Citation Activity of Journal of Korean Medical Science in 2011–2020:Reflection on the Most and Least Cited Items

Background@#The Journal of Korean Medical Science (JKMS) is a weekly periodical published by the Korean Academy of Medical Sciences. JKMS invites global researchers to submit articles covering various areas in general medicine. The present article’s aim was to analyze citations of JKMS articles in 2011–2020 for updating editorial policies. @*Methods@#Citation records of JKMS articles were tracked in Web of Science (WoS), Clarivate ®from August 2021 to June 2022. @*Results@#In 2011–2020, JKMS published 2,880 articles, including 2,757 (96.0%) ever cited. All reviews (57/57) and 96% of original research reports (2,184 out of 2,264) received at least one citation. Brief communications, opinions, and images were least cited items. Of 36 subject categories covered by JKMS, only biomedical engineering was significantly less advantageous citation-wise. Five articles published in 2012–2017 attracted more than 100 citations. Most other articles were cited less than 50 times. Article categories of nationwide epidemiology, disease or patient registries, clinical trials, and infectious diseases were distinguished as well cited. Of 378 articles published in 2020, 10 were cited at least 100 times; all these ten items were related to severe acute respiratory syndrome coronavirus 2 and coronavirus disease 2019. In the past 5 years, studies on health care laws, management, and some specific topics in clinical specialties were not cited. The citation trends in WoS, Crossref, and Scopus were similar while PubMed Central records were roughly twice less. @*Conclusion@#Most of JKMS articles are cited during 5 years post publication, with 1.4% noncitation rate. The obtained results suggest that inviting review articles in clinical sciences, research reports on hot medical topics, and nationwide database analyses may attract more author interest and related citations.

Identifying Adverse Events Using International Classification of Diseases, Tenth Revision Y Codes in Korea: A Cross-sectional Study / 예방의학회지

OBJECTIVES@#The use of administrative data is an affordable alternative to conducting a difficult large-scale medical-record review to estimate the scale of adverse events. We identified adverse events from 2002 to 2013 on the national level in Korea, using International Classification of Diseases, tenth revision (ICD-10) Y codes.@*METHODS@#We used data from the National Health Insurance Service-National Sample Cohort (NHIS-NSC). We relied on medical treatment databases to extract information on ICD-10 Y codes from each participant in the NHIS-NSC. We classified adverse events in the ICD-10 Y codes into 6 types: those related to drugs, transfusions, and fluids; those related to vaccines and immunoglobulin; those related to surgery and procedures; those related to infections; those related to devices; and others.@*RESULTS@#Over 12 years, a total of 20 817 adverse events were identified using ICD-10 Y codes, and the estimated total adverse event rate was 0.20%. Between 2002 and 2013, the total number of such events increased by 131.3%, from 1366 in 2002 to 3159 in 2013. The total rate increased by 103.9%, from 0.17% in 2002 to 0.35% in 2013. Events related to drugs, transfusions, and fluids were the most common (19 446, 93.4%), followed by those related to surgery and procedures (1209, 5.8%) and those related to vaccines and immunoglobulin (72, 0.3%).@*CONCLUSIONS@#Based on a comparison with the results of other studies, the total adverse event rate in this study was significantly underestimated. Improving coding practices for ICD-10 Y codes is necessary to precisely monitor the scale of adverse events in Korea.

Identifying Adverse Events Using International Classification of Diseases, Tenth Revision Y Codes in Korea: A Cross-sectional Study / 예방의학회지

