Graded chronic pain scale revised: validation in a Veteran sample

Abstract

Objective

The Graded Chronic Pain Scale (GCPS) is frequently used in pain research and treatment to classify mild, bothersome, and high impact chronic pain. This study’s objective was to validate the revised version of the GCPS (GCPS-R) in a US Veterans Affairs (VA) healthcare sample to support its use in this high-risk population.

Methods

Data were collected from Veterans (n = 794) via self-report (GCPS-R and relevant health questionnaires) and electronic health record extraction (demographics and opioid prescriptions). Logistic regression, adjusting for age and gender, was used to test for differences in health indicators by pain grade. Adjusted odds ratio (AOR) with 95% confidence intervals (CIs) were reported with CIs not including an AOR of 1 indicating that the difference exceeded chance.

Results

In this population, the prevalence of chronic pain (pain present most or every day, prior 3 months) was 49.3%: 7.1% with mild chronic pain (mild pain intensity and lower interference with activities); 23.3% bothersome chronic pain (moderate to severe pain intensity with lower interference); and 21.1% high impact chronic pain (higher interference). Results of this study mirrored findings in the non-VA validation study; differences between bothersome and high impact were consistent for activity limitations and present but not fully consistent for psychological variables. Those with bothersome chronic pain or high impact chronic pain were more likely to receive long-term opioid therapy compared to those with no/mild chronic pain.

Conclusions

Findings highlight categorical differences captured with the GCPS-R, and convergent validity supports use of the GCPS-R in US Veterans.

Introduction

The 2016 National Health Interview Survey (NHIS) estimated approximately one in five US adults has chronic pain and 8.0% of US adults (19.6 million) have high impact chronic pain,¹ defined as persistent pain with substantial restriction of participation in work, social and self-care activities.² From this report, Veterans reported a significantly higher prevalence of chronic pain (26%), but not high impact chronic pain (9.6%), than civilians.¹ The burden of chronic pain is far-reaching, from psychosocial sequelae at the individual and interpersonal levels³ to increased financial burden from higher healthcare utilization and lost productivity at the national level.⁴ Prior work has suggested that the consequences of pain as well as the targets for treatment may be different for patients with high impact chronic pain.⁵ Appropriate and effective treatment of chronic pain is facilitated by accurate classification of pain, which requires an assessment tool that captures the multidimensional quality of chronic pain.⁶

The Graded Chronic Pain Scale (GCPS)⁷ is a commonly used assessment tool in the fields of chronic pain research and clinical management.^8–10 To better align with advances in chronic pain metrics and definitions, the Graded Chronic Pain Scale was revised by Von Korff and colleagues and validated in a sample receiving care at a private integrated healthcare system, Kaiser Permanente.¹¹ Modifications to the scale, as detailed in the initial validation paper,¹¹ were informed by updated definitions of chronic pain and high impact chronic pain, a simplification of the assessment and scoring, and a shift from anatomically specific to generic chronic pain assessment as supported by the literature. Results from the initial validation of the GCPS-R showed significant associations with concurrently measured unfavorable health status, negative pain coping beliefs, activity limitations, and long-term opioid use in a sample of participants receiving care at Kaiser Permanente locations in the Pacific Northwest.¹¹

Pain is the most commonly treated condition in Department of Veteran Affairs (VA) clinics.¹² Prevalence of any pain, as well as prevalence of severe pain specifically, are higher among Veterans than civilians.¹³ As such, there is a pervasive need for a valid, reliable, and easy to administer assessment scale for research and clinical use in VA settings. This study aimed to validate the GCPS-R in a U.S. Veteran sample to support the use of the GCPS-R in this population. We hypothesized that, in a sample of Veterans receiving care in VA health system, the GCPS-R would reliably discriminate those with and without chronic pain. Among those with chronic pain, we hypothesized that the measure would reliably discriminate subgroups identified on the basis of degree of interference with functioning and life enjoyment and other negative health indicators.

Methods

Data sources

Sources of literature reviewed for this project included published articles accessed from journals directly, complemented by a PubMed search of articles relevant to this topic. Primary data sources include survey responses and electronic health record data from participants identified via the VA’s Corporate Data Warehouse (CDW). The study was approved by the VACHS Human Studies Subcommittee (Institutional Review Board).

