Does nurse use of a standardized flowsheet to document communication with advanced providers provide a mechanism to detect pulse oximetry failures? A retrospective study of electronic health record data.

BACKGROUND: Pulse oximetry guides clinical decisions, yet does not uniformly identify hypoxemia. We hypothesized that nursing documentation of notifying providers, facilitated by a standardized flowsheet for documenting communication to providers (physicians, nurse practitioners, and physician assistants), may increase when hypoxemia is present, but undetected by the pulse oximeter, in events termed "occult hypoxemia." OBJECTIVE: To compare nurse documentation of provider notification in the 4 h preceding cases of occult hypoxemia, normal oxygenation, and evident hypoxemia confirmed by an arterial blood gas reading. METHODS: We conducted a retrospective study using electronic health record data from patients with COVID-19 at five hospitals in a healthcare system with paired SpO2 and SaO2 readings (measurements within 10 min of oxygen saturation levels in arterial blood, SaO2, and by pulse oximetry, SpO2). We applied multivariate logistic regression to assess if having any nursing documentation of provider notification in the 4 h prior to a paired reading confirming occult hypoxemia was more likely compared to a paired reading confirming normal oxygen status, adjusting for characteristics significantly associated with nursing documentation. We applied conditional logistic regression to assess if having any nursing documentation of provider notification was more likely in the 4-hour window preceding a paired reading compared to the 4-hour window 24 h earlier separately for occult hypoxemia, visible hypoxemia, and normal oxygenation. RESULTS: There were data from 1910 patients hospitalized with COVID-19 who had 44,972 paired readings and an average of 26.5 (34.5) nursing documentation of provider notification events. The mean age was 63.4 (16.2). Almost half (866/1910, 45.3 %) were White, 701 (36.7 %) were Black, and 239 (12.5 %) were Hispanic. Having any nursing documentation of provider notification was 46 % more common in the 4 h before an occult hypoxemia paired reading compared to a normal oxygen status paired reading (OR 1.46, 95 % CI: 1.28-1.67). Comparing the 4 h immediately before the reading to the 4 h one day preceding the paired reading, there was a higher likelihood of having any nursing documentation of provider notification for both evident (OR 1.45, 95 % CI 1.24-1.68) and occult paired readings (OR 1.26, 95 % CI 1.04-1.53). CONCLUSION: This study finds that nursing documentation of provider notification significantly increases prior to confirmed occult hypoxemia, which has potential in proactively identifying occult hypoxemia and other clinical issues. There is potential value to encouraging standardized documentation of nurse concern, including communication to providers, to facilitate its inclusion in clinical decision-making.

Higher Plasma Omega-3 Levels are Associated With Improved Exacerbation Risk and Respiratory-Specific Quality of Life in COPD.

Background: Omega-3 polyunsaturated fatty acids (PUFAs) have been associated with systemic anti-inflammatory responses. Dietary intake of omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has also been associated with lower COPD morbidity using self-report food frequency questionnaires. Objective: To investigate the relationship between measured PUFA intake using plasma EPA+DHA levels and COPD morbidity. Methods: Former smokers with moderate-severe COPD living in low-income communities were enrolled in a 6-month prospective cohort study. Participants completed standardized questionnaires, spirometry, and plasma samples at 3-month intervals. Total plasma PUFAs were analyzed using gas chromatography/ mass spectrometry for DHA and EPA concentrations. Linear or logistic mixed model regression was used to evaluate EPA+DHA's and COPD morbidity's association, accounting for demographics, lung function, pack years, comorbidities, and neighborhood poverty. Results: 133 plasma EPA+DHA samples from 57 participants were available. Participants exhibited average plasma EPA and DHA levels of 14.7±7.3 µg/mL and 40.2±17.2 µg/mL, respectively, across the three clinic visits. Each standard deviation increase in EPA+DHA levels was associated with 2.7 points lower SGRQ score (95% CI -5.2, -0.2) and lower odds of moderate exacerbation (OR 0.4; 95% CI 0.2, 0.9) but lacked significant association with CAT score (95% CI -2.4, 0.8), mMRC (95% CI -02, 0.2), or severe exacerbations (95% CI 0.3, 1.4). Conclusion: Plasma EPA+DHA levels are associated with better respiratory-specific quality of life and lower odds of moderate exacerbations in patients with moderate-to-severe COPD. Further research is warranted to investigate the efficacy of an omega-3 dietary intervention in the management of COPD morbidities.