OBJECTIVES: The use of administrative data is an affordable alternative to conducting a difficult large-scale medical-record review to estimate the scale of adverse events. We identified adverse events from 2002 to 2013 on the national level in Korea, using International Classification of Diseases, tenth revision (ICD-10) Y codes. METHODS: We used data from the National Health Insurance Service-National Sample Cohort (NHIS-NSC). We relied on medical treatment databases to extract information on ICD-10 Y codes from each participant in the NHIS-NSC. We classified adverse events in the ICD-10 Y codes into 6 types: those related to drugs, transfusions, and fluids; those related to vaccines and immunoglobulin; those related to surgery and procedures; those related to infections; those related to devices; and others. RESULTS: Over 12 years, a total of 20 817 adverse events were identified using ICD-10 Y codes, and the estimated total adverse event rate was 0.20%. Between 2002 and 2013, the total number of such events increased by 131.3%, from 1366 in 2002 to 3159 in 2013. The total rate increased by 103.9%, from 0.17% in 2002 to 0.35% in 2013. Events related to drugs, transfusions, and fluids were the most common (19 446, 93.4%), followed by those related to surgery and procedures (1209, 5.8%) and those related to vaccines and immunoglobulin (72, 0.3%). CONCLUSIONS: Based on a comparison with the results of other studies, the total adverse event rate in this study was significantly underestimated. Improving coding practices for ICD-10 Y codes is necessary to precisely monitor the scale of adverse events in Korea.

Epidemiologic research on lung damage caused by humidifier disinfectants / 한국역학회지

In April 2011 a tertiary hospital located in Seoul, Korea reported several cases of severe respiratory distress of unknown origin in young adults. To find the route of transmission, causative agent and patient risk factors of the outbreak, an investigation of the epidemic was initiated. A hospital based case-control study was conducted to indicate that humidifier detergent use was the cause of the outbreak. This information led the Ministry of Health and Welfare of Korea issued an order that humidifier detergents should be withdrawn from the market. Here, we describe the major events of planning, execution, and interpretation of the study, and discussions between researchers and public authorities following the decision to perform an epidemiologic study, chronologically.

Inhalation Lung Injury Associated with Humidifier Disinfectants in Adults

We recently established a novel disease entity presented as progressive respiratory failure associated with the inhalation of humidifier disinfectants. In April 2011, we encountered a series of peripartum patients with complaints of respiratory distress of unknown etiology, which was an uncommon phenomenon. Accordingly, we created a multidisciplinary team comprising intensivists, radiologists, pathologists, epidemiologists, and the Korea Centers for Disease Control and Prevention (KCDC). Further, we defined the disease entity and performed a case-control study, epidemiologic investigation, and animal study to determine the etiology. The study findings indicated that the lung injury outbreak was related to the inhalation of humidifier disinfectants and showed that household chemical inhalation can cause severe respiratory failure. Following the withdrawal of humidifier disinfectants from the Korean market in 2012, no such cases were reported. This tragic event is a warning that appropriate safety regulations and monitoring for potential toxic household chemicals are critical to protect public health.

Perceptions of Healthcare Workers of Health Risks of Electromagnetic Fields

BACKGROUND: This study assessed the perceptions of healthcare staff of the health risks of exposure to electromagnetic fields (EMF). METHODS: In total, 328 healthcare workers (e.g., physicians, nurses, medical students, and paramedics) completed a self-administered questionnaire. The questionnaire assessed the following: risk perceptions of 17 environmental factors as potential health threats; EMF sources; information for the potential risks of EMF; and thoughts on how to protect the public from potential EMF-related health risks. RESULTS: Of the included environmental factors, high-tension power lines and mobile phone handsets were ranked as the second and fourth lowest perceived risk, respectively. Approximately 60% of respondents were concerned about the potential health risks of EMF and dissatisfied with the information they received. The main reason for dissatisfaction was insufficient information. The most frequently cited action was that the government should review the available scientific evidence on potential EMF-related health risks. CONCLUSIONS: Having scientific basis through well-designed researches and providing accurate information to the public on the potential health risks of EMF will be important in the future.

