psychometrics – American ME and CFS Society

Comparing Frequency and Severity Ratings for ME/CFS versus Controls

Abstract:

Most questionnaires for somatic symptoms focus on occurrence, frequency, or severity, and in doing so, they might not be able to comprehensively assess the burden that symptoms present to patients. For example, a symptom might occur at a high frequency but only a minimal severity, so that it is less likely to be a burden on a patient; whereas a symptom that has both a high frequency and severity is more likely to be negatively impacting a patient.

Study 1 examined frequency and severity scores for classic Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) symptoms among patients with ME/CFS versus a control group. Findings in Study 1 indicate there were more frequency/severity discrepancies for individuals with ME/CFS versus the control group. Study 1 concluded that collecting data on both measures of symptom burden provides unique indicators that can better assess the burden of the symptoms on patients.

In a separate data set, Study 2 reported reliability data on slight differences in the time period and the way the severity was assessed. Study 2 findings indicated high levels of reliability for these changes in the time period and the way questions were asked. These studies provide important psychometric properties that could lead to more reliable and valid assessments of patients with post-viral illnesses.

Source: Jason LA, Benner S, Hansel N. Comparing Frequency and Severity Ratings for ME/CFS versus Controls. Psych. 2023; 5(3):662-669. https://doi.org/10.3390/psych5030042 https://www.mdpi.com/2624-8611/5/3/42 (Full text)

Assessing sleep and pain among adults with myalgic encephalomyelitis/chronic fatigue syndrome: psychometric evaluation of the PROMIS® sleep and pain short forms

Abstract:

Purpose: To evaluate the psychometric properties of the patient-reported outcome measurement information system® (PROMIS) short forms for assessing sleep disturbance, sleep-related impairment, pain interference, and pain behavior, among adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Methods: Data came from the Multi-Site ME/CFS study conducted between 2012 and 2020 at seven ME/CFS specialty clinics across the USA. Baseline and follow-up data from ME/CFS and healthy control (HC) groups were used to examine ceiling/floor effects, internal consistency reliability, differential item functioning (DIF), known-groups validity, and responsiveness.

Results: A total of 945 participants completed the baseline assessment (602 ME/CFS and 338 HC) and 441 ME/CFS also completed the follow-up. The baseline mean T-scores of PROMIS sleep and pain measures ranged from 57.68 to 62.40, about one standard deviation above the national norm (T-score = 50). All four measures showed high internal consistency (ω = 0.92 to 0.97) and no substantial floor/ceiling effects. No DIF was detected by age or sex. Known-groups comparisons among ME/CFS groups with low, medium, and high functional impairment showed significant small-sized differences in scores (η² = 0.01 to 0.05) for the two sleep measures and small-to-medium-sized differences (η² = 0.01 to 0.15) for the two pain measures. ME/CFS participants had significantly worse scores than HC (η² = 0.35 to 0.45) for all four measures. Given the non-interventional nature of the study, responsiveness was evaluated as sensitivity to change over time and the pain interference measure showed an acceptable sensitivity.

Conclusion: The PROMIS sleep and pain measures demonstrated satisfactory psychometric properties supporting their use in ME/CFS research and clinical practice.

Source: Yang M, Keller S, Lin JS. Assessing sleep and pain among adults with myalgic encephalomyelitis/chronic fatigue syndrome: psychometric evaluation of the PROMIS® sleep and pain short forms. Qual Life Res. 2022 Jul 27. doi: 10.1007/s11136-022-03199-8. Epub ahead of print. PMID: 35896905. https://pubmed.ncbi.nlm.nih.gov/35896905/

The assessment of fatigue: Psychometric qualities and norms for the Checklist individual strength

Abstract:

OBJECTIVE: The Checklist Individual Strength (CIS) measures four dimensions of fatigue: Fatigue severity, concentration problems, reduced motivation and activity. On the fatigue severity subscale, a cut-off score of 35 is used. This study 1) investigated the psychometric qualities of the CIS; 2) validated the cut-off score for severe fatigue and 3) provided norms.

METHODS: Representatives of the Dutch general population (n=2288) completed the CIS. The factor structure was investigated using an exploratory factor analysis. Internal consistency and test-retest reliability were determined. Concurrent validity was assessed in two additional samples by correlating the CIS with other fatigue scales (Chalder Fatigue Questionnaire, MOS Short form-36 Vitality subscale, EORTC QLQ-C30 fatigue subscale). To validate the fatigue severity cut-off score, a Receiver Operating Characteristics analysis was performed with patients referred to a chronic fatigue treatment centre (n=5243) and a healthy group (n=1906). Norm scores for CIS subscales were calculated for the general population, patients with chronic fatigue syndrome (CFS; n=1407) and eight groups with other medical conditions (n=1411).

RESULTS: The original four-factor structure of the CIS was replicated. Internal consistency (α=0.84-0.95) and test-retest reliability (r=0.74-0.86) of the subscales were high. Correlations with other fatigue scales were moderate to high. The 35 points cut-off score for severe fatigue is appropriate, but, given the 17% false positive rate, should be adjusted to 40 for research in CFS.

CONCLUSION: The CIS is a valid and reliable tool for the assessment of fatigue, with a validated cut-off score for severe fatigue that can be used in clinical practice.

Source: Worm-Smeitink M, Gielissen M, Bloot L, van Laarhoven HWM, van Engelen BGM, van Riel P, Bleijenberg G, Nikolaus S, Knoop H. The assessment of fatigue: Psychometric qualities and norms for the Checklist individual strength. J Psychosom Res. 2017 Jul;98:40-46. doi: 10.1016/j.jpsychores.2017.05.007. Epub 2017 May 8. https://www.ncbi.nlm.nih.gov/pubmed/28554371

Assessment of activity limitations and participation restrictions with persons with chronic fatigue syndrome: a systematic review

Abstract:

PURPOSE: To summarize measurement instruments used to evaluate activity limitations and participation restrictions in patients with chronic fatigue syndrome (CFS) and review the psychometric properties of these instruments.

