The Results of Femorofemoral Bypass Using a Saphenous Vein Graft as an Alternative to PTFE Grafts

Purpose@#This study aimed to report the results of femorofemoral bypass (FFB) using a great saphenous vein (GSV) graft as an alternative to polytetrafluoroethylene (PTFE) grafts. @*Materials and Methods@#From January 2012 to December 2021, 168 patients who underwent FFB (PTFE, 143; GSV, 25) were included. The patients’ demographic features and surgical intervention results were retrospectively reviewed. @*Results@#There were no intergroup differences in patients’ demographic features.In GSV vs. PTFE grafts, the superficial femoral artery provided statistically significant inflow and outflow (P<0.001 for both), and redo bypass was more common (P=0.021). The mean follow-up duration was 24.7±2.3 months. The primary patency rates at 3 and 5 years were 84% and 74% for PTFE grafts and 82% and 70% for GSV grafts, respectively. There was no significant intergroup difference in primary patency (P=0.661) or clinically driven target lesion revascularization (CD-TLR)-free survival (P=0.758). Clinical characteristics, disease details, and procedures were analyzed as risk factors for graft occlusion. Multivariate analysis revealed that none of the factors was associated with an increased risk of FFB graft occlusion. @*Conclusion@#FFB using PTFE or GSV grafts is a useful method with an approximately 70% 5-year primary patency rate. The GSV and PTFE grafts showed no difference in primary patency or CD-TLR–free survival during follow-up; however, FFB using GSV may be an option in selective situations.

Content Analysis of YouTube Videos on the Effect of Vitamin C on Common Cold / 가정의학회지

Background@#With the growth of the Internet, social media platforms have emerged as major sources of medical information. We assessed the reliability, quality, and accuracy of the most-viewed YouTube videos containing information on the effect of vitamin C on the common cold. @*Methods@#The YouTube videos were searched on August 1, 2022, using the keywords: (“ascorbic acid” OR “vitamin C” OR “Sodium Ascorbate” OR “L-ascorbic”) AND “common cold”. The 30 most-viewed videos were included in our study. The reliability and quality of the videos were analyzed using modified DISCERN and Global Quality Scales, respectively. When the videos included at least one correct or inaccurate scientific statement about the effect of vitamin C on the common cold, they were classified as accurate or misleading videos, respectively; those without any pertinent information were considered neither accurate nor misleading. If a video contained both accurate and inaccurate statements, it was classified as misleading. @*Results@#Of the 30 most-viewed videos, 73% were unreliable, and 67% contained misleading information and were of a poor quality. Of these 30 videos, 14 videos were produced and posted by customers who were not specialized in medicine or nutrition. Moreover, these videos were of significantly lower reliability, quality, and accuracy than those produced by nutrition or fitness channels or by medical or nutrition professionals. @*Conclusion@#The reliability, quality, and accuracy of videos uploaded by non-professionals were low. Therefore, video creators should upload reliable, high-quality videos to ensure the dissemination of accurate medical information.

The principles of presenting statistical results using figures / 대한마취과학회지

Tables and figures are commonly adopted methods for presenting specific data or statistical analysis results. Figures can be used to display characteristics and distributions of data, allowing for intuitive understanding through visualization and thus making it easier to interpret the statistical results. To maximize the positive aspects of figure presentation and increase the accuracy of the content, in this article, the authors will describe how to choose an appropriate figure type and the necessary components to include. Additionally, this article includes examples of figures that are commonly used in research and their essential components using virtual data.

Baseline use of hydroxychloroquine or immunosuppressive drugs and the risk of coronavirus disease 2019

