Smoothed quantile residual life regression analysis with application to the Korea HIV/AIDS cohort study.

BACKGROUND: The residual life of a patient with human immunodeficiency virus (HIV) is of major interest to patients and their physicians. While existing analyses of HIV patient survival focus mostly on data collected at baseline, residual life analysis allows for dynamic analysis based on additional data collected over a period of time. As survival times typically exhibit a right-skewed distribution, the median provides a more useful summary of the underlying distribution than the mean. In this paper, we propose an efficient inference procedure that fits a semiparametric quantile regression model assessing the effect of longitudinal biomarkers on the residual life of HIV patients until the development of dyslipidemia, a disease becoming more prevalent among those with HIV. METHODS: For estimation of model parameters, we propose an induced smoothing method that smooths nonsmooth estimating functions based on check functions. For variance estimation, we propose an efficient resampling-based estimator. The proposed estimators are theoretically justified. Simulation studies are used to evaluate their finite sample performances, including their prediction accuracy. We analyze the Korea HIV/AIDS cohort study data to examine the effects of CD4 (cluster of differentiation 4) cell count on the residual life of HIV patients to the onset of dyslipidemia. RESULTS: The proposed estimator is shown to be consistent and normally distributed asymptotically. Under various simulation settings, our estimates are approximately unbiased. Their variances estimates are close to the empirical variances and their computational efficiency is superior to that of the nonsmooth counterparts. Two measures of prediction performance indicate that our method adequately reflects the dynamic character of longitudinal biomarkers and residual life. The analysis of the Korea HIV/AIDS cohort study data shows that CD4 cell count is positively associated with residual life to the onset of dyslipidemia but the effect is not statistically significant. CONCLUSIONS: Our method enables direct prediction of residual lifetimes with a dynamic feature that accommodates data accumulated at different times. Our estimator significantly improves computational efficiency in variance estimation compared to the existing nonsmooth estimator. Analysis of the HIV/AIDS cohort study data reveals dynamic effects of CD4 cell count on the residual life to the onset of dyslipidemia.

Significance of Decreasing Rate of HIV and HBV Co-infection in a Nationwide Korean HIV/AIDS Cohort.

From December 2006 to December 2016, 1093 human immunodeficiency virus (HIV) individuals < 70 years enrolled in Korea human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) cohort were analyzed to investigate the prevalence of HIV/HBV co-infection rate and hepatitis B virus surface antibody (HBsAb) positive rate based on birth year. The HBV co-infection prevalence rate was the highest (8.8%) in patients born between 1960 and 1964 and the lowest (0%) among those born between 1995 and 1999. A decreasing linear trend of HBV co-infection rate was observed according to the 5-year interval changes. HBsAb-positive rate was only 58.1% in our study. The national HBV vaccination programs have effectively lowered the HBV co-infection rate in HIV population. However, it is identified that the HIV population has low HBsAb positive rate. Further evidences supporting efficacy of booster immunization for HBsAb negative HIV patients are required and efforts should be made to increase HBsAb positive rates among HIV patients to prevent horizontal transmission.

Comparison of HIV characteristics across 3 datasets: the Korea HIV/AIDS Cohort Study prospective, retrospective, and national reporting system.

OBJECTIVES: The Korea HIV/AIDS Cohort Study has been conducted prospectively for 18 years. However, it faces limitations in representing the entire population of patients with human immunodeficiency virus (HIV) in Korea. To address these limitations and validate the study design, we analyzed characteristics across several HIV datasets. METHODS: We compared epidemiological and clinical characteristics from 3 datasets: the Korea HIV/AIDS Cohort Study (dataset 1, n=1,562), retrospective cohort data (dataset 2, n=2,665), and the national HIV reporting system of the Korea Disease Control and Prevention Agency (KDCA) (dataset 3, n=17,403). RESULTS: The demographic characteristics of age, sex, and age at HIV diagnosis did not differ significantly across datasets. However, dataset 3 contained a higher proportion of patients diagnosed after 2008 (69.5%) than the other datasets. Regarding transmission routes, same-sex contact accounted for a greater proportion of dataset 1 (59.8%) compared to datasets 2 (20.9%) and 3 (32.6%). The proportion of patients with CD4 T-cell counts below 200/mm3 at HIV diagnosis was higher in datasets 1 (39.4%) and 2 (33.3%) compared to dataset 3 (16.3%). Initial HIV viral load measurements were not obtained for dataset 3. CONCLUSIONS: The Korea HIV/AIDS Cohort Study demonstrated representativeness regarding the demographic characteristics of Korean patients. Of the sources, dataset 1 contained the most data on transmission routes. While the KDCA data encompassed all HIV patients, it lacked detailed clinical information. To improve the representativeness of the Korea HIV/AIDS Cohort Study, we propose expanding and revising the cohort design and enrolling more patients who have been recently diagnosed.

