National unintentional carbon monoxide poisoning estimates using hospitalization and emergency department data

Carbon monoxide poisoning cases in the emergency department are increasing in the last decade in Jerusalem

BACKGROUND AND AIMS

The aim of our study was to describe the epidemiology of Carbon monoxide poisoning in the Emergency Department.

METHODS

A retrospective descriptive analysis of patients with Carbon monoxide poisoning who were presented to the Emergency Department of Hadassah hospital in Jerusalem from 2007 to 2016. All patients that were included are confirmed cases [carboxyhemoglobin level > 5%]. Sources of exposure, seasonal variation, and demographic characteristics were analyzed.

RESULTS

There were 244 patients (60% males) with 37 family clusters that accounted for 135 (55.3%) patients. One hundred seventy-three (70.9%) patients presented during the winter months. The main sources of exposure were: non-gas residential heating system, mainly charcoal grills and kerosene stoves (n = 100, 41%). Other sources were fires (n = 70, 28.7%), faulty gas heater (n = 34, 13.9%) and smoking (n = 15, 6.1%). The estimated annual incidence increased from an average of 20.8 cases a year between 2007-2011 to an average of 34 cases in 2011-2016. High-risk poisoning (levels > 25%) occurred in 28 patients (11.5%). Factors associated with severe poisoning were female gender and exposure in clusters compared with individual patients.

CONCLUSION

Our current study has showed an increase of Carbon Monoxide poisoning in contrary to our study performed in the previous decade. Fortunately, we did find a lower rate of cases with severe poisoning. Beside the implementation of safer standards for residential heating systems, customized public education is advised in order to lower rates of poisoning in the future. A predicted heavy snow fall should be considered a trigger for a public health warning regarding the risk of CO poisoning.

Screening patients for unintentional carbon monoxide exposure in the Emergency Department: a cross-sectional multi-centre study

BACKGROUND

Low-level exposure to carbon monoxide (CO) is a significant health concern but is difficult to diagnose. This main study aim was to establish the prevalence of low-level CO poisoning in Emergency Department (ED) patients.

METHODS

A prospective cross-sectional study of patients with symptoms of CO exposure was conducted in four UK EDs between December 2018 and March 2020. Data on symptoms, a CO screening tool and carboxyhaemoglobin were collected. An investigation of participants' homes was undertaken to identify sources of CO exposure.

RESULTS

Based on an ED assessment of 4175 participants, the prevalence of suspected CO exposure was 0.62% (95% CI; 0.41-0.91%). CO testing in homes confirmed 1 case of CO presence and 21 probable cases. Normal levels of carboxyhaemoglobin were found in 19 cases of probable exposure and in the confirmed case.

CONCLUSION

This study provides evidence that ED patients with symptoms suggestive of CO poisoning but no history of CO exposure are at risk from CO poisoning. The findings suggest components of the CO screening tool may be an indicator of CO exposure over and above elevated COHb. Clinicians should have a high index of suspicion for CO exposure so that this important diagnosis is not missed.

Carbon monoxide poisoning mortality in the United States from 2015-2021

INTRODUCTION

Most carbon monoxide poisoning is preventable. Tracking of longitudinal trends in carbon monoxide-related mortality is needed to guide public health efforts. This study sought to describe mortality in the United States from carbon monoxide poisoning, examine the epidemiology of unintentional ("accidental") and intentional exposures, and identify trends in both.

METHODS

The Centers for Disease Control and Prevention's Wonder databases were utilized to extract online data from National Center for Health Statistics files containing mortality data in the United States from 2015-2021. Extracted were deaths, crude death rates, intent of exposure, and demographics of persons dying from carbon monoxide poisoning, excluding cases related to fires. Also extracted was the number of suicidal deaths of all types. Carbon monoxide deaths related to consumer products were obtained from the Consumer Product Safety Commission. Information on state legislation mandating residential carbon monoxide alarms was obtained from online resources.

RESULTS

Total carbon monoxide deaths decreased from 1,253 in 2015 to 1,067 in 2021. An increase in accidental poisoning deaths was offset by a larger decrease in intentional deaths, despite an increase in suicides of all types in the country. For the first time in the United States, accidental carbon monoxide deaths (543) outnumbered intentional deaths (524) in 2021. The increase in accidental deaths is consistent with those recently reported from carbon monoxide-emitting consumer products by the Consumer Product Safety Commission. Furthermore, even though over one-half of accidental deaths occurred at home, no evidence of a protective effect of state laws requiring residential carbon monoxide alarms was seen.

