Table 2.
Overall treatment effectc
|
Contrasts
|
||||
---|---|---|---|---|---|
MI vs. Controld | MI+HealthCall vs. Controld | MI+HealthCall vs. MIe | |||
χ2, df | p | Incidence risk ratio (95% confidence interval) | |||
NumDUa | |||||
End of intervention (at 60 days) (n = 224) | 2.78, 2 | 0. 25 | 0.68 (0.43–1.08) | 0.77 (0.49–1.21) | 1.13 (0.71–1.78) |
6 month follow-up (n = 211) | 7.27, 2 | 0.03 | 0.49 (0.29–0.85) | 0.59 (0.35–1.00) | 1.20 (0.70–2.06) |
12 month follow-up (n = 208) | 4.88, 2 | 0.09 | 0.54 (0.31–0.94) | 0.81 (0.47–1.38) | 1.51 (0.87–2.62) |
QuantUb | |||||
End of intervention (at 60 days) (n = 224) | 0.53, 2 | 0.77 | 0.83 (0.49–1.43) | 0.85 (0.51–1.44) | 1.02 (0.60–1.74) |
6 month follow-up (n = 211) | 15.92, 2 | <0.01 | 0.50 (0.28–0.90) | 0.75 (0.42–1.33) | 1.50 (0.84–2.67) |
12 month follow-up (n = 208) | 15.08, 2 | 0.04 | 0.45 (0.25–0.83) | 0.72 (0.40–1.31) | 1.60 (0.87–2.93) |
Incidence risk ratios of treatment group contrasts at study time points.
MI = motivational interviewing.
NumDU = mean number of days used primary drug during the 30 days prior to study visit.
QuantDU = mean dollar amount per day used over 30 days prior to study visit.
Corresponds to the omnibus test of treatment as a predictor of drug use outcome.
Control = Reference group.
MI = Reference group.