Performance Status: In the Eye of the Beholder?

Low performance status (PS) scores, as measured by a scoring system like the Eastern Cooperative Oncology Group (ECOG) scale, can influence treatment decisions. For instance, the cutoff points between ECOG PS 1(“restricted but ambulatory”) and 2 (“ambulatory but unable to work”) or between PS levels 2 and 3 (“capable of limited self-care, confined to bed more than 50% of waking hours”) are routinely used to select patients for participating in clinical trials, say researchers from the cancer center at St. James’s Hospital in Dublin, Ireland.

Performance status scoring tends to be lower in older patients with cancer, the researchers note. Good PS is associated with a better response to treatment and quality of life; poor PS with fatigue and a higher risk of treatment-related toxicity. However, they question whether patients are being categorized correctly. Thus, the researchers designed a study to, first, find out whether the ECOG score and/or physical activity (PA) had any relationship to a patient’s age. Second, they would compare those measures to subjective PA as estimated by the International Physical Activity Questionnaire (IPAQ).

In the study, 100 patients with treatment-naïve cancer wore an accelerometer (a motion sensor that registers acceleration of limbs and trunk) continuously during waking hours for about 6 days, except when bathing or swimming. During the initial evaluation, the physicians assigned the ECOG PS, and the patients completed the IPAQ to determine their PA. Seventy-five patients were aged < 65 years, 25 patients were aged ≥ 65 years, and 2 were aged ≥ 80 years. The older patients had significantly higher comorbidity scores.

Eighty-nine percent of the patients were assigned a good PS score, but patients of all ages spent a “striking” amount of their time resting, according to the accelerometry. Resting time increased with worsening assigned PS. Only 17 patients spent > 50% of their waking hours in any activity, however light; all were assigned an ECOG score of 0 or 1. Notably, of those patients, 4 were aged ≥ 65 years.

Despite higher comorbidity scores, the older cohort was no less active than the younger cohort, the researchers say. However, that was not reflected in the PS scoring. In fact, the researchers say, there was a trend among the group assigned a PS of 0 for the patients aged ≥ 65 years to being less sedentary than were younger patients.

Does that mean the PS scores the physicians assigned were wrong? Actually, the researchers do not dismiss the “subtle concept of physician judgment.” They say it is probably more related to PS measuring something different from physical activity (as evidenced by the low correlation between those variables). As they put it, PS may be considered more a measure of what you could potentially do and PA a measure of what you are doing. Health care professionals may expect higher levels of PA in younger patients and those with fewer comorbidities and, therefore, assign them better PS scores.

Their study raises interesting questions, they believe, about how we assess fitness for cancer therapy in a sedentary society—and whether physician expectations about patients’ activity levels influence their PS scores. Objective PA measures might help select fit elderly patients, they suggest, who could tolerate intensive treatment well.

Source
Broderick JM, Hussey J, Kennedy MJ, O’ Donnell DM. J Geriatr Oncol. 2014;5(1):49-56.
doi: 10.1016/j.jgo.2013.07.010.