Air Pollution and Acute Kidney Injury in the U.S. Medicare Population: A Longitudinal Cohort Study.

BACKGROUND: Recent studies have reported the association between air pollution exposure and reduced kidney function. However, it is unclear whether air pollution is associated with an increased risk of acute kidney injury (AKI). OBJECTIVES: To address this gap in knowledge, we investigated the effect estimates of long-term exposures to fine particulate matter [PM ≤2.5µm in aerodynamic diameter (PM2.5)], nitrogen dioxide (NO2), and ozone (O3) on the risk of first hospital admission for AKI using nationwide Medicare data. METHODS: This nationwide population-based longitudinal cohort study included 61,300,754 beneficiaries enrolled in Medicare Part A fee-for-service (FFS) who were ≥65 years of age and resided in the continental United States from the years 2000 through 2016. We applied Cox-equivalent Poisson models to estimate the association between air pollution and first hospital admission for AKI. RESULTS: Exposure to PM2.5, NO2, and O3 was associated with increased risk for first hospital admission for AKI, with hazard ratios (HRs) of 1.17 (95% CI: 1.16, 1.19) for a 5-µg/m3 increase in PM2.5, 1.12 (95% CI: 1.11, 1.13) for a 10-ppb increase in NO2, and 1.03 (95% CI: 1.02, 1.04) for a 10-ppb increase in summer-period O3 (June to September). The associations persisted at annual exposures lower than the current National Ambient Air Quality Standard. DISCUSSION: This study found an association between exposures to air pollution and the risk of the first hospital admission with AKI, and this association persisted even at low concentrations of air pollution. Our findings provide beneficial implications for public health policies and air pollution guidelines to alleviate health care expenditures and the disease burden attributable to AKI. https://doi.org/10.1289/EHP10729.

Associations between greenness and kidney disease in Massachusetts: The US Medicare longitudinal cohort study.

BACKGROUND: Recent studies have identified the association of environmental stressors with reduced kidney function and the development of kidney disease. While residential greenness has been linked to many health benefits, the association between residential greenness and the development of kidney disease is not clear. We aimed to investigate the association between residential greenness and the development of kidney disease. METHODS: We performed a longitudinal population-based cohort study including all fee-for-service Medicare Part A beneficiaries (aged 65 years or older) in Massachusetts (2000-2016). We assessed greenness with the annual average Enhanced Vegetation Index (EVI) based on residential ZIP codes of beneficiaries. We applied Cox-equivalent Poisson models to estimate the association between EVI and first hospital admission for total kidney disease, chronic kidney disease (CKD), and acute kidney injury (AKI), separately. RESULTS: Data for 1,462,949 beneficiaries who resided in a total of 644 ZIP codes were analyzed. The total person-years of follow-up for total kidney disease, CKD, and AKI were 9.8, 10.9, and 10.8 million person-years, respectively. For a 0.1 increase in annual EVI, the hazard ratios (HRs) were 0.95 (95% CI: 0.93 to 0.97) for the first hospital admission for total kidney disease, and the association was more prominent for AKI (HR: 0.94 with 95% CI: 0.92 to 0.97) than CKD (HR: 0.98 with 95% CI: 0.95-1.01]). The estimated effects of EVI on kidney disease were generally more evident in White beneficiaries and those residing in metropolitan areas compared to the overall population. CONCLUSIONS: This study found that higher levels of annual residential greenness were associated with a lower risk of the first hospital admission for kidney diseases. Results are consistent with the hypothesis that higher residential greenness benefits kidney patients.

Economic Impact of Donating a Kidney on Living Donors: A Korean Cohort Study.

RATIONALE & OBJECTIVE: Although existing studies have reported adverse health outcomes after kidney donation, its socioeconomic impact on living donors requires further study. STUDY DESIGN: A retrospective observational cohort study including a matched comparison group. SETTING & PARTICIPANTS: 1,285 living kidney donors from 7 tertiary hospitals between 2003 and 2016, and a matched comparison group consisting of the same number of health screening examinees with similar baseline clinical characteristics and socioeconomic status. All participants were receiving Korean national health insurance. EXPOSURE: Kidney donation as reflected in the Korean National Health Insurance System (NHIS) database. OUTCOME: Changes in household economic status estimated by Korean national health insurance fees and changes in employment status reflected in the NHIS database. ANALYTICAL APPROACH: The outcomes of the donor group and matched control group were compared annually using multivariable logistic regression analyses adjusted for clinical and demographic characteristics. RESULTS: The median ages of the donors and matched controls were 45 and 46 years, respectively; 44.6% of both groups were male. Compared to the comparison group, living donors were at higher risk of being unemployed or losing employment during the first 2 years after donation (eg, first-year loss of employment: odds ratio (OR), 2.27 [95% CI, 1.55-3.33]); however, this association did not persist. Donors also had a significantly lower odds of improvement in economic status (OR, 0.57 [95% CI, 0.47-0.71]) and a higher odds of deterioration in financial status (OR, 1.54 [95% CI, 1.23-1.93]) in the first year after transplantation and subsequently. LIMITATIONS: Unmeasured differences between donors and matched controls creating residual selection bias and confounding. CONCLUSIONS: Living kidney donors may suffer loss of employment and poor economic status after their voluntary donation. The socioeconomic impact on these donors should be considered in conjunction with the potential long-term adverse health outcomes after donation.