Background/Aims@#The preventive role of hydroxychloroquine (HCQ) on coronavirus disease 2019 (COVID-19) remains unclear. The aim of this study was to examine the effects of HCQ and other immunosuppressive drugs on the incidence of COVID-19. @*Methods@#The data were collected from the South Korea National Health Insurance Sharing-COVID-19 database. All individuals who underwent nasopharyngeal and oropharyngeal swab tests for COVID-19 from January 2020 to May 2020 are included. The association between COVID-19 risk and HCQ use was examined in a propensity score-matched population. Factors associated with COVID-19 were identified using multiple logistic regression analysis. @*Results@#Total 8,070 patients with COVID-19 and 121,050 negative controls were included from the database. Among all participants, 381 were HCQ users. In a propensity score-matched population, the incidence of COVID-19 was 7.1% in HCQ users and 6.8% in non-users. The odds ratio (OR) for HCQ use was 1.05 with a 95% confidence interval (CI) of 0.58 to 1.89. Among the subpopulation of patients with rheumatoid arthritis (RA), 33 were diagnosed with COVID-19 and 478 were not. Use of HCQ, glucocorticoids, or other immunosuppressive drugs was not associated with COVID-19 risk, whereas abatacept use was. Chronic lung disease was an independent risk factor for COVID-19 diagnosis in patients with RA (adjusted OR, 6.07; 95% CI, 1.10 to 33.59). @*Conclusions@#The risk of COVID-19 did not differ between HCQ users and non-users. Glucocorticoids, conventional disease-modifying antirheumatic drugs (DMARDs), and biological DMARDs other than abatacept did not increase the risk of COVID-19.

The principles of presenting statistical results: Table / 대한마취과학회지

General medical journals such as the Korean Journal of Anesthesiology (KJA) receive numerous manuscripts every year. However, reviewers have noticed that the tables presented in various manuscripts have great diversity in their appearance, resulting in difficulties in the review and publication process. It might be due to the lack of clear written instructions regarding reporting of statistical results for authors. Therefore, the present article aims to briefly outline reporting methods for several table types, which are commonly used to present statistical results. We hope this article will serve as a guideline for reviewers as well as for authors, who wish to submit a manuscript to the KJA.

The principles of presenting statistical results: Table / 대한마취과학회지

General medical journals such as the Korean Journal of Anesthesiology (KJA) receive numerous manuscripts every year. However, reviewers have noticed that the tables presented in various manuscripts have great diversity in their appearance, resulting in difficulties in the review and publication process. It might be due to the lack of clear written instructions regarding reporting of statistical results for authors. Therefore, the present article aims to briefly outline reporting methods for several table types, which are commonly used to present statistical results. We hope this article will serve as a guideline for reviewers as well as for authors, who wish to submit a manuscript to the KJA.

Comparison of three risk stratification models for non-clear cell renal cell carcinoma patients treated with temsirolimus as first-line therapy

Background/Aims@#For metastatic renal cell carcinoma (RCC), various prognostic scoring systems have been developed. However, owing to the low prevalence of nonclear cell RCC, the three most commonly used tools were mainly developed based on patients with clear cell histology. Accordingly, this study applied three prognostic models to Korean non-clear cell RCC patients treated with first-line temsirolimus. @*Methods@#This study analyzed data for 74 patients with non-clear cell RCC who were treated with temsirolimus as the first-line therapy at eight medical centers between 2011 and 2016. The receiver-operating characteristic (ROC) curves for the different prognostic models were analyzed. @*Results@#Twenty-seven (36.5%), 24 (32.4%), and 44 patients (59.5%) were assigned to the poor prognosis groups of the Memorial Sloan-Kettering Cancer Center (MSKCC), International Metastatic RCC Database Consortium (IMDC), and Advanced Renal Cell Carcinoma (ARCC) risk stratification models, respectively. All three prognostic models reliably discriminated the risk groups to predict progression-free survival and overall survival (p < 0.001). The area under the ROC curve (AUC) for progression and survival was highest for the ARCC model (0.777; 0.734), followed by the IMDC (0.756; 0.724) and the MSKCC (0.742; 0.712) models. Furthermore, the sensitivity and specificity for predicting progression were highest with the ARCC model (sensitivity 63.6%, specificity 85.7%), followed by the MSKCC (sensitivity 58.2%, specificity 86.5%) and the IMDC models (sensitivity 56.4%, specificity 85.7%). @*Conclusions@#All three prognostic models accurately predicted the survival of the non-clear cell RCC patients treated with temsirolimus as the first-line therapy. Furthermore, the ARCC risk model performed better than the other risk models in predicting survival.

