Effect of Receiving an Intervention Specifically About an Existing Risk Behavior on the Proportion of Participants Reporting a Positive Change in that Risk Behavior at Follow-up*

Positive Change After Behavior-Specific InterventionComparisonInterventionRelative RiskRisk DifferenceNumber Needed to Treat
n/N%n/N%RR95% CIRD (%)95% CI
3-mo follow-up
Seatbelt use (<“always”)55/12544.043/6962.31.42(1.08, 1.85)18.3(4.0, 32.6)5.5
Bicycle helmet use (=“never”)4/2714.86/1346.23.11(1.06, 9.16)31.3(1.1, 61.5)3.2
Driving after drinking4/580.02/2100.01.25(0.81, 1.94)20.0(−15.1, 55.1)5.0
Riding with an impaired driver29/3876.35/862.50.82(0.47, 1.44)−13.8(−50.0, 22.4)
Binge drinking30/5257.78/1361.51.06(0.65, 1.74)3.8(−25.8, 33.5)26.3
Carrying a weapon21/2584.04/580.00.95(0.59, 1.53)−4.0(−41.9, 33.9)
6-mo follow-up
Seatbelt use (<“always”)55/12944.044/6963.81.49(1.14, 1.95)21.1(6.9, 35.3)4.7
Bicycle helmet use (=“never”)1/273.76/1060.016.20(2.22, 118.36)56.3(25.1, 87.5)1.8
Driving after drinking5/771.41/1100.01.40(0.88, 2.23)28.6(−4.9, 62.0)3.5
Riding with an impaired driver29/4170.77/977.81.10(0.74, 1.64)7.0(−23.4, 37.6)14.3
Binge drinking32/5657.16/1346.20.81(0.48, 1.52)−10.9(−41.0, 19.1)
Carrying a weapon18/240.751/250.00.67(0.16, 2.71)−25.0(−96.4, 46.2)
  • RR indicates relative risk; RD, risk difference.

  • * Comparison is made to those in the control group who also endorsed the risk behavior at baseline.

  • Those participants randomized to the comparison group who endorsed this risk behavior at baseline.

  • Those participants randomized to the intervention group who endorsed this risk behavior at baseline and received BCC specific to the behavior.

  • §The number of interventions carried out to effect 1 positive change in injury-related risk behavior.