Causal linkage between adult height and kidney function: An integrated population-scale observational analysis and Mendelian randomization study.

As adult height is linked to various health outcomes, further investigation of its causal effects on kidney function later in life is warranted. This study involved a cross-sectional observational analysis and summary-level Mendelian randomization (MR) analysis. First, the observational association between height and estimated GFR determined by creatinine (eGFRcreatinine) or cystatin C (eGFRcystatinC) was investigated in 467,182 individuals aged 40-69 using UK Biobank. Second, the genetic instrument for adult height, as reported by the GIANT consortium, was implemented, and summary-level MR of eGFRcreatinine and CKDcreatinine in a CKDGen genome-wide association study was performed (N = 567,460), with multivariable MR being adjusted for the effects of genetic predisposition on body mass index. To replicate the findings, additional two-sample MR using the summary statistics of eGFRcystatinC and CKDcystatinC in UK Biobank was performed (N = 321,405). In observational analysis, adult height was inversely associated with both eGFRcreatinine (per 1 SD, adjusted beta -1.039, standard error 0.129, P < 0.001) and eGFRcystatinC (adjusted beta -1.769, standard error 0.161, P < 0.001) in a multivariable model adjusted for clinicodemographic, anthropometric, metabolic, and social factors. Moreover, multivariable summary-level MR showed that a taller genetically predicted adult height was causally linked to a lower log-eGFRcreatinine (adjusted beta -0.007, standard error 0.001, P < 0.001) and a higher risk of CKDcreatinine (adjusted beta 0.083, standard error 0.019, P < 0.001). Other pleiotropy-robust sensitivity MR analysis results supported the findings. In addition, similar results were obtained by two-sample MR of eGFRcystatinC (adjusted beta -1.303, standard error 0.140, P < 0.001) and CKDcystatinC (adjusted beta 0.153, standard error 0.025, P < 0.001) in UK Biobank. In conclusion, the results of this study suggest that a taller adult height is causally linked to worse kidney function in middle-aged to elderly individuals, independent of the effect of body mass index.

Socioeconomic dependency and kidney transplantation accessibility and outcomes: a nationwide observational cohort study in South Korea.

BACKGROUND: Socioeconomic status is an important determinant for patients' accessibility to, and prognosis of, kidney transplantation. However, the association between socioeconomic dependency and kidney transplantation accessibility or prognosis after kidney transplantation remains unclear. METHODS: In this nationwide cohort study, based on the claims database of South Korea, we included 12,889 kidney transplant recipients from 2007 to 2015 and stratified them according to health insurance categories that reflect socioeconomic dependency: workplace-independent (employed, N = 3257), workplace-dependent (dependent to the workplace-independent, N = 3661), community-representative (heads of the household but self-employed or unemployed, N = 2479), community-member (N = 1618), aided-representative (heads of household receiving medical aid from the government, N = 1580), and aided-member (N = 294). The incidence of kidney transplantation was calculated to evaluate its accessibility. The risk of graft failure was assessed using the Cox regression analysis, adjusted for clinicodemographic variables, including financial status. RESULTS: End-stage kidney disease patients who were employed (workplace-independent group) had the highest incidence proportion of kidney transplantation. The dependent groups' prognoses were worse than those of their independent counterparts [workplace-dependent versus workplace-independent, HR 1.26 (1.11-1.43) and community-dependent versus community-independent, HR 1.46 (1.23-1.74)], although no difference was observed between the aided subgroups [aided-dependent versus aided-independent, adjusted HR 1.16 (0.90-1.50)]. CONCLUSION: Disparities in kidney transplantation accessibility were present in South Korea according to socioeconomic dependency; these differences may have an impact on prognosis.