Participants and procedures

Participants were Veterans in care at the VA Connecticut Healthcare System (VACHS), a tertiary care healthcare system, from December 2017 to November 2018, and data were collected via survey in this same time frame. To increase the number of participants with high impact chronic pain, a stratified sampling approach similar to the sampling approach from the original validation effort¹¹ was employed. A randomly selected cohort of 10 000 Veterans was identified via an electronic search of the VA’s Corporate Data Warehouse (CDW). To sample Veterans likely to experience high impact chronic pain, half of the cohort included individuals who had high pain-related health care utilization in the past 2 years (ie, the top 10% of utilizers of services defined as likely to be related to care for pain, for example, specialty pain medicine clinics, physical therapy, acupuncture, chiropractic care). The other half of the cohort included individuals from the general population. A multi-staged process was employed to optimize recruitment. First, Veterans in the cohort were mailed letters inviting them to participate in the online survey and providing them with information about how to securely access the survey (administered within the survey platform DatStat Illume, Chicago, IL). The letter explained that participants needed to agree to the linking of their survey response data with select data from their electronic health record (EHR). They were informed that participation was voluntary, and they were offered an opportunity to opt out of future contact by contacting study staff within 7 days. Otherwise, they were informed that they would be contacted by email and/or by phone. Veterans with documented email addresses who did not opt out or who had not already completed the survey were then contacted via email. Study staff also attempted up to three phone calls to the individuals in the cohort who did not respond to the prior mailed or emailed outreach. When reached by phone, Veterans were offered the opportunity to complete the survey by telephone interview with trained research staff who administered the survey and entered the data into the secure DatStat Illume survey. Ultimately, 794 Veterans (approximately 8% of Veterans who were sent information letters) completed the survey via phone or electronically and composed the sample for the study. Participants were compensated $10 for their participation. Demographic and opioid prescription information for the participants was obtained from the EHR.

Measures

Gcps-r

The GCPS-R is composed of six items.¹¹ Responses were used to categorize respondents into one of four “grades” ranging from Grade 0 (no chronic pain) to Grade 3 (high impact chronic pain), consistent with the approach employed for the original GPRS development and for the development of the GCPS-R.^7,11 In the report on the original GCPS, a Guttman scale analysis showed that pain intensity and disability measures formed a reliable hierarchical scale. Pain intensity measures appeared to scale the lower range of global severity while disability measures appeared to scale the upper range of global severity.⁷ Following from the approach employed in the development of the GCPS-R, simple scoring rules were employed to define the four chronic pain grades.¹¹ The first two GCPS-R questions are designed to identify the presence of chronic pain and its perceived impact on daily functioning. These items are complemented by the three item PEG scale that assesses average Pain intensity and the perceived degree of interference of pain on Enjoyment and General Activity on 11-point numeric rating scales (0–10) over the past week.¹⁴ Thus, PEG scores range from 0 to 30. A sixth question asks respondents, “Are you not working or unable to work due to pain or a pain condition?” This item is used to further characterize respondents with regard to their working status and attributions about pain as a contributor.

Item 1 of the GCPS-R is, “In the past 3 months, how often did you have pain?” Those responding “Never” or “Some days” were categorized as Grade 0 (no chronic pain). Those responding “Most days” or “Every day” were considered to have chronic pain. Participants with chronic pain who responded “Most days” or “Every day” to item 2 on the GCPS-R, “Over the past 3 months, how often did pain limit your life or work activities?” were categorized as Grade 3 (high impact chronic pain). For participants with chronic pain who answered “Never” or “Some days” to item 2, total PEG scores were employed to further distinguish Grades 1 and 2. Because scores of 4 or greater on numeric rating scales of pain intensity and pain interference are commonly considered thresholds for clinically significant pain severity, a PEG score of 12, that is, a score representing an average score on each of the three items of the PEG of ≥4, was considered a threshold for bothersome pain. Those with total PEG scores <12 were categorized as Grade 1 (mild chronic pain), while those with total PEG scores ≥12 were categorized as Grade 2 (bothersome chronic pain).¹¹

Convergent validity indicators

Health status: Participants self-rated their current health status, which is predictive of a variety of health outcomes:¹⁵ excellent, very good, good, fair, or poor. Responses of excellent, very good, and good were categorized as favorable. Fair and poor were categorized as unfavorable.

