[Comparison of Hannover Functional Ability Questionnaire (FFbH) and the SF-36 subscale "Physical Functioning"].

Pretesting of a questionnaire for evaluating day-patient rehabilitation, which included comparison of the "Hannover Functional Ability Questionnaire" (FFbH) and the SF-36 subscale "physical functioning" (SF-36 PF), gave rise to more extensive validity testing of the two instruments. In the framework of an expanded pretest, a questionnaire including FFbH and SF-36 PF was sent out to 520 adult former patients who had undergone inpatient orthopaedic rehabilitation following total hip or knee replacement an average 16 months ago. Return rate was 76%. Checks on plausibility showed no complaints about the Hannover Functional Ability Questionnaire while, on the SF-36 subscale, it was found that 16 of 374 patients (4.3%) had confused positive and negative ratings. Moreover, problems were found concerning the wording of several items (understanding, multidimensionality). In contrast to the FFbH, the SF-36 subscale shows weaknesses in the formulation of its items and particularly its ratings.