Page 126 - Bladder Dysfunction in the Context of the Bladder-Brain Connection - Ilse Groenendijk.pdf

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Chapter 6
Floor and ceiling effects
In the patient group, no floor or ceiling effects were seen for the two subscales (Table 4). In the reference group, floor effects were seen for the symptom bother subscale; 17.6% scored the lowest possible score of 0. Moreover, in the HRQOL subscale, a ceiling effect was seen, in that 29.4 % of patients scored the highest possible score.
Table 4. Floor and ceiling effects at baseline.
DISCUSSION
The primary aim of this study was to translate and validate the OAB-q SF in the Dutch language. The results of this study showed that this Dutch version is valid, reliable and consistent. This enables the use of the OAB-q SF in daily practice in the Netherlands. A valid tool to measure both symptom bother and health-related quality of life in patients with OAB in an easy and fast way.
The content validity of the questionnaire was confirmed during the face-to-face evaluation. Question 8 of the OAB-q SF HRCOL subscale was discussed. One patient commented on question 8 in the health-related quality of life subscale: ‘During the past 4 weeks, how often have your bladder symptoms caused you to have problems with your partner or spouse?’. The issue was that response option ‘not applicable’ was lacking for those who had no partner. Because adding this response option would complicate the scoring manual, we discussed this problem with the designers of the original ques- tionnaire.9 In the cohort of Coyne et al, patients either leaved the question blank, and it was recorded as missing, or patients answer was ‘None of the time’ given that when it is not applicable, it really is none of the time. Therefor the Dutch version did not insert ‘not applicable’ as answer option, and no changes were made as a result of this discus- sion.9 Moreover, according to the scoring manual of the OAB-q SF, the total score can be adapted to up to 50% of missing items, still creating a score ranging from 0 to 100.
The significantly different scores in the patient group (higher in symptom bother and lower in HRQOL) compared to the reference group, indicated a good discriminative abil- ity and possible diagnostic value of the OAB-q SF. Comparable to the Cronbach’s alphas of the original OAB-q SF (0.82 & 0.91) and the Spanish validation (0.81 & 0.92),9,18 the Cronbach’s alphas of the Dutch OAB-q SF were good (0.83 to 0.89), and demonstrated an excellent internal consistency. Using the change in scores between the test-retest, the
References N = 51
Patients N= 52
Floor (%)
Ceiling (%)
Floor (%)
Ceiling (%)
OAB-q SF Symptom bother
9 (17.6 %)
1 (2%)
0 (0%)
4 (7.7%)
OAB-q SF HRQOL
0 (0%)
15 (29.4%)
0 (0%)
0 (0%)