Introduction
Methods
Ethics
Development of the initial C-CAP questionnaires
Patients
Questionnaire procedures
Sample size
Description of C-CAP questionnaires
Domain | Question/item numbers | Domain description |
---|---|---|
Pre-validation, pre-ablation questionnaire (C-CAP1) | ||
Pre-ablation patient expectations | 1–5 | Contains a 4 item Likert scale (Q1–3b) with five response options (each item scored 0–4); each explored patients’ treatment expectations prior to the procedure. The “treatment expectations” multi-item scale had a minimum score of 0 and a maximum of 16 (the 4 items in the scale were given equal weight, and each had a minimum score of 0 and a maximum of 4). This domain also asked whether this is the patient’s first ablation (Q4) and for the number of previous ablations received (Q5) |
Condition and symptoms | 6, 7, 8, 13 | This domain was a modified version of the disease-specific Patient Perception of Arrhythmia Questionnaire (PPAQ) originally developed by Wood et al. [21]. Following adaptations for use in a UK population with specialist, lay and patient input, this updated tool included elements which were divided into three multi-item scales where a high score reflects a worse health state: Symptom severity (Q6a–o): 15 item symptom scale, each symptom/item had 4 response options (scored 0–3). The minimum score was 0 and the maximum was 45 (equal weight was given to each item in the scale and all subsequent scales) Frequency and duration of symptoms (Q7–8): two item scale, each item had 5 response options (scored 0–4). The minimum score was 0 and the maximum was 8 Impact on life (Q13a–j): 10 item scale, each item had 4 response options (scored 0–3). The minimum score was 0 and the maximum score was 30 |
Restricted activity days and healthcare visits | 9a–12b | This domain was modified from the PPAQ [20] and aimed to count how many days (either work/school/college, social activities, or normal daily activities) in the last 30 have been affected by arrhythmia symptoms. The number of visits to a GP or hospital in the last 30 days was also recorded |
Medication and general health | 14–17 | Q14 asked whether the respondent normally takes medication (yes/no); Q15 asked for the name and dose of medication (free text); Q16 asked how important a reduction in medication is for the respondent (Likert scale with 4 response categories scored from 0 to 3); Q17 asked whether the respondent had been diagnosed with any one of a list of 12 common conditions (with a “tick all that apply” instruction) |
EQ-5D-5L | Not numbered | This comprised the widely used global health questionnaire which provides a simple descriptive profile and a single index value for health status [10]. The EQ-5D-5L questionnaire consists of five questions related to mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each question can be answered on five different levels. The EQ-5D-5L also includes a visual analogue scale (question 19) from 0 (worst health imaginable) to 100 (best health imaginable). Therefore, a higher score is related to a better outcome, in contrast to the other scoring systems used elsewhere in this paper |
Pre-validation post-ablation questionnaire (C-CAP2) | ||
