Gestational Exposure to Maternal Systemic Glucocorticoids and Childhood Risk of CKD.

RATIONALE & OBJECTIVE: The potential effects of antenatal glucocorticoid exposure on the health of children are unclear. We examined the association of gestational exposure to maternal systemic glucocorticoids and the risk of developing chronic kidney disease (CKD) in childhood. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Newborns cared for at the largest health care delivery system in Taiwan between 2004 and 2018. EXPOSURE: Maternal prescriptions for systemic glucocorticoids between the last menstrual period and birth as a proxy for gestational exposure. OUTCOME: Incidence of childhood CKD, including congenital anomalies of the kidney and urinary tract (CAKUT) and other kidney diseases (non-CAKUT), over 10 years. ANALYTICAL APPROACH: Cox proportional hazards models with stabilized inverse probability of treatment weighting and robust sandwich estimator were used to estimate the average association between systemic glucocorticoids and incident CKD after adjustment for offspring characteristics (adjusted HR: AHR). RESULTS: Among 23,363 singleton-born children, gestational systemic glucocorticoid exposure was significantly associated with a higher risk of childhood CKD (AHR, 1.69 [95% CI, 1.01-2.84]). Stratified analyses showed stronger associations between systemic glucocorticoids and childhood CKD within the strata of birth<37 weeks' gestational age (AHR, 2.38 [95% CI, 1.19-4.78]), male sex (AHR, 1.89 [95% CI, 1.00-3.55]), gestational exposure in the second trimester (AHR, 6.70 [95% CI, 2.17-20.64]), and total dose of>24mg hydrocortisone equivalent (AHR, 1.91 [95% CI, 1.05-3.47]). LIMITATIONS: Study was limited to the Taiwan health care delivery system and childhood CKD events through the age of 10 years. CONCLUSIONS: The findings of this study suggest that gestational exposure to systemic glucocorticoids is associated with the occurrence of kidney disease in childhood. If these findings are confirmed, they may inform clinicians who are considering prescribing systemic glucocorticoids during pregnancy. PLAIN-LANGUAGE SUMMARY: In a singleton-born cohort of neonates, maternal exposure to antenatal systemic glucocorticoids was significantly associated with a 1.7-fold increased risk of the children developing chronic kidney disease over the first 10 years of life. Children of mothers who received>24mg of hydrocortisone equivalent, systemic glucocorticoid treatment in second trimester of gestation, and children born at<37 weeks of gestational age had a higher risk of childhood kidney disease after gestational systemic glucocorticoid exposure. If these findings are confirmed, they may inform clinicians who are considering prescribing systemic glucocorticoids during pregnancy.

Guideline-Adherent Hypertension in Children and Adolescents: A Multi-Institutional Database Analysis from Taiwan.

BACKGROUND/AIMS: Childhood-onset hypertension is associated with cardiovascular morbidity and adult mortality. This study aimed to assess guideline-adherent hypertension among Taiwanese youth and the agreement on hypertension between the 2017 American Academy of Pediatrics guidelines and the 2004 Fourth Report. METHODS: In this cross-sectional study, we collected outpatient blood pressure (OBP) measurements obtained during routine care visits from a large healthcare delivery system between 2009 and 2018 to evaluate the rate of guideline-adherent hypertension and assess patient-related factors of pediatric hypertension. RESULTS: In total, 12,469 children and adolescents who underwent three separate ≥3 OBP measurements over 33,369 person-years with a total of 95,608 BP measurements in an outpatient setting were analyzed. According to the 2017 American Academy of Pediatrics (AAP) guidelines, the rate of pediatric hypertension in the study setting, which included participants aged 1 to 17 years, ranged from 0.78 to 5.95 per 1000 persons. Although there was perfect agreement between the thresholds of the two guidelines for defining hypertension in the age groups of 1-7, 8-12, and 13-17 years (all κ statistic ≥ 0.85), the use of the AAP threshold classified more adolescents as having hypertension. Children and adolescents with hypertension often had complex chronic diseases and required substantial healthcare services in outpatient, emergency, and inpatient settings. CONCLUSIONS: The present study provides evidence of guideline-adherent pediatric hypertension and highlights the importance of regularly monitoring blood pressure to identify and manage hypertension in children and adolescents. Further research is required to determine the impact of new thresholds on the detection of target organ damage at a pediatric age.

Cardiovascular diseases morbidity and mortality among children, adolescents and young adults with dialysis therapy.