Changes in Neck Angle, Neck Length, Maximum Diameter, Maximum Area and Thrombus after Endovascular Aneurysm Repair

Purpose@#The correlation of initial anatomy of the aneurysm, aneurysmal remodeling and endoleaks is controversial. We performed a retrospective study to measure aneurysmal remodeling with time, and to assess the structural changes in the aneurysm neck after endovascular aneurysm repair (EVAR). @*Materials and Methods@#From January 2013 to February 2018, 108 patients with abdominal aortic aneurysms (AAA) underwent EVAR. Follow-up computed tomography images were available for 90 patients. Anatomic variables, including the neck angle, neck length, maximal diameter, maximal area, and thrombus volume were measured. Temporal changes were measured preoperatively, immediate postoperatively (within 1 week after EVAR), and at 6 months, 1 year, and 2 years post-EVAR. Correlation between the variables according to the temporal changes and presence of type Ia endoleaks (T1aE) was analyzed. @*Results@#The mean follow-up period was 10.63±20.34 months. Significant decreases in neck angle and length occurred immediately postoperative (P<0.001 and 0.036). Maximum diameter decreased at 6 months post-EVAR (P=0.003), but no significant changes in the maximal area occurred over time (P=0.142). Thrombus volume in the aneurysm sac increased immediately post-EVAR (P=0.008). There was no significant relationship between T1aE and neck changes in the group and time comparison (P=0.815 and 0.970). @*Conclusion@#Changes in neck angle, length and thrombus volume occurred immediately after EVAR, whereas a change in the maximum diameter of the AAA was noted 6 months after EVAR. Preoperative anatomic variables related with T1aE were not found.

Fasting Plasma Glucose Level Independently Predicts the Mortality of Patients with Coronavirus Disease 2019 Infection: A Multicenter, Retrospective Cohort Study

Background@#Coronavirus disease 2019 (COVID-19) has become a global pandemic, which prompts a consensus for the necessity to seek risk factors for this critical disease. Risk factors affecting mortality of the disease remain elusive. Diabetes and hyperglycemia are known to negatively affect a host’s antiviral immunity. We evaluated the relationship between a history of diabetes, fasting plasma glucose (FPG) levels and mortality among severely ill patients with COVID-19. @*Methods@#This was a retrospective cohort study that assessed 106 adult inpatients (aged ≥18 years) from two tertiary hospitals in Daegu, South Korea. The participants were transferred to tertiary hospitals because their medical condition required immediate intensive care. The demographic and laboratory data were compared between COVID-19 patients who survived and those who did not. @*Results@#Compared with the survivor group, age, and the proportions of diabetes, chronic lung disease and FPG were significantly higher in the deceased group. In the Cox proportional hazards regression model for survival analysis, FPG level and age were identified as significant predictors of mortality (P68 years and FPG of 168 mg/dL, respectively. Among those without diabetes, high FPG remained a significant predictor of mortality (P<0.04). @*Conclusion@#High FPG levels significantly predicted mortality in COVID-19, regardless of a known history of diabetes. These results suggest intensive monitoring should be provided to COVID-19 patients who have a high FPG level.

Long-term benefits of chest compression-only cardiopulmonary resuscitation training using real-time visual feedback manikins: a randomized simulation study

Objective@#Cardiopulmonary resuscitation (CPR) education with a feedback device is known to result in better CPR skills compared to one without the feedback device. However, its long-term benefits have not been established. The purpose of this study was to evaluate the long-term CPR skill retention after training using real-time visual manikins in comparison to that of non-feedback manikins. @*Methods@#We recruited 120 general university students who were randomly divided into the real-time feedback group (RTFG) and the non-feedback group. Of them, 95 (RTFG, 48; non-feedback group, 47) attended basic life support and automated external defibrillation training for 1 hour. For comparison of retention of CPR skills, the two groups were evaluated based on 2-minute chest compression performed immediately after training and at 3, 6, and 9 months. The CPR parameters between the two groups were also compared using a generalized linear model. @*Results@#At immediately after training, the performance of RTFG was better in terms of average chest compression depth (51.9±1.1 vs. 45.5±1.1, p<0.001) and a higher percentage of adequate chest compression depth (51.0±4.1 vs. 26.9±4.2, p<0.001). This significant difference was maintained until 6 months after training, but there was no difference at 9 months after training. However, there was no significant difference in the chest compression rate and the correct hand position at any time point. @*Conclusion@#CPR training with a real-time visual feedback manikin improved skill acquisition in chest compression depth, but only until 6 months after the training. It could be a more effective educational method for basic life support training in laypersons.