A De-identification Method for Bilingual Clinical Texts of Various Note Types

De-identification of personal health information is essential in order not to require written patient informed consent. Previous de-identification methods were proposed using natural language processing technology in order to remove the identifiers in clinical narrative text, although these methods only focused on narrative text written in English. In this study, we propose a regular expression-based de-identification method used to address bilingual clinical records written in Korean and English. To develop and validate regular expression rules, we obtained training and validation datasets composed of 6,039 clinical notes of 20 types and 5,000 notes of 33 types, respectively. Fifteen regular expression rules were constructed using the development dataset and those rules achieved 99.87% precision and 96.25% recall for the validation dataset. Our de-identification method successfully removed the identifiers in diverse types of bilingual clinical narrative texts. This method will thus assist physicians to more easily perform retrospective research.

Prophylactic Effect of Erythropoietin Injection to Prevent Acute Mountain Sickness: An Open-Label Randomized Controlled Trial

This study was performed to evaluate whether increasing hemoglobin before ascent by prophylactic erythropoietin injections prevents acute mountain sickness (AMS). This open-label, randomized, controlled trial involved 39 healthy volunteers with hemoglobin or =3 were present. Immediate descent criteria followed US Army recommendations. Two groups differ in hemoglobin levels on day 29 (15.4+/-1.1 vs 14.2+/-1.0 g/dL, P=0.001). At ABC, erythropoietin group had a significantly lower mean LLS, AMS incidence, and number of subjects who met immediate descent criteria. Multiple logistic regression analysis showed that SaO2<87% and control group, but not hemoglobin<15.0 g/dL, independently predicted satisfaction of immediate descent criteria. Erythropoietin-related adverse effects were not observed. In conclusion, erythropoietin may be an effective prophylaxis for AMS.(Clinical Trial Registry Number; NCT 01665781).

Pulmonary Tuberculosis and Lung Cancer Risk in Current Smokers: The Seoul Male Cancer Cohort Study

Authors evaluated pulmonary tuberculosis (PTB) history as a risk factor for lung cancer in current male smokers in a prospective, population-based cohort study. The subjects were the 7,009 males among the participants in the Seoul Male Cancer Cohort Study for whom there was full information on PTB history and smoking habits. With a 16-yr follow-up, 93 cases of lung cancer occurred over the 99,965 person-years of the study. The estimated relative risk (RR) of PTB history of current smokers in lung cancer after adjusting for three confounders - intake of coffee and tomatoes, and age at entry - was 1.85 (95% CI: 1.08-3.19). The observed joint RRs and attributable risks (ARs) across strata of three confounders were greater than the expected, indicating a positive interaction. Thus a history of PTB in current smokers may be another risk factor for lung cancer. Based on a synergic interaction, a heavy male smoker with a PTB history would be expected to belong to the group at high risk of lung cancer.

Lung Cancer Incidence by Smoking Status in Korean Men: 16-Years of Observations in the Seoul Male Cancer Cohort Study

The relative risk (RR) of smoking and mortality of lung cancer in British doctors was previously reported to have increased throughout a 40-yr period. Here, we evaluated this RR based on the incidence of lung cancer in Korean men using a longer follow-up period. We compared our data to the RR reported in a study using a 10-yr follow-up period; the subjects and methods were identical to those of the previous paper with the exception of the follow-up period, which ended on December 31, 2008. We found that the RR of smoking habits in patients with lung cancer did not increase, and that the data showed narrowing 95% confidence intervals over a longer observation in Korean men. Estimated lung cancers attributable to smoking were 55.6%. These results highlight the need for an intervention program to help patients quit smoking in Korea.

Cardiovascular Health Metrics and All-cause and Cardiovascular Disease Mortality Among Middle-aged Men in Korea: The Seoul Male Cohort Study / 예방의학회지