Background: The age-specific burden of cardiovascular disease (CVD) and mortality in pediatric and young adult patients with end-stage kidney disease (ESKD) remains unclear. We aimed to examine the prevalence and incidence of CVD and all-cause mortality in children and adolescents compared with adults with dialysis in Taiwan. Methods: This retrospective observational cohort study comprised 3,910 patients with more than 2 time point receipts of dialysis therapy in a year, including 156 aged <12 years (children), 250 aged 13-20 years (adolescents), 1,036 aged 21-30 years (young adults) and 2,468 aged 31-40 years (adults) in a large healthcare delivery system in Taiwan (2003-2017). Age groups were classified by the date of first receipt of dialysis therapy. The outcomes include the composite of CVD events and any cause of death. Death-censored Cox proportional hazard models were used to evaluate the composite outcome risk of CVD in the four age groups. Results: Among patients receiving dialysis treatment, the risk of composite CVD events [HR, 1.63 (1.22-2.19)] and mortality [HR, 1.76 (1.38-2.25)] was greater in children than the dialysis initiated in older patients. Non-atherosclerotic CVD was more prevalent, especially in younger patients, within the first 6 months after the initiation of dialysis. After 6 months of initial dialysis, the risk of atherosclerotic CVD was higher in adults than those for adolescents and children. The magnitude of CVD risk in adolescents who initiated dialysis therapy was higher in females [HR, 2.08 (1.50-2.88)] than in males [HR, 0.75 (0.52-1.10)]. Conclusion: Younger patients undergoing chronic dialysis with a higher risk of CVD events than older patients are associated with a faster onset of non-atherosclerotic CVD and a higher risk of both CVD- and non-CVD-related mortality.

Differences in health-related quality of life in children with chronic kidney disease as reported by children and parent proxies.

BACKGROUND: Correlation between reports of children and parent for health-related quality of life (HRQOL) is not well studied. This study aims to assess the degree of agreement between child self- and parent proxy-rated HRQOL and to identify factors associated with discordance at baseline and during follow-up in Taiwanese children with chronic kidney disease (CKD). METHODS: This study includes pediatric patients aged 5-18 years with confirmed CKD. Participants completed the generic version of the Pediatric Quality of Life Inventory (PedsQL) at baseline and every 6 months during follow-up. Child-parent agreement on HRQOL reports was assessed using intraclass correlation coefficient (ICC). Multivariate regression models were used to determine factors associated with child-parent discordance. RESULTS: Of the 112 child-parent dyads included in the analysis, 97 dyads with 640 patient visits were assessed in 4.5 years. Children reported higher total scores on the physical and psychosocial domains as compared to their parent proxies. ICC was low (< 0.5) for the psychosocial domain and moderate for the physical health domain at initial assessment and slightly increased for the physical health (0.62) and for school functioning (0.51) during follow-up. Development of mineral bone disorder/anemia (ß, 11.75 [3.77-19.72]) and proteinuria (ß, 8.48 [1.15-15.81]) in the follow-up were associated with increased discordance in school functioning, and fathers with chronic disease were associated with increased discordance in social functioning (ß, 4.21 [0.68-7.74]). CONCLUSIONS: Parent proxy consistently estimated lower PedsQL score compared to self-reports of children. Child self-rated psychosocial health domains should be evaluated whenever possible to better elucidate treatment outcome over time. A higher resolution version of the Graphical abstract is available as Supplementary information.

Kidney Function Trajectory within Six Months after Acute Kidney Injury Inpatient Care and Subsequent Adverse Kidney Outcomes: A Retrospective Cohort Study.

Timing and extent of kidney function recovery after an acute kidney injury (AKI) episode are associated with chronic kidney disease onset and progression. This study aimed to categorize AKI recovery patterns within 6 months after index hospital discharge and associate them with kidney outcomes. This was a retrospective cohort study of 234,867 patients, hospitalized between 2010 and 2017, and classified as AKI or no AKI. Kidney function recovery from pre-hospitalization baseline within 1.5× serum creatinine (SCr) were evaluated at 3 and 6 months after hospital discharge and categorized as persistent non-recovery (PNR: SCr not recovered at 3 and 6 months), non-recovery (NR: SCr not recovered at 6 months), and recovery (SCr recovered at 6 months). A composite of incident chronic kidney disease, kidney replacement therapy, and estimated glomerular filtration rate reduction >30% from baseline and <15 mL/min/1.73 m2 was evaluated. Of 14,673 AKI surviving patients, 10.18% had PNR and 14.33% showed NR. Compared with no AKI, PNR and NR of AKI were associated with an increased risk of composite adverse outcomes (adjusted subdistribution hazard ratio (SHR) 4.55; 95% CI, 4.05−5.11; SHR, 3.54; 95% CI, 3.18−3.94, respectively). Patients with NR showed a greater risk of adverse outcomes than those with non-rapid recovery at 3 months after hospital discharge. The AKI recovery pattern within 6 months following inpatient care revealed an increasing continuum of risk of long-term adverse kidney outcomes. Risk stratification and a kidney function monitoring plan at discharge are needed to improve post-AKI care.

