AN EVALUATION OF AMBULATORY VISIT GROUPS IN RHEUMATOLOGY OUT-PATIENTS

The development of case mix measures for National Health Service (NHS) care has become of great importance recently. Much effort has been pu t into devising measures for in-patient care, but measures for ambulat ory (out-patient, day care and primary care) visits are less developed . Ambulatory Visit Groups (AVGs) is an American system devised to aggr egate ambulatory visits into iso-resource groups. However, some assump tions made in the construction of the AVG system may not hold for the UK health service, including the use of consultation time as a proxy f or the total resource use associated with the out-patient attendance. To test AVGs in the UK context, a three-month prospective study of rhe umatology out-patient attendances at two hospitals in Newcastle upon T yne assembled a database of 3393 'visits', together with resource use data. The AVGs derived from these were analysed to evaluate the homoge neity of the groups with respect to consultation time, the homogeneity of the groups with respect to resource use, and the degree to which c onsultation time can be considered a proxy for resource use in this se tting. Consultation time distributions were markedly skewed, and requi red log transformation before analysis. Variation in log consultation time was found to depend as much on the clinician as on the AVG, and t he two were observed to interact. Resource use distributions were also skewed, and were similarly transformed for analysis. Non-parametric a nalysis of variance showed resource use to be significantly associated with AVG, but the amount of variation associated with the AVG appeare d to be small and inconsistent. The utility of AVGs in the NHS is cons idered in the light of these findings, and proposals are made for the next steps to develop a better understanding of out-patient activity.