Association between obesity and cancer risk in adults with HIV in Korea.

INTRODUCTION: This study aimed to investigate the association between obesity and cancer risk as well as site-specific cancer risks in adults with HIV using a nationwide health screening database in Korea. METHODS: Of the 16,671 adults with a new diagnosis of HIV from 2004 to 2020, 456 incident cancer cases and 1814 individually matched controls by sex, year of birth, year of HIV diagnosis, and follow-up duration (1 : 4 ratio) were included in this nested case-control study. The association between obesity (BMI ≥25 kg/m 2 ) and cancer risks was estimated and presented as odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: Of the 456 cancer incident cases, there were 146 AIDS-defining cancer cases and 310 non-AIDS-defining cancer cases. Compared with nonobese adults with HIV, obese adults with HIV were at higher risk of non-AIDS-defining cancer (OR = 1.478, 95% CI = 1.118-1.955). Otherwise, the overall risk of AIDS-defining cancer (OR = 0.816, 95% CI = 0.520-1.279) and each type of AIDS-defining cancer (Kaposi sarcoma and non-Hodgkin's lymphoma) were not high in obese adults with HIV. Of the specific types of non-AIDS-defining cancers, obesity was associated with an increased risk of colorectal cancer (OR = 3.090, 95% CI = 1.110-8.604) and liver, bile duct, and pancreatic cancers (OR = 2.532, 95% CI = 1.141-5.617). CONCLUSION: Obesity, which is one of the important health concerns in HIV management, was associated with an increased risk of non-AIDS-defining cancer but not AIDS-defining cancer.

Chest tomosynthesis deblurring using CNN with deconvolution layer for vertebrae segmentation.

BACKGROUND: Limited scan angles cause severe distortions and artifacts in reconstructed tomosynthesis images when the Feldkamp-Davis-Kress (FDK) algorithm is used for the purpose, which degrades clinical diagnostic performance. These blurring artifacts are fatal in chest tomosynthesis images because precise vertebrae segmentation is crucial for various diagnostic analyses, such as early diagnosis, surgical planning, and injury detection. Moreover, because most spinal pathologies are related to vertebral conditions, the development of methods for accurate and objective vertebrae segmentation in medical images is an important and challenging research area. PURPOSE: The existing point-spread-function-(PSF)-based deblurring methods use the same PSF in all sub-volumes without considering the spatially varying property of tomosynthesis images. This increases the PSF estimation error, thus further degrading the deblurring performance. However, the proposed method estimates the PSF more accurately by using sub-CNNs that contain a deconvolution layer for each sub-system, which improves the deblurring performance. METHODS: To minimize the effect of the spatially varying property, the proposed deblurring network architecture comprises four modules: (1) block division module, (2) partial PSF module, (3) deblurring block module, and (4) assembling block module. We compared the proposed DL-based method with the FDK algorithm, total-variation iterative reconstruction with GP-BB (TV-IR), 3D U-Net, FBPConvNet, and two-phase deblurring method. To investigate the deblurring performance of the proposed method, we evaluated its vertebrae segmentation performance by comparing the pixel accuracy (PA), intersection-over-union (IoU), and F-score values of reference images to those of the deblurred images. Also, pixel-based evaluations of the reference and deblurred images were performed by comparing their root mean squared error (RMSE) and visual information fidelity (VIF) values. In addition, 2D analysis of the deblurred images were performed by artifact spread function (ASF) and full width half maximum (FWHM) of the ASF curve. RESULTS: The proposed method was able to recover the original structure significantly, thereby further improving the image quality. The proposed method yielded the best deblurring performance in terms of vertebrae segmentation and similarity. The IoU, F-score, and VIF values of the chest tomosynthesis images reconstructed using the proposed SV method were 53.5%, 28.7%, and 63.2% higher, respectively, than those of the images reconstructed using the FDK method, and the RMSE value was 80.3% lower. These quantitative results indicate that the proposed method can effectively restore both the vertebrae and the surrounding soft tissue. CONCLUSIONS: We proposed a chest tomosynthesis deblurring technique for vertebrae segmentation by considering the spatially varying property of tomosynthesis systems. The results of quantitative evaluations indicated that the vertebrae segmentation performance of the proposed method was better than those of the existing deblurring methods.