Trajectory of low-density lipoprotein cholesterol in patients with chronic kidney disease and its association with cardiovascular disease.

Background: The role of longitudinal temporal trends in LDL-C in cardiovascular disease (CVD) in patients with chronic kidney disease (CKD) and diabetes is unclear. This study categorized the long-term LDL-C trajectory and determined its association with the incidence of atherosclerotic CVD in patients with CKD according to diabetes status and estimated glomerular filtration rate (eGFR). Methods: The risk of atherosclerotic CVD was estimated in 137,127 Taiwanese patients with CKD using six LDL-C trajectory classes determined by the latent class mixed model as optimal, near optimal, above optimal, borderline, sustained high, and declined high over 5 years. Results: The risk of CVD was higher in the sustained high LDL-C [>160 mg/dL over time; adjusted hazard ratio (aHR) = 1.68, 95% CI = 1.45-1.94], declined high LDL-C (>160 to <100 mg/dL; aHR = 1.23, 95% CI = 1.11-1.38), and borderline LDL-C (approximately 140 mg/dL over time; aHR = 1.16, 95% CI = 1.07-1.26) groups than in the optimal LDL-C group (<100 mg/dL over time). There was no such association in patients with an eGFR <15 mL/min/1.73 m2. Persistent diabetes was associated with a 1.15-2.47-fold increase in CVD in patients with high LDL-C (>120 mg/dL). Conclusion: The LDL-C trajectory pattern was associated with the phenotype of CVD risk. The degree of risk varied according to eGFR and diabetes status. A stable low LDL-C over time was potentially beneficial for prevention of CVD. Intensive lipid management and periodic assessment of LDL-C is essential to reduce the risk of CVD in patients with CKD and diabetes.

Continuity and Completeness of Electronic Health Record Data for Patients Treated With Oral Hypoglycemic Agents: Findings From Healthcare Delivery Systems in Taiwan.

Objective: To evaluate the continuity and completeness of electronic health record (EHR) data, and the concordance of select clinical outcomes and baseline comorbidities between EHR and linked claims data, from three healthcare delivery systems in Taiwan. Methods: We identified oral hypoglycemic agent (OHA) users from the Integrated Medical Database of National Taiwan University Hospital (NTUH-iMD), which was linked to the National Health Insurance Research Database (NHIRD), from June 2011 to December 2016. A secondary evaluation involved two additional EHR databases. We created consecutive 90-day periods before and after the first recorded OHA prescription and defined patients as having continuous EHR data if there was at least one encounter or prescription in a 90-day interval. EHR data completeness was measured by dividing the number of encounters in the NTUH-iMD by the number of encounters in the NHIRD. We assessed the concordance between EHR and claims data on three clinical outcomes (cardiovascular events, nephropathy-related events, and heart failure admission). We used individual comorbidities that comprised the Charlson comorbidity index to examine the concordance of select baseline comorbidities between EHRs and claims. Results: We identified 39,268 OHA users in the NTUH-iMD. Thirty-one percent (n = 12,296) of these users contributed to the analysis that examined data continuity during the 6-month baseline and 24-month follow-up period; 31% (n = 3,845) of the 12,296 users had continuous data during this 30-month period and EHR data completeness was 52%. The concordance of major cardiovascular events, nephropathy-related events, and heart failure admission was moderate, with the NTU-iMD capturing 49-55% of the outcome events recorded in the NHIRD. The concordance of comorbidities was considerably different between the NTUH-iMD and NHIRD, with an absolute standardized difference >0.1 for most comorbidities examined. Across the three EHR databases studied, 29-55% of the OHA users had continuous records during the 6-month baseline and 24-month follow-up period. Conclusion: EHR data continuity and data completeness may be suboptimal. A thorough evaluation of data continuity and completeness is recommended before conducting clinical and translational research using EHR data in Taiwan.