Depressive and anxiety symptoms: The Patient Health Questionnaire 4-item scale (PHQ-4) assessed the frequency of two depressive and two anxiety symptoms in the past 2 weeks on a 0–4 scale of “Not at all,” “A few days,” “More than half the days,” and “Nearly every day.” A sum score of 6 or greater was considered moderate to severe symptoms.¹⁶ Depressive and anxiety symptoms have been shown to relate to chronic pain outcomes.¹⁷

Negative pain coping: Negative pain coping was assessed via an agree/disagree fear avoidance item, “It’s not really safe for a person with a pain condition like mine to be physically active” and an agree/disagree catastrophizing item, “I feel that my pain is terrible, and it’s never going to get any better.” These items were adapted from the STarT Back Screening Tool and have shown prognostic relation to chronic pain outcomes.¹⁸

Activity limitations: Pain-related activity limitation was assessed with the item “Over the past 3 months, how much has pain interfered with your life activities?” with “No interference,” “Mild interference,” “Moderate interference,” or “Severe interference” response options.⁵ Health-related activity limitations (not specifically related to pain) were assessed with items adapted from the United States National Health Interview Survey that addressed four categories: 1) Participating in social or leisure activities; 2) Getting out with friends or family; 3) Doing household chores such as cooking and cleaning; and 4) Using transportation to get places you want to go, with “No, not limited at all” “Yes, limited a little,” or “Yes, limited a lot” response options.¹⁹

Long-term opioid therapy: Participants receiving at least 60 days’ supply of opioids in the three months prior to the sampling date, were identified via the EHR and defined as receiving long-term opioid therapy.²⁰

Analytic plan

The survey over-sampled Veterans with frequent use of health care for pain. To obtain unbiased estimates for the entire surveyed population, conventional weighting methods for a stratified random sample were used,²¹ obtained by dividing the number in the source population within strata (high utilizer of pain-related services versus not) by the number of survey respondents in each stratum. Convergent validity of the GCPS-R was assessed with indicators of unfavorable health status, depressive and anxiety symptoms, negative pain coping beliefs, activity limitations, and receipt of long-term opioid therapy.

Using PROC SURVEYFREQ²² for a stratified random sample, the percent of participants with unfavorable health status and chronic pain indicators by pain grade was compared, providing unbiased estimates of population percentages. Differences in percentages across pain grades were examined using chi-square tests. Sample weights were estimated and applied for unbiased estimates for the populations surveyed. SAS logistic regression, that accounted for the weighting (SURVEYLOGISTIC) and adjusted for age and gender, was used to test for differences in health indicators by pain grade. A C-statistic threshold of 0.5 was considered to be prediction no better than chance, ≥0.7 to be good prediction, and ≥0.8 to be strong prediction. Adjusted odds ratio (AOR) with 95% confidence intervals (CIs) were reported with CIs not including an AOR of 1 indicating that the difference exceeded chance.

Results

Description of study sample

Weighted and unweighted descriptive data for study participants can be found in Table 1; weighted results are presented here. Although a statistical comparison between survey responders and nonresponders was not possible, reported demographics were as expected for a VA healthcare system sample in the New England region. The majority of the sample was male (92.84%) and non-Hispanic White (84.77%). Most survey respondents were married (62.70%) and retired (54.29%). The average age was 65 years (SD = 15) with the majority of participants being 65 or older (66.75%).

Table 1.

Participant descriptive information (n = 794)

	N	%	Weighted
Age, mean (SD)	65 (15)	n/a	Mean (95% CI) 67 (66, 69)
<45	94	11.84	11.63
45–64	226	28.46	21.62
≥65	474	59.70	66.75
Gender
Female	77	9.70	7.16
Male	717	90.30	92.84
Race/Ethnicity
White	654	82.37	84.77
Black	66	8.31	4.65
Hispanic/Latino	33	4.16	4.06
Other	41	5.16	6.51
Marital status
Divorced	140	17.63	14.07
Married	467	58.82	62.70
Never married	106	13.35	10.92
Separated	17	2.14	1.69
Unknown/other	10	1.26	2.49
Widowed	54	6.80	8.13
Work status
Homemaker	5	0.63	0.78
Retired	398	50.13	54.29
Student	10	1.26	0.87
Unable	89	11.21	5.76
Unemployed	22	2.77	2.24
Working	231	29.09	30.73
Unknown/missing	39	4.91	5.32
Opioid receipt
No	708	89.17	96.37
Yes	86	10.83	3.63
Long-term opioid receipt (≥60 days’ supply of opioids in prior 3 months)a	39	45.35	44.83
Over the past 6 months, on about how many days have you had pain?b
On less than half the days	211	27.76	39.26
On more than half the days, but not every day	122	16.05	17.88
Every day, but not all the time	272	35.79	31.17
All day, every day, without break	155	20.39	11.69
In the past 3 months, how often did you have pain?b
Never	66	8.63	13.82
Some days	212	27.71	36.88
Most days	155	20.26	17.18
Every day	332	43.40	32.12
PEG, mean (SD)	14 (8)	n/a	Mean (95% CL) 11 (10,12)
Chronic Pain Grade (GCPS-R)
Grade 0: No chronic pain	278	35.01	48.44
Grade 1: Mild chronic pain	50	6.30	7.14
Grade 2: Bothersome chronic pain	206	25.94	23.34
Grade 3: High impact chronic pain	260	32.75	21.08
Depression/anxiety (PHQ-4 ≥ 6)	171	22.59	13.95
Fair/poor health (Unfavorable health status)	195	25.76	15.86
Pain-related Interference	385	50.79	35.76
Limited activitiesc
Participating in leisure/social activities	157	20.71	12.22
Getting out with friends/family	133	17.55	10.79
Doing household chores	130	17.17	10.76
Using transportation	78	10.32	7.81

