011-A survey and 0.2% in 2019-B survey. Bias for the major reagents and instruments differed depending on the manufacturer. Enzymatic assays generally showed desirable bias ranging from –3.9% to 3.2% at all Cr concentrations and lower interlaboratory variability than non-enzymatic assays (enzymatic vs. non-enzymatic, 3.3%– 7.2% vs. 6.3%–9.1%). @*Conclusions@#Although the mean percentage bias of Cr assays tends to decrease over time, it is necessary to continuously strive to improve Cr assay accuracy, especially at low concentrations.

Immunosuppressive Drug Measurement by Liquid Chromatography Coupled to Tandem Mass Spectrometry: Interlaboratory Comparison in the Korean Clinical Laboratories

Background@#Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is increasingly used for immunosuppressive drug tests. However, most LC-MS/MS tests are laboratory-developed and their agreement is unknown in different Korean laboratories.This interlaboratory comparison study evaluated test reproducibility and identified potential error sources. @*Methods@#Test samples containing three concentrations of tacrolimus, sirolimus, everolimus, cyclosporine, and mycophenolic acid were prepared by pooling surplus samples from patients undergoing routine therapeutic drug monitoring and tested in duplicate in the participating 10 clinical laboratories. Reconstitution and storage experiments were conducted for the commonly used commercial calibrator set. The robust estimators of reproducibility parameters were calculated. Spearman’s rank correlation coefficient (rho, ρ) was used to evaluate the correlation between drugs. Multiple linear regression was used to determine whether the experimental conditions alter the calibration curves. @*Results@#The reproducibility coefficient of variation exceeded 10% only for sirolimus concentrations 1 and 2 (10.8% and 12.5%, respectively) and everolimus concentrations 1 and 2 (12.3% and 11.4%, respectively). The percent difference values showed weak correlations between sirolimus and everolimus (ρ = 0.334, P = 0.175). The everolimus calibration curve slope was significantly altered after reconstitution following prolonged 5°C storage (P = 0.015 for 14 days; P = 0.025 for 28 days); the expected differences at 6 ng/mL were 0.598% for 14 days and 0.384% for 28 days. @*Conclusions@#LC-MS/MS test reproducibility for immunosuppressive drugs seems to be good in the Korean clinical laboratories. Continuous efforts are required to achieve test standardization and harmonization, especially for sirolimus and everolimus.

Evaluation of Seroprevalence of SARS-CoV-2 IgG in Healthcare Workers in a Tertiary Hospital in Seoul / 대한임상미생물학회지

Healthcare workers (HCWs) may be at high risk for exposure to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) because of their frequent contact with patients or the direct handling of respiratory samples. We investigated the seroprevalence of SARS-CoV-2 IgG in HCWs in Seoul compared to those in coronavirus disease (COVID-19) patients and community-based individuals to evaluate the antibody response. A total of 358 samples from 348 individuals (155 HCWs, 7 COVID-19 patients, and 186 community-based individuals) were collected from April to November 2020. SARS-CoV-2 IgG was detected in 1 of 155 HCWs (1 of 46 HCWs with direct contact), 7 of 7 COVID-19 patients, and none of the 186 communitybased individuals (95% CI: 0.6%, 0.1 - 3.6%; 100%, 64.5 - 100%; 0.0%, 0.0 - 2.0%, respectively).The single HCW with a positive result showed 2.32 signal-to-cutoff (S/C) and 2.31 S/C at a 3-week interval. Therefore, it was assumed to be a false positive due to autoantibody or medication. The positive samples from 7 patients had a median of 3.79 S/C (range 1.72 - 6.54). The seroprevalence of SARS-CoV-2 IgG in HCWs was very low. The current infection control standard seems to be effective in protecting HCWs from COVID-19.

Evaluation of Seroprevalence of SARS-CoV-2 IgG in Healthcare Workers in a Tertiary Hospital in Seoul / 대한임상미생물학회지

Healthcare workers (HCWs) may be at high risk for exposure to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) because of their frequent contact with patients or the direct handling of respiratory samples. We investigated the seroprevalence of SARS-CoV-2 IgG in HCWs in Seoul compared to those in coronavirus disease (COVID-19) patients and community-based individuals to evaluate the antibody response. A total of 358 samples from 348 individuals (155 HCWs, 7 COVID-19 patients, and 186 community-based individuals) were collected from April to November 2020. SARS-CoV-2 IgG was detected in 1 of 155 HCWs (1 of 46 HCWs with direct contact), 7 of 7 COVID-19 patients, and none of the 186 communitybased individuals (95% CI: 0.6%, 0.1 - 3.6%; 100%, 64.5 - 100%; 0.0%, 0.0 - 2.0%, respectively).The single HCW with a positive result showed 2.32 signal-to-cutoff (S/C) and 2.31 S/C at a 3-week interval. Therefore, it was assumed to be a false positive due to autoantibody or medication. The positive samples from 7 patients had a median of 3.79 S/C (range 1.72 - 6.54). The seroprevalence of SARS-CoV-2 IgG in HCWs was very low. The current infection control standard seems to be effective in protecting HCWs from COVID-19.

