The basis of the analysis was a within-group comparison study. This would appear to be an appropriate design to answer the research question, but confirmation on the objectivity of measures to determine redness, swelling and bleeding (indicating a need for re-siting) would have given strength to the internal validity of the study. In addition, although some analysis of patient preference for the different devices was implicitly conducted, no further details on the methods and results were supplied. There was little information on the characteristics of the patients, other than gender and age. However, as most patients were described as having metastatic malignant disease, it is likely that they were representative of terminally ill hospice patients. The lack of an analysis on potential biases and confounding factors does, however, represent a further threat to the validity of the findings.
Although a number of patients did not complete the study, these patients were appropriately accounted for in the analysis of withdrawals. The final analysis, which was conducted on an intention to treat basis, represented a strong aspect of the research process. No power calculations were reported, thus it was not possible to ascertain whether the results obtained were due to the intervention or to chance.