Rate of and Risk Factors for Loss to Follow Up in HIV-Infected Patients in Korea: The Korea HIV/AIDS Cohort Study.

BACKGROUND: Owing to antiretroviral therapy (ART), acquired immune deficiency syndrome (AIDS)-related mortality has significantly decreased. Retaining in care is an essential step for human immunodeficiency virus (HIV) care cascade. This study investigated the incidence of and risk factors for loss to follow-up (LTFU) in Korean people living with HIV (PLWH). MATERIALS AND METHODS: Data from the Korea HIV/AIDS cohort study (including prospective interval cohort and retrospective clinical cohort) were analyzed. LTFU was defined as not visiting the clinic for more than 1 year. Risk factors for LTFU were identified using the Cox regression hazard model. RESULTS: The study enrolled 3,172 adult HIV patients (median age, 36 years; male 92.97%). The median CD4 T cell count at enrollment was 234 cells/mm3 (interquartile range [IQR]: 85 - 373) and the median viral load at enrollment was 56,100 copies/mL (IQR: 15,000 - 203,992). The total follow-up duration was 16,487 person-years, and the overall incidence rate of LTFU was 85/1,000 person-years. In the multivariable Cox regression model, subjects on ART were less likely to have LTFU than subjects not on ART (hazard ratio [HR] = 0.253, 95% confidence interval [CI]: 0.220 - 0.291, P <0.0001). Among PLWH on ART, female sex (HR = 0.752, 95% CI: 0.582 - 0.971, P = 0.0291) and older age (>50: HR = 0.732, 95% CI: 0.602 - 0.890; 41 - 50: HR = 0.634, 95% CI: 0.530 - 0.750; 31 - 40: HR = 0.724, 95% CI: 0.618 - 0.847; ≤30: reference, P <0.0001) were associated with high rate of retention in care. The viral load at ART initiation ≥1,000,001 (HR = 1.545, 95% CI: 1.126 - 2.121, ≤10,000: reference) was associated with a higher rate of LTFU. CONCLUSION: Young and male PLWH may have a higher rate of LTFU, and an increased rate of LTFU may induce virologic failure.

Assessment of Disease Burden and Immunization Rates for Vaccine-Preventable Diseases in People Living with HIV: The Korea HIV/AIDS Cohort Study.

