Results
Increase in Registrations
On the day of the announcement of the Facebook organ donor initiative, 57 451 Facebook users updated their organ donor profile on the site (Figure 1A). The number of new updates per day decreased steadily to 538 on May 13, increased to 2454 on May 14 and then decreased to 316 on May 27. Similarly, on the first day of the initiative, there were 13 012 new online donor registrations across the 44 states for which data were available, representing a 21.2-fold increase over the baseline daily registration rate of 616. The number dropped over the next 12 days, but remained at an elevated rate (Table 1). Both Facebook profile updates and new online donor registrations were fewer on weekends than on weekdays. The total number of new registrations over the 13-day study period was 39 818, which was 32 958 more than would have been expected from the baseline registration rate. The difference in profile updates and new online registrations (approximately 67 000) represents those who updated their Facebook profile but had registered at the DMV previously or elected not to continue with the online process of registration.
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Figure 1.
(A) Facebook organ donor status updates, and online registrations with state donor registries, following the introduction of the Facebook organ donor status tool. Data shown on a log scale. Red numbers along the X axis denote weekend days. (B) Comparison of the proportional increase relative to baseline in online new donor registrations and DMV new donor registrations, May 1–3, 2012. Based on data from four states: Michigan, Montana, Texas and Washington. The increase in online registrations in these four states was similar to the increase observed nationwide, but DMV registrations saw only a slight increase in registrations.
In the four states for which DMV data were available, online registration showed a Facebook effect similar to the national effect: 13.7× on May 1, 12.9× on May 2 and 5.2× on May 3 (Figure 1B). However, DMV registration barely increased over this period, with a change of 1.2× on May 1 and May 2 and 1.0× (baseline) on May 3.
Temporal Pattern of Increased Registration
The state-level Facebook effect for May 1 ranged from 6.9× (Michigan) to 108.9× (Georgia) (Figure 2). States with a higher Facebook effect on May 1 continued to have a higher Facebook effect on subsequent days, particularly in the first week (Figure 3); correlation between state-level Facebook effect in the first week (between May 1 and May 6) was 0.808. Among those states with the highest impact (top quintile), the overall Facebook effect was 63.5× on May 1 and 5.9× on May 6; among those with the lowest impact (bottom quintile), the overall Facebook effect was 7.7× on May 1 and 1.6× on May 6.
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Figure 2.
Facebook effect (relative increase in online organ donor registrations) on the first day of the Facebook organ donor initiative, by state.
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Figure 3.
Magnitude of Facebook effect by state, by quintile of Facebook effect on the first day for which the organ donation status module was available. States that had a higher Facebook effect on the first day continued to have a higher Facebook effect on subsequent days. Facebook effect (relative growth in donor registration resulting from Facebook organ donor initiative) is shown on a log scale.
Factors Associated With Increased Registration
States with higher rates of online registration before the Facebook organ donor initiative had, on average, higher rates of online registration after the initiative was introduced (Figure 4A), but a lower proportional increase (a lower Facebook effect; Figure 4B) than states with lower rates of online registration before the Facebook organ donor initiative was begun. The association between baseline registration and registration after the initiative was suggestive, but not statistically significant; one additional registration per day per million people during baseline period was associated with 4.0 additional registrations per million people on May 1 (95% CI −0.3 to +8.3, p = 0.10; Figure 4A). Conversely, one additional registration per day per million people during baseline period was associated with a decrease in Facebook effect of 5.8 (95% CI −8.7 to −3.0, p < 0.001; Figure 4B).
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Figure 4.
Comparison of new donor registrations by state before and after the Facebook donor status tool became available. New donor registrations per capita after the Facebook tool became available were somewhat higher in states where baseline registrations per capita had been higher (A). However, the Facebook effect was higher in states where baseline registrations per capita had been lower (B). The line in each graph shows association between the two variables, calculated using linear regression, weighted by state population