Anti-Sm Antibody, Damage Index, and Corticosteroid Use Are Associated with Cardiac Involvement in Systemic Lupus Erythematosus: Data from a Prospective Registry Study

Background@#Disease-specific factors that predispose patients to diverse cardiac diseases in systemic lupus erythematosus (SLE) have been established. The aim of this study was to identify risk factors for cardiac involvement in patients with SLE drawn from the Korean Lupus Network (KORNET) registry. @*Methods@#A total of 437 patients with SLE recruited from the KORNET registry were included in the analysis. The Cox proportional hazard model was used to identify risk factors for the development of cardiac involvement during the follow-up period. The hazard ratios for risk factors of cardiac involvement were assessed using Kaplan-Meier curves and log-rank test. @*Results@#Of 437 patients with SLE, 12 patients (2.7%) developed new cardiac involvement during a median follow-up period of 47.6 months. Frequencies in men and in patients with anti-Sm antibody, anti-Ro antibody, and at least one Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index (SDI) score in patients with cardiac involvement were higher, compared to those without cardiac involvement (P < 0.001, P = 0.026, P = 0.015, and P < 0.001, respectively). Men gender, older age, anti-Sm antibody, SDI, and corticosteroid dosage were potent predictors for cardiac involvement in patients with SLE in the determination of risk factors for cardiac involvement. Men, anti-Sm antibody positivity, and SDI ≥ 1 increased incidence rates of cardiac involvement for (P < 0.001, P = 0.036, and P < 0.001, respectively). @*Conclusion@#The results of this study reveal that SLE-related factors such as anti-Sm antibody, SDI, and corticosteroid dosage at baseline are risk factors for cardiac involvement in SLE.

Normality Test in Clinical Research

In data analysis, given that various statistical methods assume that the distribution of the population data is normal distribution, it is essential to check and test whether or not the data satisfy the normality requirement. Although the analytical methods vary depending on whether or not the normality is satisfied, inconsistent results might be obtained depending on the analysis method used. In many clinical research papers, the results are presented and interpreted without checking or testing normality. According to the central limit theorem, the distribution of the sample mean satisfies the normal distribution when the number of samples is above 30. However, in many clinical studies, due to cost and time restrictions during data collection, the number of samples is frequently lower than 30. In this case, a proper statistical analysis method is required to determine whether or not the normality is satisfied by performing a normality test. In this regard, this paper discusses the normality check, several methods of normality test, and several statistical analysis methods with or without normality checks.

Daclatasvir and asunaprevir combination therapy for patients with chronic hepatitis C virus genotype 1b infection in real world

BACKGROUND/AIMS@#Previous studies have reported a high rate of sustained virologic response (SVR) and a low rate of serious adverse events with the use of daclatasvir (DCV) and asunaprevir (ASV) combination therapy. We evaluated the efficacy and safety of DCV and ASV combination therapy for patients with chronic hepatitis C virus (HCV) genotype 1b infection in real world.@*METHODS@#We enrolled 278 patients (184 treatment-naïve patients) from five hospitals in Daegu and Gyeongsangbuk-do. We evaluated the rates of rapid virologic response (RVR), end-of-treatment response (ETR), and SVR at 12 weeks after completion of treatment (SVR12). Furthermore, we investigated the rate of adverse events and predictive factors of SVR12 failure.@*RESULTS@#The mean age of patients was 59.5 ± 10.6 years, and 140 patients (50.2%) were men. Seventy-seven patients had cirrhosis. Baseline information regarding nonstructural protein 5A (NS5A) sequences was available in 268 patients. Six patients presented with pretreatment NS5A resistance-associated variants. The RVR and the ETR rates were 96.6% (258/267) and 95.2% (223/232), respectively. The overall SVR12 rate was 91.6% (197/215). Adverse events occurred in 17 patients (7.9%). Six patients discontinued treatment because of liver enzyme elevation (n = 4) and severe nausea (n = 2). Among these, four achieved SVR12. Other adverse events observed were fatigue, headache, diarrhea, dizziness, loss of appetite, skin rash, and dyspnea. Univariate analysis did not show significant predictive factors of SVR12 failure.@*CONCLUSIONS@#DCV and ASV combination therapy showed high rates of RVR, ETR, and SVR12 in chronic HCV genotype 1b-infected patients in real world and was well tolerated without serious adverse events.