Changing trends in dialysis modalities utilization and mortality in children, adolescents and young adults with acute kidney injury, 2010-2017.

The aim of the study was to assess trends in the relative use of dialysis modalities in the hospital-based pediatric cohort and to determine risk factors associated with in-hospital morality among pediatric patients receiving dialysis for acute kidney injury (AKI). Patients aged < 20 years who received dialysis between 2010 and 2017 were identified from electronic health records databases of a Taiwan's healthcare delivery system. The annual uses of intermittent hemodialysis (HD), continuous and automated peritoneal dialysis (PD) and continuous kidney replacement therapy (CKRT) were assessed using Cochran-Armitage Tests for trend. Among patients who received their first dialysis as inpatients for AKI, a multivariate logistic regression model was employed to assess mortality risks associated with dialysis modalities, patient demographics, complexity of baseline chronic disease, and healthcare service use during their hospital stays. Kidney dialysis was performed 37.9 per patient per year over the study period. Intermittent hemodialysis (HD) (73.3%) was the most frequently used dialysis modality. In the inpatient setting, the relative annual use of CKRT increased over the study period, while HD use concomitantly declined (P < 0.0001). The overall in-hospital mortality rate after dialysis for AKI was 33.6%, which remained steady over time (P = 0.2411). Patients aged < 2 years [adjusted odds ratio: (aOR) 3.36; 95% confidence interval (CI) 1.34-8.93] and greater vasoactive regimen use (aOR: 17.1; 95% CI: 5.3-55.21) were significantly associated with dialysis-related mortality. Overall treatment modality used for dialysis in pediatric patients increased slowly in the study period, and HD and CRKT modality uses largely evolved in the inpatient setting. Younger ages and use of more vasoactive medication regimens were independently associated with increased early mortality in patients on AKI-dialysis.

Trends in Antimicrobial Susceptibility of Escherichia coli Isolates in a Taiwanese Child Cohort with Urinary Tract Infections between 2004 and 2018.

The aim of this study was to investigate the annual incidence of Escherichia coli isolates in urinary tract infections (UTIs) and the antimicrobial resistance of the third-generation cephalosporin (3GCs) to E. coli, including the factors associated with the resistance in hospitalized children in Taiwan. A large electronic database of medical records combining hospital admission and microbiological data during 2004-2018 was used to study childhood UTIs in Taiwan. Annual incidence rate ratios (IRR) of E. coli in children with UTIs and its resistant rate to the 3GCs and other antibiotics were estimated by linear Poisson regression. Factors associated with E. coli resistance to 3GCs were assessed through multivariable logistic regression analysis. E. coli UTIs occurred in 10,756 unique individuals among 41,879 hospitalized children, with 92.58% being community associated based on urine culture results reported within four days after the hospitalization. The overall IRR E. coli UTI was 1.01 (95% confidence interval (CI) 0.99-1.02) in community-associated (CA) and 0.96 (0.90-1.02) in healthcare-associated infections. The trend in 3GCs against E. coli increased (IRR 1.18, 95% CI 1.13-1.24) over time in CA-UTIs. Complex chronic disease (adjusted odds ratio (aOR), 2.04; 95% CI, 1.47-2.83) and antibiotics therapy ≤ 3 months prior (aOR, 1.49; 95% CI, 1.15-1.94) were associated with increased risk of 3GCs resistance to E. coli. The study results suggested little or no change in the trend of E. coli UTIs in Taiwanese youths over the past 15 years. Nevertheless, the increase in 3GCs-resistant E. coli was substantial. Interventions for children with complex chronic comorbidities and prior antibiotic treatment could be effective in reducing the incidence of 3GCs-resistant E. coli in CA-UTIs in this region and more generally.

The association between denture self-satisfaction rates and OHRQoL - a follow-up study.

