Do local hospitals meet the analytical goals for the use of common reference intervals?

Combined reports on serum calcium and discriminant functions increase the diagnostic rate of hypercalcaemia

Hypercalcaemia is a condition easily overlooked by the clinician. Prompted by the observation that computerized reminders could increase the awareness, we have examined whether the combined reporting of increased serum calcium results and the results from diagnostic discriminating calculations could increase the clinical awareness of hypercalcaemia. Albumin-corrected serum calcium was estimated in all 4500 patients admitted to the hospital during a period of 2 months. Eighty-seven patients were found with hypercalcaemia and were assigned randomly to 2 groups: A (40 patients) and B (47 patients). In group A, the increased serum calcium and the results of the discriminant functions were reported; in group B, the serum calcium was reported only if requested and the discrimination diagnosis withheld. The clinical records were examined 3 weeks after admission. At this time the records in group A contained a relevant clinical diagnosis explaining the hypercalcaemia in 81% of the cases. This was in contrast to only 31% of the records in group B. We conclude that this combined reporting leads to a considerable improvement in the clinical awareness of hypercalcaemia and results in a diagnosis explaining the condition in the majority of cases.

Transfer of hypercalcemia discriminant functions between local hospitals

Transferability of discriminant functions is potentially useful both from an economical point of view and because, in general, medical knowledge, in this case discriminant functions, should be transferable. In the present study we have evaluated the transferability of discriminant functions, estimated from routine laboratory analysis, age and sex in two consecutively recorded populations with hypercalcemia including 162 and 257 patients with hypercalcemia. Discriminant functions were developed for each sex to distinguish between hypercalcemia associated with malignancy and hypercalcemia associated with other medical diseases. The total diagnostic accuracy in Herlev was 82 and 78%, in women and men, and increased to 87 and 86% in both sexes considering cases classified with posterior probability levels of 60%. In Hvidovre the total diagnostic accuracy was 81 and 84% in women and men, and increased to 83 and 89% at posterior probability levels higher than 60%. Transfer of the discrimination functions between the hospitals was followed by a decrease in diagnostic accuracy of 6-16%. At a posterior probability of 60% the diagnostic accuracies were 79% or more in the receiving hospital, in both sexes, except for men in Hvidovre. In relation to these results the concept of genuine and non-genuine transfer factors is introduced and discussed.

Within-centre evaluation of hypercalcaemia discriminant functions 5 years after their development

Diagnostic hypercalcaemia discriminant functions, discriminating between clinically significant and non-significant hypercalcaemia, were tested 5 years after their development in order to evaluate the impact of time on their diagnostic capacity. Two populations, consisting of 257 and 129 patients with hypercalcaemia, were consecutively recorded, during six and three months respectively, 5 years apart under similar circumstances. The prevalence of hypercalcaemia was comparable in both populations, being 2.57 and 2.38% respectively (non-significant) (NS). The female/male ratio was 1.9 and 1.7 (NS). The discriminant functions correctly classified 81 and 80% of the women, respectively (NS) and respectively 75% and 64% of the men (NS) in the first and second recorded populations.