Direct-to-Consumer Pharmacogenomic Testing
Figure 1 depicts enrolment numbers and outcomes. Descriptive statistics and comparisons between PGx recipients (n=481) and non-recipients (n=844) on demographic and baseline outcome variables are shown in Table 1 . Individuals who received PGx were younger, less likely to be in a health-related profession and more likely to have completed the 3-month follow-up assessment. Notably, however, there were no differences between recipients and non-recipients in baseline measures of either primary outcome variable (ie, number of physician visits and state anxiety). The average follow-up interval was 14.0 (SD=1.3) and did not differ between study groups. The same baseline comparisons were also performed between PGx recipients at high risk (n=41) versus low risk (n=434; see online supplementary Table 1). Of note, nearly the entire cohort reported having health insurance (1321 out of 1325 individuals, or 99.7%).
(Enlarge Image)
Figure 1.
Enrolment, study groups and outcomes. Individuals who withdrew cited financial reasons, insurance concerns and change of mind. Non-compliance was when an individual had not completed the baseline health assessment after three email requests. Technical issues means that the individual submitted duplicate or triplicate surveys, and protocol deviation indicates that the individual's genetic results were unintentionally released to them prior to completion of the baseline health assessment. Twelve-month follow-up assessments were solicited from individuals who had completed the 3-month follow-up and individuals who had not completed the 3-month follow-up. PGx, pharmacogenomic; QC, quality control.
All individuals in the study had previously received personal genomic testing for risk of 28 common diseases. Therefore, we also compared these risk estimates between PGx recipients and non-recipients (see online supplementary Table 2) to ensure that disease risk was not a confounding factor in our analysis. As shown, after correcting for multiple comparisons (ie, 28), there were no significant differences in the risk estimates between the groups.
Healthcare Utilisation
PGx test recipients had an increase in physician visits at follow-up (p=0.04; see online supplementary figure 3) and were more likely to share their results with their physician (p=0.001; Table 2 ) relative to non-recipients. Further, the within-subjects change (increase) in physician visits was statistically significant for the group that received PGx results (p=0.03) and non-significant for those awaiting PGx results (p=0.73).
PGx recipients were also more likely to report that their physician ordered additional tests (p=0.01) based on their genomic results, and were more likely to discuss their results with a genetic counsellor (p<0.0005). There were no group differences at follow-up in number of visits to non-physician healthcare providers (p=0.22).
For those individuals who received PGx results, we assessed the length of time these participants had had access to their results at the time they completed the 12-month follow-up assessment. The mean number of days with access was 68.8 (2.29 months). We further tested the extent to which the number of days with access to PGx results was correlated with the change in number of physician visits from baseline to 12-month follow-up and found a significant positive correlation (rs=0.120, p=0.009) characterised by a greater number of days with access to PGx results being associated with a greater increase in physician visits at 12-month follow-up.
Both groups showed a non-significant decrease in anxiety symptoms from baseline to follow-up, with a trend for PGx recipients to show less of a decrease compared with non-recipients (p=0.10; Table 2). There were no group differences in follow-up test-related distress (p=0.67).
The majority of individuals in both study groups indicated that their results were useful (No PGx: 56.7% yes, 38.1% somewhat; Received PGx: 70.0% yes, 27.1% somewhat; see online supplementary figure 4) and that they understood their results (No PGx: 69.9% yes, 28.5% somewhat; Received PGx: 82.6% yes, 16.6% somewhat), though individuals in the PGx group were more likely to report utility (p<0.0005) and understandability (p<0.0005; Table 3). Although the majority of individuals in both study groups also indicated that they did not have privacy concerns (No PGx: 69.6% no; Received PGx: 62.5%), individuals in the PGx group were more likely to report privacy concerns (p=.02).
Although a greater percentage of PGx recipients versus non-recipients indicated that they shared their results with a family member (No PGx: 84.8%; Received PGx: 89.2%) this difference was not statistically significant (p=0.08; Table 3). The majority of individuals in both groups also indicated that they would recommend the test to others, however, PGx recipients were more likely to indicate that they would recommend it to family members (p=0.002) and non-family members (p=0.002; Table 3).
Among PGx recipients, the median number of PGx risks returned was 2 out of a total of 12 that were tested (Mean=2.4, SD=1.2). Further, of those who received PGx, there were a total of 41 individuals who had at least one instance of receiving a PGx risk for a medication they were either currently taking or had previously taken (see online supplementary Table 3).
Individuals at high PGx risk had a greater increase in physician visits (p=0.006; see online supplementary figure 3), were more likely to share their results with their physician (p=0.04), and were more likely to speak with a genetic counsellor about their results (p=0.02) at follow-up relative to individuals at low PGx risk (Table 4). The within-subjects change (increase) in physician visits among those individuals at low PGx risk was significant (p=0.02), however, among those at high PGx risk this effect did not reach statistical significance (p=0.85), likely due to low power to detect the effect with such a small sample size (n=41).
Individuals at high PGx risk did not differ from those in the low risk group in terms of whether or not their physician ordered additional tests based on their genomic results (p=0.40) or in their number of visits to a non-physician healthcare provider (p=0.74) at follow-up.
Individuals at high PGx risk were not found to differ from low risk individuals in anxiety symptoms between baseline and follow-up (p=0.99), and there were no group differences in follow-up test-related distress (p=0.41).
Individuals at high PGx risk did not differ from low risk individuals with respect to their perceptions of DTC genomic testing or with respect to any of the social outcomes assessed (see online supplementary Table 4).
