Responsiveness of the numeric pain rating scale in patients with shoulder pain and the effect of surgical status

J Sport Rehabil. 2011 Feb;20(1):115-28. doi: 10.1123/jsr.20.1.115.


Context: 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.

Design: Single-group repeated measures.

Setting: Outpatient rehabilitation clinics.

Patients: Patients with shoulder pain (N = 136).

Main outcome measures: 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.

MeSH terms

  • Adult
  • Aged
  • Area Under Curve
  • Data Interpretation, Statistical
  • Female
  • Humans
  • Male
  • Middle Aged
  • Outcome Assessment, Health Care / methods*
  • Pain Measurement / methods*
  • ROC Curve
  • Self Report
  • Shoulder Joint / physiopathology
  • Shoulder Joint / surgery*
  • Shoulder Pain / diagnosis
  • Shoulder Pain / rehabilitation
  • Shoulder Pain / surgery*
  • Surveys and Questionnaires*
  • Treatment Outcome