The Effect of Mycophenolate Mofetil on Non-Renal Manifestations in Systemic Lupus Erythematosus: Results from Korean Lupus Network Registry

BACKGROUND: The objective of this study was to identify the effects of mycophenolate mofetil (MMF) on non-renal manifestations in systemic lupus erythematosus (SLE). METHODS: The study population comprised 439 SLE patients from the Korean Lupus Network registry who were followed up annually and completed the baseline survey and two follow-up visits from 2014 to 2018. Disease activity, laboratory markers, and clinical manifestations including mucocutaneous lesions, arthritis, serositis, neurological disorders, and hematologic/immunologic abnormalities were assessed. All variables by group (MMF and non-MMF) effects with time (baseline, 1st follow-up, and 2nd follow-up) were analyzed by generalized estimation equation. RESULTS: Seventy-two patients were treated with MMF. There was significant difference in frequencies of malar rash, arthritis, renal disorder, and hematologic disorder between MMF and non-MMF groups in total SLE patients. In subgroup analysis of hematologic abnormalities in total patients, frequency of leukopenia was significantly different between the two groups during follow-up (P = 0.001), but frequencies of hemolytic anemia, lymphopenia, and thrombocytopenia were not. In addition, frequencies of leukopenia in patients without lupus nephritis were significantly decreased in MMF group compared to non-MMF group (P = 0.012). CONCLUSION: This study showed that MMF might be a beneficial treatment for hematologic abnormalities, especially leukopenia, in SLE.

What Should We Consider Carefully When Performing Survival Analysis? / 임상소아혈액종양

The survival data and the survival analysis are the data and analysis methods used to study the probability of survival. The survival data consist of a period from the juncture of a start event to the juncture of the end event (occurrence event). The period is called the survival period or survival time. In this way, the method of analysing the survival time of subjects and appropriately summarizing the degree of survival is called survival analysis. To understand and analyse survival analysis methods, researchers must be aware of some concepts. Concepts to be aware of in the survival analysis include events, censored data, survival period, survival function, survival curve and so on. This review focuses on the terms and concepts used in the survival analysis. It will also cover the types of survival data that should be collected and prepared when using actual survival analysis method and how to prepare them.

Can the Zero-Profile Implant Be Used for Anterior Cervical Discectomy and Fusion in Traumatic Subaxial Disc Injury? A Preliminary, Retrospective Study

OBJECTIVE: The zero-profile implant (Zero-P) is accepted for use in anterior cervical fusion for the treatment of degenerative cervical disease. However, evidence pertaining to its efficiency and safety in traumatic cervical injury is largely insufficient. This study aimed to compare the overall outcomes of patients who underwent Zero-P for traumatic cervical disc injury.METHODS: Data from a total of 53 consecutive patients who underwent surgery for traumatic or degenerative cervical disc disease using the Zero-P were reviewed. Seventeen patients (group A) had traumatic cervical disc injury and the remaining 36 (group B) had degenerative cervical disc herniation. The fusion and subsidence rates and Cobb angle were measured retrospectively from plain radiographs. The patients’ clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) score and Odom’s criteria.RESULTS: The C2–7 Cobb and operative segmental angles increased by 3.45±7.61 and 2.94±4.59 in group A; and 2.46±7.31 and 2.88±5.49 in group B over 12 postoperative months, respectively. The subsidence and fusion rate was 35.0% and 95.0% in group A; and 36.6% and 95.1% in group B, respectively. None of the parameters differed significantly between groups. The clinical outcomes were similar in both groups in terms of increasing the JOA score and producing a grade higher than “good” using Odom’s criteria.CONCLUSION: The application of Zero-P in patients with traumatic cervical disc injury was found to be acceptable when compared with the clinical and radiological outcomes of degenerative cervical spondylosis.

Disparity in Crohn’s disease activity between home and clinics is associated with unscheduled hospital visits due to disease flares

BACKGROUND/AIMS: E-health technologies have been implemented for the management of Crohn’s disease (CD). We aimed to identify differences between patient activities at home and at routine clinic visits using a web-based self-reporting CD symptom diary (CDSD) and to determine the impact of this disparity on clinical outcomes. METHODS: Patients with CD from three tertiary hospitals were invited to assess their symptoms at least once a week using CDSD. We identified patients who showed disparities in disease activity (high activity at home but normal at the next hospital visit) and evaluated clinical outcomes of these patients such as unscheduled visits due to flares using Kaplan-Meier analyses. RESULTS: One hundred and forty-three patients recorded their symptoms weekly for at least 3 consecutive months and were included. Forty-eight patients (33.6%) showed disparate disease activities between at home and at the next outpatient clinic visit. The cumulative risk of unscheduled visits was significantly higher in this disparity group than in the concordant group (p = 0.001). Disparity in activity (p = 0.003), and anti-tumor necrosis factor use (p = 0.002) were independent risk factors of unscheduled visits due to disease flares. CONCLUSIONS: Disparity in disease activity is considerable in CD patients and is related to the risk of unscheduled hospital visit.

