Table 1.

Comparison of methodology in studies of dietary supplement use in cardiac patients.

Study	Dates of study	Geographic location	Mode of data collection	Validity & reliability of measure	Sample size	Response rate	Representativeness of sample	Definition of dietary supplements (nonsupplement CAM surveyed are not listed)	Definition of use
Ackman et al. (1999) [7]	July 1995–June 1996	Canada, Alberta	Patient survey	Piloted survey	180	75%	Respondents and nonrespondents comparable in age and gender	Vitamins/minerals, nutritional supplements, health food or herbal products	Used at least once weekly over last 3 months
Ai and Bolling (2002) [8]	May 1999–December 2000	US, Michigan	Face-to-face interview followed by telephone interview	—	225	48%	—	Herbal medicine, megavitamins, homeopathy, folk remedies	Use in last 1 year
Albert et al. (2009) [9]	April 2007–February 2008	US, Ohio & Pennsylvania	Telephone or face-to-face interview	Survey reviewed by research committee	374	—	—	Herbal therapies	—
Amira and Okubadejo (2007) [10]	3 month period	Nigeria, Lagos	Face-to-face interview	—	225	—	—	Dietary supplements and herbs	—
*Artz et al. (2006) [11]	Data from 2000-2002 Minnesota Heart Survey	US, Minnesota	Face-to-face interview	Validated interview, trained interviewers	315	—	Respondents compared to local census data	Nonvitamin/mineral dietary supplement, vitamin/mineral dietary supplement.	Use in last 2 weeks
Barraco et al. (2005) [12]	3 month period	US, Michigan	Face-to-face interview	Trained Interviewers	223	26%	—	Folk remedies, herbal therapy, homeopathy, megavitamin therapy (not daily vitamin), minerals (not calcium or iron), native American medicine, Tibetan medicine, traditional Chinese medicine	Use in last 12 months
*Buettner et al. (2007) [13]	Data from 1999-2000 and 2001-2002 National Health and Nutrition Examination Surveys	US	Face-to-face interview	—	1066 and 2482	82% and 84%	Representative respondents sampled	Vitamins, minerals, other dietary supplements	Use in last 1 month
Chagan et al. (2005) [14]	February 2001–December 2002	US, New York	Face-to-face interview	—	198	—	—	Herbal supplements, vitamins, mineral supplements	Use in last 12 months
Dal Corso et al. (2007) [15]	August-September 2005	Italy, Verona	Face-to-face interview	—	153	57%	—	Herbal remedies, integrators (vitamins, minerals, salts)	Ever used
Gohar et al. (2008) [16]	February–April 2006	UK, Birmingham	Face-to-face interview	—	153	79%	—	Alternative medical system, Vitamin supplements, dietary supplement, herbal medicine	Use in last 1 year
Krasuski et al. (2006) [17]	—	US, Texas	Patient survey	—	210	75%	—	Herbal medications, vitamin supplements (unless prescribed), dietary supplements	Use in last 6 months
Liu et al. (2000) [18]	March–May 1998	US, New York	Patient survey	—	263	70%	—	Chelation, herbs, homeopathy, naturopathy, nutritional therapy, vitamins	Ever used
Pharand et al. (2003) [19]	December 1998–February 1999	Canada, cross-country	Patient survey	Survey used in Ackman et al. (1999) [7]	306	—	Respondents distributed across country similarly to population	Vitamins or mineral products, nutritional supplements, health food or herbal products (home remedies, oriental remedies)	Used daily or at least once weekly in last 6 months
Shafiq et al. (2003) [20]	May 2001–October 2001	India, Chandigarh	Face-to-face interview	—	521	100%	—	Herbal medicine, homeopathy	Current and past use
Stys et al. (2004) [21]	—	US, New York	Physician interview	—	187	—	—	Vitamin, mineral or herbal supplements	Current (medication history)
Wong et al. (2003) [22]	May 2001	Hong Kong	Physician interview	—	107	100%	NA	Herbal decoctions, proprietary medicines containing herbs, “cool tea”, “herbal soup”, tonics	Use in last 1 week
Wood et al. (2003) [23]	—	Canada, Nova Scotia	Telephone interview	Trained interviewers	107	88%	Respondents younger (64 versus 69) but similar gender mix to nonrespondents	Megavitamins, herbal therapy, nutritional supplements, homeopathy, folk remedies, chelation	—
*Yeh et al. (2006) [6]	Data from 2002 National Health Interview Survey	US	Face-to-face interview	—	10572	74%	Representative respondents sampled	Alternative medical systems, chelation, folk medicine, herbal products, large-dose vitamins, special diets	Ever used, used in last 12 months
Yilmaz et al. (2007) [24]	—	Turkey	Face-to-face interview	Survey piloted	310	—	—	Herbals	Ever used, use daily, duration of use
Zick et al. (2005) [25]	January 2000–February 2004	US, Michigan	Patient survey	—	252	80%	—	Herbs, vitamins, minerals, amino acids, other	Use in last 6 months

Note: -: not reported, NA: not applicable, ∗Study analysed data from a population survey.