Operationalizing Substantial Reduction in Functioning Among Young Adults with Chronic Fatigue Syndrome, 2018, Jason et al

Andy · Jun 6, 2018

Abstract
Purpose

Chronic fatigue syndrome and myalgic encephalomyelitis are fatiguing illnesses that often result in long-term impairment in daily functioning. In reviewing case definitions, Thrope et al. (Fatigue 4(3):175–188, 2016) noted that the vast majority of case definitions used to describe these illnesses list a “substantial reduction” in activities as a required feature for diagnosis. However, there is no consensus on how to best operationalize the criterion of substantial reduction.

Method
The present study used a series of receiver operating curve (ROC) analyses to explore the use of the Medical Outcomes Study Short-Form-36 Health Survey (SF-36), designed by Ware and Shelbourne for operationalizing the substantial reduction criterion in a young adult population (18–29 years old). We compared the sensitivity and specificity of various cutoff scores for the SF-36 subscales and assessed their usefulness in discriminating between a group of young adults with a known diagnosis of chronic fatigue syndrome or myalgic encephalomyelitis (n = 98) versus those without that diagnosis (n = 272).

Results
The four top performing subscales and their associated cutoffs were determined: Physical Functioning ≤ 80, General Health ≤ 47, Role Physical ≤ 25, and Social Functioning ≤ 50. Used in combination, these four cutoff scores were shown to reliably discriminate between the patients and controls in our sample of young adults.

Conclusion
The implications of these findings for employing the substantial reduction criterion in both clinical and research settings are discussed.
Click to expand...

Paywalled at https://link.springer.com/article/10.1007/s12529-018-9732-1

Indigophoton · Jun 6, 2018

Full paper, http://sci-hub.tw/10.1007/s12529-018-9732-1

Dolphin · Aug 9, 2018

Results
The four top performing subscales and their associated cutoffs were determined: Physical Functioning ≤ 80, General Health ≤ 47, Role Physical ≤ 25, and Social Functioning ≤ 50. Used in combination, these four cutoff scores were shown to reliably discriminate between the patients and controls in our sample of young adults.
Click to expand...

The abstract doesn't make clear that they found that requiring three out of four of these yielded the best result when weighing sensitivity and specificity equally.

And requiring two out of the four and even one out the four was still a lot better than requiring all four of the four.

Requiring all four of the four did have 100% specificity but only a sensitivity of 81.6%.

Dolphin · Aug 9, 2018

The majority of case definitions specify "substantial reduction in activity" as a key characteristic of the ME or CFS illness, making it one of the few criteria that remain consistent across case definitions.

[..]

assessing previous activity levels continues to be a challenge as more often than not pre-illness data are not available

[..]

While this approach may prove sufficient for patients who have developed an ongoing rapport with their practitioner prior to the development of illness, one study found that 71% of patients saw four or more doctors before they were able to receive a diagnosis [8], making it unlikely that many patients will have a single physician capable of assessing a 50% reduction in activity over time.
Click to expand...

Dolphin · Aug 9, 2018

The two remaining subscales (Mental Health Functioning = 0.573 and Role Emotional = 0.470) had AUCs and accompanying confidence intervals that suggested these scales performed no better than chance at discriminating between young adults with CFS and those without.
Click to expand...

Furthermore, the ROC findings indicated that the SF-36 subscales that assessed for impairment as a result of mental health issues (Mental Health Functioning and Role Emotional) were no better than chance at discriminating between known patients and controls in our sample. This underscores the physical nature of the impairment associated with the ME and CFS and fits with previous data that questioned the accuracy the Role Emotional component of the SF-36 in measuring substantial reduction [14, 16].
Click to expand...

Dolphin · Aug 9, 2018

A discussion about how criteria used clinically don't necessarily have to be the same as those used in research.

While the present study employed the Youden Index to assess for the best balance between sensitivity and specificity, decisions on whether cutoff scores should place a higher priority on including true positives or on excluding false positives can be highly dependent on the intended purpose of the diagnostic grouping. In a clinical setting, one may wish to prioritize sensitivity, ensuring that the maximum number of potential patients is identified, with less concern placed on limiting over-inclusivity and false positives. When using the SF-36 to determine substantial reduction in young adults for clinical purposes, the recommendations outlined in this article may be loosened by increasing one or more cutoff values or by reducing the number of scales required to meet the substantial reduction criterion. However, in research settings, high levels of specificity may be more important to ensure that studies minimize the number of false positives. Including unacceptably high levels of non-patients in patient samples would result in skewed findings. Indeed, Jason, McManimen, Sunnquist, Newton, and Strand [32] have recommended that the field move towards developing a research case definition that would be less inclusive than most of the currently available clinical case definitions. Retaining strict cut-point standards for research purposes, thus prioritizing specificity, would ensure greater homogeneity among patient samples by excluding more false positives. Homogeneous or "pure" samples, containing a minimum of falsely identified individuals as "patients," would reduce bias and aid in overall efforts to specify the etiology and effectiveness of treatment for this illness.
Click to expand...

Dolphin · Aug 9, 2018

Sensitivity represents the probability that the scale correctly identifies patients as having CFS. Specificity represents the probability that the scale correctly identifies controls as NOT having CFS.
Click to expand...

Log in or Sign up

Operationalizing Substantial Reduction in Functioning Among Young Adults with Chronic Fatigue Syndrome, 2018, Jason et al

Andy Committee Member

Indigophoton Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Share This Page

Log in or Sign up

Operationalizing Substantial Reduction in Functioning Among Young Adults with Chronic Fatigue Syndrome, 2018, Jason et al

Andy Committee Member

Indigophoton Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Dolphin Senior Member (Voting Rights)

Share This Page

Useful Searches