Post-ablation change in symptoms | 1–3b, 7 | This domain consists of 4 items each with 4 available responses relating to changes in patients’ arrhythmia-related symptoms since receiving a procedure to treat their condition (scored from 1 to 4 for each scale). Therefore, the change in symptoms multi-item scale has a minimum score of 0 and a maximum of 16. This domain also asks whether the outcome of the procedure met the patients’ expectations |
Procedure-related complications | 4–6 | This domain comprised a binary question relating to whether patients experienced any ablation-related complications and two tables asking patients whether they were warned of or experienced any of a list of complications |
Condition and symptoms | 8, 9, 10, 15 | As described for C-CAP1 |
Restricted activity days and healthcare visits | 11a–13b | As described for C-CAP1 |
Medication and general health | 16–19 | As described for C-CAP1 |
EQ-5D-5L | Not numbered | As described for C-CAP1 |
Data management and statistics
Validation of C-CAP instrument
Feasibility and acceptability
Reliability
Validity
Responsiveness and minimal clinically important difference (MCID)
Results
Questionnaire feasibility
Demographic | Enrolled patients (n = 517) | Patients with valid C-CAP1 and C-CAP2 (n = 434) |
---|---|---|
Male/female | 288/227 (56 %/44 %) | 246/187 (57 %/43 %) |
Mean/median age (years) | 60 (SD 13)/62 (IQR 52–68) | 61 (SD 12)/63 (IQR 54–68) |
Arrhythmia substrate | ||
Atrial fibrillation | 245 (47 %) | 214 (49 %) |
AVNRT | 75 (15 %) | 70 (16 %) |
Atrial flutter (all) | 79 (15 %) | 72 (17 %) |
Uncommon | 10 | 9 |
Accessory pathways (all) | 32 (6 %) | 27 (6 %) |
Overt | 16 | 12 |
Concealed | 8 | 7 |
Other | 8 | 8 |
Ventricular extrasystoles/ectopics | 12 (2 %) | 8 (2 %) |
Ventricular tachycardia | 12 (2 %) | 11 (3 %) |
Missing | 62 (12 %) | 32 (7 %) |
Previous intervention | ||
None | 188 (36 %) | 162 (37 %) |
Percutaneous ablation | 113 (22 %) | 99 (23 %) |
Pacemaker fitted | 22 (4 %) | 16 (4 %) |
Coronary angioplasty | 6 (1 %) | 5 (1 %) |
Cardiac surgery | 14 (3 %) | 13 (3 %) |
Other | 1 (0 %) | 1 (0 %) |
Missing | 173 (33 %) | 138 (32 %) |
Item acceptability
Score mean | Missing data | Floor/ceiling effectsa
| |
---|---|---|---|
C-CAP1 (pre-ablation) n = 517 | |||
Q1–3b: treatment expectations (4 items; score range 0–16) | 4.9 (SD 2.0) | 3.5 % | 0.6 %/0.2 % |
Q4: first ablation procedure (1 item; binary) | 71 % (Y); 27 % (N) | 1.4 % | N/A |
Q6: symptom severity index (15 items; score range 0–45) | 15.6 (SD 8.6) | 16.2 % | 1.8 %/0.0 % |
Q7–8: frequency and Duration (2 items; score range 0–8) | 4.6 (SD 2.0) | 3.1 % | 7.4 %/9.2 % |
Q9: days impact (work/school) (1 item; score range 0–30) | 6.1 (SD 10.3) | 2.1 % (65.0 % N/Ab) | 52.9 %/12.9 % |
Q10: days impact (social activities) (1 item; score range 0–30) | 8.6 (SD 10.3) | 3.9 % (34.4 % N/Ab) | 27.0 %/12.2 % |
Q11: days impact (normal activities) (1 item; score range 0–30) | 8.7 (SD 10.4) | 4.1 % (30.2 % N/Ab) | 26.0 %/13.5 % |
Q12a: GP visits in last 30 days (1 item; score range 0–30) | 0.6 (SD 1.1) | 25.0 % | 66.0 %/0 % |
Q12b: hospital visits in last 30 days (1 item; score range 0–30) | 0.7 (SD 1.0) | 22.8 % | 58.4 %/0 % |