OBJECTIVES: This study estimated the association of cardiovascular health behaviors with the risk of all-cause and cardiovascular disease (CVD) mortality in middle-aged men in Korea. METHODS: In total, 12 538 men aged 40 to 59 years were enrolled in 1993 and followed up through 2011. Cardiovascular health metrics defined the following lifestyle behaviors proposed by the American Heart Association: smoking, physical activity, body mass index, diet habit score, total cholesterol, blood pressure, and fasting blood glucose. The cardiovascular health metrics score was calculated as a single categorical variable, by assigning 1 point to each ideal healthy behavior. A Cox proportional hazards regression model was used to estimate the hazard ratio of cardiovascular health behavior. Population attributable risks (PARs) were calculated from the significant cardiovascular health metrics. RESULTS: There were 1054 total and 171 CVD deaths over 230 690 person-years of follow-up. The prevalence of meeting all 7 cardiovascular health metrics was 0.67%. Current smoking, elevated blood pressure, and high fasting blood glucose were significantly associated with all-cause and CVD mortality. The adjusted PARs for the 3 significant metrics combined were 35.2% (95% confidence interval [CI], 21.7 to 47.4) and 52.8% (95% CI, 22.0 to 74.0) for all-cause and CVD mortality, respectively. The adjusted hazard ratios of the groups with a 6-7 vs. 0-2 cardiovascular health metrics score were 0.42 (95% CI, 0.31 to 0.59) for all-cause mortality and 0.10 (95% CI, 0.03 to 0.29) for CVD mortality. CONCLUSIONS: Among cardiovascular health behaviors, not smoking, normal blood pressure, and recommended fasting blood glucose levels were associated with reduced risks of all-cause and CVD mortality. Meeting a greater number of cardiovascular health metrics was associated with a lower risk of all-cause and CVD mortality.

Psychometric Properties of the Korean Version of the Overactive Bladder Questionnaire (OAB-q) in a Korean Population / 대한배뇨장애요실금학회지

PURPOSE: Psychometric properties of the overactive bladder questionnaire (OAB-q) were recently examined. However, since the cross-cultural adaptation of a non-English version of the OAB-q has never been demonstrated, we evaluated the psychometric properties of a Korean version of the OAB-q in a Korean population with OAB. METHODS: A prospective cohort study involving 116 women with 58 OAB and 58 control subjects was performed and convergent validity was assessed. Total and subscale OAB-q scores of the control and OAB groups were compared to their sensitivity to score changes before and after administering anti-cholinergic medication for 12 weeks. Short form 36 and King's health questionnaire (KHQ) were also used for comparison or correlation. RESULTS: Assessment of face validity showed that the Korean version of the OAB-q was reasonable with OAB-q subscale scores being significantly different between the control and patient groups. Significant correlation (range, -0.29 to -0.81) was found between the OAB-q scores and KHQ results for the OAB patients. Cronbach's alpha coefficients (range, 0.77 to 0.95) indicated excellent internal consistency and test-retest analysis involving 35 OAB patients showed that each questions as well as subscale scores were reproducible. Each score of OAB-q also showed statistically significant sensitivity to changes following anti-muscarinic treatment for OAB (n=27, P<0.001 except for social, P=0.059). CONCLUSIONS: The Korean version of the OAB-q is a valid and reliable instrument to measure outcomes in Korean patients with OAB.

Cancer Rehabilitation: Experience, Symptoms, and Needs

The aim of this study was to examine the experience of cancer patients undergoing rehabilitation, to identify symptoms associated with rehabilitation from cancer, and to assess the need for rehabilitation services for cancer patients. Cancer patients (n = 402) at the Asan Medical Center (Seoul, Korea) were enrolled from June to September 2008. A chart review was used to collect demographic and clinical data, including type of cancer, current treatment, time from initial diagnosis to screening, and cancer stage. Each participant provided informed consent and was then given a questionnaire that asked about experience with rehabilitation, symptoms associated with rehabilitation, and the need for different types of rehabilitation services. Clinicians recommended rehabilitation for 8.5% of patients, and 6.7% underwent rehabilitation. Among study patients, 83.8% had one or more symptoms associated with rehabilitation, and 71.6% of patients with symptoms wanted rehabilitation management. The need for rehabilitation was associated with the presence of metastasis, advanced cancer stage, time to diagnosis, and type of current treatment. Our results provide specific information about particular functional symptoms and the rehabilitative needs of subgroups of cancer patients. It is suggested to develope and implement rehabilitation programs for cancer patients.

