Ethical Dilemmas in a Randomized Trial of Asthma Treatment Can Bayesian Statistical Analysis Explain the Results?

• Published in: Academic emergency medicine 2001-12, Vol.8 (12), p.1128-1135
• Main Authors: Holley, Mark T., Morrissey, Thomas K., Seaberg, David C., Afessa, Bekele, Wears, Robert L.
• Format: Article
• Language: English
• Subjects: Adult; asthma; Bayes Theorem; Bayesian statistics; Bioethics; BiPAP; Bronchodilator Agents - administration & dosage; Clinical Protocols - standards; Combined Modality Therapy; Emergency Service, Hospital; Ethics, Medical; Female; Follow-Up Studies; Humans; Length of Stay - economics; Length of Stay - statistics & numerical data; Male; Middle Aged; positive pressure ventilation; Positive-Pressure Respiration - methods; Probability; Prospective Studies; Sensitivity and Specificity; Severity of Illness Index; Statistics, Nonparametric; status asthmaticus; Status Asthmaticus - diagnosis; Status Asthmaticus - therapy; Steroids - administration & dosage; Treatment Outcome
• ISSN: 1069-6563; 1553-2712
• DOI: 10.1111/j.1553-2712.2001.tb01128.x

Objectives: The original objective was to determine whether the use of bilevel positive airway pressure (BiPAP) ventilation would reduce the need for endotracheal intubation, the length of hospital stay, and hospital charges in patients with status asthmaticus. The development of physician treatment bias made patient enrollment difficult. The article subsequently describes the use of Bayesian statistics to explain study results when this bias occurs. Methods: This study was a prospective, randomized controlled clinical trial conducted over a 34.5‐month period at an urban university hospital with an emergency department census of 94,000 annual visits. Patients remaining in status asthmaticus after initial standard treatment with inhaled beta‐agonists and steroids were randomized to receive BiPAP ventilation plus standard treatment versus standard treatment alone (non‐BiPAP), with intubation for either group as needed. Patients with concurrent cardiac or other pulmonary diseases were excluded. The primary outcome measures were endotracheal intubation rate and length of hospital stay. Secondary outcome measures included vital signs (respiratory rate, pulse rate, blood pressure), changes in expiratory peak flow, changes in pulse oximetry values, and hospital charges. Data were analyzed using Fisher's exact test, Mann‐Whitney tests, and Bayesian statistics. For patients enrolled in the study more than once, data analysis was performed on the first enrollment only. Results: Nineteen patients were enrolled in the BiPAP group and 16 patients in the non‐BiPAP group. Patients were frequently enrolled more than once and the data from the subsequent enrollments were excluded from the analysis. A marked decrease in enrollment, due to physician treatment bias, led to a premature termination of the study. Demographics showed that the groups were similar in age, sex, initial peak flow rate, and arterial blood gas measurements. There was a 7.3% increase (95% CI = ‐22 to +45) in the intubation rate in the non‐BiPAP group (n = 2) compared with that for the BiPAP group (n = 1). No significant difference was seen in length of hospital stay or hospital charges, although there was a favorable trend toward the BiPAP group. Complications encountered in the BiPAP group included one patient with discomfort associated with the nasal BiPAP mask. Bayesian analysis demonstrated that in order for the collected data to be convincing at the 95% confidence level, the prior conviction among