Changes in Spirometry Interpretative Strategies: Implications for Classifying COPD and Predicting Exacerbations.

BACKGROUND: Recent guidelines for spirometry interpretation recommend both race-neutral reference equations and use of z score thresholds to define severity of airflow obstruction. RESEARCH QUESTION: How does the transition from race-specific to race-neutral equations impact severity classifications for patients with COPD when using % predicted vs z score thresholds, and do changes in severity correspond to clinical risk? STUDY DESIGN AND METHODS: This retrospective cohort study included Black and White patients with COPD and available spirometry from the Johns Hopkins Health System. Global Lung Function Initiative (GLI) 2012 (race-specific) equations and GLI Global (race-neutral) equations were used to determine FEV1 % predicted and z score values. Patients were classified as having mild, moderate, or severe disease according to % predicted or z score thresholds. Associations between a change in severity classification from race-specific to race-neutral with COPD exacerbations and all-cause hospitalizations were evaluated using logistic regression. RESULTS: This cohort included 13,324 patients, of whom 9,232 patients (69.3%) were White (mean age, 65.7 years) and 4,092 patients (30.7%) were Black (mean age, 61.1 years). More Black than White patients showed a change in severity classification between approaches when using % predicted thresholds (20.2% vs 6.1%; P < .001), but not with z score thresholds (12.6% vs 12.3%; P = .68). An increased severity classification with a race-neutral approach was associated with increased risk of exacerbation when using z score thresholds (OR, 2.34; 95% CI, 1.51-3.63), but not when using % predicted thresholds (OR, 1.08; 95% CI, 0.61-1.93). A decreased severity classification with a race-neutral approach was associated with lower risk of exacerbation with both % predicted (OR, 0.49; 95% CI, 0.28-0.87) and z score (OR 0.67; 95% CI, 0.50-0.90) thresholds. INTERPRETATION: The proportions of Black and White individuals reclassified were similar with z score thresholds, and changes in severity corresponded to clinical risk with z scores. These results support recent recommendations for use of race-neutral equations and z score thresholds for spirometry interpretation.

Indoor particulate matter concentrations and air cleaner intervention association with biomarkers in former smokers with COPD.

BACKGROUND: Indoor pollutants have been associated with worse clinical outcomes in chronic obstructive pulmonary disease (COPD). Elevated biomarkers are associated with ambient pollution exposure, however the association with indoor pollution remains unclear. METHODS: Former smokers with spirometry-confirmed COPD were randomized to portable air cleaner or placebo. Indoor particulate matter (PM2.5, PM10, and ultrafine particles [UFP; PM<0.1]) and biomarkers were measured longitudinally at pre-specified intervals and course PM fraction (PM10-2.5) was calculated. Biomarkers were categorized based on associations with biologic mechanisms: inflammation (white blood cell count, interleukin [IL]-6, IL-8, IL-1ß, tumor necrosis factor-α, interferon-γ, serum amyloid A), platelet activation (P-selectin, CD40 ligand [CD40L], 11-dehdydro-thromboxane-B2 [11dTxB2]), endothelial dysfunction (Vascular Cell Adhesion Molecule [VCAM]-1, Intercellular Adhesion Molecule [ICAM]-1), and oxidative stress (thiobarbituric acid reactive substances [TBARS], 8-hydroxydeoxyguanosine, 8-isoprostane). Associations between PM concentrations and each biomarker were analyzed using multivariable linear mixed models. An intention-to-treat analysis was performed to evaluate the air cleaner intervention on the biomarker levels longitudinally. RESULTS: Fifty-eight participants were randomized to each group. Finer PM was more strongly associated with higher IL-8 (mean difference per doubling: UFP 13.9% [p = 0.02], PM2.5 6.8% [p = 0.002], PM10-2.5 5.0% [p = 0.02]) while interferon-γ was associated with UFP and IL-1ß with PM10-2.5. UFP and PM2.5 were associated with elevated levels of the oxidative stress biomarkers TBARS and 8-isoprostane respectively. For platelet activation markers, UFP was associated with higher 11dTxB2 while PM2.5 was associated with higher P-selectin and CD40L. Pollutants were not associated with biomarkers of endothelial dysfunction. In intention-to-treat analysis there was no association of the air cleaner intervention with any of the biomarkers. DISCUSSION: Among former smokers with COPD, elevated levels of indoor air pollutants, particularly ultrafine particles (PM<0.1), were associated with elevated biomarkers of inflammation, platelet activation, and oxidative stress. However, an air cleaner intervention that reduced PM did not significantly reduce biomarker levels.