Disparity in Accessibility to and Prognosis of Kidney Transplantation According to Economic Inequality in South Korea: A Widening Gap After Expansion of Insurance Coverage.

BACKGROUND: Nationwide studies on the effects of wealth inequality on kidney transplantation are rare, particularly in a country with an expanded National Health Insurance Service and in Asian countries. METHODS: In this nationwide, population-based cohort study, we reviewed the national claims database of Korea in which details of nationwide health insurance are provided. From 2007 to 2015, 9 annual cohorts of end-stage renal disease patients were included. The annual financial statuses were collected and stratified into 5 subgroups in each year: the aided group in which insurance fee was waived and the 4 other groups divided by quartiles of their medical insurance fee. Time trends of incidence proportion of kidney transplantation among end-stage renal disease patients in each year were initially assessed. The risk of graft failure, both including death-censored graft failure and death with a functioning graft, was analyzed as a prognostic outcome within the transplant recipients. RESULTS: Significant disparity in the accessibility of kidney transplantation was present, and it was further widening, particularly from 2009 in which the National Health Insurance Service started to cover desensitized kidney transplantation. Desensitized or preemptive transplantation was less common in the poorest group who were more frequently receiving transplantation after 5 years of dialysis in the latter years. The prognosis of kidney transplantation was significantly worse in the poorer people, and this disparity also worsened during the study period. CONCLUSIONS: Prominent disparity regarding accessibility to and prognosis of kidney transplantation was observed in Korea according to wealth inequality, and this disparity was worsening.

Can a semi-quantitative method replace the current quantitative method for the annual screening of microalbuminuria in patients with diabetes? Diagnostic accuracy and cost-saving analysis considering the potential health burden.

OBJECTIVES: Diabetes is a global epidemic, and the high cost of annually and quantitatively measuring urine albumin excretion using the turbidimetric immunoassay is challenging. We aimed to determine whether a semi-quantitative urinary albumin-creatinine ratio test could be used as a screening tool for microalbuminuria in diabetic patients. METHODS: We assessed the diagnostic accuracy of the semi-quantitative method. The costs of false results in the semi-quantitative method were calculated based on the annual probability of disease progression analyzed through a systematic literature review and meta-analysis. The pooled long-term cost-saving effect of the semi-quantitative method compared with the quantitative test was assessed using a Markov model simulating a long-term clinical setting. Diagnostic accuracy and the cost-saving effect were also validated in an independent external cohort. RESULTS: Compared with the quantitative test, the semi-quantitative method had sensitivities of 93.5% and 81.3% and specificities of 61.4% and 63.1% in the overall sample of diabetic patients (n = 1,881) and in diabetic patients with eGFR ≥60 ml/min/1.73 m2 and a negative dipstick test (n = 1,110), respectively. After adjusting for direct and indirect medical costs, including the risk of disease progression, which was adjusted by the meta-analyzed hazard ratio for clinical outcomes, it was determined that using the semi-quantitative method could save 439.4 USD per person for 10 years. Even after adjusting the result to the external validation cohort, 339.6 USD could be saved for one diabetic patient for 10 years. CONCLUSIONS: The semi-quantitative method could be an appropriate screening tool for albuminuria in diabetic patients. Moreover, it can minimize the testing time and inconvenience and significantly reduce national health costs.

Three-year income trends in Korean adults commencing haemodialysis: A prospective cohort.

AIM: This study aimed to explore the trends in individual income and to estimate the change in average monthly income for patients undergoing haemodialysis therapy. METHODS: The main data source was the Clinical Research Center (CRC) for End-Stage Renal Disease in Korea. In addition to the cohort data, a survey was conducted to capture personal income for 3 years. To estimate the change in monthly income over time using repeated measures, a random coefficient model using penalized quasi-likelihood methods based on restricted or residual maximum likelihood estimation was used. RESULTS: During the 3-year study period, 138 subjects aged 20 and over who answered the question about pre-dialysis income were traced and analyzed. The median value of monthly income was $US564.4 in the 1st year, $470.4 in the 2nd year, and $733.8 in the 3rd year, representing a 70%, 75%, and 61% decrease compared to pre-dialysis income ($1881.5), respectively. By using mixed analysis, we found that monthly income change was $1283 (95% CI, -1621.5, -945.1), $1182 USD (95% CI, -1540.8, -823.1), and $1041 (95% CI, -1457.6, -623.6) in the 1st , 2nd , and 3rd year, respectively, compared to pre-dialysis income after controlling for other covariates. Women and less educated patients had a relatively higher reduction of income, despite the low starting point. CONCLUSIONS: The monthly income of dialysis patients reduced substantially over the study period, especially at the time of the first survey. Considering the social security system, haemodialysis patients face significant personal financial burdens due to their ESRD unrelated to the direct costs of dialysis treatment.