^aAmong those with opioid use.

^b4% missing.

^c5% missing.

The prevalence of chronic pain among survey respondents, defined as pain on most days or every day in the prior 3 months, was 49.30%. As assessed by the GCPS-R, the prevalence of high impact chronic pain was 21.08%, bothersome chronic pain was 23.34%, and mild chronic pain was 7.14%. There was a statistically significant difference for each health status indicator by GCPS-R chronic pain grade (see Table 2).

Table 2.

Frequency and weighted percent with unfavorable indicators by GCPS-R chronic pain grade

	Grade 0: No Chronic Pain (n = 278)	Grade 1: Mild Chronic Pain (n = 50)	Grade 2: Bothersome Chronic Pain (n = 206)	Grade 3: High Impact Chronic Pain (n = 260)	χ2P value
Negative pain coping beliefs
It is not safe for a person with a pain condition like mine to be physically active (n (%) agree)	16 (3)	2 (0.3)	26 (2)	103 (9)	<.001
I feel that my pain is terrible and will never get better (n (%) agree)	19 (4)	1 (0.02)	61 (8)	166 (16)	<.001
Unfavorable health status
Self-rated health (n (%) fair or poor)	28 (3)	1 (0.3)	45 (3)	121 (9)	<.001
Elevated PHQ-4 depression/anxiety score (n (%) 6 or greater)	17 (3)	0 (0)	39 (4)	115 (7)	<.001
Activity limitations
Health limits doing household chores (n (%) limited a lot)	17 (3)	0 (0)	19 (2)	94 (7)	<.001
Health limits using transportation (n (%) limited a lot)	16 (2)	1 (0.3)	14 (1)	47 (4)	.002
Health limits leisure or social activities (n (%) limited a lot)	18 (2)	0 (0)	20 (2)	119 (9)	<.001
Health limits getting out with friends or family (n (%) limited a lot)	11 (2)	1 (0.3)	19 (2)	102 (7)	<.001
Pain medication use
Receipt of long-term opioid therapy (n (%) received ≥60 days supply of opioids in 3 months)	9 (0.4)	4 (0.1)	24 (1)	49 (2)	<.001

Bothersome and high impact chronic pain compared to no/mild chronic pain

Due to the small sample size of participants classified as having grade 1: mild chronic pain, to promote model stability for logistic regression analyses, categories of grade 0: no chronic pain and grade 1: mild chronic pain were collapsed into grade 0/1: no or mild chronic pain to increase category sample size.

Relative to persons with no/mild chronic pain, those with bothersome chronic pain were more likely to report the negative pain coping belief “I feel that my pain is terrible and will never get better” and elevated depressive/anxiety symptoms. While those with bothersome chronic pain were more likely to report pain-related activity limitations, they did not show greater likelihood of general health-related activity limitations on household chores, using transportation, leisure/social activities, or getting out with friends or family. Similarly, those with high impact chronic pain were also more likely than those with no/mild chronic pain to report the negative pain coping belief “I feel that my pain is terrible and will never get better” and elevated depressive/anxiety symptoms and, additionally, were more likely to report the negative pain coping belief “It is not safe for a person with a pain condition like mine to be physically active,” and unfavorable self-rated health status. Those with high impact chronic pain were consistently more likely to report both pain-related and general health-related activity limitations compared to those with no/mild chronic pain. Both those with bothersome chronic pain and those with high impact chronic pain were more likely to receive long-term opioid therapy compared to those with no/mild chronic pain. All models indicating significance showed good to strong prediction (C-statistics 0.72–0.88), with the exception of transportation limitation (C-statistic = 0.64) and long-term opioid receipt (C-statistic = 0.69). See Table 3.

