Lack of Congruence Among Tools Used to Assess Cancer-Related Cognitive Dysfunction
THE ASSESSMENT of cognitive dysfunction in patients who have undergone chemotherapy is complex, and although a number of strategies are available, each has its limitations, according to Karin Olson, RN, PhD, Professor in the Faculty of Nursing at the University of Alberta, Edmonton, Canada.
Karin Olson, RN, PhD
At the 2018 Multinational Association of Supportive Care in Cancer (MASCC)/International Society of Oral Oncology (ISOO) Annual Meeting in Vienna, Dr. Olson discussed the currently available approaches to assessing cognition among adult patients with cancer and how some tools might be improved in order to better assess cognitive changes after cancer treatment.1
How Do Patients Describe Cognitive Changes?
COGNITION IS defined as a process comprising eight domains: attention, concentration, information-processing speed, memory, language, executive function, visuospatial ability, and psychomotor ability. Cognitive function (sometimes referred to as intellectual function) is the ability of the brain to acquire, process, store, and retrieve information.
Cognitive changes are often explained in the context of fatigue. Patients typically describe their fatigue as having several components, including difficulty thinking clearly, emotional lability (exaggerated changes in mood), social withdrawal, decreased functional ability, and decreased sleep quality.
According to Dr. Olson, patients who are tired often say they are “forgetful” or “not sharp.” Patients with fatigue often say they “can’t concentrate,” whereas those with cognitive changes beyond fatigue tend to say they are “confused.”
DESPITE PERCEIVED changes in cognition, testing for cognitive changes using standardized assessment tools has historically returned negative results.
“Part of the problem we face in symptom management is that the clinical issues we deal with are complex, so it’s hard to represent them in a way that’s comprehensive,” she said. “Additionally, baseline data are not typically collected in these patients, so it’s hard to know whether the changes were there prior to diagnosis or treatment.”
Many of the tests currently available, including screening, subjective/objective assessment, and imaging approaches, test across a variety of cognitive domains but still raise questions about whether these tools are sufficiently sensitive to detect subtle changes in cognition. Some of the cognitive screening tools available include the Mini-Mental State Examination, the Mini-Cog, and the Montreal Cognitive Assessment. These tests are not diagnostic, but positive results indicate that further follow-up is needed.
“I think we need to worry less about the [type of] testing and more about the distress of our patients and what we’re going to do about it.”— Karin Olson, RN, PhD
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According to Dr. Olson, the Mini-Mental State Examination has demonstrated a poor ability to detect mild cognitive impairment compared to clinical assessment, and the Mini-Cog was validated against the Mini-Mental State Examination, a tool with established low validity. In contrast, the Montreal Cognitive Assessment has 90% sensitivity and 87% specificity compared to clinical judgment but does not assess the domain of processing speed, “an important element of cognition,” she noted.
Subjective tests such as the Functional Assessment of Cancer Therapy (FACT)-Cog are available in many languages, but they often present with a host of correlation and validation issues. Additionally, the use of some tests—particularly standardized neuropsychological tests and imaging—require highly trained professional staff and are too time- and labor-intensive for inclusion in busy clinical settings.
“The point is, these cognitive changes are associated with significant distress,” she noted. “I think we need to worry less about the [type of ] testing and more about the distress of our patients and what we’re going to do about it.”
Lack of Congruence Among Studies
DR. OLSON and her colleagues conducted a scoping review to assess cognitive function in adults during or following chemotherapy and published their research in Supportive Care in Cancer.2 They evaluated studies that included at least seven of the eight domains of cognition in adults at least 18 years of age who were receiving chemotherapy or had received chemotherapy in the past. Studies that included noncancer patients or patients with dementia, brain metastases, or other injuries were excluded.
The investigators searched Medline, PsycINFO, Scopus, Web of Science, and the Social Sciences Citation Index from inception to February 2013, with key data updated to May 2018. After removing 268 articles that did not meet inclusion criteria, the scoping review included 11 articles that utilized screening, subjective assessment, objective assessment, and imaging approaches.
Dr. Olson reported that the studies were difficult to compare due to the variety of tools used, as well as differences in the type of cancer, age, gender, and study design (mostly cross-sectional).
EIGHT DOMAINS OF COGNITION
- Information-processing speed
- Executive function
- Visuospatial ability
- Psychomotor ability
“We had hoped that by including only studies with measurements of at least seven dimensions of cognition, the congruence between objective and subjective measures would be higher, but this was not the case,” she said.
According to Dr. Olson, several methodologic issues contributed to the lack of congruence, including a lack of patient self-assessment, a lack of baseline data for comparison, protocols too long for inclusion in a clinical setting, and no distinction between the cognitive domains of attention and concentration.
Improving the Screening Tools Available
THE INTERNATIONAL Cognition and Cancer Task Force (ICCTF) recommendations focus on four key dimensions of cognition that are most vulnerable to the adverse effects of chemotherapy: learning, memory, executive function, and processing speed. The recommended tests for assessing these various functions include the Hopkins Verbal Learning Test–Revised (for learning and memory), Trail Making Test (for executive function and processing speed), and Controlled Oral Word Association Test (for executive function).
Dr. Olson recommends screening using the ICCTF recommendations in order to identify those patients who need follow-up, but with a slight variation. She suggests developing one screening question for each of the four ICCTF dimensions, validating them by comparing the results to patients’ perceptions of their cognitive changes, and referring necessary patients for follow-up with the aforementioned validated tools.
Suggested screening questions to compare with prediagnosis status might include:
- Learning: Do you have more trouble learning new things?
- Memory: Do you have more trouble remembering things?
- Executive function: Do you have more trouble making decisions? Do you have trouble finding the words you want to use?
- Processing speed: Does it take you longer to solve problems?
Importantly, she added, take baseline measurements for comparison; stratify for age and gender; and control for possible confounders that patients with cancer often face, such as depression, fatigue, dementia, and anxiety. “This can help minimize the overtasking of resources in our cancer centers,” she said. ■
DISCLOSURE: Dr. Olson reported no conflicts of interest.
1. Olson K: Measurement of cognitive dysfunction (adult). 2018 Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology International Symposium on Supportive Care in Cancer. Invited lecture. Presented June 30, 2018.
2. Olson K, Hewit J, Slater LG, et al: Assessing cognitive function in adults during or following chemotherapy: A scoping review. Support Care Cancer 24:3223-3234, 2016.