[Examination of calibrated item banks for the assessment of work capacity in an outpatient sample of cardiological patients].

BACKGROUND

Work capacity is a major outcome variable in cardiological rehabilitation. However, there is a lacks of capacious and economic assessment instruments for work capacity. By developing item response theory based item banks a first step to close this gap is done. The present study aims to validate the work capacity item banks for cardiovascular rehabilitation inpatients (WCIB-Cardio) in a sample of cardiovascular rehabilitation outpatients. Additionally, we examined differences between in- and outpatients with regard to their work capacity.

METHODS

Data of 283 cardiovascular rehabilitation inpatients and 77 cardiovascular rehabilitation outpatients were collected in 15 rehabilitation centres. The WCIB-Cardio contains the 2 domains of "cognitive work capacity"(20 items) and "physical work capacity"(18 items). Validation of the item bank for cardiological outpatients was conducted with separate Rasch analysis for each domain.

RESULTS

For the domain of cognitive work capacity 10 items showed satisfying quality criteria (Rasch reliability=0.71; overall model fit=0.07). For the domain of physical work capacity good values for Rasch-reliability (0.83) and overall -model fit (0.65) could be proven after exclusion of 3 items. Unidimensionality and a broad ability spectrum could be covered for both domains. With regard to content, outpatients evaluate themselves less burdened than inpatients for the domain of cognitive work capacity (‾X outpatient =-2.06 vs. ‾X inpatient =-2.49; p<0.07) similarly for the domain of physical work capacity (‾X outpatient =-3.68 vs. ‾X inpatient =-2.88; p<0.01).

DISCUSSION

With the WCIB-Cardio II there is a precondition to develop self-report instruments of work capacity in cardiological in- and outpatients.