a1 Saw Swee Hock School of Public Health, National University of Singapore
a2 Department of Pharmacy, National University of Singapore
a3 Saw Swee Hock School of Public Health, National University of Singapore; Center for Molecular Epidemiology, National University of Singapore; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet; Genome Institute of Singapore; Yong Loo Lin School of Medicine, National University of Singapore
a4 Department of Pharmacy, National University of Singapore; Department of Rheumatology and Immunology, Singapore General Hospital
Introduction: Genetic factors affecting warfarin maintenance dose have been well established, but patient acceptance is a necessary consideration for the successful clinical implementation of warfarin pharmacogenetic testing (WPGT). In this study, we aimed to determine the attitudes toward WPGT among Singaporean Chinese.
Methods: A total of 194 warfarin patients and 187 members of the public completed a structured survey on paper and the Internet, respectively. Attitudes were expressed as willingness to undergo WPGT (single item with 5-point response) and expectations and concerns about WPGT (two multi-item scales). Relationships between attitudes and socio-demographic and clinical variables were explored using Fisher's exact test, Student's t-test, one-way analysis of variance or Pearson's correlation.
Results: Majority of respondents were willing to or neutral about undergoing WPGT. Both patients and public had relatively high expectations (mean [SD]: 3.77 [0.63], and 3.97 [0.55], respectively) and moderately high concerns (mean [SD]: 3.30 [0.69] and 3.33 [0.68], respectively) about WPGT. Willingness to undergo WPGT was associated with gender, educational status, length of warfarin treatment, and number of chronic diseases among warfarin patients, and with history of adverse drug reactions and number of chronic diseases among the public. Higher expectation of WPGT was associated with higher willingness (p < .001 in both populations), while higher concern was associated with lower willingness to undergo WPGT among the public (p = .004) but not among patients (p = .072).
Conclusion: Patient acceptance is not a major barrier to clinical implementation of WPGT but patient education is necessary and the ethical, social, and legal issues should be addressed.
The authors thank Dr Tiong Cheng Yeo, Dr Te-Chih Liu, Ms Nancy Yong, Ms Yashi Saw, and staff at the National University Health System Heart Centre and National University Hospital Cancer Centre Annex for their assistance in patient recruitment, and all respondents for their participation. We also thank A/Prof Yik Ying Teo for kindly providing us with the use of his server for the Web survey. CSL also acknowledges Sawtooth Software, Inc. for an academic grant to use of their software for this survey. This work was supported by the National University of Singapore start-up grant R-148-000-103-133 awarded to H.L. Wee.