Table 3.

Age-gender adjusted odds ratios (AOR) and 95% confidence intervals for comparison of pain-related variables between persons at different GCPS-R-determined chronic pain grades with grade 0/1: no or mild chronic pain as comparison group

	Grade 0/1: No or Mild Chronic Pain (Reference Category)	Grade 2: Bothersome Chronic Pain (Relative to Grade 0/1)	Grade 3: High Impact Chronic Pain (Relative to Grade 0/1)	C-statistic
Negative pain coping beliefs
It is not safe for a person with a pain condition like mine to be physically active (% agree)	AOR = 1.0	AOR = 0.93 (0.36–2.38)	*AOR =7.27 (3.48–15.19)	0.72
I feel that my pain is terrible and will never get better (% agree)	AOR = 1.0	*AOR = 4.02 (2.00–8.07)	*AOR = 17.38 (8.74–34.58)	0.79
Unfavorable health status
Self-rated health (% fair or poor)	AOR = 1.0	AOR =2.16 (0.99–4.71)	*AOR = 9.19 (4.63–18.24)	0.74
Elevated PHQ-4 depression/anxiety score (% 6 or greater)	AOR = 1.0	*AOR =3.79 (1.73–8.30)	*AOR = 7.15 (3.47–14.72)	0.78
Activity limitations
Pain interference with life activities (% moderate or severe)	AOR = 1.0	*AOR =5.59 (3.11–10.05)	*AOR = 38.99 (18.69–81.33)	0.88
Health limits doing household chores (% limited a lot)	AOR = 1.0	AOR =1.37 (0.51–3.69)	*AOR = 8.94 (4.12–19.42)	0.76
Health limits using transportation (% limited a lot)	AOR = 1.0	AOR =0.95 (0.32–2.81)	*AOR = 3.81 (1.68–8.68)	0.64
Health limits leisure or social activities (% limited a lot)	AOR = 1.0	AOR =1.93 (0.67–5.53)	*AOR = 18.58 (8.17–41.91)	0.78
Health limits getting out with friends or family (% limited a lot)	AOR = 1.0	AOR =1.70 (0.59–4.88)	*AOR = 12.57 (5.47–28.93)	0.78
Pain medication use
Receipt of long-term opioid therapy (% received ≥60 days’ supply of opioids in 3 months)	AOR = 1.0	*AOR = 5.85 (1.48–23.12)	*AOR = 12.29 (3.55–42.51)	0.69

High impact chronic pain compared to bothersome chronic pain

The contrast between high impact and bothersome chronic pain was greater than chance expectation for both negative pain coping beliefs (“It is not safe for a person with a pain condition like mine to be physically active;” “I feel that my pain is terrible and will never get better”) and for self-rated unfavorable health status but not for elevated depressive/anxiety symptoms (PHQ-4). The contrast was greater than chance expectation for all activity limitation items assessed (pain-related interference with life activities; and health-related limitation of household chores, transportation, leisure/social activities, getting out with friends or family), with more high impact chronic pain participants reporting significant limitation compared to those categorized as bothersome. A greater than chance difference between the two groups was not found for long-term opioid use. All models indicating significance showed good to strong prediction (C-statistics 0.71–0.88), with the exception of transportation limitation (C-statistic = 0.65). See Table 4.

Table 4.

Age-gender adjusted odds ratios (AOR) and 95% confidence intervals for comparison between respondents with grade 3: high impact chronic pain and grade 2: bothersome chronic pain on pain-related variables

