Carbon Monoxide Poisoning and Chronic Kidney Disease Risk: A Nationwide, Population-Based Study

Analysis of the association between glomerular filtration rate, proteinuria and metabolic syndrome in chronic kidney patients based on longitudinal data

Chronic kidney disease (CKD) is a group of chronic diseases caused by kidney damage from multiple causes. Metabolic syndrome (MS) manifests as dysfunction of endothelial cells and chronic functional inflammatory states, and may be involved in pathological changes related to renal impairment. Based on longitudinal data analysis of the association between estimated glomerular filtration rate (eGFR), proteinuria and MS in patients with CKD, this study aims to provide new ideas for the pathophysiological mechanism of CKD and a theoretical basis for the early prevention and effective intervention of MS-related kidney damage. A total of 126 patients with CKD were divided into non-MS group and MS group. According to the eGFR level, 126 patients with CKD were divided into G1 group, G2 group, G3a group, G3b group, G4 group and G5 group. Serum markers such as eGFR, urine protein, and triglycerides (TG) were collected. The correlation between eGFR, urine protein and MS-related indexes was analysed, and the risk factors affecting CKD complicated by MS were analysed. In patients with CKD, the levels of urine protein, abdominal circumference, TG, systolic blood pressure (SBP), diastolic blood pressure (DBP), and fasting blood glucose (FPG) were increased with the course of the disease, but the levels of eGFR and high density lipoprotein (HDL-C) were decreased (p < 0.05). Abdominal circumference, TG, SBP, DBP, FP were significantly negatively correlated with eGFR, but HDL-C was positively correlated with eGFR (p < 0.05). Diabetes, hyperlipidemia, UA, and SBP were independent risk factors affecting CKD complicated MS, and eGFR were independent protective factors (p < 0.05). The combination of diabetes, hyperlipidemia, UA, SBP, and eGFR exhibited higher prediction value for the CKD patients complicated by MS. There was a certain correlation between between MS components with eGFR and urinary protein in patients with CKD. The early intervention treatment of MS was helpful in delaying the development of CKD and reducing proteinuria.

Validation of Diagnostic Codes to Identify Carbon Monoxide Poisoning in Taiwan’s Claims Data

Purpose: Previous studies identified the study cohort or outcome of carbon monoxide poisoning (COP) by using the relevant disease diagnosis codes in secondary databases, but the validity of diagnosis codes of COP is unclear in such secondary databases. This study aimed to evaluate the accuracy of case definitions for COP using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes in Taiwan’s health insurance claims data.

Methods: We selected a 10% simple random sample from an original cohort of patients newly undergoing carboxyhemoglobin (COHb) testing under any clinical diagnosis at four Chang Gung Memorial Hospitals in Taiwan during 2011–2020. Two clinical doctors independently ascertained the COP diagnosis by reviewing the medical records as the reference standard. We estimated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various case definitions (e.g., ICD-9-CM code, ICD-10-CM code and the uses of hyperbaric oxygen therapy) in the claims data.

Results: We randomly selected 557 cases from the original cohort of 5,571 cases newly receiving COHb test in the study hospitals. We found 90, 35, and 9 cases were true-positive, false-positive, and false-negative episodes of COP, respectively, among 278 cases with an ICD-9-CM code of 986. A further 111, 34, and 6 cases were true-positive, false-positive, and false-negative episodes of COP, respectively, among 279 cases with an ICD-10-CM code of T58. Using ICD-9-CM codes, the sensitivity, specificity, PPV and NPV for COP were 90.9, 80.4, 72, and 94.1%, respectively. Using ICD-10-CM codes they were 94.9, 79, 76.6, and 95.5%, respectively. PPV typically increased when COP was the primary diagnosis and could reach 100% if patients with ICD-CM code 986 or T58 also received hyperbaric oxygen therapy during hospitalization.

Conclusion: The COP-related ICD-CM codes alone did not accurately identify COP patients, but accuracy improved after including oxygen therapy data with the ICD-CM codes in Taiwan’s claims data.