Table 1.

Overview on identified studies.  

Author, year	Main question	Type of study	Diagnosis	N   (f/m)	Mean age, range (years)	Religious background of participants	Central findings
Ai et al., 2002 [29]	How is private prayer used among middle-aged and older patients to cope with cardiac surgery?	Mixed-methods	Heart problems	246   (109/137)	62,   36–86	Protestant: 52.8% Catholic: 26.8%  Orthodox: 2.0%  Jewish: 3.7%  Other religions: 3.7%  No preference: 11.0%	88% of participants expressed a belief in the importance of prayer and used private prayer as a way to deal with surgery-related difficulties. The most common form of prayer was “conversation with God.” Prayer was positively correlated with optimism.
Ai et al., 2007 [30]	How is prayer for coping with cardiac surgery associated with patients' outcomes?	Mixed-methods	Heart problems	310  (130/180)	62,  35–89	Judeo-Christian: 87%	88% of participants expressed a belief in the importance of prayer and used private prayer as a way to deal with surgery-related difficulties. The most common form of prayer was “conversation with God.” Prayer was positively correlated with optimism.
Cotton et al., 2012 [46]	What is the content and frequency of prayer among children with SCD?	Qualitative  (semistructured interviews)	Sickle cell disease	19  (11/8)	8,   5–10	Protestant: 47%  Catholic: 16%  None: 16%  Others: 16%	A majority of the children used prayer/religion to manage their disease and prayers were mostly about getting well, not getting sick again, or getting out of the hospital.
Crane et al., 2000 [33]	What role does prayer play in HIV-infected women's decisions regarding treatment options?	Qualitative  (semistructured interviews)	HIV	51  (51/0)	13–19: 10%; 20–29: 31%; 30–39: 35%; 40 and up: 24%	No information	Nearly all participants believed that prayer was an important part of HIV decision-making and that prayer allowed them to accept their disease.
Harvey and Silverman 2007 [36]	What role does spirituality play in the self-management of chronic illness in adults?	Qualitative  (semistructured interviews)	Chronic illness	88  (41/47)	74	Protestant: 68.2%  Catholic: 27.3%  Others (1 Jewish, 1 none): 4.5%	Prayer played a vital role in the self-management of chronic disease and helped patients accept their illness. Participants asked for alleviation from their illness and used prayer to shape their experience of the disease.
Harvey and Cook 2010 [37]	What role does spirituality play in the self-management of chronic illness among adult women with chronic conditions?	Qualitative  (semistructured interviews)	Chronic illness	41  (41/0)	73,  66–85	No information	Prayer was used as a method of pain management and many participants experienced relief from their pain as the result of prayer.
Klafke et al., 2014 [39]	How and why do Australian men with cancer practice complementary therapies (CTs) and how do their significant others contribute to the regular uptake of CTs?	Qualitative  (semistructured interviews)	Cancer	26  (0/26)	68,   61–75	No information	Participants used meaning-based coping, that is, prayer, to cope with physical, emotional, and spiritual issues related to their disease.
Lagman et al., 2014 [34]	What meaning does spirituality and religion have for Filipina immigrants with a breast cancer diagnosis?	Qualitative  (semistructured interviews)	Breast cancer	10  (10/0)	54	Catholic: 100%	Prayer was the most common religious practice for coping with the disease. Prayer helped participants to find strength and see their illness in a positive light.
Levine et al., 2009 [35]	How does the use of prayer differ between breast cancer survivors from different ethnic groups and how is it related to mood and quality of life?	Mixed-methods	Breast cancer	175  (175/0)	58,  31–74	Catholic: 25%  Protestant: 33%  Jewish: 4%  Buddhist: 4%  Others: 4%  None/nonpracticing: 18%	Women who prayed were able to find more positive contributions from their breast cancer experience. Most women prayed for healing but also offered thanks and asked for guidance, strength, comfort, and protection before surgery or for others.
Meraviglia 2002 [31]	How can an instrument for assessing prayer activities, experiences, and attitudes of people with cancer be adapted?	Cross-sectional survey	Cancer	32  (24/8)	56,  31–74	Christian: 100%	Prayers helped patients adjust to their diagnosis and provided them with guidance regarding treatment decisions. As physical functioning decreased, the use of prayer increased.
Rezaei et al., 2008 [25]	How does prayer impact Iranian cancer patients undergoing chemotherapy?	Cross-sectional survey	Cancer	360  (171/189)	20–39 years: 46.1%;  40–59 years: 36.9%;  60-61 years: 17%	Muslim: 100%	Participants most often prayed for forgiveness and for guidance in decision-making. Individual characteristics (e.g. age, education, and sex) had an important effect on prayer.
Richmond et al., 2010 [38]	Why do adults with CHC use mind-body medicine?	Mixed-methods	Hepatitis C	133  (70/63)	52	No information	88% of participants reported praying for their health as a type of mind-body medicine and felt that prayer provided emotional support and improved the effectiveness of conventional medical treatments.
Smith et al., 2012 [32]	How do patients with advanced cancer pray and how is prayer used to cope with cancer?	Qualitative (focus group)	Lung/ovarian cancer	13  (13/0)	Late 30 s–early 80 s	No information	Prayer was used to find one's own way, find   renewed appreciation for life, gain strength and  courage, and strengthen their spiritual connection. Participants most often used   conversational prayer, petitionary  prayer, ritual prayer, and thanksgiving prayer.
Taylor et al., 1999 [26]	What spiritual conflicts are experienced by persons with cancer?	Qualitative  (semistructured interviews)	Cancer	30  (16/14)	58,  19–77	Christian (various denominations), Jewish	Many participants struggled to pray for certain things, such as a cure. Also, participants questioned the meaning of having cancer, the nature of God, why God does not always answer prayers.
Taylor and Outlaw 2002 [27]	Why, when, and how do person with cancer pray and what outcomes do they expect?	Qualitative  (semistructured interviews)	Cancer	30  (16/14)	58,  19–77	Christian (various denominations), Jewish	Participants prayed to ease the physical, emotional, and spiritual distress of their disease. In particular, patients often prayed for healing, guidance regarding treatment, and help getting through day to day life.
Walton and Sullivan 2004 [28]	What meaning does spirituality have for men with prostate cancer and how does it influence their treatment?	Qualitative  (semistructured interviews)	Prostate cancer	11  (0/11)	54–71	Christian: 100%	Prayer was an important aspect of coping with cancer and provided them with hope and inner strength. Participants shared their fears with God and asked for guidance regarding treatment decisions.