Influence of site differences between urban and rural American and Central European opioid-dependent pregnant women and neonatal outcome characteristics.

BACKGROUND: Multi-center trials enable the recruitment of larger study samples, although results might be influenced by site-specific factors.METHODS: Site differences of a multi-center prospective double-blind, double-dummy randomized controlled trial (7 centers: Central Europe (Vienna)/USA (3 urban/3 rural centers)) comparing safety and efficacy of methadone and buprenorphine in pregnant opioid-dependent women and their neonates.RESULTS: Urban US women had the highest rate of concomitant opioid (p = 0.050) and cocaine consumption (p = 0.003), the highest dropout rate (p = 0.001), and received the lowest voucher sums (p = 0.001). Viennese neonates had significantly higher Apgar scores 1 min (p = 0.001) and 5 min after birth (p < 0.001) and were more often born by cesarean section (p = 0.024). Rural US newborns had a significantly shorter neonatal abstinence syndrome treatment duration compared to Viennese and urban US sites (p = 0.006), in addition to other site-specific differences, suggesting a more severely affected group of women in the urban US sites.CONCLUSION: This clinical trial represents a role model for pharmacological treatment in this unique sample of pregnant women and demonstrates the clinical importance of considering site-specific factors in research and clinical practice.

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