Characteristics and management of patients with inflammatory bowel disease between a secondary and tertiary hospitals: a propensity score analysis

BACKGROUND/AIMS: This study aimed to compare the clinical characteristics and management patterns of inflammatory bowel disease (IBD) patients in a secondary hospital (SH) with those in tertiary referral centers (TRC). METHODS: Data from IBD patients in SH and 2 TRCs were retrospectively reviewed. The cumulative thiopurine use rate was compared between hospitals after controlling for different baseline characteristics using propensity score matching. RESULTS: Among the total of 447 patients with IBD, 178 Crohn's disease (CD) and 269 ulcerative colitis (UC) patients were included. Regarding initial CD symptoms, patients from SH were more likely to show perianal symptoms, such as anal pain or discharge (56.6% vs. 34.3%, P=0.003), whereas those from TRCs more often had luminal symptoms, such as abdominal pain (54.9% vs. 17.1%, P < 0.001), diarrhea (44.1% vs. 18.4%, P < 0.001), and body weight loss (9.8% vs. 1.3%, P=0.025). Complicating behaviors, such as stricturing and penetrating, were significantly higher in TRCs, while perianal disease was more common in SH. Ileal location was more frequently observed in TRCs. For UC, SH had a more limited extent of disease (proctitis 58.8% vs. 21.2%, P < 0.001). The cumulative azathioprine use rate in SH was significantly lower than that in TRCs in both CD and UC patients after controlling for disease behavior, location, and perianal disease of CD and extent of UC. CONCLUSIONS: The clinical characteristics and management of the IBD patients in SH were substantially different from those in TRCs. Thiopurine treatment was less commonly used for SH patients.

Can the Zero-Profile Implant Be Used for Anterior Cervical Discectomy and Fusion in Traumatic Subaxial Disc Injury? A Preliminary, Retrospective Study

OBJECTIVE: The zero-profile implant (Zero-P) is accepted for use in anterior cervical fusion for the treatment of degenerative cervical disease. However, evidence pertaining to its efficiency and safety in traumatic cervical injury is largely insufficient. This study aimed to compare the overall outcomes of patients who underwent Zero-P for traumatic cervical disc injury. METHODS: Data from a total of 53 consecutive patients who underwent surgery for traumatic or degenerative cervical disc disease using the Zero-P were reviewed. Seventeen patients (group A) had traumatic cervical disc injury and the remaining 36 (group B) had degenerative cervical disc herniation. The fusion and subsidence rates and Cobb angle were measured retrospectively from plain radiographs. The patients’ clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) score and Odom’s criteria. RESULTS: The C2–7 Cobb and operative segmental angles increased by 3.45±7.61 and 2.94±4.59 in group A; and 2.46±7.31 and 2.88±5.49 in group B over 12 postoperative months, respectively. The subsidence and fusion rate was 35.0% and 95.0% in group A; and 36.6% and 95.1% in group B, respectively. None of the parameters differed significantly between groups. The clinical outcomes were similar in both groups in terms of increasing the JOA score and producing a grade higher than “good” using Odom’s criteria. CONCLUSION: The application of Zero-P in patients with traumatic cervical disc injury was found to be acceptable when compared with the clinical and radiological outcomes of degenerative cervical spondylosis.

Central limit theorem: the cornerstone of modern statistics / 대한마취과학회지

According to the central limit theorem, the means of a random sample of size, n, from a population with mean, µ, and variance, σ², distribute normally with mean, µ, and variance, σ²/n. Using the central limit theorem, a variety of parametric tests have been developed under assumptions about the parameters that determine the population probability distribution. Compared to non-parametric tests, which do not require any assumptions about the population probability distribution, parametric tests produce more accurate and precise estimates with higher statistical powers. However, many medical researchers use parametric tests to present their data without knowledge of the contribution of the central limit theorem to the development of such tests. Thus, this review presents the basic concepts of the central limit theorem and its role in binomial distributions and the Student's t-test, and provides an example of the sampling distributions of small populations. A proof of the central limit theorem is also described with the mathematical concepts required for its near-complete understanding.