Retrospective analysis of the financial break-even point for intrathecal morphine pump use in Korea.

BACKGROUND: The high cost of intrathecal morphine pump (ITMP) implantation may be the main obstacle to its use. Since July 2014, the Korean national health insurance (NHI) program began paying 50% of the ITMP implantation cost in select refractory chronic pain patients. The aims of this study were to investigate the financial break-even point and patients' satisfaction in patients with ITMP treatment after the initiation of the NHI reimbursement. METHODS: We collected data retrospectively or via direct phone calls to patients who underwent ITMP implantation at a single university-based tertiary hospital between July 2014 and May 2016. Pain severity, changes in the morphine equivalent daily dosage (MEDD), any adverse events, and patients' satisfaction were determined. We calculated the financial break-even point of ITMP implantation via investigating the patient's actual medical costs and insurance information. RESULTS: During the studied period, 23 patients received ITMP implantation, and 20 patients were included in our study. Scores on an 11-point numeric rating scale (NRS) for pain were significantly reduced compared to the baseline value (P < 0.001). The MEDD before ITMP implantation was 0.59 [IQR: 0.55-0.82]. The total MEDD increased steadily to 0.77 [IQR: 0.53-1.08] at 1 year, which was 126% of the baseline (P < 0.001). More than a half (60%) responded that the ITMP therapy was somewhat satisfying. The financial break-even point was 28 months for ITMP treatment after the NHI reimbursement policy. CONCLUSIONS: ITMP provided effective chronic pain management with improved satisfaction and reasonable financial break-even point of 28 months with 50% financial coverage by NHI program.

Intrathecal Morphine Infusion Therapy in Management of Chronic Pain: Present and Future Implementation in Korea.

PURPOSE: Intrathecal morphine pump (ITMP) infusion therapy is efficient in managing malignant and nonmalignant chronic pain refractory to standard treatment. However, the high cost of an ITMP is the greatest barrier for starting a patient on ITMP infusion therapy. Using the revised Korean reimbursement guidelines, we investigated the cost effectiveness of ITMP infusion therapy and conducted a patient survey. MATERIALS AND METHODS: A retrospective chart review of 12 patients who underwent ITMP implantation was performed. Morphine dose escalation rates were calculated, and numeric rating scale (NRS) scores were compared before and after ITMP implantation. We surveyed patients who were already using an ITMP as well as those who were candidates for an ITMP. All survey data were collected through in-person interviews over 3 months. Data on the cost of medical treatment were collected and projected over time. RESULTS: The NRS score decreased during the follow-up period. The median morphine dose increased by 36.9% over the first year, and the median time required to reach a financial break-even point was 24.2 months. Patients were more satisfied with the efficacy of ITMP infusion therapy than with conventional therapy. The expected cost of ITMP implantation was KRW 4000000-5000000 in more than half of ITMP candidates scheduled to undergo implantation. CONCLUSION: The high cost of initiating ITMP infusion therapy is challenging; however, the present results may encourage more patients to consider ITMP therapy.

Infrared thermographic imaging in the assessment of successful block on lumbar sympathetic ganglion.

This study examined the net changes in temperature at various regions of the lower extremities in an attempt to identify the regions demonstrating the most significant temperature changes following a lumbar sympathetic ganglion block (LSGB). Thermography was performed before and after the LSGB in 26 sympathetic nerve system disorder cases. The inspection points were the anterior and posterior surfaces of the thigh, the knee and leg, and the dorsal and plantar surfaces of the feet. The net increases in skin temperature following the LSGB (deltaT(net)) at the plantar and dorsal surfaces of the feet, were 6.2 +/- 2.68 degrees C (mean +/- SD) and 3.9 +/- 1.89 degrees C, respectively, which were higher than those observed in the other regions of the lower extremities (p < 0.05). The areas, in order of decreasing deltaT(net), are as follows: the plantar surface of the foot, the dorsal surface of the foot, the shin, the anterior surface of the knee, the calf, the posterior surface of the knee, the anterior surface of the thigh, and the posterior surface of the thigh. There was one case of orthostatic hypotension during the thermography procedure. In conclusion, thermographic imaging is a useful method for demonstrating the success of a LSGB in various diseases. An evaluation of the deltaT(net) on the plantar surface of the feet using thermographic imaging is the most effective, simple, and safe method for assessing a successful LSGB.