The Effects of Water Temperature on the Cold Pressor Test
Condition: Chronic Pain
MeSH terms: Chronic Pain
Study type: Observational

Summary: 
      This current study is intended to be completed under the umbrella of the current GHUCCTS IRB-
      approved study "Opioid-Induced Hyperalgesia In Prescription Opioid Abusers: Effects of
      Pregabalin" (Lyrica study) (PRO00000669). In this proposed study, 10 healthy male, 10 healthy
      female participants and 5 male, 5 female OIH participants (from the parent Lyrica study), who
      are prescription opioid abusers with chronic pain currently taking Suboxone, will be asked to
      take the cold pressor test at 1, 5, and 9 degrees Celsius and to report the time at which
      pain has completely gone away following each test. The purpose of this study is to examine
      how the water temperature of the cold pressure test might affect the participants' response
      (i.e., the participants pain threshold and pain tolerance) and to see if there is a
      difference in how each participation group is affected.
    

Detailed description: 
      Since the 1940s, the cold pressor test (CPT) has been used experimentally as a pain induction
      method due to its reliability, cost effectiveness and minimal production of side effects. In
      the CPT, a patient is asked to place his or her hand and forearm in an ice bath until the
      pain is too great to remain in the water. Researchers have employed the CPT to test a wide
      range of pain management techniques, including medications, cognitive- based therapies, or
      acupuncture, as well as to explore pain perception. The CPT has been performed on a variety
      of participants, including adolescents, drug abusers, and those suffering from chronic back
      pain.

      In their classic 1989 paper, Walsh and colleagues developed the normative model of the CPT
      demonstrating that variations in response are dependent upon age, sex and ethnicity. In 2004,
      however, Mitchell et al. discovered that the water temperature of the CPT also plays a
      crucial role in the pain tolerance time of the subjects, noting that a temperature variation
      of 4°C produced significantly different results for the same subject. While the Mitchell
      investigations improved upon the standard for the proper CPT technique, as seen implemented
      in the works of Rash and Campbell, their discoveries were based on healthy individuals.

      Researchers have explored the CPT responses of patients with an altered pain perception, such
      as patients with Opioid-Induced Hyperalgesia (OIH), in comparison to healthy controls,
      demonstrating greater sensitivity in OIH patients. What has not been studied is the effect of
      temperature on CPT response in OIH patients. Further, the CPT has been shown to have a
      relatively lengthy recovery time averaging around 10 minutes; however, the recovery time for
      hypersensitive patients, such as OIH patients, has yet to be studied.

      As an extension of the work of Mitchell and colleagues, the proposed research will assess the
      effects of temperature difference and recovery time of the CPT on patients with OIH in
      comparison to healthy normal control patients. This work is a sub-study of a larger study,
      Opioid-Induced Hyperalgesia In Prescription Opioid Abusers: Effects of Pregabalin
      (PRO00000669), conducted by principal investigator Dr. Peggy Compton. The goal of the parent
      study is to evaluate the ability of pregabalin to diminish chronic low back or arthritic pain
      and OIH in a sample of prescription opioid abusers (POAs) opioid therapy. This current study
      is not assigning specific interventions to study subjects. Healthy control and OIH
      participants will complete all study measures in a single two-hour study session.
    

Intervention name(s): Cold pressor test
Intervention type(s): Other
Intervention description(s): The cold pressor test is a procedure used for examining pain threshold and tolerance by subjects placing their forearm in an ice bath. Each participant will take the CPT at 1 °C, 5°C, and 9°C. The first CPT will always be at 1 °C, to ensure participants tolerate the ice bath at the standard temperature. The order of the subsequent CPT at 5°C and 9°C, will be randomized to control for differential carry over effects. Participants will be instructed to say "Pain" when pain is initially detected (threshold). Then they will be asked to keep the immersed limb in the container until the pain can no longer be tolerated and say "Stop" and remove the arm from the water when tolerance is reached.
Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        A total of 10 prescription opioid abusers with chronic low back or arthritis pain and
        stable on opioid therapy (on methadone or buprenorphine) will be enrolled in the study.
        Meeting the same inclusion exclusion criteria of the prescription opioid abusers (except
        treatment methadone or buprenorphine), a total of 20 male and female healthy controls will
        be recruited.
      
Keywords: Chronic pain; Narcotic abuse; Opioid related disorders; Opiate substitution treatment; Buprenorphine; Pregabalin; Methadone