BACKGROUND: Prophylactic immunization is important for human immunodeficiency virus (HIV)-infected patients; however, there are insufficient data on the burden of vaccine-preventable diseases (VPDs), vaccination rates, and factors influencing vaccination. MATERIALS AND METHODS: The incidence and prevalence of VPDs in HIV-infected patients between 2006 and 2017 were estimated using the Korean HIV/acquired immune deficiency syndrome (AIDS) cohort database. In addition, we evaluated the vaccination rates and influencing factors for vaccination in HIV-infected patients through multilevel analysis of clinico-epidemiological factors, immune status, and psychological status. A questionnaire survey was conducted among experts to determine whether they recommend vaccination for HIV-infected patients. RESULTS: The incidence rates of hepatitis B virus (HBV) infection, herpes zoster, and anogenital warts were 1.74, 7.38, and 10.85 per 1,000 person-years, respectively. The prevalence of HBV infection and anogenital warts at enrollment was 4.8% and 8.6%, respectively, which increased to 5.3% and 12.0%, respectively, by 2017. In HIV-infected patients, HBV (21.7% in 2008, 56.3% in 2013, and 75.4% in 2017) and pneumococcal vaccination rates (3.0% in 2015, 7.6% in 2016, and 9.6% in 2017) increased annually, whereas the influenza vaccination rate remained similar by season (32.7 - 35.6%). In the multilevel analysis, peak HIV viral load (≥50 copies/mL: odds ratio [OR] = 0.64, 95% confidence interval [CI]: 0.44 - 0.93; reference, <50 copies/mL) was an influencing factor for pneumococcal vaccination, while nadir CD4 T-cell counts (200 - 350 cells/mm3: OR = 0.54, 95% CI: 0.38 - 0.76; <200 cells/mm3: OR = 0.89, 95% CI: 0.62 - 1.28; reference, ≥350 cells/mm3) was an influencing factor for HBV vaccination. Influenza vaccination was associated with male sex (OR = 1.94) and the number of antiretroviral therapy (ART) regimen change (OR = 1.16), but was not significantly associated with HIV viral load or CD4 T-cell counts. Most experts responded that they administer hepatitis A virus, HBV, pneumococcal, and influenza vaccines routinely, but not human papillomavirus (12.9%) or herpes zoster vaccines (27.1%). CONCLUSION: The burden of vaccine-preventable diseases was quite high in HIV-infected patients. Nadir CD4 T-cell counts, peak HIV viral loads, and the number of ART regimen change are significant factors related to vaccination. Considering the low vaccination rates for VPDs, there was a discordance between experts' opinions and real clinical practice in the medical field.

Effect of characteristics on the clinical course at the initiation of treatment for human immunodeficiency virus infection using dimensionality reduction.

The beginning of human immunodeficiency virus (HIV) infection treatment depends on various factors, which are significantly correlated with the initial CD4 cell number. However, a covariate correlation between these factors may not reflect the correct outcome variable. Thus, we evaluated the effects of a combination of fixed factors (reduced dimensions), which determine when to start treatment for the first time, on short-term outcome, long-term outcome, and survival, considering correlations between factors. Multiple correspondence analysis was performed on variables obtained from 925 patients who participated in a Korean HIV/acquired immunodeficiency syndrome cohort study (2006-2017). Five reduced dimension groups were derived according to clinical data, viral load, CD4 cell count at diagnosis, initial antiretroviral therapy, and others. The dimension group with high initial viral loads (55,000 copies/mL) and low CD4 cell counts (< 200 cells/mm3) should start treatment promptly after diagnosis. Groups with high initial CD4 cell counts (> 350 cells/mm3) that did not require immediate treatment according to previous guidelines had a higher failure rate for long-term relative CD4 recovery. Our results highlight the importance of early diagnosis and treatment to positively influence long-term disease outcomes, even if the initial immune status is poor, given the patient's combination of early diagnostic symptoms.

Two-phase learning-based 3D deblurring method for digital breast tomosynthesis images.

In digital breast tomosynthesis (DBT) systems, projection data are acquired from a limited number of angles. Consequently, the reconstructed images contain severe blurring artifacts that might heavily degrade the DBT image quality and cause difficulties in detecting lesions. In this study, we propose a two-phase learning approach for artifact compensation in a coarse-to-fine manner to mitigate blurring artifacts effectively along all viewing directions of the DBT image volume (i.e., along the axial, coronal, and sagittal planes) to improve the detection performance of lesions. The proposed method employs a convolutional neural network model comprising two submodels/phases, with Phase 1 performing three-dimensional (3D) deblurring and Phase 2 performing additional 2D deblurring. To investigate the effects of loss functions on the proposed model's deblurring performance, we evaluated several loss functions, such as the pixel-based loss function, adversarial-based loss function, and perception-based loss function. Compared with the DBT image, the mean squared error of the image and the root mean squared errors of the gradient of the image decreased by 82.8% and 44.9%, respectively, and the contrast-to-noise ratio increased by 183.4% in the in-focus plane. We verified that the proposed method sequentially restored the missing frequency components as the DBT images were processed through the Phase 1 and Phase 2 steps. These results indicate that the proposed method performs effective 3D deblurring, significantly reducing the blurring artifacts in the in-focus plane and other planes of the DBT image, thus improving the detection performance of lesions.

