Development of an International, Multicenter, Hyperbaric Oxygen Treatment Registry and Research Consortium: Protocol for Outcome Data Collection and Analysis

Abstract

Background: Hyperbaric oxygen (HBO₂)-oxygen at pressures higher than atmospheric-is approved for 14 indications by the Undersea and Hyperbaric Medical Society. HBO₂'s main effect is to increase oxygen content in plasma and body tissues, which can counteract hypoxia or ischemia. Laboratory studies show that HBO₂ has effects beyond relieving hypoxia (eg, promoting angiogenesis in irradiated tissue, anti-inflammatory effects, radiosensitization of tumors, hypoxia preconditioning, and fungal growth inhibition) and has potential to treat conditions such as inflammatory bowel disease and pyoderma gangrenosum. Lack of consistently collected outcome data on a large cohort of individuals receiving HBO₂ therapy limits its use for both established and new indications. A course of therapy often involves 30-40 visits to a hyperbaric chamber, so the number of patients seen at any given center is constrained by chamber capacity. As a result, published HBO₂ outcome data tend to be from small case series because few patients with a particular condition are treated at a given center. To solve this problem, a registry that collects and pools data systematically from multiple institutions has been established.

Objective: The aim of this study is to collect consistent outcome data across multiple hyperbaric centers to assess treatment effectiveness and establish a research consortium.

Methods: A consortium of hyperbaric centers who have agreed to collect consistent outcome data on all patients seen has been assembled. Data are collected at each participating center using Research Electronic Data Capture (REDCap), a web-based, data collection system used frequently for research. Standard outcome measures have been defined for each condition, which are programmed into the REDCap data collection templates. Governance is through a consortium agreement that defines data security, data sharing, publications, liability, and other issues. Centers obtain Institutional Review Board (IRB) and ethics approval to participate, either from their own institutions or by relying on the IRB at the coordinating center at Dartmouth College. Dissemination will occur through a yearly report and by publications based on the data in the registry.

Results: Early results from some common indications show significant pretreatment to posttreatment changes. Additional indications and outcome measures are being added using the procedures outlined in the consortium agreement.

Conclusions: The registry collects consistent outcome information for a therapy that needs further study and a stronger evidence base. It also overcomes the challenge of collecting data from an adequate number of patients for both established and emerging indications by combining data collection from multiple centers. The data entry requirements should be within the capabilities of existing staff at any given hyperbaric center. By using REDCap, the registry can be expanded to include detailed information on particular indications and long-term follow-up on selected patients without significantly increasing the basic data entry requirements. Through the registry, a network of enrolled hyperbaric centers has been established that provides the basis for a clinical trial network.

International registered report identifier (irrid): DERR1-10.2196/18857.

Keywords: effectiveness; health data; hyperbaric oxygenation; measure; outcome; oxygen treatment; patient reported; patient-reported outcome measures; registries; registry; treatment.

Figure 1

Delayed radiation injury. Scores on the Head and Neck Questionnaire before and after hyperbaric oxygen (HBO₂) are shown: lower scores indicate fewer symptoms. This questionnaire is administered to any patient who had experienced head and neck radiation and is being treated for radiation injury in the head and neck region. Although responses vary between patients, results show lower scores posttreatment (16.9 pretreatment to 14.3 posttreatment, P=.03, Wilcoxon signed-rank test). By identifying patients who did not respond or who worsened, these data can guide further analyses.

Figure 2

Delayed radiation injury. Scores on the xerostomia (ie, dry mouth) questions within the Head and Neck Questionnaire are shown: lower scores indicate fewer symptoms. Dry mouth is a common complication of head and neck radiation, and whether hyperbaric oxygen (HBO₂) helps with this symptom is an open question. Early results from the registry suggest improvement (11.9 pretreatment to 8.9 posttreatment, P=.01, Wilcoxon signed-rank test).

Figure 3

Delayed radiation injury, radiation cystitis. Scores on the hematuria scale before and after hyperbaric oxygen (HBO₂) treatment are shown: 0=no hematuria, 1=microscopic hematuria, 2=occasional macroscopic hematuria, 3=frequent macroscopic hematuria, and 4=severe hemorrhagic cystitis. Most patients see an improvement in hematuria score (2.5 pretreatment to 1.0 posttreatment, P<.001, Wilcoxon signed-rank test). As the number of entries in the registry grows, these data may be useful for assessing the number of treatments needed for successful outcomes.

Figure 4

Idiopathic sudden sensorineural hearing loss. Four-frequency pure-tone averages on audiometry before and after hyperbaric oxygen treatment (HBO₂) are shown: a lower number indicates an improvement in hearing. Most patients are experiencing an improvement in audiometric thresholds (89.9 dB hearing loss [HL] pretreatment to 72.3 dB HL posttreatment, P=.03, Wilcoxon signed-rank test). As the number of cases in the registry grows, these data could be used to assess how long after the hearing loss HBO₂ may be useful.