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Neurourol Urodyn. 2018 Mar;37(3):1095-1100. doi: 10.1002/nau.23420. Epub 2017 Oct 4.

Evaluating the 8-item overactive bladder questionnaire (OAB-v8) using item response theory.

Author information

1
Centre for Health Services and Policy Research, University of British Columbia, Vancouver, British Columbia, Canada.
2
Vesia [Alberta Bladder Centre], Calgary, Alberta, Canada.
3
Department of Surgery, University of Calgary, Calgary, Alberta, Canada.

Abstract

AIMS:

The OAB-v8 is a patient-reported outcome questionnaire used to screen for overactive bladder and measure symptom bother. This study uses modern validation methods to assess the item and test characteristics of the OAB-v8, and determine whether it should be scored differently for men and women.

METHODS:

A secondary analysis of data from patients with lower urinary tract symptoms prospectively recruited from a urology clinic in Calgary, Canada. Item-response theory (IRT) was used to evaluate the dimensionality, reliability, and validity of the OAB-v8, and differential functioning analysis (DIF) was used to determine whether the OAB-v8 should be scored differently for men and women.

RESULTS:

A total of 1128 patients were included for analysis, of which 28% were female. Mean OAB-v8 scores indicated meaningful levels of symptom bother, and women scored 2 points higher, on average, than men (P = 0.005). Reliability was high (Cronbach's alpha = 0.901) for a wide range of patients (between -2 and 2.5 standard deviations of the mean). Samejima's graded response model best fit the data, and the scale demonstrated essential unidimensionality. Items #5 and #6 were excessively correlated. There was no evidence of differential functioning.

CONCLUSIONS:

OAB-v8 demonstrated high reliability and would be appropriate for a wide range of patients. Items #5 and #6 may need to be re-worded. The OAB-v8 should not be scored differently for men and women, although women do appear to experience higher average levels of symptom bother from OAB than men.

KEYWORDS:

OAB-v8; lower urinary tract symptoms; overactive; patient reported outcome measures; psychometrics; quality of life; reliability and validity; urinary bladder; validation studies

PMID:
28976596
DOI:
10.1002/nau.23420

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