Comparison of Three Cardiovascular Risk Scores among HIV-Infected Patients in Korea: The Korea HIV/AIDS Cohort Study.

BACKGROUND: We investigated cardiovascular disease (CVD), risk factors for CVD, and applicability of the three known CVD risk equations in the Korean human immunodeficiency virus/ Acquired Immune Deficiency Syndrome (HIV/AIDS) cohort. MATERIALS AND METHODS: The study parcitipants were HIV-infected patients in a Korean HIV/AIDS cohort enrolled from 19 hospitals between 2006 and 2017. Data collected at entry to the cohort were analyzed. The 5-year CVD risk in each participant was calculated using three CVD risk equations: reduced CVD prediction model of HIV-specific data collection on adverse effects of anti-HIV drugs (R-DAD), Framingham general CVD risk score (FRS), and Korean Coronary Heart Disease Risk Score (KRS). RESULTS: CVD events were observed in 11 of 586 HIV-infected patients during a 5-year (median) follow-up period. The incidence of CVD was 4.11 per 1,000 person-years. Older age (64 vs. 41 years, P = 0.005) and diabetes mellitus (45.5% vs. 6.4%, P <0.001) were more frequent in patients with CVD. Using R-DAD, FRS, and KRS, 1.9%, 2.4%, and 0.7% of patients, respectively, were considered to have a very high risk (≥10%) of 5-year CVD. The discriminatory capacities of the three prediction models were good, with c-statistic values of 0.829 (P <0.001) for R-DAD, 0.824 (P <0.001) for FRS, and 0.850 (P = 0.001) for KRS. CONCLUSION: The FRS, R-DAD, and KRS performed well in the Korean HIV/AIDS cohort. A larger cohort and a longer period of follow-up may be necessary to demonstrate the risk factors and develop an independent CVD risk prediction model specific to Korean patients with HIV.

Cancer Incidence Among Adults With HIV in a Population-Based Cohort in Korea.

Importance: In combination with a decreased risk of AIDS-defining cancers and improved survival of people infected with HIV, the burden of non-AIDS-defining cancer has increased markedly. Although a substantial number of studies have measured the cancer risk among people with HIV in developed countries, little research has been conducted on the risk of cancer in HIV-infected people in Asia. Objective: To examine the cancer incidence and the estimated risk of cancer among people in Korea infected with HIV compared with the general population. Design, Setting, and Participants: This retrospective cohort study evaluated patients without cancer newly diagnosed with HIV from January 1, 2006, to December 31, 2018, using a nationwide population-based claims database embedded in the National Health Insurance Service database. Data were analyzed between December 6, 2021, and February 28, 2022. Exposures: Infection with HIV. Main Outcomes and Measures: Cancer incidence and standardized incidence rate (SIR) through indirect standardization. Results: A total of 11 552 individuals without cancer (10 444 male [90.4%]; mean [SD] age, 39.9 [11.2] years) diagnosed with HIV were identified. The SIR for all cancers was 1.68 (95% CI, 1.50-1.87) in men and 1.26 (95% CI, 0.89-1.64) in women. In men, the highest SIRs were for Kaposi sarcoma (SIR, 349.10; 95% CI, 196.10-502.20) and anal cancer (SIR, 104.20; 95% CI, 55.56-149.90). The incidence of non-Hodgkin lymphoma (SIR, 15.62; 95% CI, 11.85-19.39), Hodgkin lymphoma (SIR, 16.67; 95% CI, 4.32-29.02), and oropharyngeal cancer (SIR, 2.97; 95% CI, 1.36-4.58) in men infected with HIV was higher than in the general population. In women infected with HIV, an increased incidence of cervical cancer (SIR, 4.98; 95% CI, 1.29-8.66) and non-Hodgkin lymphoma (SIR, 11.78; 95% CI, 2.35-21.21) compared with the general population was observed. The SIR of thyroid cancer in patients with HIV was lower than in the general population in both men (SIR, 0.63; 95% CI, 0.27-0.99) and women (SIR, 0.48; 95% CI, 0.06-0.90). Conclusions and Relevance: In this cohort study, cancer risks, especially AIDS-defining cancer and virus-related cancer, were elevated in people with HIV. Efforts for cancer prevention, screening, and better accessibility to medical care in HIV-infected people are warranted.