BACKGROUD: The objectives of this study were to try to identify the key dimension in satisfaction from the combination of satisfaction clusters, and its effect on the change of OHRQoL(Oral Health-related Quality of Life) of elderly denture users. METHODS: This follow-up study was conducted in subjects aged 65 years and over. All participants (n = 2128) completed questionnaires before and approximately 6 months after receiving complete denture. Information obtained by questionnaire included demographic characteristics, patients' self-satisfaction rate and OHRQoL. The 6 satisfaction dimensions (including speaking, stability, esthetic, chewing, doctor and general dimensions) were classified as 5 cluster groups, which is the group of not at all satisfied in all dimensions (NAS); only satisfied with doctor and general dimensions(SDG); moderate satisfaction group(MS); quite satisfied group(QS); the highly satisfied group(HS) by an analysis of PCA (Principle component analysis) and CA (cluster analysis). Multiple linear regression was adapted to estimate the association between satisfaction and the responsiveness of OHIP-7T (Oral Health Impact Profile). RESULTS: When compared to the cluster "NAS", the greatest improvement of OHRQoL after treatment was found in the group "HS" (ß = 7.31(6.26-8.36), followed by group "QS" (ß = 4.71(3.54-5.87)), group "MS" (ß = 4.33(2.92-5.74)) and group "SDG" (ß = 3.25(2.10-4.41)). An increasing trend was detected in patient-rating satisfaction and OHRQoL. The satisfaction cluster group is an important factor of OHRQoL after adjusting for other confounders. CONCLUSION: Psychological-related aspects is the greatest impacting dimension on OHRQoL among denture wearers in Taiwan elderly. Better communication from the dental professional team with denture patients would improve their OHRQoL.

Continuity of care and multiple chronic conditions impact frequent use of outpatient services.

This study investigated the association between care continuity and chronic conditions in relation to highly frequent use of outpatient service in order to find constructive suggestions to bring efficient, high-quality care for patients with multiple chronic conditions. The National Health Insurance database was used and 333,294 patients were identified from 2007 to 2009. The continuity of care index indicates the dispersion of a patient's ambulatory visits among providers. Multivariate logistic regression was used to estimate adjusted odds ratios with 95 percent confidence intervals. Continuity of care index was significantly associated with age, sex, urbanization level, socioeconomic status, emergency department visits, hospitalization, psychological disorders, chronic diseases, and catastrophic illness card; those with low continuity of care index were likely to use outpatient care highly frequently. Improving continuity of care is fundamental, and the best way is to advance the practice of family medicine for primary care.

Assessing a conceptual model with both oral health and health related quality of life in community-dwelling elders.

PURPOSE: The objective of this study was to test a hypothesized conceptual model for both the clinical and non-clinical status of oral health and health related quality of life (OHRQoL & HRQoL) among community-dwelling elders. MATERIALS AND METHODS: Study participants (n = 517), who were recruited as part of a Taiwanese elderly community survey, were collected via dental examinations and questionnaires. We collected measures of clinical variables, self-reported symptom status, OHRQoL, nutritional status and HRQoL. The 517 participants were randomly assigned to one of two samples, to provide one training sample for estimation and one testing sample for validation. The path analysis with all observed variables was conducted based on the proposed theoretical model delineating pathways. RESULTS: All of the direct pathways hypothesized by the model were significant. Functional status (OHRQoL measured by OHIP-14T) mediated clinical occlusion, and symptom status mediated nutritional status (MNA) and HRQoL (WHOQOL-BREF). The model accounted for 29% of the variance in HRQoL and demonstrated a good fit with the data. CONCLUSIONS: This conceptual model suggests that OHRQoL, as an important mediator, links clinical conditions, symptom status, nutritional status, and overall HRQoL. Therefore, when therapeutic efforts are made to improve the outcomes for patients with oral diseases, not only can the OHRQoL be enhanced, but also the HRQoL can be improved as a result.

Incidence, clinical characteristics, and associated diseases in patients with immune thrombocytopenia: A nationwide population-based study in Taiwan.

INTRODUCTION: Immune thrombocytopenia (ITP) is an immune-mediated disease; it has been reported to be associated with several diseases. The data on ITP in patients with hepatitis B, tuberculosis, or thyroid diseases are relatively scarce. In addition, these diseases are not rare in Taiwan, together with hepatitis C and Helicobacter pylori which are also related to ITP. METHODS AND MATERIALS: We identified 1223 ITP patients and characterized these patients between 2000 and 2013 from the National Health Insurance Research Database. The adult ITP patients were matched with non-ITP patients. RESULTS: The overall incidence of ITP was 2.59/100,000 person-years. The frequencies of hepatitis B and C in adult ITP patients were much higher than those indicated in previous studies. The frequencies of non-traumatic intracerebral hemorrhage and gastrointestinal bleeding during hospitalization among ITP patients were low. The diseases associated with increased risks of ITP included hepatitis B (OR = 18.70, 95% CI = 9.71-36.03), hepatitis C (OR = 54.43, 95% CI = 15.94-185.88), hepatitis B and hepatitis C (OR = 7.02, 95% CI = 1.47-33.56), tuberculosis (OR = 5.37, 95% CI = 2.72-10.61), Helicobacter pylori infection (OR = 5.93, 95% CI = 3.16-11.10), hyperthyroidism (OR = 3.43, 95% CI = 2.09-5.64), hypothyroidism (OR = 6.70, 95% CI = 2.35-19.13), and simple and unspecified goiter (OR = 2.68, 95% CI = 1.43-5.03). CONCLUSIONS: Surveying for the diseases which are frequent and related to increased risks of ITP among patients with newly diagnosed ITP should be considered.

