Observational Study of Intravenous versus Oral Corticosteroids for Acute Asthma: An Example of Confounding by Severity

Clark, Sunday; Costantino, Thomas; Rudnitsky, Gail; Camargo, Carlos A.

doi:10.1111/j.1553-2712.2005.tb01545.x

Cited by 14 publications

(7 citation statements)

References 16 publications

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“…The apparent increased risk of admission among patients with an AP does not imply a causal relationship. One must keep in mind confounding by severity (28); in a non-randomized study, it is likely that only the most severely ill patients with APs actually presented to the ED. Randomized trials have demonstrated that APs reduce morbidity and use of medical services (26).…”

Section: Discussionmentioning

confidence: 99%

A Prospective Multicenter Study of Written Action Plans among Emergency Department Patients with Acute Asthma

et al. 2008

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Background The prevalence of written “action plans” (APs) among emergency department (ED) patients with acute asthma is unknown. Objective To determine the prevalence of APs among ED patients, to describe the demographic and clinical profile of patients with and without APs, and to examine the appropriateness of response to an asthma exacerbation scenario. Methods Using a standard protocol, 49 North American EDs performed a prospective cohort study involving interviews of 1,756 patients, ages 2–54, with acute asthma. Among children only, a random sample was contacted two years after the index ED visit to assess current AP status and parents’ self-management knowledge. Results The overall prevalence of APs was 32% (95% confidence interval [CI], 30%–34%), and was higher among children than adults (34% vs. 26%, respectively; p = 0.001). Patients with APs had worse measures of chronic asthma severity (p < 0.05) and were more likely to be hospitalized (multivariate odds ratio, 1.5; 95%CI, 1.1–2.1). After 2 years, most children with an AP at the index ED visit still had one but only 20% of those without an AP had obtained one; moreover, many of the APs appeared inadequate. Parents of children with a current AP performed slightly better on the asthma scenario, but both groups overestimated their asthma knowledge. Conclusion The prevalence of APs among ED patients with acute asthma is unacceptably low, and many of these APs appear inadequate. “Confounding by severity” will complicate any non-randomized analysis of the potential impact of APs on asthma outcomes in ED patients.

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Section: Discussionmentioning

confidence: 99%

A Prospective Multicenter Study of Written Action Plans among Emergency Department Patients with Acute Asthma

et al. 2008

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“…Anticoagulation data were extracted from pharmacy billing files and included hospital day of administration, quantity, route, and dosing. To attenuate unmeasured confounding by illness severity owing to patients’ ability to take oral anticoagulant medications during sepsis, 15 we restricted our definition of anticoagulant exposure in the primary analysis to initial use of parenteral intravenous or subcutaneous administration of anticoagulants in doses greater than those used for prophylaxis of venous thromboembolism (ie, intravenous heparin sodium, >20 000 U daily, subcutaneous enoxaparin sodium twice daily [total daily dose >80 mg], subcutaneous dalteparin sodium, >5000 IU daily, and fondaparinux sodium, >2.5 mg daily). We allowed for oral anticoagulants (eg, warfarin sodium) later during hospitalization among patients who received an intravenous or subcutaneous anticoagulant initially, but excluded patients who received oral anticoagulants as their initial anticoagulant in the primary analysis.…”

Section: Methodsmentioning

confidence: 99%

Practice Patterns and Outcomes Associated With Use of Anticoagulation Among Patients With Atrial Fibrillation During Sepsis

