Vasculitis

The Role of Patch Testing in Evaluating Delayed Hypersensitivity Reactions to Medications

Confirming drug imputability is an important step in the management of cutaneous adverse drug reactions (CADR). Re-challenge is inconvenient and in many cases life threatening. We review the literature on ideal patch testing technique for specific CADRs. Testing should be performed approximately 3 months after the resolution of the eruption using standard patch testing techniques. Commercially available patch test preparations are available for a minority of drugs, so in most cases, testing should be performed with the drug at various recommended concentrations and in different vehicles. Testing to all known excipients, such as dyes, vehicles and preservatives is also important. Immunosuppressive medications should be discontinued or down titrated to the lowest tolerable dose to decrease the risk of false negative reactions. We provide an overview of expert recommendations and extant evidence on the utility of patch testing for identifying the culprit drug in common CADRs and for specific drug or drug classes. Overall, there appears to be significant variability in the patch test positivity of different drugs, which is likely the result of factors intrinsic to the drug such as dermal absorption (as a function of lipophilicity and molecular size) and whether the drug itself or a downstream metabolite is implicated in the immune reaction. Drugs with high patch test positivity rates include beta-lactam antibiotics, aromatic anticonvulsants, phenytoin, and corticosteroids, among others. Patch testing positivity varies both as a function of the drug and type of CADR. The sum of the evidence suggests that patch testing in the setting of morbilliform eruptions, fixed drug eruption, acute generalized exanthematous pustulosis, and possibly also drug-induced hypersensitivity syndrome, photoallergic and eczematous reactions may be worthwhile, although utility of testing may vary on the specific drug in question for the eruption. It appears to be of limited utility and is not recommended in the setting of other complex CADR, such as SJS/TEN and leukocytoclastic vasculitis.

Total Haemolytic Complement Activity at Diagnosis as an Indicator of the Baseline Activity of Antineutrophil Cytoplasmic Antibody-associated Vasculitis

Objective

The total haemolytic complement activity (CH50) assay evaluates the functioning of the complement system Accumulating evidence indicates that the activation of the complement system plays a critical role in the pathogenesis of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) Therefore, this study aimed to investigate whether CH50 levels at diagnosis could reflect the baseline activity of AAV.

Methods

This retrospective study included 101 immunosuppressive drug-naïve patients with AAV At diagnosis, all patients underwent clinical assessments for disease activity, including measurement of the Birmingham Vasculitis Activity Score (BVAS) and Five Factor Score (FFS), and laboratory evaluations, such as tests for CH50, C3, and C4 levels The association between CH50 levels and disease activity was determined.

Results

The median BVAS and FFS at diagnosis were 120 and 10, respectively, whereas the median CH50 level was 604 U/mL There was a negative correlation between the CH50 level and BVAS (r=-0241; p=0015) A CH50 cut-off value of 621 U/mL was used to classify the patients into two groups: patients with CH50 levels <621 U/mL (low-CH50 group) and those with CH50 levels ≥621 U/mL (high-CH50 group) The low-CH50 group had a higher proportion of patients with high disease activity, based on the BVAS, than the high-CH50 group (525% vs 238%, p=0004) Additionally, the low-CH50 group exhibited a lower relapse-free survival rate than the high-CH50 group; however, this difference was not statistically significant (p=0082).

Conclusion

Low CH50 levels at diagnosis may reflect high baseline activity of AAV.

Increase of complement fragment C5a in cerebrospinal fluid during exacerbation of neuromyelitis optica

Complement is thought to play a pivotal role in neuromyelitis optica (NMO) pathogenesis. Anaphylatoxins (C3a, C4a, and C5a), produced in complement activation, have proinflammatory potential, and thereby may play an important role. We measured concentrations of anaphylatoxins in CSF and sera, obtained from patients with NMO (n=15), multiple sclerosis (MS) (n=15), and other neurological disease (OND) (n=12), and evaluated their clinical implications. The CSF-C5a levels were elevated significantly in NMO patients, especially in patients with multiple enhanced lesions on MRI. The CSF-C5a levels correlated with the severity of exacerbation. Our results may provide a rationale for anti-complement therapies of NMO.

Cardiac sequelae of Kawasaki disease among recurrent cases

OBJECTIVE

This study was undertaken to clarify whether cardiac sequelae due to Kawasaki disease are more frequent among recurrent cases than initial onset cases.

STUDY DESIGN

A cross sectional study using data from nationwide surveys of Kawasaki disease in Japan was conducted. A total of 33,976 patients reported were divided into two groups: initial onset cases (32,923 patients) and recurrent cases (1053 patients). Proportions of cardiac sequelae such as coronary aneurysms/dilatation, coronary stenosis/narrowing, myocardial infarction, and valvular lesions were compared between the two groups.

RESULTS

The proportions of patients with the sequelae were significantly more common among recurrent cases. In men 25.5% of the recurrent cases had the sequelae in comparison with 14.9% for initial onset cases, and in women 16.1% of recurrent cases had the sequelae compared with 9.8% of initial onset cases. Giant coronary aneurysms were twice as likely in men in whom the disease was recurring than in initial onset cases, and 1.5 times more likely in women in whom the disease was recurring than in initial onset cases.

CONCLUSION

Cardiac sequelae of Kawasaki disease are more likely to appear on recurrent case patients.