Food Insecurity is Associated With COPD Morbidity and Perceived Stress.

Background: Low socioeconomic status (SES) has been associated with worse clinical outcomes in chronic obstructive pulmonary disease (COPD). Food insecurity is more common among individuals with low SES and has been associated with poor outcomes in other chronic illnesses, but its impact on COPD has not been studied. Methods: Former smokers with spirometry-confirmed COPD were recruited from low-income areas of Baltimore, Maryland, and followed for 9 months as part of a cohort study of diet and indoor air pollution. Food insecurity and respiratory outcomes, including COPD exacerbations and patient-reported outcomes, were assessed at regular intervals. The association between food insecurity and COPD outcomes was analyzed using generalized linear mixed models. Additional analyses examined the association of COPD morbidity with subdomains of food insecurity and the association of food insecurity with psychological well-being measures. Results: Ninety-nine participants had available data on food insecurity and COPD outcomes. A total of 26.3% of participants were food insecure at 1 or more times during the study. After adjusting for individual SES, neighborhood poverty, and low healthy food access, food insecurity was associated with a higher incidence rate of moderate and severe exacerbations and worse dyspnea, COPD health status, and respiratory-specific quality of life. Subdomains of food insecurity were independently associated with worse patient-reported outcomes. Food insecurity was additionally associated with higher perceived stress. Discussion: Among former smokers with COPD, food insecurity was associated with a higher incidence of exacerbations, worse patient-reported outcomes, and higher perceived stress. Subdomains of food insecurity were independently associated with worse patient-reported outcomes.

Diffusing Capacity as a Predictor of Hospitalizations in a Clinical Cohort of Chronic Obstructive Pulmonary Disease.

Rationale: Chronic obstructive pulmonary disease (COPD) hospitalizations are a major burden on patients. Diffusing capacity of the lung for carbon monoxide (DlCO) is a potential predictor that has not been studied in large cohorts. Objectives: This study used electronic health record data to evaluate whether clinically obtained DlCO predicts COPD hospitalizations. Methods: We performed time-to-event analyses of individuals with COPD and DlCO measurements from the Johns Hopkins COPD Precision Medicine Center of Excellence. Cox proportional hazard methods were used to model time from DlCO measurement to first COPD hospitalization and composite first hospitalization or death, adjusting for age, sex, race, body mass index, smoking status, forced expiratory volume in 1 second (FEV1), history of prior COPD hospitalization, and comorbidities. To identify the utility of including DlCO in risk models, area under the receiver operating curve (AUC) values were calculated for models with and without DlCO. Results were externally validated in a separate analogous cohort. Results: Of 2,793 participants, 368 (13%) had a COPD hospitalization within 3 years. In adjusted analyses, for every 10% decrease in DlCO% predicted, risk of COPD hospitalization increased by 10% (hazard ratio, 1.1; 95% confidence interval, 1.1-1.2; P < 0.001). Similar associations were observed for COPD hospitalizations or death. The model including demographics, comorbidities, FEV1, DlCO, and prior COPD hospitalizations performed well, with an AUC of 0.85 and an AUC of 0.84 in an external validation cohort. Conclusions: Diffusing capacity is a strong predictor of COPD hospitalizations in a clinical cohort of individuals with COPD, independent of airflow obstruction and prior hospitalizations. These findings support incorporation of DlCO in risk assessment of patients with COPD.

Skin Pigmentation and Pulse Oximeter Accuracy in the Intensive Care Unit: a Pilot Prospective Study.

