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Table 1 PU-QOL-P scale level analyses - Reliability and scaling assumptions: Validity within-scale analysis

From: A patient-reported pressure ulcer health-related quality of life instrument for use in prevention trials (PU-QOL-P): psychometric evaluation

PU-QOL-P scale (n items) Internal consistency Mean inter-item correlation Inter-item correlationa Scaling Assumptions -Corrected ITCa
Nc Cronbach’s alpha
Pain (12) 617 0.864 0.355 0.128–0.713 0.364–0.642
Exudate (8) 60b 0.860 0.451 −0.024 – 0.865 0.337–0.824
Odour (6) 61b 0.795 0.492 −0.017 – 1.000 − 0.017 – 0.893
Sleep (7) 333 0.937 0.682 0.540–0.827 0.753–0.871
Movement & mobility (9) 177 0.963 0.744 0.593–0.928 0.803–0.909
Daily activities (6) 186 0.937 0.705 0.476–0.900 0.581–0.914
Malaise (5) 215 0.915 0.680 0.559–0.844 0.669–0.846
Emotional well-being (15) 220 0.970 0.681 0.447–0.900 0.630–0.869
Self-consciousness and appearance (7) 305 0.921 0.645 0.532–0.786 0.695–0.818
  1. SEM standard error mean; IIC inter-item correlation; ITC item-total correlation (corrected for overlap)
  2. aRange
  3. bsample n = 62; only patients with a category ≥2 PU complete exudate and odour scale
  4. cn estimated based on listwise deletion; observations that have one or more missing values across all variables are removed from analysis