Based on the hierarchy of evidence, the study falls under the category of randomized controlled trials, but without definitive results. This falls in the middle of the hierarchy pyramid, midway between strong reliability and weak reliability of evidence.
While the sample size of the study was small, most of the participants in the study were able to describe either one of the three methods of visits (dog visit, human visit, quiet reading session) as beneficial and even recommended them to other patients as well. The findings might very well produce the same results if given the chance to be repeated in other settings.
The patients in the study were more or less similar to the patients in the PICO question. The age range of the cancer patients in the study was from 39-77 years of age, with the mean ages from 58-61 years.
Johnson, R.; Meadows, R.; Haubner, J.; Sevedge, K. (2008). Animal-assisted activity among patients with cancer: effects on mood, fatigue, self-perceived health, and sense of coherence. Oncology Nursing Forum, 35(2):