Purpose: Different evaluation systems and indicators have recently been used to measure the activity volumes of Italian hospital departments, and in particular of Diagnostic Imaging Units. These measurements have mostly been based on more or less complex and repeatable indicators such as total accesses, accesses per imaging modality, type and number of exams. The aim of this study was to compare four models for measuring and evaluating productivity to assess their features and propose a common method for measuring activity volumes in a Diagnostic Imaging Unit. The models considered are: a) the numerical count, b) the model proposed by SNR-SAGO-SIRM, c) the model based on transfer prices in use in the Emilia Romagna Region (RER), d) the model used by the U.S. Health Care Financing Agency (HCFA-USA), based on a complex system of weights named RVUs (Relative Value Units).
Materials and methods: The period under review considers two years of activity (2000-2001) at our Diagnostic Imaging Unit. The data were collected by grouping the radiological procedures into homogeneous groups (macroaggregates) which were then assessed with the four models. The reference parameters considered in order to produce homogeneous data were: the number of procedures per physician hour, the score per hour according to the SNR-SAGO-SIRM model, the score per hour according to the RER model, the number of work-RVUs per hour worked. With regard to the HCFA-USA system, the following indicators were used: the work component (work-RVU), the insurance component (malpractice RVU) and the technical component (practice expense-RVU), the equivalent units of physician time (FTE: Full Time Equivalent), such as the number of procedures per FTE, the difficulty index, and the number of RVUs per FTE.
Results: a) The total number of procedures was 55,884, the number of procedures per hour ranged from 2.43 (August 2000) to 4.20 (March 2000); based on the numerical count conventional radiology accounted for the most of the Unit's activity (40%). b) The total score according to the SNR-SAGO-SIRM model was 147,358; the weight of each physician hour ranged from 6.37 (August 2000) to 9.80 (October 2001). The SNR-SAGO-SIRM model indicates that the most significant macroaggregate in the Unit's activity was ultrasound (42%). c) The total score according to the RER model was 4,313,047, the weight of each physician hour varied between 159 (August 2000) and 316 (April 2000). Based on the RER model, CT (42%) accounted for most of the Unit's activity. d) According to the RVU model, the total number of work-RVUs was 37,619, and the physician weight per hour ranged from 1.45 (August 2000) to 2.86 (March 2000). The predominant method was ultrasound (35%); the number of total practice expense-RVUs was 192,749; the month with the highest score was March 2000 (9,398), while the one with the lowest score was August 2000 (4,710); the total number of malpractice RVUs was 9,940, and the months with the highest scores were April 2000 (487) and March 2000 (487), while the month with the lowest score was August 2000 (243), and the modality carrying the highest insurance risks was MRI (38%). We also calculated the number of procedures per FTE (6,141), the number of work-RVUs per FTE (4,134); the difficulty index resulting from the ratio between work-RVUs and number of procedures (0.67); the number of work-RVUs per hour worked (3.06).
Conclusions: Based on the numerical count, conventional radiology and ultrasound play a predominant role (40% and 34%, respectively, total 74%). This approach therefore fails to reflect the weight of more technologically advanced procedures. The SNR-SAGO-SIRM model gives adequate importance to the combination ''number- weight of patients'' among the macroaggregates analysed. The RER model rewards the use of more expensive technologies, as it assesses the overall weight of the service and not only the weight of the radiologist's activity. The RVU model, with its distribution of weights, differentiates the different work, cost, and insurance components of the macroaggregates. It also introduces an important aspect that is new to our professional and scientific culture: evaluation of the ''insurance component'', whose role will become increasingly important in Italy. The difficulty index (work-RVUs/no. of procedures), which expresses the ratio between the number of modalities and their complexity, is particularly interesting. This index, adjusted to reflect the Italian situation, might help to assess the true technological and scientific content of the department's activity.