Are Patch Testing Reactions Underrecognized in Skin of Color? Evaluating the Frequency of Borderline Reactions by Fitzpatrick Skin Type.

Background

Patch testing reactions can be difficult to interpret in patients with skin of color (higher Fitzpatrick skin types [FSTs]) due to limited erythema or vesiculation. Missed reactions may lead to prolonged allergic contact dermatitis duration and prevent disease clearance in this population.

Objective

To compare the frequency of borderline patch test reactions in patients with different FSTs (I, II, III, IV, V, VI).

Methods

Retrospective study of 1899 patients comprehensively patch tested in a major metropolitan area over a 4-year period. Borderline (doubtful, ±) reaction frequency and patient FST were recorded and used for analysis.

Results

There were statistically significant differences in the frequency of borderline reactions between FSTs I/II and V/VI (P < 0.0001) and across all 6 FSTs (P < 0.0001). Patients with FST V or VI had 43% lower odds of having a borderline reaction (OR: 0.57, 95% CI: 0.47-0.69) compared with patients with FST I or II. Patients with FST VI showed the lowest proportion of borderline reactions.

Conclusions

Among patients with skin of color, borderline reactions are diagnosed less commonly and may be missed. This has the potential to prolong dermatitis symptoms and prevent disease clearance.