Rationale: Despite multiple reports of pulse oximeter inaccuracy among hospitalized Black individuals, regulatory testing of pulse oximeters is performed on healthy volunteers. Objective: Evaluate pulse oximeter accuracy among intensive care unit patients with diverse skin pigmentation. Methods: Skin pigmentation was measured using a chromameter in 12 patients and individual typology angle (ITA), a measure of constitutive pigmentation, calculated. Arterial blood gas (ABG) arterial oxygen saturation (SaO 2 ) sampling was precisely matched to pulse oximetry (SpO 2 ) using arterial line waveforms analysis. Error (SpO 2 -SaO 2 ), bias, and average root mean square error (A RMS ) were calculated. Multivariable linear mixed effects models evaluated the association of SpO 2 -SaO 2 with skin pigmentation. Measurements and Main Results: Sampling time was determined for 350 ABGs. Five participants (N=96 ABGs) were darkly pigmented (forehead ITA<-30°), and 7 lighter pigmented (N=254 ABGs). Darkly pigmented individuals had 1.05% bias and 4.15% A RMS compared to 0.34% bias and 1.97% A RMS among lighter pigmented individuals. After adjusting for SaO 2 , pH, heart rate, and mean arterial pressure, SpO 2 -SaO 2 was falsely elevated by 1.00% more among darkly pigmented individuals (95% confidence interval: 0.25-1.76%). SpO 2 significantly overestimated SaO 2 for dark, brown, and tan forehead or forearm pigmentation and brown and tan finger pad pigmentation compared to intermediate/light pigmentation. Conclusions: The pulse oximeter in clinical use at an academic medical center performed worse in darkly pigmented critically ill patients than established criteria for FDA clearance. Pulse oximeter testing in ICU settings is feasible, and could be required by regulators to ensure equivalent device performance by skin pigmentation among patients.

Clinical Outcomes Associated With Overestimation of Oxygen Saturation by Pulse Oximetry in Patients Hospitalized With COVID-19.

Importance: Many pulse oximeters have been shown to overestimate oxygen saturation in persons of color, and this phenomenon has potential clinical implications. The relationship between overestimation of oxygen saturation with timing of COVID-19 medication delivery and clinical outcomes remains unknown. Objective: To investigate the association between overestimation of oxygen saturation by pulse oximetry and delay in administration of COVID-19 therapy, hospital length of stay, risk of hospital readmission, and in-hospital mortality. Design, Setting, and Participants: This cohort study included patients hospitalized for COVID-19 at 186 acute care facilities in the US with at least 1 functional arterial oxygen saturation (SaO2) measurement between March 2020 and October 2021. A subset of patients were admitted after July 1, 2020, without immediate need for COVID-19 therapy based on pulse oximeter saturation (SpO2 levels of 94% or higher without supplemental oxygen). Exposures: Self-reported race and ethnicity, difference between concurrent SaO2 and pulse oximeter saturation (SpO2) within 10 minutes, and initially unrecognized need for COVID-19 therapy (first SaO2 reading below 94% despite SpO2 levels of 94% or above). Main Outcome and Measures: The association of race and ethnicity with degree of pulse oximeter measurement error (SpO2 - SaO2) and odds of unrecognized need for COVID-19 therapy were determined using linear mixed-effects models. Associations of initially unrecognized need for treatment with time to receipt of therapy (remdesivir or dexamethasone), in-hospital mortality, 30-day hospital readmission, and length of stay were evaluated using mixed-effects models. All models accounted for demographics, clinical characteristics, and hospital site. Effect modification by race and ethnicity was evaluated using interaction terms. Results: Among 24 504 patients with concurrent SpO2 and SaO2 measurements (mean [SD] age, 63.9 [15.8] years; 10 263 female [41.9%]; 3922 Black [16.0%], 7895 Hispanic [32.2%], 2554 Asian, Native American or Alaskan Native, Hawaiian or Pacific Islander, or another race or ethnicity [10.4%], and 10 133 White [41.4%]), pulse oximetry overestimated SaO2 for Black (adjusted mean difference, 0.93 [95% CI, 0.74-1.12] percentage points), Hispanic (0.49 [95% CI, 0.34-0.63] percentage points), and other (0.53 [95% CI, 0.35-0.72] percentage points) patients compared with White patients. In a subset of 8635 patients with a concurrent SpO2 - SaO2 pair without immediate need for COVID-19 therapy, Black patients were significantly more likely to have pulse oximetry values that masked an indication for COVID-19 therapy compared with White patients (adjusted odds ratio [aOR], 1.65; 95% CI, 1.33-2.03). Patients with an unrecognized need for COVID-19 therapy were 10% less likely to receive COVID-19 therapy (adjusted hazard ratio, 0.90; 95% CI, 0.83-0.97) and higher odds of readmission (aOR, 2.41; 95% CI, 1.39-4.18) regardless of race (P for interaction = .45 and P = .14, respectively). There was no association of unrecognized need for COVID-19 therapy with in-hospital mortality (aOR, 0.84; 95% CI, 0.71-1.01) or length of stay (mean difference, -1.4 days; 95% CI, -3.1 to 0.2 days). Conclusions and Relevance: In this cohort study, overestimation of oxygen saturation by pulse oximetry led to delayed delivery of COVID-19 therapy and higher probability of readmission regardless of race. Black patients were more likely to have unrecognized need for therapy with potential implications for population-level health disparities.