Mortality and Causes of Death among Individuals Diagnosed with Human Immunodeficiency Virus in Korea, 2004-2018: An Analysis of a Nationwide Population-Based Claims Database.

The mortality rate and causes of death among individuals diagnosed with human immunodeficiency virus (HIV) infection in Korea were described and compared to those of the general population of Korea using a nationwide population-based claims database. We included 13,919 individuals aged 20-79 years newly diagnosed with HIV between 2004 and 2018. The patients' vital status and cause of death were linked until 31 December 2019. Standardized mortality ratios (SMRs) for all-cause death and specific causes of death were calculated. By the end of 2019, 1669 (12.0%) of the 13,919 HIV-infected participants had died. The survival probabilities of HIV-infected individuals at 1, 5, 10, and 15 years after diagnosis in Korea were 96.2%, 91.6%, 85.9%, and 79.6%, respectively. The main causes of death during the study period were acquired immunodeficiency syndrome (AIDS; 59.0%), non-AIDS-defining cancer (8.2%), suicide (7.4%), cardiovascular disease (4.9%), and liver disease (2.7%). The mortality rate of men and women infected with HIV was 5.60-fold (95% CI = 5.32-5.89) and 6.18-fold (95% CI = 5.30-7.09) that of men and women in the general population, respectively. After excluding deaths due to HIV, the mortality remained significantly higher, with an SMR of 2.16 (95% CI = 1.99-3.24) in men and 3.77 (95% CI = 3.06-4.48) in women. HIV-infected individuals had a higher overall mortality than the general population, with AIDS the leading cause of mortality. Additionally, mortality due to non-AIDS-related causes was higher in HIV-infected individuals.

Prospective cohort data quality assurance and quality control strategy and method: Korea HIV/AIDS Cohort Study.

OBJECTIVES: The aim of effective data quality control and management is to minimize the impact of errors on study results by identifying and correcting them. This study presents the results of a data quality control system for the Korea HIV/AIDS Cohort Study that took into account the characteristics of the data. METHODS: The HIV/AIDS Cohort Study in Korea conducts repeated measurements every 6 months using an electronic survey administered to voluntarily consenting participants and collects data from 21 hospitals. In total, 5,795 sets of data from 1,442 participants were collected from the first investigation in 2006 to 2016. The data refining results of 2015 and 2019 were converted into the data refining rate and compared. RESULTS: The quality control system involved 3 steps at different points in the process, and each step contributed to data quality management and results. By improving data quality control in the pre-phase and the data collection phase, the estimated error value in 2019 was 1,803, reflecting a 53.9% reduction from 2015. Due to improvements in the stage after data collection, the data refining rate was 92.7% in 2019, a 24.21%p increase from 2015. CONCLUSIONS: Despite this quality management strategy, errors may still exist at each stage. Logically possible errors for the post-review refining of downloaded data should be actively identified with appropriate consideration of the purpose and epidemiological characteristics of the study data. To improve data quality and reliability, data management strategies should be systematically implemented.

Survival Trend of HIV/AIDS Patients Starting Antiretroviral Therapy in South Korea between 2001 and 2015.