Construction and Validation of Hospital-Based Cancer Registry Using Various Health Records to Detect Patients with Newly Diagnosed Cancer: Experience at Asan Medical Center / 예방의학회지

OBJECTIVES: An accurate estimation of cancer patients is the basis of epidemiological studies and health services. However in Korea, cancer patients visiting out-patient clinics are usually ruled out of such studies and so these studies are suspected of underestimating the cancer patient population. The purpose of this study is to construct a more complete, hospital-based cancer patient registry using multiple sources of medical information. METHODS: We constructed a cancer patient detection algorithm using records from various sources that were obtained from both the in-patients and out-patients seen at Asan Medical Center (AMC) for any reason. The medical data from the potentially incident cancer patients was reviewed four months after first being detected by the algorithm to determine whether these patients actually did or did not have cancer. RESULTS: Besides the traditional practice of reviewing the charts of in-patients upon their discharge, five more sources of information were added for this algorithm, i.e., pathology reports, the national severe disease registry, the reason for treatment, prescriptions of chemotherapeutic agents and radiation therapy reports. The constructed algorithm was observed to have a PPV of 87.04%. Compared to the results of traditional practice, 36.8% of registry failures were avoided using the AMC algorithm. CONCLUSIONS: To minimize loss in the cancer registry, various data sources should be utilized, and the AMC algorithm can be a successful model for this. Further research will be required in order to apply novel and innovative technology to the electronic medical records system in order to generate new signals from data that has not been previously used.

Cigarette Smoking and Risk of Lung Cancer in Korean Men: The Seoul Male Cancer Cohort Study

Lung cancer is the leading cause of cancer deaths in Korea. The aim of this study was to estimate lung cancer risk of cigarette smoking in Korean men by a 10-yr follow-up prospective cohort study using the primary databases. The number of subjects was 14,272 men, who had full information of smoking habits among participants in the Seoul Male Cancer Cohort Study (SMCC). Total 125,053 personyears were calculated by determining the number of days from the start of followup, January 1, 1993, until the date of lung cancer diagnosis, death from another cause, or the end of follow-up, December 31, 2002, followed by converting the number of days to years. The information of outcome was obtained by the database of Korea Central Cancer Registry, Seoul Regional Cancer Registry, and Korea Statistical Office. The relative risk (RR) and its 95% confidence interval (CI) values of smoking were calculated using Cox proportional hazards regression stratified on potential confounders. During the follow-up periods, 78 cases of lung cancer occurred. The cigarette smoking is the major risk factor and increases the 4.18-fold risk of lung cancer in Korean men. In order to control lung cancer, intervention of quitting smoking is needed.

The Reliability and Validity of the Rhodes Index of Nausea, Vomiting and Retching in Postoperative Nausea and Vomiting / 대한마취과학회지

BACKGROUND: The Rhodes index of nausea, vomiting and retching (RINVR) is a patient self-report instrument to assess the objective and subjective factors of nausea and vomiting. The aim of this study is to evaluate the reliability and validity of the RINVR in postoperative nausea and vomiting (PONV). METHODS: The RINVR, VAS for nausea and incidence of emetic episodes were administered to 150 patients approximately 30 minutes apart at 6 hours and 24 hours after surgery. The validity was evaluated by Spearman's correlation and internal consistency of reliability was determined using Cronbach's alpha. To determine test-retest reliability, second administration of the RINVR was done 2 hours after the first. The test-retest reliability was evaluated by Spearman's correlation and agreement. RESULTS: Cronbach's alpha of nausea, vomiting, retching and total experience scores of the RINVR ranged from 0.912 to 0.968. Test-retest scores of all items were strongly correlated (Spearman's coefficients: 0.962-1.000, P< 0.0001) and highly agreed (weighted kappa: 0.932-1.000). Coefficients of construct validity for nausea components (vs VAS for nausea) and emetic components (vs incidence of emetic episodes) of the RINVR were 0.860-0.928 and 0.724-0.811, respectively (P<0.0001). The overall weighted kappa between the incidences of PONV assessed by the RINVR and by patient self-assessment of VAS for nausea and incidence of emetic episodes was 0.917-0.945. The number of patients in "great" total experience category was 1.33% or less. There was no significant difference of VAS for nausea between "severe" and "great" nausea experience categories. CONCLUSIONS: The RINVR was a reliable and valid instrument to assess PONV.