CONCLUSIONS

Accidental carbon monoxide poisoning deaths increased from 2015-2021 for the first time in four decades. Exploration of the possibility they are due to consumer products warrants attention and prevention efforts. We were unable to demonstrate the preventive effect of residential carbon monoxide alarm legislation.

Comparative Evaluation of Carboxyhemoglobin Quantification in Postmortem Whole Blood by CO-Oximetry and Headspace Gas Chromatography with Flame Ionization Detection and Atom Absorption Spectrophotometry

A comparative evaluation of two methods used for carboxyhemoglobin (COHb) determination in postmortem whole blood was performed: carbon monoxide (CO)-oximetry measuring at 128 wavelengths and headspace gas chromatography with flame ionization detection (HS-GC--FID) where CO was determined after catalytic reduction of CO to CH4 and Fe was determined by atom absorption spectrophotometry (AAS, 248.3 nm). An aliquot of 100 µL whole blood was loaded into the CO-oximetry module. In the HS-GC--FID analysis, to 1.0 mL of whole blood, 3.0 mL of saponin solution was added, mixed and centrifuged. To 20 mL HS vials, 400 µL of the supernatant was added and the vials were immediately sealed. One milliliter of potassium hexacyanoferrat (III) solution was added through the HS septum and mixed. The samples were incubated at 70°C for 5 min. CO was separated using He as carrier gas and a CP-Molsieve 5 Å PLOT capillary column. Fe was determined using 400 µL of the saponin supernatant diluted to 10 mL by water. During a period of ∼3 years, 124 postmortem whole blood samples were analyzed. Bland-Altman method comparison showed satisfactory agreement and no significant bias between the methods for the whole saturation range (5 to 85% COHb). Five samples, all with %COHb >40, showed deviations of more than 10% COHb in absolute terms. One sample, in the lower COHb range <10%, was false negative on the CO-oximetry method. The between-assay accuracy, reported as bias, at 60% COHb was -0.8% and -9.0%, and precision, reported as relative standard deviation, was 1.6% and 7.7%, for the CO-oximetry and HS-GC--FID-AAS methods, respectively. Both methods obtained satisfactory results in proficiency testing rounds, with z-scores <±2 (n = 11). This study showed that the CO-oximetry method based on the 128-wavelength principle and the HS-GC--FID-AAS method are comparable and satisfactory for %COHb determination in postmortem whole blood.

Morbidity and Mortality of Unintentional Carbon Monoxide Poisoning: United States 2005 to 2018

STUDY OBJECTIVE

Centers for Disease Control and Prevention conducts case surveillance through the National Notifiable Diseases Surveillance System (NNDSS). This study aimed to provide surveillance report of unintentional carbon monoxide poisoning across multiple data sources to provide baseline data for the new NNDSS carbon monoxide poisoning surveillance.

METHODS

For the period 2005 to 2018, we used 4 data sources to describe unintentional carbon monoxide poisoning: exposures reported by poison centers, emergency department (ED) visits, hospitalizations, and deaths. We conducted descriptive analyses by the cause of exposure (fire, nonfire, or unknown), age, sex, season, and US census region. Additional analyses were conducted using poison center exposure case data focusing on the reported signs and symptoms, management site, and medical outcome.

RESULTS

Annually, we observed 39.5 poison center exposure calls (per 1 million, nationally), 56.5 ED visits (per 1 million, across 17 states), 7.3 hospitalizations (per 1 million, in 26 states), and 3.3 deaths (per 1 million, nationally) due to unintentional carbon monoxide poisoning. For 2005 to 2018, there was a decrease in the crude rate for non-fire-related carbon monoxide poisonings from hospital, and death data. Non-fire-related cases comprised 74.0% of ED visits data, 60.1% of hospitalizations, and 40.9% of deaths compared with other unintentional causes. Across all data sources, unintentional carbon monoxide poisonings were most often reported during the winter season, notably in January and December. Children aged 0 to 9 years had the highest reported rates in poison center exposure case data and ED visits (54.1 and 70.5 per 1 million, respectively); adults older than 80 years had the highest rates of hospitalization and deaths (20.2 and 9.9 per 1 million, respectively); and deaths occurred more often among men and in the Midwest region. Poison center exposure call data revealed that 45.9% of persons were treated at a health care facility. Headaches, nausea, and dizziness/vertigo were the most reported symptoms.

CONCLUSION

The crude rates in non-fire-related carbon monoxide poisonings from hospitalizations, and mortality significantly decreased over the study period (ie, 2005 to 2018). This surveillance report provides trends and characteristics of unintentional carbon monoxide poisoning and the baseline morbidities and mortality data for the Centers for Disease Control and Prevention national surveillance system of carbon monoxide poisoning.

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.

Temporal trends and demographic risk factors for hospital admissions due to carbon monoxide poisoning in England

Unintentional non-fire related (UNFR) carbon monoxide (CO) poisoning is a preventable cause of morbidity and mortality. Epidemiological data on UNFR CO poisoning can help monitor changes in the magnitude of this burden, particularly through comparisons of multiple countries, and to identify vulnerable sub-groups of the population which may be more at risk. Here, we collected data on age- and sex- specific number of hospital admissions with a primary diagnosis of UNFR CO poisoning in England (2002-2016), aggregated to small areas, alongside area-level characteristics (i.e. deprivation, rurality and ethnicity). We analysed temporal trends using piecewise log-linear models and compared them to analogous data obtained for Canada, France, Spain and the US. We estimated age-standardized rates per 100,000 inhabitants by area-level characteristics using the WHO standard population (2000-2025). We then fitted the Besag York Mollie (BYM) model, a Bayesian hierarchical spatial model, to assess the independent effect of each area-level characteristic on the standardized risk of hospitalization. Temporal trends showed significant decreases after 2010. Decreasing trends were also observed across all countries studied, yet France had a 5-fold higher risk. Based on 3399 UNFR CO poisoning hospitalizations, we found an increased risk in areas classified as rural (0.69, 95% CrI: 0.67; 0.80), highly deprived (1.77, 95% CrI: 1.66; 2.10) or with the largest proportion of Asian (1.15, 95% CrI: 1.03; 1.49) or Black population (1.35, 95% CrI: 1.20; 1.80). Our multivariate approach provides strong evidence for the identification of vulnerable populations which can inform prevention policies and targeted interventions.

Temporal trends and demographic risk factors for hospital admissions due to carbon monoxide poisoning in England

Unintentional non-fire related (UNFR) carbon monoxide (CO) poisoning is a preventable cause of morbidity and mortality. Epidemiological data on UNFR CO poisoning can help monitor changes in the magnitude of this burden, particularly through comparisons of multiple countries, and to identify vulnerable sub-groups of the population which may be more at risk. Here, we collected data on age- and sex- specific number of hospital admissions with a primary diagnosis of UNFR CO poisoning in England (2002-2016), aggregated to small areas, alongside area-level characteristics (i.e. deprivation, rurality and ethnicity). We analysed temporal trends using piecewise log-linear models and compared them to analogous data obtained for Canada, France, Spain and the US. We estimated age-standardized rates per 100,000 inhabitants by area-level characteristics using the WHO standard population (2000-2025). We then fitted the Besag York Mollie (BYM) model, a Bayesian hierarchical spatial model, to assess the independent effect of each area-level characteristic on the standardized risk of hospitalization. Temporal trends showed significant decreases after 2010. Decreasing trends were also observed across all countries studied, yet France had a 5-fold higher risk. Based on 3399 UNFR CO poisoning hospitalizations, we found an increased risk in areas classified as rural (0.69, 95% CrI: 0.67; 0.80), highly deprived (1.77, 95% CrI: 1.66; 2.10) or with the largest proportion of Asian (1.15, 95% CrI: 1.03; 1.49) or Black population (1.35, 95% CrI: 1.20; 1.80). Our multivariate approach provides strong evidence for the identification of vulnerable populations which can inform prevention policies and targeted interventions.

Availability of Bedside and Laboratory Testing for Carbon Monoxide Poisoning in the Upper Midwestern United States

INTRODUCTION

The objective of this study was to assess the ability to test patients for carbon monoxide (CO) exposure in all hospitals in three United States (U.S.) Midwestern states.

METHODS

We surveyed hospitals in three states. Telephone queries assessed processes for measuring carboxyhemoglobin, including capacity for real-time vs send-out testing. Facilities were separated based on their location's population size for further analysis. Descriptive statistics are reported.

RESULTS

Of the 250 hospitals queried, we ultimately excluded 25. Nearly all (220, 97.8%) reported a process in place to test for CO exposure. Over 40% (n=92) lacked real-time testing. Testing ability was positively associated with increasing population size quartile (range 32.6% - 100%). Hospitals in the lowest-quartile population centers were more likely to report that they were unable to test in real time than those in the largest-quartile population centers (67.4% vs 0%).

CONCLUSION

In a large geographic region encompassing three states, hospital-based and real-time capacity to test for CO exposure is not universal. Hospitals in smaller population areas are more likely to lack real-time testing or any testing at all. This may have significant public health, triage, and referral implications for patients.