Study designs of evaluations included in the review
Randomised controlled trials (RCTs) were initially eligible for inclusion. Having failed to identify relevant RCTs, the author broadened the inclusion criteria to relevant prospective studies in which the treatment and control groups were treated equally apart from the intervention of interest, with explicit definition of the method used to assess the outcome and more than 80% follow-up. The studies also had to provide some interpretative description of the results.
Specific interventions included in the review
Studies that compared hyoscine hydrobromide with glycopyrronium were eligible for inclusion. The studies did not have to specify administration of hyoscine by injection to be included. Hyoscine could be given as a single injection or as a continuous subcutaneous infusion. One included study used a six-step protocol for drug administration, according to which both groups received glycopyrronium as steps four to six.
Participants included in the review
Studies in terminally ill patients were eligible for inclusion. In the included studies, treatment was administered to hospice patients who had a 'death rattle'.
Outcomes assessed in the review
The eligible outcome was assessment of respiratory secretions. The included studies used either a point scoring system or subjective observer rating (mild, moderate, severe) to record respiratory noise volume. Measurements were recorded before treatment and 30 minutes after any administration of treatment, and change was assessed as better, same or worse. One study took observations every 4 hours until death. The results were expressed as response to treatment.
How were decisions on the relevance of primary studies made?
The author did not state how the papers were selected for the review, or how many reviewers performed the selection.