Evaluation of reliability, validity, and responsiveness of the CDASI and the CAT-BM.

To properly evaluate therapies for cutaneous dermatomyositis (DM), it is essential to administer an outcome instrument that is reliable, valid, and responsive to clinical change, particularly when measuring disease activity. The purpose of this study was to compare two skin severity DM outcome measures, the Cutaneous Disease and Activity Severity Index (CDASI) and the Cutaneous Assessment Tool-Binary Method (CAT-BM), with the Physician Global Assessment (PGA) as the "gold standard". Ten dermatologists evaluated 14 patients with DM using the CDASI, CAT-BM, and PGA scales. Inter- and intra-rater reliability, validity, responsiveness, and completion time were compared for each outcome instrument. Responsiveness was assessed from a different study population, where one physician evaluated 35 patients with 110 visits. The CDASI was found to have a higher inter- and intra-rater reliability. Regarding construct validity, both the CDASI and the CAT-BM were significant predictors of the PGA scales. The CDASI had the best responsiveness among the three outcome instruments examined. The CDASI had a statistically longer completion time than the CAT-BM by about 1.5 minutes. The small patient population may limit the external validity of the findings observed. The CDASI is a better clinical tool to assess skin severity in DM.

Quality of life in dermatomyositis.

BACKGROUND: Quality of life (QoL) for patients with inflammatory skin disease can be significant, but has been evaluated in just one study in dermatomyositis (DM). OBJECTIVE: We sought to examine the relationship between the Cutaneous Dermatomyositis Area (CDASI) and Severity Index, a DM-specific cutaneous severity instrument, and various QoL study instruments and to determine the impact of DM on QoL. METHODS: Skin-specific QoL instruments, the Skindex and the Dermatology Life Quality Index, and global medical QoL instruments, the Short Form 36 and the Health Assessment Questionnaire-Disability Index, were used. Pruritus was evaluated by a visual analog scale and a 0-to-10 scale in DM and cutaneous lupus erythematosus (CLE) populations, respectively. RESULTS: There was a significant correlation between the CDASI and all skin-specific QoL scores (lowest P = .0377). Using the Short Form 36, DM population was found to have significantly worse QoL scores than the general population with the exception of bodily pain (all subscore P values < .01). Furthermore, DM had a significantly lower vitality score, representing energy level, compared with CLE, hypertension, diabetes, and recent myocardial infarction scores (lowest P = .003). There was a significantly lower mental health score, representing overall mood, to all compared diseases except CLE and clinical depression (P values < .01 when significant). We found that DM produces more pruritus than CLE (P < .0001). LIMITATIONS: A larger patient population needs to be studied to further assess QoL in patients with DM. CONCLUSION: We conclude that DM has a large impact on QoL, even when compared with other diseases, and that DM skin disease activity correlates with a poorer QoL.

Use of synthetic isoprenoid analogues for understanding protein prenyltransferase mechanism and structure.

Protein prenylation involves the post-translational modification of specific protein-derived cysteine residues with farnesyl or geranylgeranyl groups through thioether linkages. Because a large number of proteins that participate in signal transduction processes require this modification, there has been intense interest in developing inhibitors of these enzymes and in clarifying the biological function of prenylation. Isoprenoid analogues have proven to be versatile tools for probing the mechanism and structure of prenyltransferases. Mechanistic probes have been created to investigate the stereochemical course and substituent effects in prenyltransferase catalyzed reactions. They have also been used to measure kinetic isotope effects and search for possible cationic intermediates. Photoaffinity labeling analogues containing either diazotrifluoropropionate or benzophenone units have been used to identify the location of isoprenoid binding sites in these enzymes. Biophysical probes incorporating fluorescent moieties or isotopic labels have been used to measure isoprenoid dissociation constants or prenyl group conformation when bound to the enzyme. Analogues containing noncognate alkene isomers or bulky substituents have also contributed to an understanding of isoprenoid recognition. Most recently, photoactive and isomeric isoprenylated analogues are providing insights into the function of protein prenylation.