Table 2 CDI-DaySyms™ PRO questionnaire item performance – Day 1
Item | Score, mean (SD) at Day 1 | Floor effects at Day 1, % | Ceiling effects at Day 1, % | High correlations > 0.80 with | Low correlations < 0.20 with | Clinical input/Rationale for decision | Item decision |
|---|---|---|---|---|---|---|---|
1. Diarrhea | 2.4 (1.2) | 8.9 | 16.1 | – | Passing gas | Predominant symptom in CDI | Retain |
2. Need to empty bowels right away | 2.4 (1.2) | 8.9 | 14.3 | Bathroom more than usual | Passing gas | Describes intensity of urgency of bowel movements | Retain |
3. Need to go to the bathroom more than usual | 2.4 (1.2) | 11.4 | 13.8 | Need to empty bowels | – | Describes frequency of bowel movements | Retain |
4.Passing gas (flatulence) | 1.6 (1.1) | 17.6 | 6.1 | – | Diarrhea, empty bowels, feeling tired, lack of energy, lightheadedness, dizziness, appetite | Misfit/multidimensionality in Rasch analyses | Delete |
5. Abdominal cramping | 1.8 (1.3) | 22.6 | 10.7 | Abdominal pain | – | According to experts, pathophysiology is different from item 6 | Retain |
6. Abdominal pain | 1.7 (1.3) | 22.9 | 10.8 | Abdominal cramping | – | See item 5 | Retain |
7. Feeling bloated | 1.3 (1.3) | 38.8 | 6.7 | – | – | Most patients do complain of bloating based on expert input | Retain |
8.Feeling tired | 2.2 (1.1) | 9.5 | 13.1 | Lack of energy | Passing gas | Based on qualitative study, items 8 and 9 are different | Retain |
9.Lack of energy | 2.2 (1.2) | 10.1 | 13.7 | Feeling tired | Passing gas | See item 8 | Retain |
10. Lightheadedness | 1.0 (1.2) | 44.8 | 5.5 | – | Passing gas | Experts considered lightheadedness more relevant to CDI than dizziness | Retain |
11. Dizziness | 0.7 (1.1) | 58.5 | 3.7 | – | Passing gas | See item 10 | Delete |
12. Lack of appetite | 1.6 (1.3) | 26.9 | 11.4 | – | Passing gas | Experts noted that lack of appetite is relevant in severe disease | Retain |
13. Nausea | 0.9 (1.2) | 53.0 | 6.0 | – | – | The item had a low mean score and high floor effect across patients | Delete |