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. Author manuscript; available in PMC: 2015 Nov 1.
Published in final edited form as: Prev Med. 2014 Mar 4;0:62–70. doi: 10.1016/j.ypmed.2014.02.021

Table 3.

Opiate and cocaine thrice-weekly urinalysis results and workplace attendance for participants in the Work Reinforcement (Work), Methadone & Work Reinforcement (Methadone), and Abstinence, Methadone, & Work Reinforcement (Abstinence) conditions during the 4-week induction and the intervention evaluation period.

Observed condition means (%) Work vs. Methadone Work vs. Abstinence Methadone vs. Abstinence
Work Methadone Abstine nce p OR (95% CI) p OR (95% CI) p OR (95% CI)
Induction period
 Opiate negative
  Missing positive 32 30 22 0.78 1.10 (0.57-2.13) 0.16 1.66 (0.82-3.35) 0.24 1.51 (0.76-2.99)
  Missing missing 37 34 26 0.72 1.13 (0.58-2.21) 0.16 1.67 (0.82-3.40) 0.27 1.48 (0.74-2.95)
 Cocaine negative
  Missing positive 33 35 31 0.86 0.93 (0.41-2.10) 0.80 1.11 (0.48-2.58) 0.66 1.20 (0.54-2.67)
  Missing missing 38 39 36 0.98 0.99 (0.43-2.30) 0.75 1.15 (0.49-2.73) 0.72 1.16 (0.51-2.66)
 Opiate & cocaine negative
  Missing positive 19 17 11 0.72 1.16 (0.51-2.68) 0.21* 1.81 (0.72-4.55) 0.34 1.55 (0.62-3.87)
  Missing missing 22 19 13 0.71 1.18 (0.51-2.73) 0.22* 1.79 (0.71-4.51) 0.37 1.52 (0.61-3.79)
 Days in attendance 75 86 83 0.14 0.65 (0.87-2.72) 0.03* 0.52 (1.08-3.48) 0.46 0.80 (0.69-2.31)
 Collected samples 86 89 86 0.52 0.79 (0.63-2.54) 0.93 1.03 (0.49-1.91) 0.45 1.30 (0.39-1.52)
Intervention evaluation period
 Opiate negative
  Missing positive 43 50 65 0.37 0.75 (0.36-1.55) 0.01* 0.40 (0.39-0.40) 0.05 0.53 (0.28-1.00)
  Missing missing 57 65 78 0.25 0.73 (0.44-1.19) 0.01* 0.37 (0.37-0.37) 0.03* 0.51 (0.28-0.93)
 Cocaine negative
  Missing positive 25 44 48 0.03* 0.41 (0.39-0.44) 0.01* 0.35 (0.34-0.35) 0.63 0.84 (0.42-1.69)
  Missing missing 35 55 56 0.04* 0.45 (0.42-0.48) 0.04* 0.44 (0.41-0.48) 0.96 0.98 (0.48-2.02)
 Opiate & cocaine negative
  Missing positive 21 35 46 0.07* 0.49 (0.43-0.56) 0.01* 0.31 (0.31-0.32) 0.19 0.64 (0.33-1.25)
  Missing missing 29 44 51 0.08* 0.52 (0.45-0.61) 0.01* 0.39 (0.38-0.40) 0.42 0.76 (0.39-1.48)
 Days in attendance 68 70 70 0.78 0.90 (0.53-2.33) 0.88 0.95 (0.51-2.19) 0.89 1.05 (0.46-1.95)
 Collected samples 72 74 77 0.81 0.91 (0.51-2.38) 0.51 0.76 (0.59-2.92) 0.66 0.84 (0.55-2.60)

Note. Bold values indicate statistical significance. Asterisks indicate statistically significant differences between conditions in analyses adjusted for the three stratification variables (i.e., enrolled in methadone treatment, greater than 50% cocaine negative urine samples, and interested in methadone treatment). For the “missing positive” analyses, missing urine samples were coded as positive for opiates and cocaine. For the “missing missing” analyses, urine samples were not replaced. The study was conducted in Baltimore, MD from December 2008 to December 2012.