Defining Pain That Does Not Interfere With Activities Among Rheumatoid Arthritis Patients

The impact of pain on daily activities in patients with idiopathic inflammatory myopathies: Report from the OMERACT myositis working group

BACKGROUND

International focus groups with patients with idiopathic inflammatory myopathies (IIM) conducted by the OMERACT Myositis Working Group over the years demonstrated the pain as an important symptom experienced by these patients. In this study, we aimed to examine the frequency and degree of pain interference, the aspects of daily life impacted by pain, and the factors associated with pain interference in adults with IIM.

METHODS

This was a prospective observational study with two visits. The patients who fulfilled the probable/definite IIM (ACR/EULAR Myositis Classification Criteria) were enrolled. Pain interference was assessed with PROMIS pain interference form (6a). Myositis core set measures and PROMIS fatigue (7a) and physical function (8b) were obtained at both visits. Logistic regression and linear mixed models were performed to assess the association between pain interference and other parameters.

RESULTS

A total of 129 patients with IIM (60 % females) were recruited from U.S., South Korea, Netherlands, Sweden, and Australia. Approximately 71 % reported pain interference. The patients in the greater pain interference group were more likely to be female, had significantly worse patient/physician global disease activity, fatigue, and physical function than those in the lower pain interference group. The most commonly impacted life aspect was household chores. Manual muscle testing, patient/physician global disease activity, fatigue, and physical function were all significantly associated with pain interference score >60.

CONCLUSION

The majority of the patients with IIM experience the impact of pain on their daily activities, particularly household chores. Myositis disease activity, duration, and subtype could be associated with greater pain interference.

The use of PROMIS measures in clinical studies in patients with inflammatory arthritis: a systematic review

PURPOSE

Although the use of Patient-Reported Outcomes Measurement Information System (PROMIS) measures is widely advocated, little is known on their use in patients with inflammatory arthritis. We systematically describe the use and outcomes of PROMIS measures in clinical studies involving people with rheumatoid arthritis (RA) or axial spondyloarthritis (axSpA).

METHODS

A systematic review was conducted according to the PRISMA guidelines. Through a systematic search of nine electronic databases, clinical studies including patients with RA or axSpA and reporting the use of PROMIS measure were selected. Study characteristics, details of PROMIS measures and their outcomes, if available, were extracted.

RESULTS

In total, 29 studies described in 40 articles met the inclusion criteria, of which 25 studies included RA patients, three studies included axSpA patients and one study included both RA and axSpA patients. The use of two general PROMIS measures (PROMIS Global Health, PROMIS-29) and 13 different domain-specific PROMIS measures was reported, of which the PROMIS Pain Interference (n = 17), Physical Function (n = 14), Fatigue (n = 13), and Depression (n = 12) measures were most frequently used. Twenty-one studies reported their results in terms of T-scores. Most T-scores were worse than the general population mean, indicating impairments of health status. Eight studies did not report actual data but rather measurement properties of the PROMIS measures.

CONCLUSION

There was considerable variety regarding the different PROMIS measures used, with the PROMIS Pain interference, Physical function, Fatigue, and Depression measures being the most frequently used. In order to facilitate the comparisons across studies, more standardization of the selection of PROMIS measures is needed.

Researchers in rheumatology should avoid categorization of continuous predictor variables

BACKGROUND

Rheumatology researchers often categorize continuous predictor variables. We aimed to show how this practice may alter results from observational studies in rheumatology.

METHODS

We conducted and compared the results of two analyses of the association between our predictor variable (percentage change in body mass index [BMI] from baseline to four years) and two outcome variable domains of structure and pain in knee and hip osteoarthritis. These two outcome variable domains covered 26 different outcomes for knee and hip combined. In the first analysis (categorical analysis), percentage change in BMI was categorized as ≥ 5% decrease in BMI, < 5% change in BMI, and ≥ 5% increase in BMI, while in the second analysis (continuous analysis), it was left as a continuous variable. In both analyses (categorical and continuous), we used generalized estimating equations with a logistic link function to investigate the association between the percentage change in BMI and the outcomes.

