[The ZZP Questionnaire. Reliability of a new resource utilization measure]

Data to determine the resource utilization of care recipients need to be reliable and the items that are measured need to be useful. In 2006, the Dutch Ministry of Health and Welfare has mandated all nursing homes and homes for the elderly to measure the Resource Utilization of all residents with the ZZP Questionnaire. Are the data resulting from this measurement reliable and is each of the 54 items of the ZZP Questionnaire useful? To answer this we tested the reliability of the data in a nursing home and a home for the elderly in two wards each. For 122 residents questionnaires were completed such that the inter- and intra-rater reliability of the answers could be assessed. Ten of the 54 items in the questionnaire showed insufficient inter rater reliability (<0.40) on the weighted Cohen kappa and another sixteen moderate (0.40 - 0.60). On the intra rater reliability test seven items had an insufficient kappa and another fifteen moderate. Besides, ten clusters of items could be formed with in-cluster Spearman correlation rates of .75 or higher. From the results of the reliability tests and the item intercorrelation rates we concluded that a substantial number of items needs to be improved and that in the ZZP Questionnaire 15 of the 54 items appear to be redundant on statistical grounds.