THE USE OF DECISION-ANALYTICAL MODELING IN ECONOMIC-EVALUATION OF PATCH TESTING IN ALLERGIC CONTACT-DERMATITIS

Objective: The objective of this observational prospective study was t o demonstrate the cost effectiveness of patch testing in patients susp ected of allergic contact dermatitis (ACD) and to determine the order in which different severity groups rank in terms of cost effectiveness . Design and Setting: This observational study was conducted on 567 pa tients from 10 investigator sites in the US over a period of 1 year. A ll patients with a suspicion of contact allergy who exhibited at least moderate disease activity were included in the study and were stratif ied according to disease severity and whether or not they were patch t ested. In each severity category, the cost effectiveness of patch test ing was evaluated. Patients who were ruled out for contact allergy (wi thout the use of patch test) by the first 6 months after admission wer e excluded. A validated dermatology-specific quality of life (DSQL) in strument was administered to all patients at the start of the study, a nd at 6 and 12 months thereafter. The cost-effectiveness analysis is d emonstrated using a decision-analytical model. Costs included office v isits and prescription costs without generic substitution. The cost of patch testing was not included due to the large variation in price am ong commercially available products.Main Outcome Measures and Results: Patch testing was performed on 22% of patients with mild disease. 41% of patients with moderate disease and 50% of those with severe diseas e. There was a significant difference between the patch-tested and non -patch-tested groups in terms of the time to obtain a confirmed diagno sis (medians = 8 and 175 days, respectively) and a significant differe nce in the ratio of patients who had a confirmed diagnosis (88 and 69% , respectively). As a result of changes made in their lifestyle, 66% o f patients in the patch-tested group and 51% in the non-patch-tested g roup reported 75% or more improvement in their disease symptoms after 6 months. Early confirmation of diagnosis helped reduce the prediagnos is cost of treatment which was mostly based on preliminary diagnosis. The greatest quality-of-life (QOL) benefits from patch testing relativ e to nonpatch testing occurred in patients with recurrent/chronic ACD. Conclusions: Patch testing is most cost effective and reduces the cos t of therapy in patients with severe ACD. Greater improvements in qual ity of life were seen in patients with recurrent/chronic ACD who were patch tested than patients who were not patch tested within the same g roup. Results were not sensitive to changes due to the addition of ind irect costs or costs using generic substitution.