RESULTS

For eight of the 26 investigated outcomes (31%), the results from the categorical analyses were different from the results from the continuous analyses. These differences were of three types: 1) for six of these eight outcomes, while the continuous analyses revealed associations in both directions (i.e., a decrease in BMI had one effect, while an increase in BMI had the opposite effect), the categorical analyses showed associations only in one direction of BMI change, not both; 2) for another one of these eight outcomes, the categorical analyses suggested an association with change in BMI, while this association was not shown in the continuous analyses (this is potentially a false positive association); 3) for the last of the eight outcomes, the continuous analyses suggested an association of change in BMI, while this association was not shown in the categorical analyses (this is potentially a false negative association).

CONCLUSIONS

Categorization of continuous predictor variables alters the results of analyses and could lead to different conclusions; therefore, researchers in rheumatology should avoid it.

Correlation of self-reported pain severity and healthcare expenditures in older United States adults

OBJECTIVES

Healthcare expenditures of older United States (US) adults with different pain severity levels are important to investigate given the increasing prevalence of pain in this population. This study assessed the correlation of healthcare expenditures among older US adults with different pain severities, hypothesizing that expenditures would increase as pain severity increased.

METHODS

This retrospective cross-sectional database study used 2018 Medical Expenditure Panel Survey (MEPS) data and included US adults aged ≥50 with self-reported pain in the past four weeks and positive healthcare costs. Adjusted linear regression models with logarithmically transformed expenditure data compared differences in: total; office-based; outpatient; emergency room; inpatient; other; and prescription medication expenditures, between those with little, moderate, quite a bit, and extreme pain. Analyses were weighted to account for the complex MEPS design and to obtain nationally representative estimates. The a priori alpha level was 0.05.

RESULTS

The eligible sample of 5,123 individuals produced a weighted study population of 57,134,711 US adults aged ≥50 with pain (little = 53.1%, moderate = 21.6%, quite-a-bit = 18.5%, extreme = 6.8%). In adjusted linear regression models, compared to little pain, extreme pain had the greatest level of costs, followed by quite a bit pain and moderate pain, for total, office-based, and prescription medication costs. For instance, compared to little pain, total healthcare costs were 78% greater for those with extreme pain, 51% greater for quite a bit pain, and 37% greater for moderate pain. However, this pattern was not observed for outpatient, emergency room, inpatient, and other costs, where ≥1 comparison for each cost category was not statistically significant.

CONCLUSIONS

This study found total healthcare costs increased as pain severity increased, yet this was not always the case when analyzing subcategories of healthcare costs. Further research is needed to investigate why some types of healthcare costs are greater with increasing pain severity, yet others are not.

Estimation of Minimally Important Differences and Patient Acceptable Symptom State Scores for the Patient-Reported Outcomes Measurement Information System Pain Interference Short Form in Rheumatoid Arthritis

OBJECTIVE

Studies have supported the validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference (PI) scale in rheumatoid arthritis (RA). Here, we characterize minimally important differences (MIDs) and patient acceptable symptom state (PASS) values.

METHODS

PROMIS PI scores were collected in four periods at 6-month intervals from patients with RA (n > 3200 per period). Both anchor- and distribution-based methods estimated MIDs. Anchors were pain comparisons, pain interference, and general health. Time responses for each anchor-response group (four administrations, each with three change periods) were averaged. The mean changes of the "somewhat worse" and "somewhat better" groups were used as estimates for MID for worsening and improvement, respectively. Distribution-based MID analyses used standardized error of measurement (SEM) and SD. PASS was estimated with the question "If your health was to remain for the rest of your life as it has been in the past 48 hours, would this be acceptable?" MIDs and PASS values were also estimated by baseline pain levels.

RESULTS

Anchor-based methods yielded estimates of 1.65 to 1.84 for worsening and -1.29 to -1.73 for improvement. The SEM estimate was 1.84. The PASS estimate for the entire group was 41.6. Substantial differences in MIDs and PASS were noted among baseline pain groups.

CONCLUSION

The best estimate of a group-level MID was approximately 2 points, similar to MIDs suggested in other conditions. The PASS value for the entire group was almost an SD better than the population mean. Results should enhance use of PROMIS PI in RA by facilitating interpretation of scores and changes.