Q13: impact on life (10 items; score range 0–30) | 13.8 (SD 7.5) | 6.6 % | 1.4 %/0.3 % |
Q14: medication taken for arrhythmia (1 item; binary) | 82 % (Y); 18 % (N) | 0.4 % | N/A |
Q16: importance of reducing medication (1 item; score range 0–3) | N/A = 1 % Not important = 7 %; Quite important = 24 %; Very important = 48 % | 19.9 % | N/A |
EQ-5D-5L (5 items; score range −0.594 to 1.000) | 0.7 (SD 0.2) | 2.5 % | 0.0 %/15.5 % |
EQ-VAS (1 item; score range 0–100) | 65.2 (SD 18.9) | 0.8 % | 0.0 %/1.2 % |
C-CAP2 (post-ablation) n = 437 | |||
Q1–3b: symptom change (4 items; score range 4–16) | 8.0 (SD 3.3 %) | 5.5 % | 15.3 %/2.2 % |
Q4: ablation-related complications (1 item; binary) | 24 % (Y); 70 % (N) | 6.2 % | N/A |
Q7: expectations met or exceeded (1 item; binary) | 68 % (Y); 26 % (N) | 6.2 % | N/A |
Q8: symptom severity index (15 items; score range 0–45) | 8.8 (SD 7.8) | 16.7 % | 8.8 %/0.0 % |
Q9–10: frequency and duration (2 items; score range 0–8) | 2.6 (SD 2.6) | 3.2 % | 42.6 %/6.4 % |
Q11: days impact (work/school) (1 item; score range 0–30) | 5.4 (SD 10.6) | 2.7 % (68.4 % N/Ab) | 69.8 %/12.7 % |
Q12: days impact (social activities) (1 item; score range 0–30) | 5.7 (SD 9.6) | 4.3 % (47.6 % N/Ab) | 52.9 %/9.5 % |
Q13: days impact (normal activities) (1 item; score range 0–30) | 5.2 (SD 9.1) | 5.3 % (45.3 % N/Ab) | 53.9 %/8.3 % |
Q14a: GP visits in last 30 days (1 item) | 0.4 (SD 0.9) | 14.6 % | 75.1 %/0 % |
Q14b: hospital visits in last 30 days (1 item) | 0.3 (SD 1.1) | 22.9 % | 81.6 %/0 % |
Q15: impact on life (score range 0–30) | 7.2 (SD 7.5) | 9.6 % | 14.9 %/0.3 % |
Q16: medication taken for arrhythmia (1 item; binary) | 63 % (Y); 35 % (N) | 1.6 % | N/A |
Q18: medication intake compared with before procedure (1 item; 3 response options) | More = 11 %; same = 35 %; less = 17 % | 36.4 % | N/A |
EQ-5D-5L (score range −0.594 to 1.000) | 0.8 (SD 0.2) | 2.5 % | 0.0 %/30.5 % |
EQ-VAS (score range 0–100) | 72.6 (SD 20.1) | 1.1 % | 0.0 %/3.9 % |
Ceiling and floor effects
Internal consistency
Multi-item scale | Internal consistency measures | Test–retest reliability measures | ||||||
---|---|---|---|---|---|---|---|---|
N
| Cronbach’s alpha | Items with item-total correlation <0.3 | Items which if deleted improve overall α
|
N
| ICC (95 % CIs) | Bland–Altman plot bias value (95 % CIs; p value) | Bland–Altman plot limits of agreement | |
Pre-ablation (C-CAP1) | ||||||||
Pre-ablation treatment expectations | 499 | 0.705 | None | None | 82 | 0.817 (0.730–0.878) | −0.20 (−0.46 to 0.07; p = 0.15) | −2.59 to 2.20 |
Pre-ablation symptom severity | 433 | 0.876 |
k
a (0.135) |
k
a (α if deleted 0.880) | 68 | 0.841 (0.755–0.899) | 0.57 (−0.55 to 1.70; p = 0.31) | −8.53 to 9.68 |
Pre-ablation frequency and duration | N/A | N/A | N/A | N/A | 86 | 0.661 (0.523–0.766) | −0.07 (−0.42 to 0.28; p = 0.69) | −3.28 to 3.14 |
Pre-ablation impact on life | 483 | 0.868 | None |
i
b (α if deleted 0.872) | 77 | 0.865 (0.796–0.912) | −0.31 (−1.21 to 0.59; p = 0.49) | −8.09 to 7.47 |
Pre-ablation EQ-5D-5L | 504 | 0.772 | ec (0.286) | ec (α if deleted 0.810) | 82 | 0.845 (0.769–0.897) | −0.02 (−0.05 to 0.00; p = 0.09) | −0.27 to 0.22 |
Pre-ablation EQ-VAS | N/A | N/A | N/A | N/A | 87 | 0.847 (0.775–0.897) | −1.51 (−3.68 to 0.67; p = 0.17) | −21.47 to 18.46 |