Factors pertaining to long-term mortality following emergency visits for head and neck cancer.

BACKGROUND/PURPOSE: Avoiding mortality has been the ultimate goal in the management of head and neck cancer (HNC) patients with emergency department (ED) visits, however, risk factors and causes of mortality are not well studied. The objective of the present study is to verify the factors associated with long-term mortality of patients with HNC who visited ED. MATERIALS AND METHODS: We retrospectively collected data of 1660 HNC patients who made ED visits from the Longitudinal Health Insurance Database 2000 during 2000-2012 in Taiwan. The multivariate Cox proportional hazard model was used to measure the mortality-associated risk factors in HNC patients who made ED visits. RESULTS: The prognostic factors associated with mortality risk were age (≥65 vs. < 65 y; HR = 1.58, p < 0.0001), geographic region (central vs. northern; HR = 1.20, p = 0.0384; southern vs. northern; HR = 1.38, p = 0.0001), surgery (yes vs. no; HR = 0.61, p < 0.0001), radiotherapy (yes vs. no; HR = 1.80, p < 0.0001), chemotherapy (yes vs. no; HR = 1.68, p < 0.0001), acute myocardial infarction (yes vs. no; HR = 2.01, p = 0.0303), diabetes mellitus (yes vs. no; HR = 1.60, p < 0.0001), chronic obstructive pulmonary (yes vs. no; HR = 1.51, p = 0.0002), number of ED visits (≥4 vs. 1; HR = 0.69, p = 0.0003), and number of admissions (1 vs. 0; HR = 1.54, p < 0.0001; ≥2 vs. 0; HR = 1.48, p = 0.0002). CONCLUSION: Higher mortality was associated with older age, living in southern Taiwan, not having undergone surgery, having received radiotherapy and chemotherapy, comorbidities, and more hospital admissions. A coordinated and extended multidisciplinary approach including ED care is required to improve the long-term survival and further decrease the economic burden of HNC treatment.

Periodontal surgery improves oral health-related quality of life in chronic periodontitis patients in Asian population.

The effect of periodontal surgery on patients' quality of life was investigated. Sixty patients received regenerative surgery or resective osseous surgery. Oral health-related quality of life and health-related quality of life instruments were used to assess the participants' quality of life before surgery and 4 weeks after surgery. Periodontal surgery can improve patients' quality of life by alleviating the physical pain and psychological discomfort. The scores were lower (more favorable) in the regenerative surgery group, and the functional limitations of the regenerative surgery group improved substantially compared with those of the resective osseous surgery group (P = 0.0421). The patients' oral health-related quality of life scores improved significantly after periodontal surgery. Clinicians can take advantage of the positive functional oral health-related quality of life impacts of regenerative surgery.

Nuclear Magnetic Resonance Spectroscopy Investigation on Ultralow Melting Temperature Behavior of Dimethyl Sulfoxide-Water Solutions.

On the basis of the molecular understanding that DMSO has a trigonal pyramidal geometry with one highly polarized sulfinyl group and two hydrophobic methyl groups, we used NMR technology to rationalize why DMSO can act as antifreeze for aqueous solutions. A series of DMSO-water, DMSO-methanol, and acetone-water binary solutions with various molar ratios were tested in specified low temperature conditions. The freezing test results indicated that only DMSO-water solutions with the DMSO-water molar ratio (nDMSO) in a specific range can form apparent ultralow freezing temperature solutions. Among all DMSO-water solutions, the apparent freezing temperature lower than -130 °C was obtained for nDMSO values of 0.25, 0.30, and 0.35, respectively. Multinuclear NMR chemical shifts, 1H diffusion experiment results, and viscosity measurements suggested that molecular rearrangement resulted in the formation of the water-core DMSO-shell aggregation unit in DMSO-water solutions. The weak methyl-methyl London dispersion forces among water-core DMSO-shell aggregation units can explain the apparent ultralow freezing temperatures of these DMSO-water solutions.