The purpose of this study is to compare the risk of shopping behavior of tapentadol immediate release with the risk of shopping behavior of oxycodone immediate release.

This is a retrospective (a study that looks backward in time, usually using medical records and interviews with patients) matched cohort (designated group followed or traced over a period of time) study using IMS LRx database. This database covers 65% of all retail prescriptions in the United States and includes mail service and specialty pharmacy provider prescriptions independent of the method of payment. The study will include Opioid naive patients exposed to tapentadol immediate release (IR) or oxycodone IR from July 2009 to December 2010. A naive patient is a patient who has not received an opioid of any type in the 3 months before the index date. The index date is the date of the first prescription for tapentadol IR or oxycodone IR after June 30, 2009. Patients will be followed for 1 year from their index dates. Each tapentadol IR-exposed patient will be matched to up to 4 oxycodone IR-exposed patients. Matching will allow to control in the design for potential confounding variables such as time of the exposure, geographic area, specialty of the prescriber, and age. These are variables that have been related with the risk of shopping behavior or abuse.

Inclusion Criteria:

• Opioid naive patients (a patient who has not received an opioid of any type in the 3 months before the index date) exposed to tapentadol IR or oxycodone IR from July 2009 to December 2010 [The index date is the date of the first prescription for tapentadol IR or oxycodone IR after June 30, 2009]

Exclusion Criteria:

• Patients with use of any opioid 3 months before the index date
• Patients who within 4 days on or after the index date fill a prescription for a different opioid
• Patients who within 4 days on or after the index date fill a prescription for the same opioid but written by a different prescriber

Opioid naive patients exposed to tapentadol IR or oxycodone IR from July 2009 to December 2010 who did not fill any other opioid prescription within 4 days on or after the index date. The index date is the date of the first prescription for tapentadol IR or oxycodone IR after June 30, 2009. A naive patient is a patient who has not received an opioid of any type in the 3 months before the index date.