Indoor Pollution and Lung Function Decline in Current and Former Smokers: SPIROMICS AIR.

Rationale: Indoor pollutants have been associated with chronic obstructive pulmonary disease morbidity, but it is unclear whether they contribute to disease progression. Objectives: We aimed to determine whether indoor particulate matter (PM) and nitrogen dioxide (NO2) are associated with lung function decline among current and former smokers. Methods: Of the 2,382 subjects with a history of smoking in SPIROMICS AIR, 1,208 participants had complete information to estimate indoor PM and NO2, using individual-based prediction models, in relation to measured spirometry at two or more clinic visits. We used a three-way interaction model between time, pollutant, and smoking status and assessed the indoor pollutant-associated difference in FEV1 decline separately using a generalized linear mixed model. Measurements and Main Results: Participants had an average rate of FEV1 decline of 60.3 ml/yr for those currently smoking compared with 35.2 ml/yr for those who quit. The association of indoor PM with FEV1 decline differed by smoking status. Among former smokers, every 10 µg/m3 increase in estimated indoor PM was associated with an additional 10 ml/yr decline in FEV1 (P = 0.044). Among current smokers, FEV1 decline did not differ by indoor PM. The results of indoor NO2 suggest trends similar to those for PM ⩽2.5 µm in aerodynamic diameter. Conclusions: Former smokers with chronic obstructive pulmonary disease who live in homes with high estimated PM have accelerated lung function loss, and those in homes with low PM have lung function loss similar to normal aging. In-home PM exposure may contribute to variability in lung function decline in people who quit smoking and may be a modifiable exposure.

Decreased Cardiac Autonomic Function is Associated with Higher Exacerbation Risk and Symptom Burden in Chronic Obstructive Pulmonary Disease.

Current measures of chronic obstructive pulmonary disease (COPD) severity, including lung function, do not fully explain symptom burden, and there is a need to identify predictors of exacerbation risk and morbidity. Autonomic dysfunction may be implicated in both cardiovascular and respiratory morbidity in COPD and convey risk for exacerbations. Heart rate variability (HRV) is a marker of cardiac autonomic function that is predictive of cardiovascular health and has promise as a non-invasive COPD biomarker. The CLEAN AIR Heart study provided an opportunity to investigate the association between HRV and COPD morbidity among former smokers with moderate-severe COPD. Eighty-five participants, contributing 305 HRV measurements, underwent repeated clinical assessments over 4 study periods that included a 24-Holter monitoring assessment of HRV. HRV measures of interest were standard deviation of normal-to-normal intervals, (SDNN) (overall HRV) and root-mean-square of successive differences (RMSSD) (parasympathetic function). Exacerbation risk was assessed using negative binomial models, and mixed-effects models analyzed associations between HRV and symptoms. Decreases in SDNN (incidence rate ratio [IRR]1.40; 95% confidence interval [CI] 1.13 to1.74) and RMSSD (IRR 1.60; 95% CI 1.07 to 2.37) were associated with severe exacerbation risk. Decreases in SDNN were associated with higher St George's Respiratory Questionnaire scores, COPD Assessment Test scores, and chronic bronchitis symptoms. Findings demonstrate that HRV is associated with COPD symptom burden and exacerbation risk. HRV may represent an important biomarker with the potential to identify high-risk COPD populations.

Airway and Systemic Prostaglandin E2 Association with COPD Symptoms and Macrophage Phenotype.

Background: Polymorphisms and products of the cyclooxygenase (COX) pathway have been associated with the development of chronic obstructive pulmonary disease (COPD) and adverse outcomes. COX-produced prostaglandin E2 (PGE-2) may play a role in the inflammation observed in COPD, potentially through deleterious airway macrophage polarization. A better understanding of the role of PGE-2 in COPD morbidity may inform trials for therapeutics targeting the COX pathway or PGE-2. Methods: Urine and induced sputum were collected from former smokers with moderate-severe COPD. The major urinary metabolite of PGE-2 (PGE-M) was measured, and ELISA was performed on sputum supernatant for PGE-2 airway measurement. Airway macrophages underwent flow cytometry phenotyping (surface CD64, CD80, CD163, CD206, and intracellular IL-1ß, TGF-ß1). Health information was obtained the same day as the biologic sample collection. Exacerbations were collected at baseline and then monthly telephone calls. Results: Among 30 former smokers with COPD (mean±SD age 66.4±8.88 years and forced expiratory volume in 1 second [FEV1] 62.4±8.37 percent predicted), a 1 pg/mL increase in sputum PGE-2 was associated with higher odds of experiencing at least one exacerbation in the prior 12 months (odds ratio 3.3; 95% confidence interval: 1.3 to15.0), worse respiratory symptoms and health status. PGE-M was not associated with exacerbations or symptoms. Neither airway PGE-2 nor urinary PGE-M was uniformly associated with an M1 or M2 polarization. Conclusions: Elevated levels of sputum PGE-2, rather than systemic PGE-2, is associated with increased respiratory symptoms and history of exacerbation among individuals with COPD. Additional studies focused on mechanism of action are warranted.

