Table 2. Comparison of propensity scores between samples in 10 National Institute of Drug Use Clinical Trial Network (CTN) randomized controlled trials (RCTs) and target samples from the Treatment Episodes Data-Admission (TEDS-A).
Study type | Study Number | Mean propensity score | ∆pa | Pooled standard deviation | Standardized ∆pb | t-test | p-value | |
---|---|---|---|---|---|---|---|---|
RCT | TEDS-A | |||||||
Buprenorphine/Naloxone (Bup/Nx) Detoxification | CTN0001 | 0.69 | 0.19 | 0.50 | 0.25 | 2.07 | 22.94 | <0.001 |
CTN0002 | 0.64 | 0.25 | 0.39 | 0.23 | 1.67 | 24.99 | <0.001 | |
CTN0003 | 0.70 | 0.25 | 0.45 | 0.26 | 1.72 | 38.99 | <0.001 | |
CTN0010 | 0.69 | 0.21 | 0.48 | 0.24 | 2.03 | 25.32 | <0.001 | |
CTN0030 | 0.80 | 0.20 | 0.60 | 0.28 | 2.08 | 53.12 | <0.001 | |
Motivational enhancement/interviewing | CTN0004 | 0.61 | 0.30 | 0.31 | 0.23 | 1.35 | 28.65 | <0.001 |
CTN0005 | 0.57 | 0.33 | 0.24 | 0.23 | 1.06 | 21.74 | <0.001 | |
CTN0013 | 0.65 | 0.27 | 0.38 | 0.23 | 1.63 | 21.19 | <0.001 | |
Motivational incentives | CTN0006 | 0.57 | 0.32 | 0.25 | 0.21 | 1.20 | 25.23 | <0.001 |
CTN0007 | 0.62 | 0.28 | 0.34 | 0.23 | 1.46 | 27.59 | <0.001 | |
Pooled results | ||||||||
Pooled standardized | 95% CI | Heterogeneity statistics | ||||||
I2c | χ2 (df) | p-value | ||||||
Overall | 1.54 | 1.49 – 1.60 | 94.6% | 165.45 (df = 9) | <0.001 | |||
Buprenorphine/Naloxone(Bup/Nx) Detoxification | 1.90 | 1.81 – 1.98 | 79.6% | 19.57 (df = 4) | <0.001 | |||
Motivational enhancement/interviewing | 1.28 | 1.18 – 1.37 | 89.2% | 18.51 (df = 2) | <0.001 | |||
Motivational incentives | 1.31 | 1.21 – 1.42 | 83.3% | 5.97 (df = 1) | 0.02 |
∆p is difference between propensity scores of CTN RCT sample and TEDS-A samples.
Standardized ∆p is computed as ∆p divided by pooled standard deviation.
I2 is the percentage of observed total variation across studies that is due to heterogeneity rather than chance. It is calculated as I2 = 100% × (Q - df)/Q, where Q is Cochran's heterogeneity statistic and df the degrees of freedom (see text for further information).