Research on Intercessory Prayer: Theoretical and Methodological Considerations.

Belief in the healing power of prayer is found in various religious traditions. Spiritually grounded clinical interventions, such as intercessory prayer (IP), need to be understood in a broader sense. This essay features the IP trials, observing the controversial relationship between inconsistent results and allegedly inadequate methods and theoretical hypothesis. A survey of the literature was conducted including publications indexed until September 2013, focusing on the trials developed in the field and on the critics about the methodological design. Recent meta-analyses and multicenter studies found inconclusive results in the investigation of IP. Clinical trials on IP present some methodological difficulties: The intervention is not fully controlled; the primary outcome is not properly defined; and the theoretical models seem inconsistent. The "non-local consciousness" model may be appropriate for studies of IP. Directions for future research: greater emphasis on the evaluation of the effectiveness of this intervention in animal models; selection of subjects and healers who have previous connection; considering the hypothesis of non-local consciousness in the study design.