Results
Overall, 15,675 people participated in the HITS trial. Among those with no family members who received the offer, the incentive's efficacy was a 6.5 percentage point increase (95% CI: 5.3−7.7). The efficacy was higher among those with at least one family member who received the offer (21.1 percentage point increase (95% CI: 19.9−22.3). The difference in efficacy was statistically significant (21.1–6.5 = 14.6%; 95% CI: 9.3−19.9).