Post-ablation (C-CAP2) | ||||||||
Post-ablation symptom change | 412 | 0.875 | None | None | 80 | 0.844 (0.767–0.897) | 0.11 (−0.33 to 0.56; p = 0.62) | −3.81 to 4.03 |
Post-ablation symptom severity | 377 | 0.897 | None |
k
a (α if deleted 0.899) | 65 | 0.900 (0.840–0.938) | 0.77 (−0.15 to 1.69; p = 0.10) | −6.53 to 8.07 |
Post-ablation frequency and duration | N/A | N/A | N/A | N/A | 84 | 0.892 (0.838–0.929) | 0.13 (−0.14 to 0.40; p = 0.34) | −2.34 to 2.60 |
Post-ablation impact on life | 409 | 0.918 | None |
i
b (α if deleted 0.921) | 79 | 0.946 (0.916–0.965) | 0.28 (−0.29 to 0.85; p = 0.34) | −4.76 to 5.32 |
Post-ablation EQ-5D-5L | 426 | 0.830 | None | ec (α if deleted 0.843) | 80 | 0.807 (0.715–0.872) | −0.01 (−0.04 to 0.02; p = 0.50) | −0.28 to 0.26 |
Post-ablation EQ-VAS | N/A | N/A | N/A | N/A | 86 | 0.929 (0.894–0.953) | −1.28 (−2.94 to 0.37; p = 0.13) | −16.40 to 13.83 |
Test–retest reliability
Construct validity
Convergent and divergent validity
Responsiveness
Multi-item scale |
N
| Mean (SD) | ES | SRM | RE | ||
---|---|---|---|---|---|---|---|
Pre-ablation | Post-ablation | Change | |||||
C-CAP disease-specific scales shared across C-CAP1 and C-CAP2 | |||||||
Symptom severity (score range 0–45) | 318 | 15.5 (8.3) | 8.9 (7.9) | −6.6 (8.1)
p < 0.001 | 0.80 | 0.82 | 6.39 |
Frequency and duration (score range 0–8) | 412 | 4.7 (2.1) | 2.6 (2.6) | −2.1 (2.7)
p < 0.001 | 1.03 | 0.78 | 7.46 |
Impact on life (score range 0–30) | 372 | 13.6 (7.4) | 7.1 (7.5) | −6.5 (7.4)
p < 0.001 | 0.88 | 0.88 | 8.59 |
Generic scales | |||||||
EQ-5D-5L (score range −0.594 to 1.00) | 416 | 0.74 (0.22) | 0.79 (0.23) | 0.05 (0.17)a
p < 0.001 | −0.22 | −0.29 | 1 (Reference) |
EQ-VAS (score range 0–100) | 426 | 65.3 (18.8) | 72.8 (20.1) | 7.4 (17.4)a
p < 0.001 | −0.40 | −0.43 | 2.32 |
Mean change score in three disease-specific multi-item C-CAP instruments anchored using a range of anchor measures of minimal important change | MCID (mean of anchors) | SEM (pre/post) | SDC (pre/post) | ||||
---|---|---|---|---|---|---|---|
Symptoms have become less frequent | Symptoms have become shorter | Patient expectations were met | Global health score (EQ-5D-5L) improvement of 20 points | ||||
Symptom severity (score range 0–45) | 7.31 | 6.89 | 7.22 | 7.14 | 7.14 | 3.29/2.66 | 9.12/7.38 |
Frequency and duration (score range 0–8) | 1.85 | 1.45 | 2.95 | 0.91 | 1.79 | 1.15/0.89 | 3.19/2.47 |
Impact on life (score range 0–30) | 5.21 | 5.78 | 5.93 | 4.99 | 5.48 | 2.80/1.81 | 7.79/5.02 |
Discussion
-
Removal of passing out/fainting/blackouts from the “symptom severity” scale and my palpitations have had a financial impact from the “impact on life” scale in C-CAP1 (Q13) and C-CAP2 (Q15)
-
Removal of the free text section for medication taken by patients in C-CAP1 (Q15) and C-CAP2 (Q17)
-
Amendment of the N/A option for “days you have missed at work/school/college” to read “I do not attend work/school/college (✓)”in C-CAP1 (Q9) and C-CAP2 (Q11)
-
Removal of the N/A option from “days you have had to cut down on your social activities” and “days you have been unable to carry out normal daily activities” questions in C-CAP1 (Q10–11) and C-CAP2 (Q12–13).