PURPOSE: In the recent antiretroviral therapy (ART) era, a large proportion of Korean patients with human immunodeficiency virus (HIV) infection were shown to have low CD4 cell counts at diagnosis and during ART initiation. We investigated the survival trends in patients living with HIV/acquired immunodeficiency syndrome (AIDS) in Korea who started ART in the 2000s, and evaluated the risk factors for mortality to elucidate the association between survival and low CD4 cell counts at ART initiation. MATERIALS AND METHODS: Patients with HIV infection who were aged >18 years and had started ART between 2001 and 2015 in the Korean HIV/AIDS cohort study were enrolled. We compared the clinical characteristics, mortality, and causes of death among the enrolled subjects based on the time of ART initiation. Cox regression analysis was used to estimate the adjusted hazard ratios of mortality based on the time of ART initiation. RESULTS: Among the 2474 patients enrolled, 105 (4.24%) died during the follow-up period of 9568 patient-years. Although CD4 cell counts at the time of ART initiation significantly increased from 161 [interquartile range (IQR), 73.5-303] in 2001-2003 to 273 (IQR, 108-399) in 2013-2015 (p<0.001), they remained low during the study period. The incidence of all-cause mortality was 10.97 per 1000 patient-years during the study period. There was no decreasing trend in mortality between 2001 and 2015. Age >40 years [adjusted hazard ratio, 3.71; 95% confidence interval (CI), 2.35-5.84] and low CD4 counts (<100 cells/mm³: adjusted hazard ratio, 2.99; 95% CI, 1.44-6.23) were significant risk factors for mortality. CONCLUSION: Despite excellent HIV care available in the recent ART era, the survival of patients with HIV/AIDS undergoing ART did not improve between 2001 and 2015 in Korea.

Comparison of Characteristics and Survival between Prospective and Retrospective Korea Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome Cohort Studies.

By comparing the data of prospectively and retrospectively enrolled cohorts, we evaluated whether the prospective cohort represented all patients in the retrospective cohort. The prospectively enrolled subjects were older and had lower CD4+ T cell counts, higher viral load. In addition, the initial antiretroviral treatment regimen of the prospective cohort consisted of less integrase strand transfer inhibitor-containing regimens. The 20-year survival rate was 51.8% in the prospective cohort and 84.6% in the retrospective cohort, respectively (P = 0.844). This study suggests the prospective cohort study may not represent all patients.

Epidemiological characteristics of HIV infected Korean: Korea HIV/AIDS Cohort Study.

OBJECTIVES: To manage evidence-based diseases, it is important to identify the characteristics of patients in each country. METHODS: The Korea HIV/AIDS Cohort Study seeks to identify the epidemiological characteristics of 1,442 Korean individuals with human immunodeficiency virus (HIV) infection (12% of Korean individuals with HIV infection in 2017) who visited 21 university hospitals nationwide. The descriptive statistics were presented using the Korea HIV/AIDS cohort data (2006-2016). RESULTS: Men accounted for 93.3% of the total number of respondents, and approximately 55.8% of respondents reported having an acute infection symptom. According to the transmission route, infection caused by sexual contact accounted for 94.4%, of which 60.4% were caused by sexual contact with the same sex or both males and females. Participants repeatedly answered the survey to decrease depression and anxiety scores. Of the total participants, 89.1% received antiretroviral therapy (ART). In the initial ART, 95.3% of patients were treated based on the recommendation. The median CD4 T-cell count at the time of diagnosis was 229.5 and improved to 331 after the initial ART. Of the patients, 16.6% and 9.4% had tuberculosis and syphilis, respectively, and 26.7% had pneumocystis pneumonia. In the medical history, sexually transmitted infectious diseases showed the highest prevalence, followed by endocrine diseases. The main reasons for termination were loss to follow-up (29.9%) and withdrawal of consent (18.7%). CONCLUSIONS: Early diagnosis and ART should be performed at an appropriate time to prevent the development of new infection.

Correction of severe beam-hardening artifacts via a high-order linearization function using a prior-image-based parameter selection method.

