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Pharmacy study of natural health product adverse reactions (SONAR): a cross-sectional study using active surveillance in community pharmacies to detect adverse events associated with natural health products and assess causality

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Open access
Authors
Necyk, C.
Tsuyuki, R.
Boon, H.
Foster, B.
LeGatt, D.
Cembrowski, G.
Murty, M.
Barnes, J.
Charrois, Theresa
Arnason, J.
Ware, M.
Rosychuk, R.
Vohra, S.
Date
2014
Type
Journal Article

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Necyk, Candace and Tsuyuki, Ross Y. and Boon, Heather and Foster, Brian C. and LeGatt, Don and Cembrowski, George and Murty, Mano and Barnes, Joanne and Charrois, Theresa L. and Arnason, John T. and Ware, Mark A. and Rosychuk, Rhonda J. and Vohra, Sunita. 2014. Pharmacy study of natural health product adverse reactions (SONAR): a cross-sectional study using active surveillance in community pharmacies to detect adverse events associated with natural health products and assess causality. BMJ Open. 4 (3): pp. 1-10.
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BMJ Open
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This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. http://creativecommons.org/licenses/by-nc/3.0/

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Abstract

OBJECTIVES: To investigate the rates and causality of adverse event(s) (AE) associated with natural health product (NHP) use, prescription drug use and concurrent NHP-drug use through active surveillance in community pharmacies. DESIGN: Cross-sectional study of screened patients. SETTING: 10 community pharmacies across Alberta and British Columbia, Canada from 14 January to 30 July 2011. PARTICIPANTS: The participating pharmacy staff screened consecutive patients, or agents of patients, who were dropping or picking up prescription medications.PRIMARY OUTCOME MEASURES: Patients were screened to determine the proportions of them using prescription drugs and/or NHPs, as well as their respective AE rates. All AEs reported by the screened patients who took a NHP, consented to, and were available for, a detailed telephone interview (14%) were adjudicated fully to assess for causality.RESULTS: Over a total of 105 pharmacy weeks and 1118 patients screened, 410 patients reported taking prescription drugs only (36.7%; 95% CI 33.9% to 39.5%), 37 reported taking NHPs only (3.3%; 95% CI 2.4% to 4.5%) and 657 reported taking prescription drugs and NHPs concurrently (58.8%; 95% CI 55.9% to 61.6%). In total, 54 patients reported an AE, representing 1.2% (95% CI 0.51% to 2.9%), 2.7% (95% CI 0.4% to 16.9%) and 7.3% (95% CI 5.6% to 9.6%) of each population, respectively. Compared with patients who reported using prescription drugs, the patients who reported using prescription drugs and NHPs concurrently were 6.4 times more likely to experience an AE (OR; 95% CI 2.52 to 16.17; p<0.001). Combined with data from Ontario, Canada, a national proportion was calculated, which found that 45.4% (95% CI 43.8% to 47.0%) of Canadians who visit community pharmacies take NHPs and prescription drugs concurrently, and of those, 7.4% (95% CI 6.3% to 8.8%) report an AE.CONCLUSIONS: A substantial proportion of community pharmacy patients use prescription drugs and NHPs concurrently; these patients are at a greater risk of experiencing an AE. Active surveillance provides a means of detecting such AEs and collecting high-quality data on which causality assessment can be based.