	Grade 2: Bothersome Chronic Pain (Reference Category)	Grade 3: High Impact Chronic Pain (Relative to Grade 2)	C-statistic
Negative pain coping beliefs
It is not safe for a person with a pain condition like mine to be physically active (% agree)	AOR = 1.0	*AOR = 7.81 (3.43–17.78)	0.71
I feel that my pain is terrible and will never get better (% agree)	AOR = 1.0	*AOR = 4.33 (2.36–7.94)	0.79
Unfavorable health status
Self-rated health (% fair or poor)	AOR = 1.0	*AOR = 4.25 (2.16–8.34)	0.73
Elevated PHQ-4 depression/anxiety score (% 6 or greater)	AOR = 1.0	AOR = 1.89 (0.96–3.73)	0.78
Activity limitations
Pain interference with life activities (% moderate or severe)	AOR = 1.0	*AOR = 6.98 (3.48–13.99)	0.88
Health limits doing household chores (% limited a lot)	AOR = 1.0	*AOR = 6.55 (2.76–15.50)	0.76
Health limits using transportation (% limited a lot)	AOR = 1.0	*AOR = 4.04 (1.47–11.11)	0.65
Health limits leisure or social activities (% limited a lot)	AOR = 1.0	*AOR = 9.58 (4.03–22.79)	0.79
Health limits getting out with friends or family (% limited a lot)	AOR = 1.0	*AOR = 7.43 (3.09–17.84)	0.78
Pain medication use
Receipt of long-term opioid therapy (% received ≥60 days’ supply of opioids in 3 months)	AOR = 1.0	AOR = 2.10 (0.77–5.74)	0.69

Discussion

The GCPS-R provides a brief, simple method of classifying the degree of pain intensity and pain-related disability into grades of none, mild, bothersome, and high impact. The GCPS-R was previously validated in a sample of Kaiser Permanente health plan participants in the Pacific Northwest.¹¹ Here we expand the applicability by providing evidence of convergent validation in a VA-sample in the New England region. Similar to the initial validation study, this validation study in Veterans found that differences between bothersome and high impact chronic pain were consistent for activity limitations and present but not fully consistent for psychological variables, reinforcing the definition of high impact chronic pain being centered around activity limitations. Such replication of these patterns provides additional evidence in support of tailoring behavioral interventions depending on pain grade to target psychological or pain-related activity limitations. Minor differences between results of these GCPS-R validation studies may be explained by the different patient demographics and healthcare systems from which samples were drawn.

The sample for the present study was predominantly older, retired, non-Hispanic White, male, and married. While a general approximation of the characteristics of Veterans receiving care in the VA healthcare system, demographics in the current sample may not precisely mirror those of previous VA chronic pain survey samples nor all geographic regions of the United States. Use of versions of the scale in diverse populations^23,24 provides some support for widespread use of the GCPS-R. However, future work should endeavor to provide additional confirmatory evidence of the validity of the revised scale in diverse samples and further speak to generalizability at a national level for VA patients.

Potential limitations of the study should be noted. This was a cross-sectional survey that did not assess test-retest reliability or predictive validity. However, such analyses have been previously conducted with the scale or exact or similar items that make up the GCPS-R.^14,24 Although we anticipated approximately a 10% response rate based on studies using a similar approach, the 8% response rate may represent a threat to the reliability of the findings. Although the prevalence estimate of chronic pain is not substantially higher than previously reported in Veterans seeking care in VA primary care settings,²⁵ estimates may be biased due to self-selection and non-response biases. This may be the case because the survey was solely focused on chronic pain, and some Veterans without chronic pain may not have completed the survey if they did not perceive it to be relevant to them. Additionally, this study did not include a direct comparison between the original and revised GCPS, although all changes from the original scale had strong theoretical and evidence-based justification.¹¹ Due to the small number of Veterans receiving long-term opioid therapy (4.91%), we were not able to examine the association of long-term opioid therapy with chronic pain grade. Finally, due to the relatively small number of Veterans reporting mild chronic pain, it was necessary to collapse the mild chronic pain grade with no chronic pain. This meant it was not possible to compare mild to the other pain grades alone. However, the original GCPS-R validation study showed little evidence of reliable differences in depression/anxiety, perceived health status, and activity limitations between those with mild chronic pain and no chronic pain.¹¹

Conclusion

Scales assessing chronic pain should continue to evolve with new understanding of chronic pain metrics and characterization. This revised scale provides an updated, simple, and valid way to differentiate chronic pain severity based on both pain intensity and pain impact. It shows good convergent validity in both a VA sample and non-VA sample. This self-report scale, which can be used at no cost with no permissions, may be helpful in research that is informing clinical interventions in chronic pain as well as in clinical care.

Funding

None declared.

Conflicts of interest: Chloe Taub is employed by Blue Note Therapeutics, a digital therapeutics company. Robert Kerns receives an honorarium as Executive Editor of Pain Medicine. All other authors report no conflicts of interest.