A Clinical Study to Evaluate the Safety and Efficacy of a Patient-controlled Analgesia Pump in Post-surgical Patients / 대한마취과학회지

BACKGROUND: The disposable patient-controlled analgesia (PCA) devices are convenient for portability and management. An ideal PCA can be developed as an electronic device with various functions of safety and control. Recently, Accumate 1000(R) was developed as an electronic pump in Korea, and has passed the relevant laboratory criteria of safety and efficacy. We conducted a clinical study on the safety and efficacy when the device is applied to patients. METHODS: Fentanyl 1,500microgram, ketorolac 180 mg, and ondansetron 8 mg were used for PCA. Continuous infusion rate, bolus dose, and lockout time were set at 1 ml/h, 1 ml, and 15 min, respectively. Fifty patients were monitored for 48 h. The safety of Accumate 1000(R) was evaluated by backflow and siphonage, auto-clamp function, and lockout time intraoperatively. The efficacy was evaluated by the accuracy of bolus and total infused dose, and the satisfaction rates of patients and users. RESULTS: Backflow and siphonage did not occur, and the auto-clamp function was excellent. There was no bolus infusion during lockout time, and the bolus dose was infused accurately after lockout time. For the accuracy of the total infused dose, the mean and median value of performance error between the infused and target doses were -0.55%, and -0.29%, respectively. Noise, button sense, and convenience of cable were rated as satisfactory by 90%, 78%, and 84%, of patients respectively. CONCLUSIONS: The safety and efficacy of Accumate 1000(R) were established by clinical trial. We can provide patients with the more precise and optimal analgesia. The history of drug infusion can be used as research data.

Clinico-pathological Characteristics of Prostate Cancer in Korean Men and Nomograms for the Prediction of the Pathological Stage of the Clinically Localized Prostate Cancer: A Multi-institutional Update / 대한비뇨기과학회지

PURPOSE: In this multi institutional study, the data of 604 men with clinically localized prostate cancer, who underwent radical prostatectomy, with updated nomograms predicting the pathological stage, were analyzed. MATERIALS AND METHODS: Prostate biopsies and prostatectomy specimens from men treated with radical prostatectomy, obtained between 1990 and 2003, were included. The patient distribution with respect to clinical stage, serum prostate-specific antigen (PSA) and biopsy Gleason score, as well as final pathological findings, including organ-confined disease (OCD), extracapsular extension (ECE), seminal vesicle invasion (SVI), and lymph node metastasis (LNM), were analyzed for the construction of nomograms representing the percent probabilities of each respective pathological outcome. RESULTS: The median serum PSA at the time of surgery and biopsy Gleason score were 9.9ng/ml and 7, respectively. The preoperative serum PSA was 4ng/ml or less in 38 (6.3%) patients and the tumor was impalpable in 292 (48.2%) of patients. The biopsy Gleason scores were 7 and 8 or higher in 186 (30.7%) and 169 (27.9%), respectively. Throughout the clinical stages and PSA ranges, the Gleason score was 7 or higher in more than 50% of patients, but 8-10 in 20-30%. The overall OCD, ECE, SVI and LNM rates were 57.1, 27.8, 10.9 and 4.2%, respectively. CONCLISIONS: A significantly high proportion of prostate cancers arising in Korean men exhibited poor differentiation, with Gleason scores of 7 or higher, regardless of the clinical stage or initial serum PSA. Updated nomograms acknowledging such characteristics have been developed, which may aid in the treatment planning of these individuals.

