The Psychometric Validation of the OAB Family Impact Measure (OAB-FIM)

Aims: Although overactive bladder (OAB) impacts patient health-related quality of life, the impact of OAB on family members is not known. Presently, no validated instruments exist to assess family impact, thus we examined the psychometric properties of a new instrument, the overactive bladder family impact measure (OAB-FIM). Methods: Dyads of OAB patient-family members and control patient-family members were recruited from clinics. Family members (spouses, significant others, or daughters) completed the 32-item draft OAB-FIM. Patients completed the overactive bladder questionnaire (OAB-q) and the patient perception of bladder condition (PPBC). Both patients and family members completed two validated relationship measures. Item and exploratory factor analyses were performed to determine subscale structure; reliability and validity were assessed. Results: One hundred ninety-three patient-family member dyads (163 OAB, 30 control) participated. OAB patients were mostly women (82%); the control group was younger with fewer women (53%). Family members were predominantly men (OAB, 58%; control, 52%), and control family members were younger than OAB family members. Thirteen items were deleted from the draft OAB-FIM based on item performance and factor structure based on exploratory factor analyses, leaving 19-items in the final OAB-FIM. Four subscales (Irritation, Activities, Travel, Concern) were derived for use among all family members; two additional subscales (Sleep, Sex) were derived for use with spouses/significant others. The OAB-FIM discriminated between OAB and control family members with OAB family members demonstrating significant impact (all P < 0.0001). Internal consistency reliability (Cronbach's alpha >0.70) and 2-week test-retest reliability (intraclass correlation coefficients >0.73) were high for all subscales. Concurrent validity of the OAB-FIM was demonstrated through statistically significant (P < 0.001) Spearman correlations with the OAB-q (0.35-0.58) and the PPBC (0.31-0.56). The OAB-FIM also demonstrated known-groups validity, distinguishing between family members of OAB patients and family members of control patients. Conclusions: This study supports the reliability and validity of a new measure to assess the impact of OAB on family members and demonstrates that family members are affected by another's medical condition. Neurourol. Urodynam. 29:359-369, 2010. (C) 2009 Wiley-Liss, Inc.