Table 2. Overview of evaluated PRO instruments in advanced-stage GC: characteristics and psychometric evidence.

	EORTC QLQ-C30	EORTC QLQ-STO22	FACT-G	FACT-Ga	MDASI-GI
Concepts measured	Function (five subscales: physical, role, cognitive, emotional, and social) five symptoms (fatigue, nausea or vomiting, pain, dyspnea, diarrhoea), global health status and QOL, and financial impact	Symptoms: Dysphagia (four items) Pain or discomfort (three items) Upper GI symptoms (three items) Eating restrictions (five items) Emotional (three items) Dry mouth, hair loss, and body image	Physical well-being (seven items); social/ family well-being (seven items); emotional well-being (six items); functional well-being (seven items)	GC symptoms and impacts (e.g., pain, reflux, dysphagia, eating difficulties, tiredness, weakness, interference, and difficulty planning)	GI symptoms (constipation, diarrhoea, difficulty swallowing, change in taste, and feeling bloated), general cancer symptoms (13 items), and interference (six items)
Number of items/Time to complete/Response rate	30 (version 3.0) 10 min [24] Less than 4% missing for all items [34]	22 15 min for EORTC QLQ-C30 and QLQSTO22 [24] Less than 8% missing for all items [33]	27 (version 4) Time and response rate not reported	19 Time and response rate not reported	24 2–3 min Missing data rate of 0.18% [26]
Population of intended use	Cancer patients	Patients with GC, varying in disease stage, and treatment modality	Cancer patients	Patients with GC, varying in disease stage, and treatment modality	Patients with any GI cancer (not only GC)
Response options	28 items with a four-point Likert scale; two items with a seven-point numerical scale	Four-point Likert scale	Five-point Likert scale	Five-point Likert scale	11-point NRS
Recall period	Past week	Past week	Past seven days	Past seven days	Last 24 h
Scoring	Scores range from 0 to 100 (raw scores for items or summed subscales are transformed to 0–100) High score = worse symptoms or better function	Five subscale scores and three single-item scores High score = worse symptoms or more problems; further details not available	Subscale scores range from 0 to 24; from 0 to 28 according to the number of items in subscale Total score: 0–108 Higher score = better QOL	One subscale score range 0–76 Higher score = better QOL	Scores range from 0 to 10 for individual items Mean scale scores can be computed for the 13 symptom-severity items and for the six interference items
Internal consistency reliability	Yes [27]	Yes [24, 27, 33]	No evidence	Yes [25, 30]	Yes [26]
Test-retest reliability	No evidence	Yes [24, 34]	No evidence	Yes [25]	No evidence
Content validitya	Yes: cognitive debriefing [24]	Yes: concept elicitation [29] Yes: cognitive debriefing [24]	No evidence	Some patient inputs [30] Yes: cognitive debriefing [30]	Yes: patient interviews [26] Yes: cognitive debriefing [26]
Construct validity	Yes [27, 34]	Yes [24, 33, 34, 27]	No evidence	Yes [25]	Yes [26]
Ability to detect change	Some evidence [24]	Yes [24]	No evidence	Yes [25]	No evidence
Data-collection method	Self-administered; interviewer administered	No details available	Self-administered; interviewer-administered	No details available	No details available
Instrument adminis tration mode	Paper-pencil; computer-administered	No details available	Paper-pencil Computer-administered programs are under development	No details available	Paper-pencil
Cultural and language validation	Over 81 languages [35]	38 languages [35]	Over 53 languages [36]	Japanese translation [25, 30]	Chinese translation [37]

^aContent validity as evidenced by patient involvement in concept elicitation and/or item generation.

EORTC QLQ-C30: European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (core measure).

EORTC QLQ-STO22: European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Gastric Cancer Module.

FACT-G: Functional Assessment of Cancer Therapy-General.

FACT-Ga: Functional Assessment of Cancer Therapy-Gastric Cancer.

GC: gastric cancer.

GI: gastrointestinal.

MDASI-GI: MD Anderson Symptom Inventory-Gastrointestinal Cancer.

NRS: numerical rating scale.

QOL: quality of life.

PRO: patient-reported outcome.