et al. 2016

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IMPORTANCE Atrial fibrillation (AF) during sepsis is associated with an increased risk of ischemic stroke during hospitalization, but risks and benefits associated with anticoagulation for AF during sepsis are unclear. OBJECTIVE To determine clinician practice patterns and patient risk of stroke and bleeding associated with use of anticoagulation for AF during sepsis. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study using enhanced administrative claims data from approximately 20% of patients hospitalized in the United States July 1, 2010, to June 30, 2013, examined patients with AF during sepsis who did not have additional indications for therapeutic anticoagulation. Propensity score and instrumental variable analyses were used to evaluate risks of in-hospital stroke and bleeding associated with anticoagulation during sepsis. EXPOSURES Parenteral anticoagulants administered in doses greater than those used for prophylaxis of venous thromboembolism. MAIN OUTCOMES AND MEASURES Ischemic stroke and clinically significant bleeding events during hospitalization. RESULTS Of 113 511 patients hospitalized with AF and sepsis, 38 582 were included in our primary analysis (18 976 men and 19 606 women; mean [SD] age, 74.9 [11.7] years). A total of 13 611 patients (35.3%) received parenteral anticoagulants, while 24 971 (64.7%) did not. Hospital utilization rates of parenteral anticoagulants for AF during sepsis varied (median, 33%; 25th–75th percentile, 25%-43%). CHA2DS2VASc scores (congestive heart failure, hypertension, age ≥ 75 years [doubled], type 1 or type 2 diabetes, stroke or transient ischemic attack or thromboembolism [doubled], vascular disease [prior myocardial infarction, peripheral artery disease, or aortic plaque], age 65–75 years, sex category [female]) poorly discriminated the risk of ischemic stroke during sepsis (C statistic, 0.526). Among 27 010 propensity score–matched patients, rates of in-hospital ischemic stroke events did not differ significantly between patients who did (174 of 13 505 [1.3%]) and did not (185 of 13 505 [1.4%]) receive parenteral anticoagulation (relative risk [RR], 0.94; 95% CI, 0.77–1.15). Clinically significant bleeding occurred more often among patients who received parenteral anticoagulation (1163 of 13 505 [8.6%]) than patients who did not receive parenteral anticoagulation (979 of 13 505 [7.2%]; RR, 1.21; 95% CI, 1.10–1.32). Risk of ischemic stroke associated with parenteral anticoagulation did not differ significantly between patients with preexisting (RR, 1.12; 95% CI, 0.86–1.44) or newly diagnosed AF (RR, 0.85; 95% CI 0.57–1.27; P = .31 for interaction). Results were robust to multiple sensitivity analyses, including hospital utilization rates of parenteral anticoagulation for AF as an instrument for anticoagulation exposure (RR for stroke, 1.08; 95% CI, 0.62–1.90; RR for bleeding, 1.23; 95% CI, 0.88–1.72). CONCLUSIONS AND RELEVANCE Among patients with AF during sepsis, parenteral anticoagulation was not associated with reduced risk of ischemic st...

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“…We adopted two approaches, restriction of our sample and propensity score analysis, to address potential confounding by severity. Confounding by severity is a potential bias particularly relevant to observational studies of medication treatment that has been most thoroughly explored in the pulmonary and cardiology literature (e.g., Beasley et al 1994;Clark et al 2005;Garrett et al 1996). In our study, confounding by severity refers to the phenomenon whereby individuals who are the most severely ill and least likely to work are more likely to come to the attention of prescribers and receive medication, thus potentially distorting the relationship between medication and work.…”

Section: Introductionmentioning

confidence: 93%

Antidepressant Adequacy and Work Status Among Medicaid Enrollees with Disabilities: A Restriction-based, Propensity Score-adjusted Analysis

Smith

Henry

Zhang

et al. 2009

Community Ment Health J

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This cross-sectional study of adult survey respondents with disability and depression (n = 199) enrolled in Massachusetts' Medicaid program examined the association of adequately or inadequately prescribed antidepressant treatment and self-reported work status using conditional logistic regression, controlling for age, gender, race, marital status, education, receipt of SSI/SSDI, self-reported disabling condition, and health status. Confounding by severity was addressed by two methods: restriction of our sample and subsequent stratification by propensity score. Individuals receiving adequate antidepressant treatment had an increased odds of working compared to individuals receiving inadequate treatment, both in analyses in which restriction was used to limit confounding (OR = 3.45, 95% CI = 1.15-10.32, P < .03), and in analyses which combined restriction with adjustment by propensity score stratification (OR = 3.04, 95% CI = 1.01-9.62, P < .05). Among this sample of Medicaid enrollees with disability and depression, those receiving adequate antidepressant treatment were significantly more likely to report working.

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Observational Study of Intravenous versus Oral Corticosteroids for Acute Asthma: An Example of Confounding by Severity

Cited by 14 publications

References 16 publications

A Prospective Multicenter Study of Written Action Plans among Emergency Department Patients with Acute Asthma

A Prospective Multicenter Study of Written Action Plans among Emergency Department Patients with Acute Asthma

Practice Patterns and Outcomes Associated With Use of Anticoagulation Among Patients With Atrial Fibrillation During Sepsis

Antidepressant Adequacy and Work Status Among Medicaid Enrollees with Disabilities: A Restriction-based, Propensity Score-adjusted Analysis

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