Placebo Versus Nocebo: Effects on Pain and Anxiety During Local Anaesthetic Infiltration in Parturient Undergoing Elective Caesarean Delivery
Condition: Communication
Study type: Interventional

Summary: 
      This randomized trial compared placebo and nocebo effect over anaesthetist-patient
      communication on pain and anxiety score during local anaesthetic (LA) skin infiltration in
      parturient undergoing caesarean delivery under regional anaesthesia (RA). A secondary
      objective was to determine if education level and previous RA experience affect pain and
      anxiety scores. Parturients scheduled for elective caesarean delivery were randomised into
      Placebo (P) or Nocebo (N) group. Baseline Amsterdam Preoperative Anxiety & Information Scale
      (APAIS0) were obtained. Standardised scripts describing the LA skin infiltration for RA were
      used during the pre-anaesthetic review. (N) group were explained with words like "pain,
      prick, sharp" while words like "numb, comfort, tolerable" were used in the (P) group,
      avoiding "painful" expressions. The same scripts will be repeated before skin infiltration
      during the RA procedure. On the day of surgery, a second (APAIS1) was obtained upon arrival
      to the theatre. Pain score using the numerical rating scale (NRS) was assessed after LA
      infiltration.
    

Detailed description: 
      We randomised participants into either the nocebo (N) or placebo (P) group. We obtained a
      baseline anxiety score (APAIS0) using the Amsterdam Preoperative Anxiety and Information
      Scale (APAIS) during the pre-anaesthesia visit. Following that, we informed subjects in the N
      group a negative suggestion, using the following script: "During the local anaesthetic
      injection, you are going to feel a sharp prick at your back; this is usually the most painful
      part of the procedure". On the other hand, we used a positive suggestion on the P group: "We
      will administer some local anaesthetic to numb your back; this will allow the procedure to be
      more comfortable and tolerable for you." We obtain a second anxiety score (APAIS1) in the
      operating theatre before the caesarean section. We carried out either spinal anaesthesia or
      continuous spinal epidural according to standard hospital protocol and indication. Before the
      LA skin infiltration, the anaesthetist repeats the same script to the subjects according to
      the prior randomisation. Five millilitres of lignocaine 2% is injected intradermally and
      subcutaneously by the anaesthetist into interspinous space in a single pass through a
      22-gauge needle to create a skin wheal.

      During the LA infiltration, only the attending anaesthetist performing the procedure gave
      participants verbal instructions; other personnel remained silent throughout. We recorded the
      presence of vocalisation of pain, withdrawal movement or facial grimacing. Immediately after
      the LA infiltration, a blinded and trained general anaesthetic nurse or personnel enters the
      operating theatre to assess the subjects' pain score using the numerical rating scale (NRS).
      After collection of the pain score, the anaesthetist performed the remaining anaesthetic
      procedure as per clinical routine.
    

Intervention name(s): Placebo and Nocebo effect
Intervention type(s): Behavioral
Intervention description(s): Positive suggestion and words is used on Placebo group Negative suggestion and words is used on Nocebo group
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: We randomised participants into either the nocebo (N) or placebo (P) group using computer generated numbers
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Supportive Care
Keywords: Placebo; Nocebo; Pain; Anxiety; Local Skin Infiltration