Journal of Clinical Oncology, Vol 21, Issue 16
(August), 2003: 3178-3179
© 2003 American Society for Clinical Oncology
What Do Global Quality-of-Life Questions Really Measure? Insights From Hobday et al and the "Do Something" Rule
David Cella
Northwestern University, Evanston, IL
To the Editor: I read with great interest the report of Hobday et al1 in the December 1, 2002 issue of the Journal of Clinical Oncology, because it sheds light on the important question of what is being measured when a patient is asked to provide a single overall evaluation of quality of life. Using the European Organization for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire and the Spitzer Uniscale, this study compared the on-treatment scores of responding versus nonresponding patients. Inclusion of both instruments in one trial allowed the opportunity to evaluate two global ratings of quality of life (one from the Uniscale and one from the EORTC questionnaire) and compare them with several component scores on the EORTC questionnaire, covering a range of physical and emotional symptoms. By study design, all patients had undergone one tumor measurement (after one cycle) before completion of the first follow-up quality-of-life assessment (after two cycles). Therefore, unless patients were not allowed to access information about their first tumor measurement (available after one cycle of therapy), one assumes some patient knowledge of early radiographic data at the precycle 3 assessment. Why is this important? Cancer therapy is a highly emotionally charged, life and death enterprise. Patients feel relieved and hopeful after starting therapy. Any hopeful sign, including a statement of stable or responding disease, may promote an optimism already wired into the oncology treatment setting. Even if in some way patients were kept blind to the first radiographic follow-up, there is a predictable inflation of emotional well-being shown by patients during therapy when compared with that of the same patients at baseline. I will refer to this as the "do something" rule: that doing something to treat the cancer in and of itself makes people feel better, mostly in the emotional domain.
Indeed, this is exactly what Hobday et al1 observed (refer to Table 4): emotional functioning was significantly improved in the entire cohort of patients when comparing baseline data with first follow-up data. Emotional functioning was the only end point of 16 reported that showed improvement in the entire group of patients. This in itself is not surprising (after all, they "did something"), but it is noteworthy in that it sets a bar against which one can compare other end points that are more or less susceptible to the general positive impact we observe when we treat cancer with something, even if this something is not measurably effective beyond the "do something" rule. One could then set emotional functioning as the standard of background (from the perspective of the trialist seeking an answer regarding treatment efficacy) benefit. Predictably, the emotional functioning of patients who respond to therapy is significantly better (recall that tumor measurements occurred in the cycle before the assessment). Importantly, yet not predictably (and this is the primary reason for my letter), the only other two end points of 16 studied that showed significant improvement during therapy among the responding cohort of patients were the global ratings of quality of life. It therefore seems that these ratings bear more in common with emotional functioning than the other 13 end points from the EORTC questionnaire. I suggest this argues against selecting global quality-of-life ratings as the primary end point in clinical trials, especially in studies with no control group.
As a side note, there are two apparent errors in the report that might benefit from correction. First, in Table 4, the EORTC "Diarrhea" data seem implausible inasmuch as the overall group average is higher than the averages of either subgroup. Also, on 4575, column 2, a 10-point change is described as two standard deviations (SDs), and I suspect that this is actually intended to be 0.5 SD.
REFERENCE
1. Hobday TJ, Kugler JW, Mahoney MR, et al: Efficacy and quality-of-life data are related in a phase II trial of oral chemotherapy in previously untreated patients with metastatic colorectal carcinoma. J Clin Oncol 20:4574–4580, 2002[Abstract/Free Full Text]
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