PURPOSE: Polychromatic x-rays are used in most computed tomography scanners. In this case, a beam-hardening effect occurs, which degrades the image quality and distorts the shapes of objects in the reconstructed images. When the beam-hardening artifact is not severe, conventional correction methods can reduce the artifact reasonably well. However, highly dense materials, such as iron and titanium, can produce more severe beam-hardening artifacts, which often cannot be corrected by conventional methods. Moreover, when the size of the metal is large, severe darks bands due to photon starvation as well as beam-hardening are generated. The purpose of our study was to develop a new method for correcting severe beam-hardening artifacts and severe dark bands using a high-order polynomial correction function and a prior-image-based linearization method. METHODS: The initial estimate of an image free of beam-hardening (a prior image) was constructed from the initial reconstruction of the original projection data. Its corresponding beam-hardening-free projection data (a prior projection) were calculated by a projection operator onto the prior image. A new beam-hardening correction function G(praw ) with many high-order terms was effectively determined via a simple minimization process applied to the difference between the original projection data and the prior projection data. Using the determined correction function G(praw ), a corrected linearized sinogram pcorr can be obtained, which became effectively linear for the line integrals of the object. Final beam-hardening corrected images can be reconstructed from the linearized sinogram. The proposed method was evaluated in both simulation and real experimental studies. RESULTS: All investigated cases in both simulations and real experiments showed that the proposed method effectively removed not only streaks for moderate beam-hardening artifacts but also dark bands for severe beam-hardening artifacts without causing structural and contrast distortion. CONCLUSIONS: The prior-image-based linearization method exhibited better correction performance than conventional methods. Because the proposed method did not require time-consuming iterative reconstruction processes to obtain the optimal correction function, it can expedite the correction procedure and incorporate more high-order terms in the linearization correction function in comparison to the conventional methods.

Korea HIV/AIDS Cohort Study: study design and baseline characteristics.

The number of persons infected by HIV/AIDS has consistently increased in Korea since the first case of HIV/AIDS infection in 1985 and reached 15,208 by 2016. About 1,100 new patients with HIV/ AIDS infections have emerged every year since 2013. In Korea, the Korea HIV/AIDS Cohort Study was established for the evidenced-based prevention, treatment, and effective management of patients infected with human immunodeficiency virus (HIV) in December 2006. This study monitored 1,438 patients, who accounted for about 10% of all patients with HIV/AIDS in Korea, for 10 years with the following aims: (1) to develop an administrative system for the establishment of a HIV/AIDS cohort-based study; (2) to standardize methodologies and the case report forms; and (3) to standardize multi-cohort data and develop a data cleaning method. This study aims to monitor at least 1,000 patients (excluding those for whom investigation had been completed) per year (estimated number of patients who can be monitored by January 2018: 939). By December 2016, the sex distribution was 93.3% for men, and 6.7% for women (gender ratio, 13.9:1.0), and 98.9% of all participants were Korean. More than 50.0% of the participants were confirmed as HIV positive after 2006. This study reports competitive, long-term research that aimed to develop policies for the prevention of chronic infectious diseases for patients with HIV. The data collected over the last decade will be used to develop indices for HIV treatment and health promotion.

Patterned transparent electrode with a continuous distribution of silver nanowires produced by an etching-free patterning method.

The outstanding electrical, optical, and mechanical properties of silver nanowire transparent electrodes are attractive for use in many optoelectronic devices, and the recent developments related to these electrodes have led to their commercialization. To more fully utilize the advantages of this technology, developing new process technologies in addition to performance improvements is important. In this report, we propose a novel ultra-simple patterning technology to generate a silver nanowire transparent layer and a unique patterned structure with continuously distributed silver nanowires without any etched areas. The patterning is conducted by exposure to ultraviolet light and rinsing. The exposed and unexposed regions of the resulting layer have dramatically different electrical conductivities, which produces an electrical pathway without using any etching or lift-off processes. The unique patterned structure produced by this etching-free method creates hardly any optical difference between the two regions and results in excellent visibility of the patterned transparent electrode layer.

Causes of HIV Drug Non-Adherence in Korea: Korea HIV/AIDS Cohort Study, 2006-2015.

We aimed to determine the initial adherence of HIV cohort patients to ART (antiretroviral therapy), and reasons for non-adherence. Patients who received ART at the time of enrollment in the Korea HIV/AIDS Cohort were included in this study. Treatment adherence was determined at the baseline interview by self-reported questionnaire. Eight-hundred thirty two HIV-infected patients received ART. Of these, 253 (30.4%) patients skipped ART more than once a month. The most common reason of skipping medication was "simply forgot" (60.4%).