Research Article

Reliability and Validity of the Greek QLQ-C30 and QLQ-MY20 for Measuring Quality of Life in Patients with Multiple Myeloma

Table 1

Central tendency, variability, and reliability of the QLQ-C30 and QLQ-MY20 scales.

No. of ItemsMean (SD)95% CIMedianFloor (%)Ceiling (%)Reliabilitya

QLQ-C30
 Global health status/QoL262.6 (21.6)58.1–67.266.70.0 (3.4)100.0 (5.6)0.92
 Functional scales
  Physical functioning564.0 (22.3)59.3–68.766.70.0 (1.1)100.0 (4.5)0.80
  Role functioning268.9 (33.9)61.8–76.166.70.0 (10.1)100.0 (41.6)0.90
  Emotional functioning471.5 (25.1)66.3–76.875.00.0 (2.2)100.0 (12.4)0.84
  Cognitive functioning281.7 (23.8)76.6–86.783.30.0 (1.1)100.0 (48.3)0.57
  Social functioning279.0 (25.2)73.7–84.383.316.7 (4.5)100.0 (46.1)0.77
 Symptom scales/items
  Fatigue341.3 (27.6)35.5–47.133.30.0 (10.1)100.0 (4.5)0.89
  Nausea and vomiting28.2 (20.4)3.9–12.50.00.0 (82.0)100.0 (1.1)0.74
  Pain229.8 (27.8)23.9–35.633.30.0 (30.3)100.0 (3.4)0.80
  Dyspnoea134.5 (32.4)27.6–41.333.30.0 (34.8)100.0 (10.1)
  Insomnia132.6 (36.2)25.0–40.233.30.0 (46.1)100.0 (13.5)
  Appetite loss113.9 (29.2)7.7–20.00.00.0 (77.5)100.0 (6.7)
  Constipation122.9 (32.8)15.9–29.80.00.0 (58.4)100.0 (10.1)
  Diarrhea19.4 (18.1)5.6–13.20.00.0 (75.3)100.0 (1.1)
  Financial difficulties112.0 (22.6)7.2–16.80.00.0 (74.2)100.0 (1.1)

QLQ-MY20
 Disease symptoms620.2 (19.8)16.0–24.316.70.0 (25.8)83.3 (1.1)0.77
 Side effects of treatment1020.1 (15.5)16.8–23.318.50.0 (5.6)70.4 (1.1)0.72
 Body image172.3 (34.5)65.0–79.6100.00.0 (9.0)100.0 (53.9)
 Future perspective354.6 (29.8)48.3–60.855.60.0 (7.9)100.0 (10.1)0.80

aCronbach’s alpha.