Urine and Plasma Markers of Platelet Activation and Respiratory Symptoms in COPD.

Introduction: Antiplatelet therapy has been associated with fewer exacerbations and reduced respiratory symptoms in chronic obstructive pulmonary disease (COPD). Whether platelet activation is associated with respiratory symptoms in COPD is unknown. Methods: Former smokers with spirometry-confirmed COPD had urine 11-dehydro-thromboxane B2 (11dTxB2), plasma soluble CD40L (sCD40L), and soluble P-selectin (sP-selectin) repeatedly measured during a 6- to 9-month study period. Multivariate mixed-effects models adjusted for demographics, clinical characteristics, and medication use evaluated the association of each biomarker with respiratory symptoms, health status, and quality of life. Results: Among 169 participants (average age 66.5±8.2 years, 51.5% female, 47.5±31 pack years, forced expiratory volume in 1 second percent predicted 53.8±17.1), a 100% increase in 11dTxB2 was associated with worse respiratory symptoms reflected by higher scores on the COPD Assessment Test (ß 0.77, 95% confidence interval [CI]: 0.11-1.4) and Ease of Cough and Sputum Clearance Questionnaire ß 0.77, 95%CI: 0.38-1.2, worse health status (Clinical COPD Questionnaire ß 0.13, 95%CI: 0.03-0.23) and worse quality of life (St George's Respiratory Questionnaire ß 1.9, 95%CI: 0.39-3.4). No statistically significant associations were observed for sCD40L or sP-selectin. There was no consistent statistically significant effect modification of the relationship between urine 11dTxB2 and respiratory outcomes by history of cardiovascular disease, subclinical coronary artery disease, antiplatelet therapy, or COPD severity. Conclusions: In stable moderate-severe COPD, elevated urinary11dTxB2, a metabolite of the platelet activation product thromboxane A2, was associated with worse respiratory symptoms, health status, and quality of life.

Indoor Air Pollution and Impaired Cardiac Autonomic Function in Chronic Obstructive Pulmonary Disease.

Rationale: Indoor air pollution represents a modifiable risk factor for respiratory morbidity in chronic obstructive pulmonary disease (COPD). The effects of indoor air pollution, as well as the impact of interventions to improve indoor air quality, on cardiovascular morbidity in COPD remain unknown. Objectives: To determine the association between indoor particulate matter (PM) and heart rate variability (HRV), a measure of cardiac autonomic function tied to cardiovascular morbidity and mortality, as well as the impact of household air purifiers on HRV. Methods: Former smokers with moderate-severe COPD were recruited from a 6-month randomized controlled trial of a portable air cleaner intervention to undergo paired assessment of both in-home PM and HRV using 24-hour Holter monitoring at up to five time points. Primary outcomes were HRV measures tied to cardiovascular morbidity (standard deviation of normal-to-normal intervals [SDNN] and root mean square of successive differences between normal-to-normal intervals [RMSSD]). Measurements and Results: Eighty-five participants contributed 317 HRV measurements. A twofold increase in household PM ⩽2.5 µm in aerodynamic diameter was associated with decreases in SDNN (ß, -2.98% [95% confidence interval (CI), -5.12 to -0.78]) and RMSSD (ß, -4.57% [95% CI, -10.1 to -1.60]). The greatest effects were observed with ultrafine particles (<100 nm) (RMSSD; ß, -16.4% [95% CI, -22.3 to -10.1]) and among obese participants. Participants randomized to the active air cleaner saw improvements in RMSSD (ß, 25.2% [95% CI, 2.99 to 52.1]), but not SDNN (ß, 2.65% [95% CI, -10.8 to 18.1]), compared with the placebo group. Conclusions: This is the first U.S. study to describe the association between household PM and cardiac autonomic function among individuals with COPD, as well as the potential cardiovascular health benefits of household air cleaners.

