title: Responsiveness of the numeric pain rating scale in patients with shoulder pain and the effect of surgical status.
abstract: BACKGROUND
  The Numeric Pain Rating Scale (NPRS) is commonly used to assess pain. Change in the NPRS across time can be interpreted with responsiveness indices.
  
  
  OBJECTIVE
  To determine the minimal clinically important difference (MCID) of the NPRS.
  
  
  METHODS
  Single-group repeated measures.
  
  
  METHODS
  Outpatient rehabilitation clinics.
  
  
  METHODS
  Patients with shoulder pain (N = 136).
  
  
  METHODS
  At the initial evaluation patients completed the Penn Shoulder Score (PSS), which includes pain, satisfaction, and function sections. Pain was measured using an 11-point NPRS for 3 conditions of pain: at rest, with normal daily activities, and with strenuous activities. The NPRS average was calculated by averaging the NPRS scores for 3 conditions of pain. The final PSS was completed after 3-4 wk of rehabilitation. To determine the MCID for the NPRS average, the minimal detectible change of 8.6 points for the PSS function scale (0-60 points) was used as an external criterion anchor to classify patients as meaningfully improved (≥8.6 point change) or not improved (<8.6-point change). The MCID for the NPRS average was also determined for subgroups of surgical and nonsurgical patients. Cohen's effect sizes were calculated as a measure of group responsiveness for the NPRS average.
  
  
  RESULTS
  Using a receiver-operating-characteristic analysis, the MCID for the average NPRS for all patients was 2.17, and it was 2.17 for both the surgical and nonsurgical subgroup: area-under-the-curve range .74-.76 (95%CI: .55-.95). The effect size for all patients was 1.84, and it was 1.51 and 1.94 for the surgical and nonsurgical groups, respectively.
  
  
  CONCLUSIONS
  The NPRS average of 3 pain questions demonstrated responsiveness with an MCID of 2.17 in patients with shoulder pain receiving rehabilitation for 3-4 wk. The effect sizes indicated a large effect. However, responsiveness values are not static. Further research is indicated to assess responsiveness of the NPRS average in different types of patients with shoulder pain.
authors.affiliation: Dept of Physical Therapy, Virginia Commonwealth University, Richmond, VA, USA. lamichen@vcu.edu
authors.forename: Lori A
authors.initials: LA
authors.lastname: Michener
authors.forename: Alison R
authors.initials: AR
authors.lastname: Snyder
authors.forename: Brian G
authors.initials: BG
authors.lastname: Leggin
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D010147:Pain Measurement / Q000379:methods*; D012372:ROC Curve; D057566:Self Report; D012785:Shoulder Joint / Q000503:physiopathology / Q000601:surgery*; D020069:Shoulder Pain / Q000175:diagnosis / Q000534:rehabilitation / Q000601:surgery*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome