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What was the research about?

Chronic pain, which lasts for months or even years, can disturb people’s daily lives and their relationships with others. Doctors want to measure how chronic pain affects people’s lives so they can help their patients manage pain.

In this study, the research team wanted to measure two aspects of living with and managing chronic pain:

• Pain appraisal describes how people think about their pain. It measures how much people worry about their pain and how well they cope with pain or distract themselves from thinking about it.
• Pain-related self-efficacy describes how confident a person is that they can live well with pain.

The research team created two pools of questions, called item banks, to measure each of the two aspects of living with chronic pain. From these larger item banks, the team created and tested brief versions using two and six questions. These brief versions take people less time to finish than the full item banks.

What were the results?

The research team created a 24-question item bank for pain appraisal and a 29-question item bank for pain-related self-efficacy. Testing showed that people understood the questions well. The team also found that the questions accurately measured pain appraisal and pain-related self-efficacy. When patients completed the brief versions of the item banks, they provided information similar to that gathered by the full item banks.

Who was in the study?

The study included 795 people living with chronic pain across the United States. Of these people, 86 percent were white, 9 percent were African American, and 5 percent were other races. The average age was 55 and 64 percent were female. Patients had many different types of chronic pain, including low back pain or pain from multiple sclerosis.

What did the research team do?

To develop questions for the item banks, the research team worked with patient advisors and pain experts. Next, the team conducted focus groups and interviews with patients living with chronic pain. These patients gave feedback on whether the questions asked about important features of pain in ways that were easy to understand. Finally, the team tested the full item banks and the brief versions with a large group of people with chronic pain. These people answered the questions online or on paper.

What were the limits of the study?

The research team couldn’t include people with every type of chronic pain. For example, the study didn’t include people with carpal tunnel disease or cancer-related pain. People with types of chronic pain that weren’t in the study may have answered the questions differently.

Future research could study how people of different races or ages, or with other types of pain answer the questions. In addition, researchers could look into how to help doctors and patients use these item banks in health care.

How can people use the results?

Researchers could use the item banks in studies about treating and managing chronic pain. Doctors can use this research to help patients better manage pain.

Objective

To develop brief, flexible, and sound measures of pain catastrophizing and pain-related self-efficacy for people living with chronic pain

Study Design

An item bank is a set of items calibrated using Item Response Theory (IRT) that ask about a specific topic. Users can create custom short forms by picking sets of questions from an item bank or by using computerized adaptive testing. In this study, researchers developed separate item banks to measure pain catastrophizing and pain-related self-efficacy. Pain catastrophizing is a tendency to worry excessively about pain and to feel helpless about coping with it. Pain-related self-efficacy is the belief of people living with chronic pain that they can live well despite that pain. Existing measures of pain catastrophizing and pain-related self-efficacy were created using older methodology requiring all respondents to answer the same items. In this study, patient advisors, pain researchers, and clinicians guided item-bank development and provided feedback throughout the study.

The researchers developed the new item banks using qualitative and quantitative methodologies from the Patient-Reported Outcomes Measurement Information System (PROMIS®), including IRT, which result in flexible, brief, and clinically meaningful measures. To define the two aspects of living with chronic pain, the researchers worked with patient advisors, pain researchers, and clinicians. Then, focus group participants living with chronic pain provided feedback on the definitions and the items used to measure pain catastrophizing and pain-related self-efficacy. Using this feedback, the researchers developed items and tested them in interviews with people living with chronic pain.

Finally, the researchers conducted a field test of the item banks with 795 people living with chronic pain across the country. Of these people, 86% were white, 9% were African American, and 5% were other races. The average age was 55 and 64% were female. Respondents had a variety of chronic pain conditions such as low back pain and pain from multiple sclerosis.

To develop a scoring system and evaluate the reliability and validity of the scores, researchers conducted psychometric analyses. After finalizing the item banks, the team developed two- and six-question short forms for both pain catastrophizing and pain-related self-efficacy and calculated the correlations between the short forms and the full item banks. To evaluate test-retest reliability, the researchers examined the correlations between the scores of respondents who completed the measure a second time 40 to 80 hours later.

Results

Pain Appraisal Scale. The researchers renamed the pain-catastrophizing measure the Pain Appraisal Scale because focus group participants found the term stigmatizing. The final item bank included 24 questions. Scores from the 24-question item bank correlated highly with the two-question (r=0.71) and six-question (r=0.99) short forms. Test-retest reliability was high for the full bank (intraclass correlation [ICC]=0.93), two-question (ICC=0.85), and six-question (ICC=0.91) short forms. The item-bank scores correlated highly with the legacy Pain Catastrophizing Scale (r=0.83), supporting construct validity. Patients with mild, moderate, and severe pain had significantly different scores (p<0.05), supporting known groups validity.

Pain-related self-efficacy item bank. The final item bank included 29 questions. Scores from the full item bank correlated highly with the two-question (r=0.90) and six-question (r=0.97) short forms. Test-retest reliability was high for the full bank (ICC=0.95), two-question (ICC=0.86), and six-question (ICC=0.92) short forms. The item-bank score correlated highly with the legacy Pain Self-Efficacy Questionnaire (r=0.87), supporting construct validity. Patients with mild, moderate, and severe pain had significantly different scores (p<0.05).

Limitations

The study did not include many people with common pain conditions such as carpal tunnel or cancer-related pain. The item banks may not be valid for people with these conditions.

Conclusions and Relevance

Results support the reliability and validity of the pain appraisal and pain-related self-efficacy item banks and short forms. Epidemiologists and researchers can use the measures to examine predictors and correlates of health outcomes related to chronic pain.

Future Research Needs

Future research could include additional validity studies with people of different races or ages, or with other types of pain. Researchers could also determine and validate cutoff scores for use in clinical practice and determine what changes in scores are clinically important.