Risk factors associated with chronic kidney disease progression: Long-term retrospective analysis from Qatar.

INTRODUCTION: The risk factors influencing the natural course of chronic kidney disease (CKD) are complex and heterogeneous. Recognizing the factors associated with CKD progression can enable the identification of high-risk patients for more intensive treatment. PATIENTS AND METHODS: A retrospective evaluation of CKD patients was performed under follow-up between January 1, 2001 and December 31, 2016 at a tertiary health care center. RESULTS: Among 5370 screened patients, 1020 patients with complete data were included in the analysis. The median follow-up period for the studied patients was 9.3 years. Based on the analysis, 120 (11.8%) patients had reached end-stage kidney disease "ESKD" or death. The study revealed that the risk factors associated with reaching ESKD and/or death using Kaplan-Meier survival curve and log rank test included higher hemoglobin A1c among diabetic patients, higher grade of proteinuria, and non use of renin-angiotensin system blockers. The patients with CKD progression constituted 77.2% of all CKD patients. The study findings indicated that older age, Arab ethnicity, smoking habit, diabetes mellitus and hypertension (presumed as original kidney diseases) are among the significant risk factors associated with a further decline of the estimated glomerular filtration rate (eGFR) and further CKD progression. CONCLUSION: This study summarized the demographic and clinical risk factors associated with CKD progression and patients' outcomes among a unique and heterogeneous population in the state of Qatar. Intensive treatment of modifiable risk factors could be of value in halting the progression of CKD. However, prospective studies are warranted to confirm our findings.

Black carbon content in airway macrophages is associated with increased severe exacerbations and worse COPD morbidity in SPIROMICS.

BACKGROUND: Airway macrophages (AM), crucial for the immune response in chronic obstructive pulmonary disease (COPD), are exposed to environmental particulate matter (PM), which they retain in their cytoplasm as black carbon (BC). However, whether AM BC accurately reflects environmental PM2.5 exposure, and can serve as a biomarker of COPD outcomes, is unknown. METHODS: We analyzed induced sputum from participants at 7 of 12 sites SPIROMICS sites for AM BC content, which we related to exposures and to lung function and respiratory outcomes. Models were adjusted for batch (first vs. second), age, race (white vs. non-white), income (<$35,000, $35,000~$74,999, ≥$75,000, decline to answer), BMI, and use of long-acting beta-agonist/long-acting muscarinic antagonists, with sensitivity analysis performed with inclusion of urinary cotinine and lung function as covariates. RESULTS: Of 324 participants, 143 were current smokers and 201 had spirometric-confirmed COPD. Modeled indoor fine (< 2.5 µm in aerodynamic diameter) particulate matter (PM2.5) and urinary cotinine were associated with higher AM BC. Other assessed indoor and ambient pollutant exposures were not associated with higher AM BC. Higher AM BC was associated with worse lung function and odds of severe exacerbation, as well as worse functional status, respiratory symptoms and quality of life. CONCLUSION: Indoor PM2.5 and cigarette smoke exposure may lead to increased AM BC deposition. Black carbon content in AMs is associated with worse COPD morbidity in current and former smokers, which remained after sensitivity analysis adjusting for cigarette smoke burden. Airway macrophage BC, which may alter macrophage function, could serve as a predictor of experiencing worse respiratory symptoms and impaired lung function.

Patterns and Predictors of Air Cleaner Adherence Among Adults with COPD.

Rational: Poor indoor air quality has been associated with worse chronic obstructive pulmonary disease (COPD) morbidity. In-home portable air cleaners reduce indoor pollutants and could improve respiratory health. Factors associated with air cleaner adherence among adults with COPD remains unknown. Methods: In a 6-month trial of former smokers with COPD, participants (n=116) received active or sham portable air cleaners. Air cleaner adherence was measured by electronic monitors. Potential baseline predictors of adherence included individual factors (demographics, socioeconomic status, smoking history, psychological well-being), COPD disease severity, and housing characteristics. Time and season were also considered. Stepwise logistic regression and longitudinal fixed effect analysis were performed to assess independent predictors of adherence. Results: A total of 109 participants had an objective measure of adherence, and 76.1% used at least 1 air cleaner 80% of the time (defined a priori as adherent). Higher annual household income ≥$35,000 (odds ratio [OR]=4.4, 95% confidence interval [CI], 1.1-18.0) and use of heat pump/electricity (versus gas) for heating (OR=6.1, 95%CI, 1.7-22.4) were associated with higher odds of adherence. Further, poor quality of life (St George's Respiratory Questionnaire, per 10-point increase) and prior year exacerbations were associated with lower odds of adherence (OR=0.65, 95%CI, 0.4-1.0) and (OR=0.26, 95%CI, 0.1-0.9), respectively. Adherence was highest during the first month and lower during winter compared to other seasons. Conclusion: These findings suggest that cold weather season, use of gas for home heating, and lower annual income negatively impact adherence. Poor quality of life and worse disease control may also decrease adherence. Addressing factors associated with air cleaner adherence should be considered when designing future environmental studies.