METHOD: General information of all included measurement instruments was extracted. The methodological quality was evaluated using the COSMIN checklist. Results of the measurement properties were rated based on the quality criteria of Terwee et al. Finally, overall quality was defined per psychometric property and measurement instrument by use of the quality criteria by Schellingerhout et al.

RESULTS: A total of 68 articles were identified of which eight evaluated the psychometric properties of a measurement instrument assessing activity limitations and participation restrictions. One disease-specific and 37 generic measurement instruments were found. Limited evidence was found for the psychometric properties and clinical usability of these instruments. However, the CFS-activities and participation questionnaire (APQ) is a disease-specific instrument with moderate content and construct validity.

CONCLUSION: The psychometric properties of the reviewed measurement instruments to evaluate activity limitations and participation restrictions are not sufficiently evaluated. Future research is needed to evaluate the psychometric properties of the measurement instruments, including the other properties of the CFS-APQ. If it is necessary to use a measurement instrument, the CFS-APQ is recommended.

IMPLICATIONS FOR REHABILITATION: Chronic fatigue syndrome (CFS). Chronic fatigue syndrome causes activity limitations and participation restrictions in one or more areas of life. Standardized, reliable and valid measurement instruments are necessary to identify these limitations and restrictions. Currently, no measurement instrument is sufficiently evaluated with persons with CFS. If a measurement instrument is needed to identify activity limitations and participation restrictions with persons with CFS, it is recommended to use the CFS-APQ in clinical practice and scientific research.

Source: Vergauwen K, Huijnen IP, Kos D, Van de Velde D, van Eupen I, Meeus M. Assessment of activity limitations and participation restrictions with persons with chronic fatigue syndrome: a systematic review. Disabil Rehabil. 2015;37(19):1706-16. doi: 10.3109/09638288.2014.978507. Epub 2014 Nov 3.https://www.ncbi.nlm.nih.gov/pubmed/25365699

Psychometric properties of the Dutch Chronic Fatigue Syndrome–Activities and Participation Questionnaire (CFS-APQ)

Abstract:

BACKGROUND AND PURPOSE: The Chronic Fatigue Syndrome-Activities and Participation Questionnaire (CFS-APQ) is a recently developed disease-specific assessment tool for monitoring activity limitations and participation restrictions in patients with chronic fatigue syndrome (CFS). In this study, the convergent validity, content validity, and test-retest reliability of data obtained with the Dutch-language version of the questionnaire were examined.

SUBJECTS AND METHODS: One hundred eleven consecutive patients with CFS were enrolled, of whom 47 fulfilled all inclusion criteria. The subjects were first asked to rate their pain, fatigue, and ability to concentrate using 3 visual analog scales, to list at least 5 activities that had become difficult to perform due to their complaints, and to complete the CFS-APQ. Furthermore, subjects were asked to complete a modified version of the CFS-APQ at home and return it to the investigators. The content of the questionnaire was reviewed using the World Health Organization’s International Classification of Impairments, Disability and Health (ICIDH) beta II draft. Spearman rank correlation coefficients (R) were used for the convergent validity analysis, and intraclass correlation coefficients were computed for the assessment of the test-retest data.

RESULTS: Overall scores on the CFS-APQ correlated with the scores from the visual analog scales for pain (R=.51, P<.001) and fatigue (R=.50, P<.001). The majority of the responses (157 out of 183 answers [85.8%]) to the request to “list difficult activities” matched the content of the CFS-APQ. Using the ICIDH beta II draft, 21 out of 26 questions were found to address activities, and the remaining 5 questions measured the participation level. The Cronbach alpha coefficient was.94, and intraclass correlation coefficients for test-retest reliability of the overall scores were >or= .95 (P<.001).

DISCUSSION AND CONCLUSION: The results substantiate the convergent validity, content validity, and reliability of the CFS-APQ scores for patients with CFS.

Source: Nijs J, Vaes P, McGregor N, Van Hoof E, De Meirleir K. Psychometric properties of the Dutch Chronic Fatigue Syndrome–Activities and Participation Questionnaire (CFS-APQ). Phys Ther. 2003 May;83(5):444-54. http://ptjournal.apta.org/content/83/5/444.long (Full article)

The development of the Chronic Fatigue Syndrome Attitudes Test. A psychometric analysis

Abstract:

Chronic Fatigue Syndrome (CFS) is characterized by debilitating symptoms including persistent or relapsing fatigue. As a result of CFS, some individuals experience significant stigma that is attached to this illness. Many medical professionals are skeptical of the validity of the illness, and employers often fail to appreciate the seriousness of the symptoms. Although negative attitudes greatly affect the lives of individuals with CFS, there is presently no measurement of attitudes toward this illness and people who have CFS. The purpose of the present studies was to create a scale that measures attitudes toward individuals with CFS–the Chronic Fatigue Attitudes Test (CAT)–and to assess the scale’s reliability and validity. The 13-item scale was created using several constructs outlined in the literature regarding negative attitudes toward people with CFS, disabilities, and AIDS. Theoretical implications of the findings and the utility of the CAT are discussed.

Source: Shlaes JL, Jason LA, Ferrari JR. The development of the Chronic Fatigue Syndrome Attitudes Test. A psychometric analysis. Eval Health Prof. 1999 Dec;22(4):442-65. http://www.ncbi.nlm.nih.gov/pubmed/10623400