Results
Sample Characteristics
Figure 1 depicts enrolment numbers and outcomes. Descriptive statistics and comparisons between PGx recipients (n=481) and non-recipients (n=844) on demographic and baseline outcome variables are shown in Table 1 . Individuals who received PGx were younger, less likely to be in a health-related profession and more likely to have completed the 3-month follow-up assessment. Notably, however, there were no differences between recipients and non-recipients in baseline measures of either primary outcome variable (ie, number of physician visits and state anxiety). The average follow-up interval was 14.0 (SD=1.3) and did not differ between study groups. The same baseline comparisons were also performed between PGx recipients at high risk (n=41) versus low risk (n=434; see online supplementary Table 1). Of note, nearly the entire cohort reported having health insurance (1321 out of 1325 individuals, or 99.7%).
(Enlarge Image)
Figure 1.
Enrolment, study groups and outcomes. Individuals who withdrew cited financial reasons, insurance concerns and change of mind. Non-compliance was when an individual had not completed the baseline health assessment after three email requests. Technical issues means that the individual submitted duplicate or triplicate surveys, and protocol deviation indicates that the individual's genetic results were unintentionally released to them prior to completion of the baseline health assessment. Twelve-month follow-up assessments were solicited from individuals who had completed the 3-month follow-up and individuals who had not completed the 3-month follow-up. PGx, pharmacogenomic; QC, quality control.
All individuals in the study had previously received personal genomic testing for risk of 28 common diseases. Therefore, we also compared these risk estimates between PGx recipients and non-recipients (see online supplementary Table 2) to ensure that disease risk was not a confounding factor in our analysis. As shown, after correcting for multiple comparisons (ie, 28), there were no significant differences in the risk estimates between the groups.
Impact of Pharmacogenomic Testing
Healthcare Utilisation
PGx test recipients had an increase in physician visits at follow-up (p=0.04; see online supplementary figure 3) and were more likely to share their results with their physician (p=0.001; Table 2 ) relative to non-recipients. Further, the within-subjects change (increase) in physician visits was statistically significant for the group that received PGx results (p=0.03) and non-significant for those awaiting PGx results (p=0.73).
PGx recipients were also more likely to report that their physician ordered additional tests (p=0.01) based on their genomic results, and were more likely to discuss their results with a genetic counsellor (p<0.0005). There were no group differences at follow-up in number of visits to non-physician healthcare providers (p=0.22).
Timing of PGx Results Delivery
For those individuals who received PGx results, we assessed the length of time these participants had had access to their results at the time they completed the 12-month follow-up assessment. The mean number of days with access was 68.8 (2.29 months). We further tested the extent to which the number of days with access to PGx results was correlated with the change in number of physician visits from baseline to 12-month follow-up and found a significant positive correlation (rs=0.120, p=0.009) characterised by a greater number of days with access to PGx results being associated with a greater increase in physician visits at 12-month follow-up.
Psychological Response
Both groups showed a non-significant decrease in anxiety symptoms from baseline to follow-up, with a trend for PGx recipients to show less of a decrease compared with non-recipients (p=0.10; Table 2). There were no group differences in follow-up test-related distress (p=0.67).
Perceptions of DTC Genomicc testing
The majority of individuals in both study groups indicated that their results were useful (No PGx: 56.7% yes, 38.1% somewhat; Received PGx: 70.0% yes, 27.1% somewhat; see online supplementary figure 4) and that they understood their results (No PGx: 69.9% yes, 28.5% somewhat; Received PGx: 82.6% yes, 16.6% somewhat), though individuals in the PGx group were more likely to report utility (p<0.0005) and understandability (p<0.0005; Table 3). Although the majority of individuals in both study groups also indicated that they did not have privacy concerns (No PGx: 69.6% no; Received PGx: 62.5%), individuals in the PGx group were more likely to report privacy concerns (p=.02).
Although a greater percentage of PGx recipients versus non-recipients indicated that they shared their results with a family member (No PGx: 84.8%; Received PGx: 89.2%) this difference was not statistically significant (p=0.08; Table 3). The majority of individuals in both groups also indicated that they would recommend the test to others, however, PGx recipients were more likely to indicate that they would recommend it to family members (p=0.002) and non-family members (p=0.002; Table 3).
Impact of High versus Low Pharmacogenomic Risk
Among PGx recipients, the median number of PGx risks returned was 2 out of a total of 12 that were tested (Mean=2.4, SD=1.2). Further, of those who received PGx, there were a total of 41 individuals who had at least one instance of receiving a PGx risk for a medication they were either currently taking or had previously taken (see online supplementary Table 3).
Individuals at high PGx risk had a greater increase in physician visits (p=0.006; see online supplementary figure 3), were more likely to share their results with their physician (p=0.04), and were more likely to speak with a genetic counsellor about their results (p=0.02) at follow-up relative to individuals at low PGx risk (Table 4). The within-subjects change (increase) in physician visits among those individuals at low PGx risk was significant (p=0.02), however, among those at high PGx risk this effect did not reach statistical significance (p=0.85), likely due to low power to detect the effect with such a small sample size (n=41).
Individuals at high PGx risk did not differ from those in the low risk group in terms of whether or not their physician ordered additional tests based on their genomic results (p=0.40) or in their number of visits to a non-physician healthcare provider (p=0.74) at follow-up.
Psychological Response
Individuals at high PGx risk were not found to differ from low risk individuals in anxiety symptoms between baseline and follow-up (p=0.99), and there were no group differences in follow-up test-related distress (p=0.41).
Perceptions of DTC Genomic Testing
Individuals at high PGx risk did not differ from low risk individuals with respect to their perceptions of DTC genomic testing or with respect to any of the social outcomes assessed (see online supplementary Table 4).
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