Racial and Ethnic Discrepancy in Pulse Oximetry and Delayed Identification of Treatment Eligibility Among Patients With COVID-19.

Importance: Pulse oximetry guides triage and therapy decisions for COVID-19. Whether reported racial inaccuracies in oxygen saturation measured by pulse oximetry are present in patients with COVID-19 and associated with treatment decisions is unknown. Objective: To determine whether there is differential inaccuracy of pulse oximetry by race or ethnicity among patients with COVID-19 and estimate the association of such inaccuracies with time to recognition of eligibility for oxygen threshold-specific COVID-19 therapies. Design, Setting, and Participants: This retrospective cohort study of clinical data from 5 referral centers and community hospitals in the Johns Hopkins Health System included patients with COVID-19 who self-identified as Asian, Black, Hispanic, or White. Exposures: Concurrent measurements (within 10 minutes) of oxygen saturation levels in arterial blood (SaO2) and by pulse oximetry (SpO2). Main Outcomes and Measures: For patients with concurrent SpO2 and SaO2 measurements, the proportion with occult hypoxemia (SaO2<88% with concurrent SpO2 of 92%-96%) was compared by race and ethnicity, and a covariate-adjusted linear mixed-effects model was produced to estimate the association of race and ethnicity with SpO2 and SaO2 difference. This model was applied to identify a separate sample of patients with predicted SaO2 levels of 94% or less before an SpO2 level of 94% or less or oxygen treatment initiation. Cox proportional hazards models were used to estimate differences by race and ethnicity in time to recognition of eligibility for guideline-recommended COVID-19 therapies, defined as an SpO2 level of 94% or less or oxygen treatment initiation. The median delay among individuals who ultimately had recognition of eligibility was then compared. Results: Of 7126 patients with COVID-19, 1216 patients (63 Asian [5.2%], 478 Black [39.3%], 215 Hispanic [17.7%], and 460 White [37.8%] individuals; 507 women [41.7%]) had 32 282 concurrently measured SpO2 and SaO2. Occult hypoxemia occurred in 19 Asian (30.2%), 136 Black (28.5%), and 64 non-Black Hispanic (29.8%) patients compared with 79 White patients (17.2%). Compared with White patients, SpO2 overestimated SaO2 by an average of 1.7% among Asian (95% CI, 0.5%-3.0%), 1.2% among Black (95% CI, 0.6%-1.9%), and 1.1% among non-Black Hispanic patients (95% CI, 0.3%-1.9%). Separately, among 1903 patients with predicted SaO2 levels of 94% or less before an SpO2 level of 94% or less or oxygen treatment initiation, compared with White patients, Black patients had a 29% lower hazard (hazard ratio, 0.71; 95% CI, 0.63-0.80), and non-Black Hispanic patients had a 23% lower hazard (hazard ratio, 0.77; 95% CI, 0.66-0.89) of treatment eligibility recognition. A total of 451 patients (23.7%) never had their treatment eligibility recognized, most of whom (247 [54.8%]) were Black. Among the remaining 1452 (76.3%) who had eventual recognition of treatment eligibility, Black patients had a median delay of 1.0 hour (95% CI, 0.23-1.9 hours; P = .01) longer than White patients. There was no significant median difference in delay between individuals of other racial and ethnic minority groups and White patients. Conclusions and Relevance: The results of this cohort study suggest that racial and ethnic biases in pulse oximetry accuracy were associated with greater occult hypoxemia in Asian, Black, and non-Black Hispanic patients with COVID-19, which was associated with significantly delayed or unrecognized eligibility for COVID-19 therapies among Black and Hispanic patients. This disparity may contribute to worse outcomes among Black and Hispanic patients with COVID-19.