Table 4.

Factors Likely to Affect Patient-Reported Outcomes (PROs)

Factors Affecting Assessment	Duration of Working Effect	Construct Affected	Implicated Mechanism of Action	Possible Measures to Balance Bias
Response shift	Over time	Quality of life	Internal dynamics of adaptation to disease (recalibration/reprioritization/ reconceptualization)	Model to account for that effect (then-test)
Significant life events	Fluctuating in waves	Quality of life Symptoms burden	Social and familial dynamics	Correlation with life changes
Timing of assessments	Transient	Quality of life Symptoms burden	Anxiety and worries	Avoiding questionnaire completion in proximity of known emotional times
Location of tumor	Over time	Quality of life Symptoms burden	Judgment and mood may be impaired in frontal tumors	Subgroup analysis
Cognitive decline	Over time	Quality of life Symptoms burden	An interplay of factors may hamper assessment	Subgroup analysis