Korean Nomogram for the Prediction of Recurrence-free Survival after Definitive Surgery for Renal Cell Carcinoma / 대한비뇨기과학회지

Purpose: This multiinstitutional study was to investigate the accuracy of the Kattan nomograms for the prediction of recurrence after definitive surgery for renal cell carcinoma (RCC) in Korean patients and develop a nomogram revised to complement the shortcomings. Materials and Methods: Clinical and pathological data of 1,866 patients with RCC who had been followed for at least 2 years after surgery in each participating institutes were reviewed as well as evidence of disease recurrence, defined to include local recurrence and distant metastasis. Accuracy of the Kattan nomograms' predictability in tumors 7cm or less was tested by calculating the area under the receiver-operating characteristics curve (AUC) and actuarial recurrence-free survival by Kaplan- Meier method. We used the Cox proportional hazard analysis to identify significant variables and develop prediction nomogram, and internally validated by bootstrapping method. Mean follow-up was 56.5 months (24-184). Results: Recurrence occurred in 12.5% of the patients and correlated with the pathological stage, with 4.3%, 7.9%, 15.0%, 22.6%, 38.4%, 58.3% for stages T1a, T1b, T2, T3a, T3b/c and T4, respectively (p<0.001). The AUC of the Kattan nomograms was 0.276. Factors significantly predictive of recurrence were T stage (p<0.0001), presentation (p=0.006), preoperative hemoglobin (p=0.023) and gender (p=0.032). Actuarial 60-month recurrence- free survival was 87.9% and using the prognostic factors, nomogram predicting 60-month recurrence-free survival was constructed. Conclusions: Korean nomogram complementing the preexisting nomograms for the prediction of recurrence-free survival after definitive surgery for RCC has been constructed, which may be useful in patient prognostication, counseling and follow-up planning.

Impact of Pulmonary Vascular Compliance on the Duration of Pleural Effusion Duration after Extracardiac Fontan Procedure / 대한흉부외과학회지

BACKGROUND: Preoperative risk analysis for Fontan candidates is still less than optimal in that patients with apparently low risks may have poor surgical outcome; prolonged pleural drainage, protein losing enteropathy, pulmonary thromboembolism and death. We hypothesized that low pulmonary vascular compliance (PVC) is a risk factor for prolonged pleural effusion drainage after the Fontan operation. MATERIAL AND METHOD: A retrospective review of 96 consecutive patients who underwent the Extracardiac Fontan procedures (median age: 3.9 years) was performed. Fontan risk score (FRS) was calculated from 12 categorized preoperative anatomic and physiologic variables. PVC (mm(2)/m(2) . mmHg) was defined as pulmonary artery index (mm(2)/m(2)) divided by total pulmonary resistance (W.U . m(2)) and pulmonary blood flow (L/min/m(2)), based on the electrical circuit analogue of the pulmonary circulation. Chest tube indwelling time was log-transformed (log indwelling time, LIT) to fit normal distribution, and the relationship between preoperative predictors and LIT was analyzed by multiple linear regression. RESULT: Preoperative PVC, chest tube indwelling time and LIT ranged from 6 to 94.8 mm(2)/mmHg/m(2) (median: 24.8), 3 to 268 days (median: 20 days), and 1.1 to 5.6 (mean: 2.9, standard deviation: 0.8), respectively. FRS, PVC, cardiopulmonary bypass time (CPB) and central venous pressure at postoperative 12 hours were correlated with LIT by univariable analyses. By multiple linear regression, PVC (p=0.0018) and CPB (p=0.0024) independently predicted LIT, explaining 21.7% of the variation. The regression equation was LIT=2.74-0.0158 . PVC+0.00658 . CPB. CONCLUSION: Low pulmonary vascular compliance is an important risk factor for prolonged pleural effusion drainage after the extracardiac Fontan procedure.