[Reliability of expert assessment in disability evaluation within the scope of disability insurance]

With the introduction of the law on the statutory nursing care insurance in Germany ("Pflegeversicherung") in 1995, new benefits are provided for the most severely disabled people. Provision of benefits is contingent on a standardised examination performed by the medical service of the German statutory health insurance system (MDK). Results of the first study on the inter-rater reliability of this standardised examination are presented in this paper. The study population consisted of 218 elderly people (age range 60-99) living in 4 nursing homes in Munich. They were assessed by 2 senior medical students and 2 nurses using the standardised questionnaire of the MDK. Inter-rater reliability was assessed by means of kappa coefficients. Reliability was assessed with regard to the summary judgement of disability and the rating of single items (with regard to limitations in activities of daily living, mental status or the prognosis). Inter rater reliability was higher for the overall assessment of disability (kappa = 0.71 between medical students, kappa = 0.66 between nurses) than for most of the single items of the questionnaire such as "need of assistance with dressing" (kappa = 0.57 between medical students, kappa = 0.66 between nurses) or "ability to move" (kappa = 0.58 between medical students, kappa = 0.67 between nurses). Kappa-coefficients were particularly low for variables concerning prognosis of participants and for the mental status item "self-disorientation" (kappa = 0.19 between medical students, kappa = 0.23 between nurses). These patterns were consistently observed for the 2 rater groups (student-student, nurse-nurse). Between the 2 rater groups there was no substantial difference in reliability. However, there was a trend for higher agreement within the group of nurses. Although the overall reliability of the assessment of disability is relatively high in comparison to many other diagnostic procedures (such as x-ray readings), efforts should be made towards further improvement of this standardised examination.