Clinical Utility of Fecal Neutrophil Gelatinase-Associated Lipocalin and Calprotectin as Biomarkers of Clostridioides (Clostridium) difficile Infection

Background@#Current methods for diagnosing Clostridioides difficile infections (CDIs) fail to provide information on their severity. Fecal neutrophil gelatinase-associated lipocalin (NGAL) and calprotectin are candidate biomarkers for evaluating the severity of intestinal inflammation. We assessed fecal NGAL and calprotectin levels in patients with CDI and compared these values between subgroups of patients. We also evaluated their utility in predicting CDI clinical outcomes. @*Methods@#A total of 147 leftover fecal samples were obtained; 97 samples were from patients with CDI and 50 were from routine healthcare checkups. Fecal calprotectin and NGAL levels were measured using a Quantitative Fecal NGAL ELISA Kit and Quantitative Fecal Calprotectin ELISA Kit (Epitope Diagnostics, USA). @*Results@#Significant differences in fecal NGAL and calprotectin levels were observed between CDI patients and healthy controls (P<0.0001 for both). Significant differences in fecal NGAL and calprotectin levels were also seen between patients with high and low tcdB gene load (P=0.005 and 0.006, respectively). Fecal calprotectin levels were lower in patients with leukopenia (P=0.002), and high calprotectin levels were associated with severe CDI and treatment failure (P=0.021 and 0.033, respectively). @*Conclusions@#Fecal NGAL and calprotectin levels were higher in patients with CDI than in healthy controls and correlated with high tcdB gene loads. Leukopenia patients with CDI had significantly lower levels of calprotectin and the assessment should be regarded with caution. High fecal calprotectin levels were also associated with severe CDI and treatment failure. This warrants future studies with more patients and in-depth analyses.

Performance Evaluation of the QXDx BCR-ABL %IS Droplet Digital PCR Assay

Accurate detection of BCR-ABL fusion transcripts at and below molecular response (MR) 4 (0.01% International Scale [IS]) is required for disease monitoring in patients with chronic myeloid leukemia (CML). We evaluated the analytical performance of the QXDx BCR-ABL %IS (Bio-Rad, Hercules, CA, USA) droplet digital PCR (ddPCR) assay, which is the first commercially available ddPCR-based in vitro diagnostics product. In precision analysis, the %CV was 9.3% and 3.0%, with mean values of 0.031% IS and 9.4% IS, respectively. The assay was linear in the first order, ranging from 0.032% IS to 20% IS. The manufacturer-claimed limit of blank, limit of detection, and limit of quantification were verified successfully. There was a very strong correlation between the results of the QXDx BCR-ABL %IS ddPCR assay and the ipsogen BCR-ABL1 Mbcr IS-MMR (Qiagen, Hilden, Germany) real-time quantitative PCR assay (r=0.996). In conclusion, the QXDx BCR-ABL %IS ddPCR assay can provide reliable results for CML patients.

Absolute Change in High-Sensitivity Cardiac Troponin I at Three Hours After Presentation is Useful for Diagnosing Acute Myocardial Infarction in the Emergency Department

Background@#A rise and/or fall in cardiac troponin value with at least one value above the 99th percentile upper reference limit is essential for acute myocardial infarction (AMI) diagnosis. We evaluated the clinical usefulness of serial high-sensitivity cardiac troponin I (hs-cTnI) measurements in AMI diagnosis, in terms of the predictability of absolute and relative changes. @*Methods@#For this retrospective, forward observational study, we enrolled 281 patients older than 18 years who presented with chest pain at the emergency department (ED) between August 2015 and December 2016. The patients were grouped as AMI and nonAMI, and 73 (26%) were diagnosed as having AMI. Hs-cTnI (Abbott Diagnostics, Abbott Park, IL, USA) was measured at presentation and 3 hours later. We assessed the diagnostic performance of the absolute and relative changes in hs-cTnI. @*Results@#The cut-off values to predict AMI were 16.2 ng/L and 42.1% for the absolute and relative hs-cTnI changes, respectively. The area under the curve of hs-cTnI for AMI diagnosis was larger for absolute changes than for relative changes [0.96 (95% confidence interval [CI], 0.92–0.98) vs 0.89 (95% CI, 0.85–0.93)] (P = 0.014). @*Conclusions@#The absolute hs-cTnI change at 3 hours after presentation was superior to the relative change, and a rise and/or fall in hs-cTnI of > 16.2 ng/L at 3 hours after presentation was useful to identify AMI in patients presenting at the ED.